Catnip immunity and alternatives

Estimation of catnip immunity rates by country with meta-analysis and surveys, and discussion of catnip alternatives.
statistics, psychology, meta-analysis, R, power-analysis, survey, Bayes, genetics, experiments, cats, bibliography
2015-11-072019-06-19 in progress certainty: likely importance: 5

Not all cats respond to the cat­nip stim­u­lant; the rate of respon­ders is gen­er­ally esti­mated at ~70% of cats. A meta-analy­sis of cat­nip response exper­i­ments since the 1940s indi­cates the true value is ~62%. The low qual­ity of stud­ies and the report­ing of their data makes exam­i­na­tion of pos­si­ble mod­er­a­tors like age, sex, and coun­try diffi­cult. Cat­nip responses have been recorded for a num­ber of species both inside and out­side the Fel­i­dae fam­i­ly; of them, there is evi­dence for a cat­nip response in the Fel­i­dae, and, more uncer­tain­ly, the Para­dox­uri­nae, and Her­pesti­nae.

To extend the analy­sis, I run large-s­cale online sur­veys mea­sur­ing cat­nip response rates glob­ally in domes­tic cats, find­ing high het­ero­gene­ity but con­sid­er­able rates of cat­nip immu­nity world­wide.

As a piece of prac­ti­cal advice for cat-hal­lu­cino­gen som­me­liers, I treat cat­nip response & find­ing cat­nip sub­sti­tutes as a deci­sion prob­lem, mod­el­ing it as a Markov deci­sion process where one wishes to find a work­ing psy­choac­tive at min­i­mum cost. Bol et al 2017 mea­sured mul­ti­ple psy­choac­tives simul­ta­ne­ously in a large sam­ple of cats, per­mit­ting pre­dic­tion of responses con­di­tional on not respond­ing to oth­ers. (The solu­tion to the spe­cific prob­lem is to test in the sequence cat­nip → hon­ey­suckle → sil­vervine → Valer­ian.)

For dis­cus­sion of cat psy­chol­ogy in gen­er­al, see my review.

(Nepeta cataria) is a plant which causes stim­u­lated and excitable behav­ior in many domes­tic cats, which is fun to play with. It is the best known of at least a dozen plants with psy­choac­tive effects on cats, and far more pop­u­lar, cheap­er, and eas­ily pur­chased than alter­na­tives like , , or . How­ev­er, a large frac­tion of cats do not respond (non-re­sponse may be a genetic trait given Neil Bow­man Todd 1962’s pedi­gree chart) but may respond to one of the alter­na­tives. For exam­ple, of my fam­i­ly’s two cats, nei­ther responds to cat­nip but one responds to vale­ri­an, one to hon­ey­suck­le, and both to sil­vervine.

This raises sev­eral ques­tions:

  1. what frac­tion of cats, exact­ly, are cat­nip-im­mune?
  2. how often do the cat­nip alter­na­tives work?
  3. does immu­nity to one alter­na­tive pre­dict immu­nity to oth­ers?
  4. since some alter­na­tives can be hard to find and expen­sive, what is the opti­mal order of alter­na­tives a cat owner should try to find one that works?

Population frequency of catnip response

Literature review

Cat­nip is fre­quently dis­cussed in the pop­u­lar & sec­ondary lit­er­a­ture with­out cita­tion, and after track­ing down claims, the pri­mary lit­er­a­ture on cat­nip effects & response is rel­a­tively small1, with most research focused on the chem­i­cal syn­the­sis of the active ingre­di­ents, botan­i­cal stud­ies, or inves­ti­gat­ing the pos­si­ble com­mer­cial appli­ca­tions as insec­ti­cide & insect repel­lent; the best lit­er­a­ture review remains Tucker & Tucker 1987. Key papers:

  • McEl­vain et al 1942, “The con­stituents of the volatile oil of cat­nip. II. The neu­tral com­po­nents. Nepetalic anhy­dride”:

    tested extracted nepeta­lac­tone and caryophyl­lene on 10 lions of unspec­i­fied but mixed genders/ages; the 7 adults all responded to the nepeta­lac­tone and not the caryophyl­lene (the 3 cubs responded to noth­ing).

  • Todd 1962,

    14 respon­ders, 12 non-re­spon­ders in a Siamese breed­ing colony so 46% immu­nity rate in this sam­ple. (8 male respon­ders, 6 female respon­ders, 2 male non-re­spon­ders, 10 female non-re­spon­der­s.) Todd also sur­veyed cats in local ani­mal shelters/hospitals, find­ing 26 of 84 sam­pled were non-re­spon­ders or a ~31% immu­ni­ty. Todd con­sid­ers the genetic pat­tern most con­sis­tent with a fairly com­mon genetic vari­ant (by : ; , then ) which is auto­so­mal dom­i­nant; this would imply that breed­ing cats for cat­nip response is highly fea­si­ble.

  • Todd 1963, “The cat­nip response”

    • In sur­vey­ing the 26 breed­ing colony & 84 local cats, Todd found no large cor­re­la­tions with sex, breed type (Manx/Siamese/tabby/Agouti), white spot­ting, blue dilu­tion, poly­dacty­ly, long hair, or cas­tra­tion. (32 male respon­ders, 11 male non-re­spon­ders, 26 female respon­ders, 15 female non-re­spon­der­s.) Except the usual obser­va­tion that young kit­tens rarely dis­play a cat­nip respon­se: of 39 under 12 weeks of age, 4 respond­ed.

    • Cross-species results:

      1. Viver­rids (pg42/73), unspec­i­fied gender/age/species:

        Table 3. Results of test­ing Viver­rids with cat­nip. Fig­ure in paren­the­ses indi­cates num­ber of indi­vid­u­als test­ed. + = pos­i­tive, ?+ = pos­si­bly pos­i­tive, ?- = prob­a­bly neg­a­tive, - = neg­a­tive, I = inde­ter­mi­nate, ani­mal would not or did not inves­ti­gate leaves.
        Sub­-fam­i­lies Gen­era N + ?+ ?- - I
        Viver­ri­nae Genetta 3 0 0 0 2 1
        Viver­ri­nae Viverra 1 0 0 1 0 0
        Viver­ri­nae Civet­tic­tis 2 0 0 0 1 1
        Para­dox­uri­nae Nan­dinia 5 0 0 3 2 0
        Para­dox­uri­nae Paguma 2 0 0 1 0 1
        Para­dox­uri­nae Arc­tic­tis 3 1 1 0 0 1
        Her­pesti­nae Her­pestes 1 0 0 0 1 0
        Her­pesti­nae Ati­lax 3 0 1 1 1 0
        Her­pesti­nae Ich­neu­mia 1 0 0 0 0 1
        Cryp­to­procti­nae Cryp­to­procta 1 0 0 1 0 0
      2. Hye­nas (Hyenidae): 0⁄3 respon­ders of 2 males/1 female (pg41/72), unspec­i­fied age, genus, or species, pre­sum­ably either spot­ted or striped hye­nas.

      3. Fel­i­dae: (pg42/74). Tod­d’s table and results have been sum­ma­rized as thus by Tucker & Tuck­er:

        Within the sub­fam­ily Pan­theri­nae of the Fel­i­dae, Todd (1963) found the typ­i­cal cat­nip response in 16 lions (Pan­thera leo) (14 pos­i­tive respon­ders, 2 neg­a­tive respon­der­s), 23 tigers (Pan­thera tigris) (8 incom­plete respon­ders, 13 neg­a­tive respon­ders, 2 incon­clu­sive respon­der­s), 18 leop­ards (Pan­thera par­dus) (14 pos­i­tive respon­ders, 4 neg­a­tive respon­der­s), 8 jaguars (Pan­thera onca) (7 pos­i­tive respon­ders, 1 neg­a­tive respon­der), 4 snow leop­ards (Pan­thera uncia) (4 pos­i­tive respon­der­s), and 1 clouded leop­ard (Ne­ofe­lis [Pan­thera] neb­u­losa). Within the sub­fam­ily Acynonychi­nae of the Fel­i­dae, he found that 3 chee­tahs (Aci­nonyx juba­tus) did not respond to cat­nip. Within the sub­fam­ily Feli­nae of the Fel­i­dae, he found the typ­i­cal cat­nip response in the 2 bob­cats (Fe­lis [Lynx] rufus) (1 pos­i­tive respon­der, 1 neg­a­tive respon­der), 1 Euro­pean lynx (Fe­lis [Lynx] lynx), 5 pumas (Fe­lis [Puma] con­col­or) (2 pos­i­tive respon­ders, 2 neg­a­tive respon­ders, 1 incon­clu­sive respon­der), 1 Asi­atic golden cat (Fe­lis [Pro­fe­lis] tem­minck­i), 5 ocelots (Fe­lis [Leop­ar­dus] pardal­is) (4 pos­i­tive respon­ders, 1 neg­a­tive respon­der), and 6 mar­gay cats (Fe­lis [Leop­ar­dus] wiedii) (4 pos­i­tive respon­ders, 2 neg­a­tive respon­der­s); no cat­nip response was observed in 2 ser­vals (Fe­lis [Lep­tail­u­rus] ser­val), 1 swamp cat or jun­gle cat (Fe­lis chaus), 1 Pal­las’ cat (Fe­lis [Oc­to­colobus] man­ul), 1 leop­ard cat (Fe­lis [Pri­on­ail­u­rus] ben­galen­sis), 1 African golden cat (Fe­lis [Pro­fe­lis] aurata), 2 fish­ing cats (Fe­lis [Pri­on­ail­u­rus] viver­ri­na), 4 jaguarundis (Fe­lis [Herpailurus/Puma] yagouaroundi), and 1 pam­pas cat (Fe­lis [Lyn­chail­u­rus] pajeros).

        The sum­mary of Tod­d’s Fel­i­dae results is cor­rect but omits that Todd also used a ques­tion­naire to esti­mate 4 respon­ders & 13 non-re­spon­ders among the ocelots in addi­tion to his per­sonal test­ing of the 5 ocelots but Todd notes he “has reser­va­tions about the valid­ity of the data gath­ered by this method” (pos­si­bly because the response fre­quency 4⁄17 is so differ­ent from his per­sonal 4⁄5 response fre­quen­cy) so that data is prob­a­bly best exclud­ed. Todd also men­tions a report of a “” (fe­male hybrid of a male lion & tigress) from de Bary of the Utah Hogle Zoo­log­i­cal Gar­den who is a cat­nip non-re­spon­der. For the meta-analy­sis, I code the ‘ques­tion­able’ positive/negative responses as con­firmed respons­es. Sex is usu­ally unspec­i­fied, but indi­vid­u­al-level data is pro­vided on the lions, tigers, & leop­ards. I excluded the pam­pas cat and addi­tional ques­tion­naire data in line with Tod­d’s notes that the data were highly unre­li­able.

  • Bates & Siegel 1963, “Ter­penoids. Cis-trans- and tran­s-cis- nepeta­lac­tones”

    They chem­i­cally sep­a­rated the two ; the extracted iso­mer I was mostly inac­tive when pre­sented to 8 cats with just 1 more inter­ested in I than II (though they cau­tion there might still have been con­t­a­m­i­nat­ing II in the I extrac­t), but “three were strongly attracted” and “two showed slight pref­er­ence” for iso­mer II (_tran­s-cis-_nepeta­lac­tone), so arguably 5 out of 8 were respon­ders. (Breed and sexes unspec­i­fied.)

  • Konecny 1936, “Behav­ioral Ecol­ogy of Feral House Cats in the Gala­pa­gos Islands, Ecuador”: wild sur­vey of cats; notes suc­cess­ful use of traps baited with tuna fish & cat­nip.

  • Palen & God­dard 1966, “Cat­nip and oestrous behav­ior in the cat”

    Reac­tions: 23 respon­ders, 20 non-re­spon­ders, so 47% immu­nity rate. (37 male, 28 female, mixed breeds: 6 male respon­ders, 6 male non-re­spon­ders, 9 cas­trated male respon­ders, 5 cas­trated male non-re­spon­ders, 5 female respon­ders, 5 female non-re­spon­ders, 3 spayed female respon­ders, 4 spayed female non-re­spon­der­s.)

  • Hayashi 1968a, “Pseudo-Affec­tive Reflexes of Cats pro­duced by Extracts from the Plant Actini­dia polygama claims to have found no responses in an unspec­i­fied but prob­a­bly >4 num­ber of cats (as he used “young and old cats of both sexes”) when test­ing nepeta­lac­tone (cat­nip) and actini­dine solu­tions, aside from two actini­dine reac­tions

  • Hayashi 1968b, “Motor reflexes of cats to Actini­dia polygama (Japan) and to cat­nip (USA)”

    A 1966 con­fer­ence talk pub­lished in the 1968 pro­ceed­ings, Hayashi 1968 is light on details. Tucker & Tucker sum­ma­rize it as “Hayashi (1968), who tested a wide range of ani­mals (dogs, rab­bits, mice, rats, guinea pigs, fowls, and cats) with pow­ders of Actini­dia polygama and N. cataria, found that the cat­nip response is induced in cats alone.”, which tells one about as much as the orig­i­nal report does:

    …ac­tini­dine (1) and cat­nip…have always been the source of much inter­est…When pow­der of these plants was pre­sented to cats, they dis­played a pecu­liar behav­ior…The reflex behav­ior is induced by the smell, not by taste and not via the cir­cu­la­tion. The cat must be tamed by the exper­i­menters and must be adult: male or female are quite the same…Once I tried with Eng­lish cats in Lon­don, and with Amer­i­can cats in New York, each time tak­ing advan­tage of vis­it­ing my friend’s lab­o­ra­to­ries, but Eng­lish as well as Amer­i­can cats were rather cold…We tried exper­i­ments with dogs, rab­bits, mice, rats, guinea pigs and also with fowls but they had no such reflexes to the plant pow­der…From these results, we pre­sume that the reflex abil­ity is restricted to cats and feline species in ver­te­brates, and its reflex cen­tre would be sit­u­ated in the sub­cor­ti­cal, pre­sum­ably lim­bic, struc­tures…That the phe­nom­e­non is restricted to the cat fam­ily is said also in Japan.

    • Q [J.W. John­son Jr]: This is a sim­ple ques­tion that might be rel­e­vant to your point, Doc­tor. In North­ern Vir­ginia, where I live, there are stands or clumps of cat­nip. I’m not aware of house cats vis­it­ing the cat­nip stands while in the liv­ing state. Do you know whether this has been report­ed.
    • A [T. Hayashi]: No, I don’t think so. We have nat­ural growths of bushes of acti­dinia polygama in sev­eral parts of Japan, but nobody noticed that these bushes attracted cats from the vil­lages….In the cen­tral part of Japan we have many acti­dinia dis­trib­uted from north to south. But I have not heard that cats gather in the stands of the plant. Maybe the dry­ing of the plants or burn­ing of them is the most effec­tive.

    From this I gather that Hayashi must have tested at least 2 cats in the USA, 2 in the UK, and 2 in Japan (be­cause he always uses the plural “cats”, and he com­pares the US/UK cats to Japan­ese cat­s). Hayashi 1968a implies >=4 cats were used but not their national dis­tri­b­u­tion. To be con­ser­v­a­tive in lieu of more pre­cise data, one would have to code the Hayashi data as 2 cats per coun­try. He does men­tion that the USA/UK cats were “rather cold”, which implies an inter­me­di­ate but exis­tent response much less than the Japan­ese cats. (It is also intrigu­ing given Saku­rai et al 1988’s later pos­si­ble impli­ca­tion that 16 of 16 cats in Japan reacted to cat­nip but not for­eign breed­s.) If we assume the n of each group of cats is 2, then the response rate must be 1/1/2 respec­tive­ly, as oth­er­wise Hayashi would either have described it as no response like the other species or as the same response as the Japan­ese cats. The other species are also plu­ral­ized, so at least 2 of each, and all responses must have all been 0 respon­ders since “they had no such reflexes” and it is “restricted to cats and feline species”. Spe­cific species (pre­sum­ably the other ani­mals are either domes­tic or lab species), sex­es, breeds, and ages are not giv­en.

  • Waller et al 1969, “Feline Attrac­tant, cis,­tran­s-Nepeta­lac­tone: Metab­o­lism in the Domes­tic Cat”

    In a meta­bolic study, puri­fied nepeta­lac­tone was force-fed to 6 cats in gel cap­sules; as expected due to the olfac­tory require­ment (pre­vi­ously demon­strated by Todd with sur­gi­cal manip­u­la­tions of olfac­tion), none of the cats exhib­ited the cat­nip response and the result is irrel­e­vant.

  • Hatch 1972, “Effect of drugs on cat­nip (Nepeta cataria) induced plea­sure behav­ior in cats”

    Tested 17 cats ini­tial­ly; 14 respon­ders. (Mixed breed, both gen­ders; break­downs of response not giv­en.) Hatch’s main effort was towards using drug admin­is­tra­tions to block the cat­nip effects and under­mine the sex­ual hor­mone hypoth­e­sis.

  • Todd as quoted in R.F. Ewer 1973, The Car­ni­vores (pg244):

    Differ­en­tial aspects of the same scent on differ­ent species are illus­trated in some unpub­lished work by Dr N.B. Todd, which he has kindly allowed me to quote. He tested the responses of var­i­ous species to cat­nip and found that a num­ber of viver­rids, although clearly able to smell the cat­nip, showed lit­tle inter­est: for them it car­ried no mes­sage and had no par­tic­u­lar sig­nifi­cance. I have found the same to be true of and [African dwarf mon­goose]. In the Fel­i­dae, the cat-type sex­ual response was wide­spread but not uni­ver­sal. Amongst the large cats, lion, leop­ard, jaguar and snow leop­ard responded sex­u­ally but adult tigers did not. The behav­ior of imma­ture tigers was inter­est­ing: they were not sex­u­ally excited but instead showed vio­lent alarm and retreated prompt­ly. In view of the propen­sity of the larger species of felids to kill each oth­er’s young and of the fact that until quite recently the ranges of tiger and lion over­lapped very con­sid­er­ably, both the absence of sex­ual response in the adult tiger and the fear gen­er­ated in the young may be adap­tive: the for­mer may reflect a sex­ual iso­lat­ing mech­a­nism; the lat­ter may be pro­tec­tive. Apart from illus­trat­ing differ­en­tial responses to the same odour, these obser­va­tions also demon­strate the psy­cho­log­i­cal effects of odours. A piece of mate­r­ial impreg­nated with cat­nip is nei­ther a mate nor an enemy but it can evoke sex­ual responses or flight: to do so it must act on the cen­tral ner­vous sys­tem so as to change the ani­mal’s mood - in short, it “makes him sexy” or it “makes him afraid”.

    Tod­d’s results here refer to his PhD the­sis, but I have not found any Ewer pub­li­ca­tion on cat­nip thus far.

  • Har­ney et al 1974, “Behav­ioral activ­ity of cat­nip and its con­stituents: nepetalic acid and nepeta­lac­tone”/Harney et al 1978, “Behav­ioral and tox­i­co­log­i­cal stud­ies of cyclopen­tanoid monoter­penes from Nepeta cataria

    Con­sid­ers only injec­tions of cat­nip oil into mice/rats.

  • Hill et al 1976, “Species-char­ac­ter­is­tic Responses to Cat­nip by Undo­mes­ti­cated Felids”; Tucker & Tucker sum­mary (ap­par­ently based on count­ing the descrip­tions in Table 3 or Table 4):

    Hill et al. (1976) found that lions (5 pos­i­tive respon­ders, 6 par­tial respon­ders, 1 neg­a­tive respon­der) and jaguars (3 pos­i­tive respon­ders) are extremely sen­si­tive to cat­nip, while tigers (5 neg­a­tive respon­der­s), pumas (4 neg­a­tive respon­der­s), leop­ards (4 par­tial respon­ders, 4 neg­a­tive respon­der­s), and bob­cats (2 neg­a­tive respon­ders) gave lit­tle or no response. They also found that both males and females of the same species test alike, while repro­duc­tive-age adults are more sen­si­tive than either aged or imma­ture ani­mals.

  • Hart 1977, “Olfac­tion and feline behav­ior”: short pop­u­lar sum­mary of some aspects of cat olfac­tory capa­bil­i­ties; briefly men­tions cat­nip.

  • Rau­zon 1985, “Feral Cats on Jarvis Island: Their Effects and Erad­i­ca­tion”:

    Account of a Pacific Island; men­tions use of cat­nip in traps, with­out suc­cess, and notes that van Aarde told Rau­zon of “pre­vi­ous low suc­cess rates” using cat­nip as well; pre­sum­ably van Aarde was refer­ring to efforts on the South African Mar­ion Island (of the ), since while the two cited van Aarde papers do not men­tion cat­nip, a 2002 fol­lowup on suc­cess cites one of the authors’ mas­ter the­ses as report­ing fail­ure in use of cat­nip oil (suc­cess ulti­mately com­ing from dis­ease fol­lowed by inten­sive hunting/trapping/poisoning):

  • Saku­rai et al 1988, “Both (4a_S_, 7_S_, 7a_R_) -(+)-Nepeta­lac­tone and Its Antipode Are Pow­er­ful Attrac­tants for Cats”

    Another inves­ti­ga­tion of which isomers/enantiomers of nepeta­lac­tone are active, the iso­lated ver­sions were tested in 9 cats with vials of the liq­uid; 7 responded (while the two 6-month olds did­n’t and Saku­rai et al 1988 attrib­utes the non-re­sponse to their being ‘imma­ture’, 6 months sounds old enough for reac­tions to have devel­ope­d). The cat breeds are spec­i­fied as 4 Japan­ese, 3 Abyssini­an, and 2 Amer­i­can short­-hairs, but not sexes (although Saku­rai used a mix, given their com­ments that “the females showed more emo­tional behav­ior than the males…the females were quite reac­tive, while the males were not…both of them [iso­mers] were extremely attrac­tive to mature cats, espe­cially to females”). Pos­si­bly con­tra­dict­ing Bates & Siegel 1963’s results where only 1 iso­mer worked, Saku­rai finds both iso­mers work equally well.

    Con­fus­ing­ly, Saku­rai also men­tions a sec­ond exper­i­ment in impreg­nat­ing fil­ter paper with the iso­mers, not­ing that “six­teen Japan­ese cats reacted to the 0.01mg dose”; it’s unclear where these cats came from when only 9 cats (4 Japan­ese) were men­tioned for the first exper­i­ment, and whether they were selected out of a larger group of cats or if it’s implied that it was 16 out of 16 respon­ders - inas­much as with cat­nip response rates ~70%, it would be highly improb­a­ble for all of a group of 16 cats to be cat­nip respon­ders (0.716=0.3%). One pos­si­ble expla­na­tion is that Japan­ese cats, being a his­tor­i­cally iso­lated pop­u­la­tion (eg the ) after their intro­duc­tion ~500AD from Korea, may have much higher pop­u­la­tion fre­quen­cies or even fixed the cat­nip muta­tion due to or a 2; on the other hand, if Japan­ese cats were almost all cat­nip respon­ders, you would think some­one would have noticed by now. My GS sur­vey finds a ~28% immu­nity rate, which is not unusual at all, sug­gest­ing that Hayashi/Sakurai is some sort of sam­pling error or report­ing effect.

  • DeLuca & Kranda 1992, “Envi­ron­men­tal enrich­ment in a large ani­mal facil­ity”:

    TABLE 1. Num­ber of ani­mals, species-wide, that showed inter­est in var­i­ous toys. Key: 0 = none, 1 = 25%, 2 = 50%, 3 = the major­ity of the ani­mals. We define inter­est as the amount of toy destruc­tion and/or move­ment that we noted in daily obser­va­tions.

    • …balls: cat­nip: 3
    • balls: punch: 3
    • Cat-a-Comb: NA
    • Purrsuit: 3

    …8-12 cat­s…The cats’ favorite toys - like the 12 in. giant sheep­skin mice (Pe­tra­port, Ana­heim, CA) - con­tained cat­nip. We hung fresh cat­nip in stock­inette bags which the cats quickly pulled down and ulti­mately bat­ted into the water bowls. We gave them cat­nip-treated punch­ball toys (Pe­tra­port, Ana­heim, CA- Fig. 7)-2 in. puffs mounted by a spring to a 6 in. x 6 in. base. The cats always played with these toys, and they lasted longer than the cat­nip bags. The cats also had “Mr. Spats’ Cat-a-combs” groomer (Tarel Seven Designs, Secau­cus, NJ) mounted on the walls. They usu­ally knocked these off [of] the wall and used them as play-things (they man­aged to open the com­part­ment and dig out the cat­nip) rather than as groom­ing tools. Most of the cats spent time play­ing “Purrsuit” (Tarel Seven Designs, Secau­cus, NJ)-ev­ery morn­ing, we placed toys inside a maze and the cats chased them and tried, with a great deal of suc­cess, to get the smaller ones out. The cats had a pref­er­ence for balls or bells with cat­nip in them, and for golf balls. They ignored the Squish balls (Eth­i­cal Inc., Newark, NJ).

    So based on the reported data, we can guess that at least 5-7 cats responded to cat­nip of the 8-12 sam­ple, for a best guess of 6 respon­ders out of 10 cats. (Mixed breeds, unspec­i­fied sex.)

  • Eason et al 1992, “Toxic Bait and Bait­ing Strate­gies for Feral Cats”/Clapperton et al 1992, “Exper­i­men­tal Erad­i­ca­tion of Feral Cats (Felis Catus) from Matakohe (Lime­stone) Island, Whangarei Har­bour”: New Zealand, a mix of wild sur­vey and exper­i­ment, employ­ing a vari­ety of baits & scents includ­ing cat­nip. Cat­nip per­formed well among the NZ feral cats: for exam­ple, 6 cats observed at dusk spent a mean ~200s inves­ti­gat­ing a cat­nip odor as opposed to <50s or ~0s for 3 urine scents (Fig­ure 1), and counts of vis­its to cat­nip odor sta­tions were far higher than for urine, fish oil, or water con­trols (Table 1: 25 vs 13/12/11). Catnip/catmint only per­formed poorly when used as a food fla­vor­ing in a com­mer­cial cat food (Fig­ure 3), but then per­form­ing well alone & com­bined with in bait (Fig­ure 5/6). They then deployed their cat­nip & other baits to poi­son ~5 cats on Matakohe Island; the cat­nip bait did not lead to notice­ably more bait con­sump­tion, but from the descrip­tion, cat­nip response might not have been notice­able or just sam­pling error.

  • Clap­per­ton et al 1994, “Devel­op­ment and Test­ing of Attrac­tants for Feral Cats, Felis catus L.

    Wild sur­vey and exper­i­ment in New Zealand. Cat­nip & sil­vervine were tested as cat lures for trap­ping; simul­ta­ne­ous test­ing over mul­ti­ple envi­ron­ments showed that cat­nip, sil­vervine, and urine all gar­nered sub­stan­tial atten­tion from cats. Clap­per­ton notes that 4⁄4 domes­tics and 8⁄20 feral cats responded (pg7). (Sex not spec­i­fied, but breeds were clearly mixed as feral cats are never sin­gle breed­s.)

  • Har­ri­son 1997, “Chem­i­cal attrac­tants for Cen­tral Amer­i­can felids”: exper­i­men­tal test­ing of jaguars, jaguarundi, lit­tle spot­ted cats, mar­gays, ocelots, & pumas of cat­nip and other lures; Har­ri­son reports the data in terms of time spent inves­ti­gat­ing and “behav­ior scores” (the num­ber of observed behav­iors such as sniffing/vocalizing/rubbing/rolling), and not in terms of indi­vid­ual respon­ders. The reported data sug­gests some level of response in jaguars/jaguarundi/ocelots.

  • Edwards et al 1997, “Field eval­u­a­tion of olfac­tory lures for feral cats (Felis catus L.) in cen­tral Aus­tralia”: wild sur­vey in Aus­tralia; 15 kinds of lures were test­ed, pit­ting a cat­nip lure (#12) against var­i­ous seafood, blood­-bone mix, male/female cat urine/anal gland secre­tions; the 3 best olfac­tory lures were sun-dried prawns (#8) & male (#13)/female (#14) urine-se­cre­tions, but not cat­nip - cat­nip received 2 cat vis­its while the best 3 received 17/14/7 respec­tive­ly. Edwards notes their sur­prise at the ineffi­cacy of the cat­nip com­pared to the urine-se­cre­tions, as Clap­per­ton et al 1994 had found cat­nip much supe­rior in their NZ exper­i­ment and ask, “do cats from differ­ent areas respond differ­ently to differ­ent olfac­tory stim­uli?”

  • McDaniel et al 2000, “Effi­cacy of lures and hair snares to detect lynx”

    Used cat­nip and other com­mer­cial prod­ucts in scent sta­tions to look for activ­ity of wild lynx. Todd 1963 had already found responses in lynx/puma/bobcats, so unsur­pris­ingly McDaniel does too, but with wild lynx, it is impos­si­ble to know how many total lynx were exposed and how many react­ed.

  • Mol­sher 2001, “Trap­ping and demo­graph­ics of feral cats (Felis catus) in cen­tral New South Wales”: Aus­tralian live trap­ping study using var­ied baits; a bait com­bi­na­tion of catnip/tuna oil/“syn­thetic fer­mented eggs” (SFE); while a small sam­ple, the suc­cess in terms of cats trapped per 100 trap-nights var­ied from 0.5 (fish) to 3.8 (“PUSSON” baits + alu­minum toys on string), with the cat­nip mix at 1.1, sug­gest­ing lit­tle or no advan­tage over other baits like rab­bit.

  • Short et al 2002, “Con­trol of feral cats for nature con­ser­va­tion. III. Trap­ping”: Aus­tralian trap­ping study, vary­ing bait and tim­ing. Fresh cat­nip bait ranked roughly medi­an, below rabbit/mice/2 com­mer­cial mix­es; cat­nip worked well in the first trap­ping and then poorly after­wards, the authors spec­u­lat­ing that the decline is “per­haps due to remov­ing the pool of sus­cep­ti­ble indi­vid­u­als.” (To­tal catch­ing: 8 cats out of 118; in a head to head test of 2 traps, one cat­nip and a com­mer­cial mix, the cat­nip trap caught 8 vs 7.)

  • Wells & Egli 2004, “The influ­ence of olfac­tory enrich­ment on the behav­iour of cap­tive black­-footed cats, Felis nigripes:

    6 (Felis nigripes), cat­nip did inter­est them and cause increases in activ­i­ty, but paper does­n’t break down by cat. Not use­ful unless want to con­tact authors for indi­vid­u­al-level data.

  • Weaver et al 2005, “Use of scented hair snares to detect ocelots”: tested 32 ocelots avail­able in 9 facil­i­ties, as well as a wild sur­vey; 27 of the 32 responded to their bait, which was a com­bi­na­tion of a mix “Weaver’s Cat Call” and dried cat­nip; Weaver reports that the com­bi­na­tion was ear­lier estab­lished in bob­cats & lynx to be much more effec­tive than cat­nip alone, so 84% rep­re­sents an over­es­ti­mate of cat­nip’s effect on ocelots.

  • Ellis 2007, “Sen­sory enrich­ment for cats (Fe­lis sil­vestris catus) housed in an ani­mal res­cue shel­ter”; appar­ently repub­lished as Ellis & Wells 2010, “The influ­ence of olfac­tory stim­u­la­tion on the behav­iour of cats housed in a res­cue shel­ter”

    Shel­ter ani­mals were given cat­nip-in­fused clothes to play with; Ellis notes that the cat­nip toys were played with more than other scents on aver­age in the cat­nip group, but made no effort to ascer­tain how many were cat­nip respon­ders.

  • Mas­soco et al 1995, “Behav­ioral effects of acute and long-term admin­is­tra­tion of cat­nip (Nepeta cataria) in mice”; Bernardi et al 2010, “Anti­de­pres­san­t-like effects of an apo­lar extract and chow enriched with Nepeta cataria (cat­nip) in mice”

    There is appar­ently a vein of stud­ies try­ing cat­nip in humans for anti­de­pres­sant effects (rather than the more tra­di­tional painkiller and psy­che­delic effect­s), lead­ing to this exper­i­ment in chronic feed­ing cat­nip to mice (ironic as that might sound), find­ing one anti­de­pres­san­t-like effect. These can’t be con­sid­ered a cat­nip respon­se, though.

  • Schmidt & Kowal­czyk 2006, “Using Scen­t-Mark­ing Sta­tions to Col­lect Hair Sam­ples to Mon­i­tor Eurasian Lynx Pop­u­la­tions” / Davoli et al 2013, “Hair snar­ing and mol­e­c­u­lar genetic iden­ti­fi­ca­tion for recon­struct­ing the spa­tial struc­ture of Eurasian lynx pop­u­la­tions”: wild sur­vey using cat­nip oil and beaver oil; 29 unique indi­vid­u­als geno­typed

  • Downey et al 2007, “Hair Snares for Non­in­va­sive Sam­pling of Felids in North Amer­i­ca: Do Gray Foxes Affect Suc­cess?”: wild sam­pling in Mex­i­co; cat­nip oil did not attract any of the tar­get wild cats, but did attract many gray foxes & 14 domes­tic cats.

  • Long et al 2007, “Com­par­ing Scat Detec­tion Dogs, Cam­eras, and Hair Snares for Sur­vey­ing Car­ni­vores”: wild sur­vey, used dried cat­nip; no detec­tion of bob­cats

  • Cas­tro-Arel­lano et al 2008, “Hair-Trap Effi­cacy for Detect­ing Mam­malian Car­ni­vores in the Trop­ics”: wild sur­vey in Mex­i­co, com­par­ing per­fume & cat­nip oil, find­ing cat­nip oil infe­rior

  • Resende et al 2011, “Influ­ence of Cin­na­mon and Cat­nip on the Stereo­typ­i­cal Pac­ing of Oncilla Cats (Leop­ar­dus tigri­nus) in Cap­tiv­ity”

    The 8 oncilla cats’ activ­ity were mea­sured over sev­eral days after each dose was intro­duced into their enclo­sures. While the doses were small (1g), the cin­na­mon pro­duced sta­tis­ti­cal­ly-sig­nifi­cant over­all aver­age differ­ence while cat­nip did not, sug­gest­ing none of the oncilla cats responded to the cat­nip. Nev­er­the­less, like Wells & Egli 2004, can­not be meta-an­a­lyzed.

  • Comer et al 2011, “Bob­cats Do Not Exhibit Rub Response Despite Pres­ence at Hair Col­lec­tion Sta­tions”: wild sur­vey using cat­nip oil; no near-zero rub­bing

  • Matthew 2012, “A Com­par­i­son of Non­in­va­sive Sur­vey Meth­ods for Mon­i­tor­ing Meso­car­ni­vore Pop­u­la­tions in Ken­tucky”: wild sur­vey; did not break down detec­tion rates by lure type

  • Hanke & Dick­man 2013, “Sniffing out the stakes: hair-snares for wild cats in arid envi­ron­ments”: Aus­tralian wild sur­vey; cat­nip & valer­ian proved ineffec­tive in attract­ing cats to the stakes, and they sug­gest that (ap­par­ently descended from domes­ti­cated cats) may sim­ply be cat­nip immune, not­ing their results par­al­lel Mol­sher 2001 & Short et al 2002. (This may be con­nected to Aus­trali­a’s import reg­u­la­tions which deter bring­ing new cats into the coun­try: a num­ber of hybrid breeds are banned as well as ori­gin coun­tries; and legal cats must be: per­mit­ted, microchipped, rabies-vac­ci­nated at least 180 days in advance & tested to con­firm immu­ni­ty, not be too preg­nant, treated for inter­nal par­a­sites, treated for exter­nal par­a­sites, clin­i­cally exam­ined by a Aus­tralian-gov­ern­men­t-ap­proved vet­eri­nar­i­an, and quar­an­tined for at least 10 days.)

  • Portella et al 2013, “Assess­ing the effi­cacy of hair snares as a method for non­in­va­sive sam­pling of Neotrop­i­cal felids” (Table 1): wild sur­vey and exper­i­ment of cinnamon/vanilla/catnip scent lures on 5 jaguars (Pan­thera onca)/10 ocelots (Leop­ar­dus pardalis)/6 oncilla cats (Leop­ar­dus tigri­nus)/7 mar­gay cats (Leop­ar­dus wiedii)/6 pumas (Puma con­color)/5 jaguarundis (Puma yagouaroundi). The wild sur­vey yielded no results, while the cap­tive exper­i­ment indi­cated that the puma did not inter­act with any lures and at least some of the ocelot/margay/oncilla did, with the strongest effect being vanil­la.

    As Portella et al 2013 mea­sures behav­ior in length of time inter­act­ing with the scent lures and reports only species-level differ­ences, it is impos­si­ble to say what frac­tion of the cats were respon­ders, other than the total lack of response of the 6 pumas to any scents show­ing that 0⁄6 of them respond­ed.

  • Scaffidi et al 2016, “Iden­ti­fi­ca­tion of the Cat Attrac­tants Isodi­hy­dronepeta­lac­tone and Isoiridomyrmecin from Aca­lypha indica”, report­ing on Aca­lypha indi­ca, men­tions in pass­ing (with­out num­bers, and appar­ently not reported else­where) that

    Christ­mas Island is a small island off the north-west coast of Aus­tralia that is well known for its unique flora and fau­na…One par­tic­u­lar project has been attempt­ing to reduce the large num­ber of feral cats on the island [4] and dur­ing this pro­ject, the research team became aware of a plant that sev­eral local res­i­dents sug­gested had a pecu­liar effect on cats when the roots of the plant were exposed…There are plants such as cat­nip (Nepeta cataria) which have sim­i­lar effects on cats due to the pres­ence of nepeta­lac­tone. [9] How­ev­er, inves­ti­ga­tion of cat­nip by the Christ­mas Island research team found that this plant had no effect on the Christ­mas Island cats.

    Founder effect?

  • Pod­dar-Sarkar & Brah­machary 2014, “Chap­ter 15: Pheromones of Tiger and Other Big Cats” note an unre­ported attempt at mea­sur­ing cat­nip response rates in wild African lions:

    Cer­tain per­sons brought cat­nip from Eng­land to George Adamson’s lion camp in Kora, Kenya, and tried to study the effect of this plant on the African lion but no con­clu­sive results were obtained (Adam­son 1988, per­sonal com­mu­ni­ca­tion).

  • Patkó et al 2015, “Sneaky felids, smelly scents: a small scale sur­vey for attract­ing cat”: wild sur­vey in Hun­gary, com­par­ing cat­nip with salmon oil/valerian/commercial-scent; 1 & 3 cats rubbed the cat­nip, 4 vale­ri­an, none oth­er­wise.

  • Patkó et al 2016, “More Hair than Wit: A Review on Car­ni­vore Related Hair Col­lect­ing Meth­ods”: lit­er­a­ture review on wild sur­vey­ing; no par­tic­u­lar con­clu­sions drawn on cat­nip.

  • Crow­ley & Hod­der 2017, “An assess­ment of the effi­cacy of rub sta­tions for detec­tion and abun­dance sur­veys of Canada lynx (Lynx canaden­sis)”: a wild sur­vey; the lynx did use both the beaver cas­tor & cat­nip oil rub sta­tions but, like McDaniel et al 2000, the method does not per­mit any quan­tifi­ca­tion of response rates in the Canada lynx although the authors infer it was <100% since the cat­nip oil rub sta­tions did not work as well as the stan­dard .

  • Shreve et al 2017, “Social inter­ac­tion, food, scent or toys? A for­mal assess­ment of domes­tic pet and shel­ter cat (Felis sil­vestris catus) pref­er­ences”: exper­i­men­tal test of 25 pet & 25 ani­mal shel­ter cats’ pref­er­ences by offer­ing the stim­uli simul­ta­ne­ously and mea­sur­ing pro­por­tion of time on each to extract a “choice”; for exam­ple, in the olfac­tory cat­e­go­ry, of the 38 cats, 6 ‘chose’ the ger­bil, 6 the cloth rubbed on another cat’s scent glands (“con­spe­cific”), and 22 the cat­nip. How­ev­er, while may look like a plau­si­ble esti­mate of cat­nip response in this sam­ple, that would be mak­ing some strong assump­tions, as Shreve et al do not men­tion try­ing to clas­sify cat­nip respon­se, and the choice is ambigu­ous: 22 of 38 cats find­ing cat­nip the most inter­est­ing smell does not mean 22 had a cat­nip response - as any of the 22 might not have had a response but sim­ply found the cat­nip a more pleas­ing or novel smell, and vice versa for the oth­er.

  • Bol et al 2017, : one of the most thor­ough stud­ies, using both a large num­ber of cats (n = 100) and the 4 major cat stim­u­lants, Bol et al 2017 is an impres­sive exper­i­ment. It’s worth high­light­ing that the 4 stim­u­lants were offered to the same set of cats, allow­ing mea­sure­ment of inter­cor­re­la­tions, cats were exposed at least twice with atten­tion given to a low-stress admin­is­tra­tion (re­duc­ing mea­sure­ment error, as empha­sized by Vil­lani 2011), gas chro­matog­ra­phy was used for a chem­i­cal analy­sis, the sam­ple size is one of the largest ever (ex­ceeded only by Vil­lani 2011/Lyons 2013 and my sur­veys), the part­ner­ship with Big Cat Res­cue extends the results to sev­eral other inter­est­ing species (bob­cats & tiger­s), and the full dataset is included with the paper.

    I extract 2 CSVs from the raw data, for cats & bobcats/tigers. Code responses of “5” or “10” (mild vs intense) are con­sid­ered respon­ders; Bol states that “Because most (80–90%) of the cats stud­ied were (blends of) domes­tic short­-haired breeds, we did not study asso­ci­a­tions between breed and respon­sive­ness to the mate­ri­als tested”, so the cats are all coded as “Amer­i­can short­-hair” breeds. Test­ing was done in the USA. Tigers/bobcats were like­wise coded as respon­ders if they had “5”/“10” codes for cat­nip. Sum­ma­ry:

    • 22⁄34 male cats responded
    • 38⁄55 female cats responded
    • 2 male tigers, both non-re­spon­ders
    • 7 female tigers, 1 respon­der
    • 1 female bob­cat, 1 respon­der
  • Espín-I­turbe et al 2017, “Active and pas­sive responses to cat­nip (Nepeta cataria) are affected by age, sex and early gonadec­tomy in male and female cats”

    Espín-I­turbe et al 2017 argues (fol­low­ing Hill et al 1976) that cat­nip response has been wrongly con­ceived as an active or non-re­spon­der (base­line) bina­ry, and “non-re­spon­ders” are in fact respond­ing in a differ­ent way by mov­ing much less & adopt­ing the “sphinx” pos­ture (based on com­put­er­ized scor­ing of video­tape in a cylin­dri­cal cham­ber after expo­sure to cat­nip). Their results also sug­gest that old­er, male, and ear­ly-neutered cats are more pas­sive respon­ders. This would sug­gest cat­nip is a drug capa­ble of both stim­u­lant and depres­sive effects, like nico­tine or mar­i­juana or alco­hol (although cat­nip would not seem to depend on dose, only indi­vid­ual differ­ences).

  • Beck et al 2018, “Effect of a Syn­thetic Feline Pheromone for Man­ag­ing Unwanted Scratch­ing”: com­mer­cial study which included 0.1% cat­nip in anti-scratch­ing solu­tion prod­uct with report­edly good results, but effect is con­founded and can’t infer indi­vid­ual cat response rates

  • Can­nas et al 2018, “Effect of a Nepeta cataria oil diffu­sor on cat behav­iour”: paper in Ital­ian; Eng­lish abstract indi­cates it was a n = 20 (10/10) between-group study of a cat­nip essen­tial oil aro­matic diffuser; results:

    Based on owner answers, 90% [9⁄10] of cats of the ther­apy group and 40% [4⁄10] of cats of the con­trol group showed an improve­ment (p≤0.05). Play behav­iour increased in the ther­apy group and decrease in the con­trol one (p = 0.06). The per­cent­age of cats show­ing hiss­ing or bit­ing attempts toward other cats and scratch­ing doors decreased sig­nifi­cantly in the ther­apy group (p≤0.05) and increased in the con­trol one. Sim­i­lar trend was seen for cats chang­ing room to go away from other ani­mals and we found a sta­tis­ti­cal differ­ence between the two groups before (p≤0.05) and post-treat­ment (p = 0.081).

    Given the con­sid­er­able improve­ment in the con­trol group, the 9⁄10 can’t be inter­preted as a response rate. If we sub­tract the con­trol group’s 4⁄10 as a base­line for regres­sion to the mean or own­er-place­bo-effect, the 5⁄10 is a plau­si­ble result for cat­nip respon­se, but is indi­rect enough that I think it’s prob­a­bly bet­ter to leave it out of the meta-analy­sis.

  • Bir­kett et al 2011, “Repel­lent activ­ity of cat­mint, Nepeta cataria, and iri­doid nepeta­lac­tone iso­mers against Afro-trop­i­cal mos­qui­toes, ixo­did ticks and red poul­try mites”; although this is not described any­where in the text of Bir­kett et al 2011, accord­ing to Sharma et al 2019:

    Bir­kett et al. (2011) syn­the­sized the unnat­ural (4aR,7R,7aS)-nepeta­lac­tone and enan­tiomer of (4aS,7S,7aR)-nepeta­lac­tone. These two mol­e­cules have been bioas­sayed against two Amer­i­can short­-hair, three Abyssini­an, and four Japan­ese cats. Almost all cats reacted strongly espe­cially the female ones towards both the enan­tiomers. Female cats have been found to be extremely attrac­tive even at the dose of 0.01 mg.

    Sharma et al 2019 seems to have either omit­ted a cita­tion or con­fused Bir­kett et al 2011 with Saku­rai et al 1988.

  • Jean-Louis 2019, “Effect of sen­sory enrich­ments on the behav­iour of cap­tive North­ern lynx (Lynx lynx lynx) and assess­ment of auto­mated behav­iour mon­i­tor­ing tech­nolo­gies”:

    Tested catnip/valerian/cinnamon on 3 lynx­es. Cat­nip resulted in sub­stan­tially more inter­ac­tion, but Jean-Louis 2019 ana­lyzes & visu­al­izes only by totals, not break­ing it down by lynx, so no esti­mate of whether it’s 1/2/3 respon­ders is pos­si­ble.


Poten­tially rel­e­vant but cur­rently unavail­able:

  • Lyons 2013, “Genome-Wide Asso­ci­a­tion Study for Cat­nip Response in Domes­tic Cats”: unpub­lished research, but abstract of results; TODO: email Leslie Lyons and ask if pub­lished any­where or if the dataset can be made pub­lic; the cat­nip response rate would be infor­ma­tive, there may be other genetic analy­ses, and would boost any future GWAS:

    Results: No Sig­nifi­cant Genetic Region Iden­ti­fied for Cat­nip Response in Cats. About 50% of cats respond to cat­nip. Funded by the Cat Health Net­work, researchers from the Uni­ver­sity of Cal­i­for­ni­a–­Davis tested 192 shel­ter cats for cat­nip response in con­trolled set­tings. DNA was col­lected from cats respond­ing to cat­nip and com­pared to DNA of non­re­spond­ing cats. Genetic analy­sis of these sam­ples did not reveal a causative gene asso­ci­ated with cat­nip response. Iden­ti­fi­ca­tion of genes respon­si­ble for cat­nip response may pro­vide clues to the mech­a­nisms involved in olfac­tory responses to drugs and chem­i­cals in cats.

Over­all, study qual­ity is low and at high risk of bias. Key vari­ables like sex/age/breed is almost always never reported and some­times even n or species is not report­ed; placebo con­trols are not used; the exper­i­menters are never blind to the sub­stance being used; impor­tant stud­ies are not avail­able in Eng­lish; the cat­nip used is not stan­dard­ized; and the ani­mals are not nec­es­sar­ily famil­iar­ized & com­fort­able with the exper­i­menter despite the need for them to be relaxed and will­ing to play in order to gauge the pres­ence or absence of a response. Prob­a­bly any esti­mate is some­thing of a lower bound as most of these biases would tend to mask a cat­nip response (like using old cat­nip or an ani­mal feel­ing stressed), and it will be diffi­cult to prove or dis­prove any sex or breed effects.


catnip <- read.csv(stdin(), header=TRUE)
Family,Genus,Species,Name,Study, Year, Responders, N, Country, Sex, Breed
Felidae,Panthera,leo,African lion,McElvain et al 1942,1942,7,7,USA,mixed,NA
Viverrinae,Civettictis,NA,NA,Todd 1962,1962,0,3,USA,mixed,NA
Viverrinae,Viverra,NA,NA,Todd 1962,1962,0,1,USA,mixed,NA
Viverrinae,Civettictis,NA,NA,Todd 1962,1962,0,2,USA,mixed,NA
Paradoxurinae,Nandinia,NA,NA,Todd 1962,1962,0,5,USA,mixed,NA
Paradoxurinae,Paguma,NA,NA,Todd 1962,1962,0,2,USA,mixed,NA
Paradoxurinae,Arctictis,NA,NA,Todd 1962,1962,2,3,USA,mixed,NA
Herpestinae,Herpestes,NA,NA,Todd 1962,1962,0,1,USA,mixed,NA
Herpestinae,Atilax,NA,NA,Todd 1962,1962,1,3,USA,mixed,NA
Herpestinae,Ichneumia,NA,NA,Todd 1962,1962,0,1,USA,mixed,NA
Cryptoproctinae,Cryptoprocta,NA,NA,Todd 1962,1962,0,1,USA,mixed,NA
Hyaenidae,NA,NA,hyena,Todd 1962,1962,0,1,USA,F,NA
Hyaenidae,NA,NA,hyena,Todd 1962,1962,0,2,USA,M,NA
Felidae,Panthera,leo,African lion,Todd 1962,1962,6,6,USA,M,NA
Felidae,Panthera,leo,African lion,Todd 1962,1962,8,10,USA,F,NA
Felidae,Panthera,tigris,tiger,Todd 1962,1962,1,9,USA,M,NA
Felidae,Panthera,tigris,tiger,Todd 1962,1962,7,13,USA,F,NA
Felidae,Panthera,leo/tigris,ligeress,Todd 1962,1962,0,1,USA,F,NA
Felidae,Panthera,pardus,leopard,Todd 1962,1962,6,8,USA,M,NA
Felidae,Panthera,pardus,leopard,Todd 1962,1962,8,10,USA,F,NA
Felidae,Panthera,onca,jaguar,Todd 1962,1962,4,5,USA,M,NA
Felidae,Panthera,onca,jaguar,Todd 1962,1962,3,3,USA,F,NA
Felidae,Panthera,uncia,snow leopard,Todd 1962,1962,2,2,USA,M,NA
Felidae,Panthera,uncia,snow leopard,Todd 1962,1962,2,2,USA,F,NA
Felidae,Neofelis,nebulosa,clouded leopard,Todd 1962,1962,1,2,USA,NA,NA
Felidae,Acinonyx,jubatus,cheetah,Todd 1962,1962,0,3,USA,NA,NA
Felidae,Felis,rufus,bobcat,Todd 1962,1962,1,2,USA,NA,NA
Felidae,Felis,lynx,European lynx,Todd 1962,1962,1,1,USA,NA,NA
Felidae,Felis,concolor,puma,Todd 1962,1962,2,3,USA,M,NA
Felidae,Felis,concolor,puma,Todd 1962,1962,1,2,USA,F,NA
Felidae,Felis,temmincki,African golden cat,Todd 1962,1962,1,1,USA,NA,NA
Felidae,Felis,aurata,Asian golden cat,Todd 1962,1962,0,1,USA,NA,NA
Felidae,Felis,pardalis,ocelot,Todd 1962,1962,4,5,USA,NA,NA
Felidae,Felis,wiedii,margay,Todd 1962,1962,4,6,USA,NA,NA
Felidae,Felis,serval,serval,Todd 1962,1962,0,2,USA,NA,NA
Felidae,Felis,chaus,swamp cat,Todd 1962,1962,0,1,USA,NA,NA
Felidae,Felis,manul,Pallas cat,Todd 1962,1962,0,1,USA,NA,NA
Felidae,Felis,bengalensis,leopard cat,Todd 1962,1962,0,1,USA,NA,NA
Felidae,Felis,viverrina,fishing cat,Todd 1962,1962,0,2,USA,NA,NA
Felidae,Felis,yagouaroundi,jaguarundi,Todd 1962,1962,0,4,USA,NA,NA
Felidae,Felis,pajeros,pampas cat,Todd 1962,1962,0,1,USA,NA,NA
Felidae,Felis,catus,cat,Todd 1962,1962,8,10,USA,M,Siamese
Felidae,Felis,catus,cat,Todd 1962,1962,6,16,USA,F,Siamese
Felidae,Felis,catus,cat,Todd 1963,1963,32,43,USA,M,mixed
Felidae,Felis,catus,cat,Todd 1963,1963,26,41,USA,F,mixed
Felidae,Felis,catus,cat,Bates & Siegel 1963,1963,5,8,USA,NA,NA
Felidae,Felis,catus,cat,Palen & Goddard 1966,1966,15,26,USA,M,mixed
Felidae,Felis,catus,cat,Palen & Goddard 1966,1966,8,17,USA,F,mixed
Felidae,Felis,catus,cat,Hayashi 1968,1966,1,2,USA,NA,NA
Felidae,Felis,catus,cat,Hayashi 1968,1966,1,2,UK,NA,NA
Felidae,Felis,catus,cat,Hayashi 1968,1966,2,2,Japan,NA,NA
Canidae,Canis,lupus,dog,Hayashi 1968,1966,0,2,Japan,NA,NA
Leporidae,Oryctolagus,cuniculus,rabbit,Hayashi 1968,1966,0,2,Japan,NA,NA
Muridae,Mus,musculus,mouse,Hayashi 1968,1966,0,2,Japan,NA,NA
Muridae,Rattus,norvegicus,rat,Hayashi 1968,1966,0,2,Japan,NA,NA
Caviidae,Cavia,porcellus,guinea pig,Hayashi 1968,1966,0,2,Japan,NA,NA
Phasianidae,NA,NA,fowl,Hayashi 1968,1966,0,2,Japan,NA,NA
Felidae,Felis,catus,cat,Hatch 1972,1972,14,17,USA,mixed,mixed
Felidae,Panthera,leo,African lion,Hill et al 1976,1976,3,4,USA,M,NA
Felidae,Panthera,leo,African lion,Hill et al 1976,1976,5,5,USA,F,NA
Felidae,Panthera,onca,jaguar,Hill et al 1976,1976,1,1,USA,M,NA
Felidae,Panthera,onca,jaguar,Hill et al 1976,1976,2,2,USA,F,NA
Felidae,Panthera,pardus,leopard,Hill et al 1976,1976,2,4,USA,M,NA
Felidae,Panthera,pardus,leopard,Hill et al 1976,1976,2,4,USA,F,NA
Felidae,Panthera,tigrus,tiger,Hill et al 1976,1976,0,1,USA,M,NA
Felidae,Panthera,tigrus,tiger,Hill et al 1976,1976,0,4,USA,F,NA
Felidae,Felis,rufus,bobcat,Hill et al 1976,1976,0,1,USA,M,NA
Felidae,Felis,rufus,bobcat,Hill et al 1976,1976,0,1,USA,F,NA
Felidae,Puma,concolor,cougar,Hill et al 1976,1976,0,2,USA,M,NA
Felidae,Puma,concolor,cougar,Hill et al 1976,1976,0,2,USA,F,NA
Felidae,Felis,catus,cat,Sakurai et al 1988,1988,4,4,Japan,mixed,Japanese
Felidae,Felis,catus,cat,Sakurai et al 1988,1988,3,3,Japan,mixed,Abyssinian
Felidae,Felis,catus,cat,Sakurai et al 1988,1988,2,2,Japan,mixed,American short-hair
Felidae,Felis,catus,cat,Sakurai et al 1988,1988,16,16,Japan,NA,Japanese
Felidae,Felis,catus,cat,DeLuca & Kranda 1992,1992,6,10,USA,NA,mixed
Felidae,Felis,catus,cat,Clapperton et al 1994,1994,12,24,USA,NA,mixed
Felidae,Felis,concolor,puma,Portella et al 2013,2013,0,6,USA,NA,NA
Felidae,Felis,catus,cat,Gwern 2017,2017,695,842,Canada,NA,NA
Felidae,Felis,catus,cat,Gwern 2017,2017,615,783,USA,NA,NA
Felidae,Felis,catus,cat,Gwern 2017,2017,463,625,UK,NA,NA
Felidae,Felis,catus,cat,Gwern 2017,2017,228,320,Japan,NA,NA
Felidae,Felis,catus,cat,Gwern 2017,2017,216,380,Germany,NA,NA
Felidae,Felis,catus,cat,Gwern 2017,2017,174,313,Brazil,NA,NA
Felidae,Felis,catus,cat,Gwern 2017,2017,108,200,Spain,NA,NA
Felidae,Felis,catus,cat,Gwern 2017,2017,403,759,Australia,NA,NA
Felidae,Felis,catus,cat,Gwern 2017,2017,94,180,Mexico,NA,NA
Felidae,Felis,catus,cat,Bol et al 2017,2017,22,34,USA,M,American short-hair
Felidae,Felis,catus,cat,Bol et al 2017,2017,38,55,USA,F,American short-hair
Felidae,Felis,catus,cat,Bol et al 2017,2017,7,10,USA,NA,American short-hair
Felidae,Panthera,tigrus,tiger,Bol et al 2017,2017,1,7,USA,F,NA
Felidae,Panthera,tigrus,tiger,Bol et al 2017,2017,0,2,USA,M,NA
Felidae,Felis,rufus,bobcat,Bol et al 2017,2017,1,1,USA,F,NA

catnip$Sex <- ordered(catnip$Sex, levels=c("F", "mixed", "M"))
catnip$Country <- relevel(catnip$Country, "USA")


Cats catnip response rate

A ran­dom-effects meta-analy­sis on the pro­por­tion of cat­nip response in domes­tic cats using metafor:

cat <- subset(catnip, Name=="cat")
sum(cat$Responders) / sum(cat$N)
# [1] 0.6795952782

r <- rma(xi=Responders, ni=N, measure="PR", slab=Study, data=cat); summary(r)
# Random-Effects Model (k = 29; tau^2 estimator: REML)
#   logLik  deviance       AIC       BIC      AICc
#  12.0648  -24.1296  -20.1296  -17.4652  -19.6496
# tau^2 (estimated amount of total heterogeneity): 0.0155 (SE = 0.0059)
# tau (square root of estimated tau^2 value):      0.1244
# I^2 (total heterogeneity / total variability):   92.25%
# H^2 (total variability / sampling variability):  12.90
# Test for Heterogeneity:
# Q(df = 28) = 382.1487, p-val < .0001
# Model Results:
# estimate      se     zval    pval   ci.ub
#   0.6714  0.0288  23.3059  <.0001  0.6150  0.7279

png(file="~/wiki/images/catnip/catnip-forest.png", width = 590, height = 610)
forest(r, xlim=c(0,1))

## some issues in the funnel plot of too-extreme values:
funnel(r); trimfill(r)
# ...Estimated number of missing studies on the right side: 0 (SE = 3.3070)

## Examine all moderators:
rall <- rma(xi=Responders, ni=N, measure="PR", slab=Study,
            mods= ~ Year + Country + Sex + Breed, data=cat)
# Mixed-Effects Model (k = 12; tau^2 estimator: REML)
#   logLik  deviance       AIC       BIC      AICc
#   1.8566   -3.7133   16.2867    7.2728  236.2867
# tau^2 (estimated amount of residual heterogeneity):     0.0058 (SE = 0.0114)
# tau (square root of estimated tau^2 value):             0.0763
# I^2 (residual heterogeneity / unaccounted variability): 42.11%
# H^2 (unaccounted variability / sampling variability):   1.73
# R^2 (amount of heterogeneity accounted for):            16.14%
# Test for Residual Heterogeneity:
# QE(df = 3) = 5.3993, p-val = 0.1448
# Test of Moderators (coefficient(s) 2:9):
# QM(df = 8) = 10.3723, p-val = 0.2399
# Model Results:
#                           estimate       se     zval    pval     ci.ub
# intrcpt                   112.4174  80.1102   1.4033  0.1605  -44.5957  269.4304
# Year                       -0.0553   0.0397  -1.3935  0.1635   -0.1330    0.0225
# CountryJapan               -2.0805   1.4876  -1.3986  0.1619   -4.9961    0.8351
# Sex.L                       0.0799   0.0592   1.3497  0.1771   -0.0361    0.1960
# Sex.Q                      -0.5159   0.2766  -1.8651  0.0622   -1.0581    0.0263
# BreedAmerican short-hair   -0.0417   0.2920  -0.1427  0.8865   -0.6141    0.5307
# BreedJapanese               0.0250   0.2387   0.1047  0.9166   -0.4429    0.4929
# Breedmixed                 -3.0163   2.1190  -1.4235  0.1546   -7.1695    1.1369
# BreedSiamese               -3.1782   2.2048  -1.4414  0.1495   -7.4996    1.1433

r_country <- rma(xi=Responders, ni=N, measure="PR", slab=Study,
            mods= ~ Country, data=cat)
# Mixed-Effects Model (k = 29; tau^2 estimator: REML)
#   logLik  deviance       AIC       BIC      AICc
#  10.7309  -21.4619   -1.4619    8.4954   22.9826
# tau^2 (estimated amount of residual heterogeneity):     0.0096 (SE = 0.0061)
# tau (square root of estimated tau^2 value):             0.0978
# I^2 (residual heterogeneity / unaccounted variability): 63.38%
# H^2 (unaccounted variability / sampling variability):   2.73
# R^2 (amount of heterogeneity accounted for):            38.23%
# Test for Residual Heterogeneity:
# QE(df = 20) = 67.8909, p-val < .0001
# Test of Moderators (coefficient(s) 2:9):
# QM(df = 8) = 19.6513, p-val = 0.0117
# Model Results:
#                   estimate      se     zval    pval   ci.ub
# intrcpt             0.6581  0.0365  18.0326  <.0001   0.5866  0.7297
# CountryAustralia   -0.1272  0.1059  -1.2006  0.2299  -0.3348  0.0804
# CountryBrazil      -0.1022  0.1081  -0.9458  0.3442  -0.3141  0.1096
# CountryCanada       0.1673  0.1052   1.5902  0.1118  -0.0389  0.3734
# CountryGermany     -0.0897  0.1074  -0.8352  0.4036  -0.3003  0.1208
# CountryJapan        0.1889  0.0695   2.7186  0.0066   0.0527  0.3250
# CountryMexico      -0.1359  0.1108  -1.2265  0.2200  -0.3531  0.0813
# CountrySpain       -0.1181  0.1102  -1.0724  0.2835  -0.3341  0.0978
# CountryUK           0.0662  0.1026   0.6453  0.5188  -0.1349  0.2673

r_year <- rma(xi=Responders, ni=N, measure="PR", slab=Study,
            mods= ~ Year + Country, data=cat)
# Mixed-Effects Model (k = 29; tau^2 estimator: REML)
#   logLik  deviance       AIC       BIC      AICc
#   9.8005  -19.6011    2.3989   12.7878   40.1132
# tau^2 (estimated amount of residual heterogeneity):     0.0104 (SE = 0.0068)
# tau (square root of estimated tau^2 value):             0.1022
# I^2 (residual heterogeneity / unaccounted variability): 60.97%
# H^2 (unaccounted variability / sampling variability):   2.56
# R^2 (amount of heterogeneity accounted for):            32.52%
# Test for Residual Heterogeneity:
# QE(df = 19) = 66.6594, p-val < .0001
# Test of Moderators (coefficient(s) 2:10):
# QM(df = 9) = 18.5649, p-val = 0.0292
# Model Results:
#                   estimate      se     zval    pval   ci.ub
# intrcpt            -0.6080  2.7891  -0.2180  0.8274  -6.0745  4.8585
# Year                0.0006  0.0014   0.4536  0.6501  -0.0021  0.0034
# CountryAustralia   -0.1455  0.1184  -1.2286  0.2192  -0.3775  0.0866
# CountryBrazil      -0.1205  0.1203  -1.0016  0.3165  -0.3563  0.1153
# CountryCanada       0.1490  0.1177   1.2656  0.2057  -0.0818  0.3797
# CountryGermany     -0.1080  0.1197  -0.9021  0.3670  -0.3427  0.1267
# CountryJapan        0.1845  0.0728   2.5331  0.0113   0.0417  0.3272
# CountryMexico      -0.1542  0.1228  -1.2559  0.2091  -0.3948  0.0864
# CountrySpain       -0.1364  0.1222  -1.1165  0.2642  -0.3759  0.1031
# CountryUK           0.0491  0.1131   0.4339  0.6644  -0.1725  0.2706

## moderately informative Bayesian meta-analysis
## (bayesmeta doesn't support moderators/meta-regression, so estimate just mean/SD):
b <- bayesmeta(y = escalc(xi=Responders, ni=N, measure="PR", data=cat),
               mu.prior.mean=0.5,; summary(b)
# ...marginal posterior summary:
#                     tau           mu        theta
# mode      0.12487373717 0.6583157958 0.6588646213
# median    0.13029833512 0.6573472098 0.6575484257
# mean      0.13317030042 0.6568159715 0.6568159715
# sd        0.02521684197 0.0295391439 0.1389217521
# 95% lower 0.08801259311 0.5980530543 0.3796963066
# 95% upper 0.18372308609 0.7145549723 0.9312941009
# (quoted intervals are shortest credibility intervals.)
# relative heterogeneity I^2 (posterior median): 0.9288449557
Meta-an­a­lytic for­est plot of cat­nip response rates in exper­i­men­tal stud­ies

The 2⁄3 rule of thumb proves to be about right, with a meta-an­a­lytic sum­mary of ~67% cat­nip response rates.

The het­ero­gene­ity of the results indi­cates that some­things are differ­ent from study to study or that biases like pub­li­ca­tion bias are at play; includ­ing the sex and breed covari­ates does­n’t help much because of the miss­ing data, but there’s inter­est­ing trends of decreases with a study being con­ducted later in time.

The sus­pi­cious Saku­rai 16⁄16 dat­a­point does­n’t show up in the full model because it has no sex infor­ma­tion and gets dropped, so the Japan­ese trend there is being dri­ven by the other Saku­rai dat­a­points; the Hayashi results fur­ther sup­port the Japan­ese anom­aly. With addi­tional data from my large-s­cale Google Sur­veys, the Japan­ese anom­aly washes out: Japan does remain one of the high­est cat­nip response coun­try but looks much more rea­son­able, with a cat­nip response rate sim­i­lar to Cana­da.

The decrease with time ini­tially observed is odd in the full mod­el, but it seems to be dis­ap­pear­ing as addi­tional stud­ies are con­duct­ed, and it’s much more likely that it’s reflect­ing early differ­ences in exper­i­men­tal pro­ce­dure or breeds or coun­tries than indi­cat­ing that cat­nip response rates are being heav­ily selected against3, espe­cially as the decrease with time dis­ap­pears entirely if I ensure the 2017 sur­veys are included (rather than dropped for lack of sex/breed infor­ma­tion).

Over­all, the data qual­ity is low as many authors (espe­cially the early chemists) did not report indi­vid­ual response rates or key details of the cats used such as their age, breed, or sex, which is par­tic­u­larly unfor­tu­nate as all the sam­ples are small enough that the orig­i­nal data could’ve been eas­ily included as short tables. This is ironic because while some authors claim that sex/breed does­n’t mat­ter at all, oth­ers claim that females react much more strongly (or was it males?), and yet most don’t report the data down by those vari­ables, so their results can’t be pooled for an answer.

Cross-species catnip response rates

Cat­nip has been tested in a num­ber of species. It would be inter­est­ing to include this data for sev­eral rea­sons: it can help the search for the genetic basis by com­par­ing cat­nip-sen­si­tive species with non-sen­si­tive look­ing for genetic vari­ants pecu­liar to the for­mer, or if there is no appar­ent clus­ter of close­ly-re­lated species which uniquely have cat­nip respons­es, it can test the­o­ries about what local envi­ron­ments might cause cat­nip sen­si­tiv­i­ty; it can poten­tially help sharpen esti­mates of sex/age/country/experimenter effects by ‘bor­row­ing strength’; zookeep­ers can enrich their ani­mals’ lives with cat­nip if they know which species respond; and since the data is already there in the papers, we might as well include it.

To exam­ine cross-species trends, we would like to fit a mul­ti­level model using family/genus/species, since one would expect the cat­nip response rate to be more sim­i­lar between, say, African lions & tigers than between snow leop­ards & hye­nas. Since each species might have differ­ent gen­der effects and pop­u­la­tion bot­tle­necks, we would ide­ally nest in each species the sex/country/breed/year covari­ates. We would also like inde­pen­dent ran­dom-effects for each study to allow for the het­ero­gene­ity we observed before (which could be inde­pen­dent of the family/genus/species hier­ar­chy, in which case it would model things like differ­ent exper­i­men­tal pro­ce­dures - eg cat­nip leaves vs extract, or the exper­i­menter being good or bad with ani­mals - or it could be species-spe­cific too). Unfor­tu­nate­ly, such a full model would require esti­mat­ing a huge num­ber of para­me­ters (with 24 species, 14 genus­es, & 6 fam­i­lies, 10 stud­ies, and 4 vari­ables for each species, that’s eas­ily 270 para­me­ters which must be fit) and there is too lit­tle data (and the avail­able data is com­pro­mised by the fre­quent miss­ing­ness of species and sex), so we have to set­tle for some­thing more mod­est, focus­ing on just the cross-species aspect.

## full model is unidentifiable due to too few data points and missingness:
# b <- bglmer(cbind(Responders, N) ~ (Sex+Country+Breed+Year|Species/Genus/Family) + (1|Study), family="binomial", data=catnip)

# levels(catnip$Name) <- c(levels(catnip$Name), as.character(catnip[$Name),]$Genus))
# catnip[$Name),]$Name <- as.character(catnip[$Name),]$Genus)
## sort by taxonomy:
catnip <- catnip[with(catnip, order(Family, Genus, Species)),]
catnip$Label <- with(catnip, Map(function(f,g,s, n) { paste0(n, " (", paste(f, g, s), ")") }, Family, Genus, Species, Name))

cross <- rma(xi=Responders, ni=N, measure="PR", slab=Label,
            mods = ~ Species, data=catnip)
# Mixed-Effects Model (k = 79; tau^2 estimator: REML)
#   logLik  deviance       AIC       BIC      AICc
#  18.1500  -36.2999   23.7001   81.0608  121.5948
# tau^2 (estimated amount of residual heterogeneity):     0.0130 (SE = 0.0048)
# tau (square root of estimated tau^2 value):             0.1141
# I^2 (residual heterogeneity / unaccounted variability): 85.31%
# H^2 (unaccounted variability / sampling variability):   6.81
# R^2 (amount of heterogeneity accounted for):            73.68%
# Test for Residual Heterogeneity:
# QE(df = 50) = 399.0507, p-val < .0001
# Test of Moderators (coefficient(s) 2:29):
# QM(df = 28) = 114.5476, p-val < .0001
# Model Results:
#                      estimate      se     zval    pval   ci.ub
# intrcpt                0.2500  0.3267   0.7651  0.4442  -0.3904  0.8904
# Speciesbengalensis     0.0000  0.4621   0.0000  1.0000  -0.9057  0.9057
# Speciescatus           0.4215  0.3279   1.2857  0.1986  -0.2211  1.0641
# Specieschaus           0.0000  0.4621   0.0000  1.0000  -0.9057  0.9057
# Speciesconcolor       -0.0429  0.3422  -0.1253  0.9003  -0.7135  0.6278
# Speciescuniculus      -0.0833  0.4075  -0.2045  0.8380  -0.8821  0.7154
# Speciesjubatus        -0.1250  0.3836  -0.3259  0.7445  -0.8768  0.6268
# Speciesleo             0.6381  0.3350   1.9048  0.0568  -0.0185  1.2946
# Speciesleo/tigris      0.0000  0.4621   0.0000  1.0000  -0.9057  0.9057
# Specieslupus          -0.0833  0.4075  -0.2045  0.8380  -0.8821  0.7154
# Specieslynx            0.5000  0.4621   1.0820  0.2792  -0.4057  1.4057
# Speciesmanul           0.0000  0.4621   0.0000  1.0000  -0.9057  0.9057
# Speciesmusculus       -0.0833  0.4075  -0.2045  0.8380  -0.8821  0.7154
# Speciesnebulosa        0.2500  0.4947   0.5053  0.6133  -0.7197  1.2197
# Speciesnorvegicus     -0.0833  0.4075  -0.2045  0.8380  -0.8821  0.7154
# Speciesonca            0.5767  0.3470   1.6618  0.0966  -0.1035  1.2568
# Speciespajeros         0.0000  0.4621   0.0000  1.0000  -0.9057  0.9057
# Speciespardalis        0.5500  0.3896   1.4118  0.1580  -0.2136  1.3136
# Speciespardus          0.4446  0.3436   1.2938  0.1957  -0.2289  1.1181
# Speciesporcellus      -0.0833  0.4075  -0.2045  0.8380  -0.8821  0.7154
# Speciesrufus           0.1837  0.3675   0.5000  0.6171  -0.5365  0.9040
# Speciesserval         -0.0833  0.4075  -0.2045  0.8380  -0.8821  0.7154
# Speciestemmincki       0.5000  0.4621   1.0820  0.2792  -0.4057  1.4057
# Speciestigris          0.0438  0.3471   0.1261  0.8996  -0.6366  0.7241
# Speciestigrus         -0.1069  0.3431  -0.3115  0.7554  -0.7794  0.5656
# Speciesuncia           0.5833  0.3693   1.5794  0.1143  -0.1406  1.3072
# Speciesviverrina      -0.0833  0.4075  -0.2045  0.8380  -0.8821  0.7154
# Specieswiedii          0.4167  0.3960   1.0522  0.2927  -0.3595  1.1928
# Speciesyagouaroundi   -0.1500  0.3712  -0.4041  0.6861  -0.8775  0.5775

png(file="~/wiki/images/catnip/catnip-forest-crossspecies.png", width = 580, height = 1600)

b <- bglmer(cbind(Responders, N) ~ (1|Species/Genus/Family) + (1|Study) + Year, family="binomial", data=catnip)
summary(b); ranef(b)
For­est plot of cat­nip responses across all sam­pled species


In com­pil­ing a meta-analy­sis of reports of , yield­ing an meta-an­a­lytic aver­age of ~2⁄3, the avail­able data sug­gests het­ero­gene­ity from cross-coun­try differ­ences in rates (pos­si­bly for genetic rea­sons) but is insuffi­cient to defin­i­tively demon­strate the exis­tence of or esti­mate those differ­ences (par­tic­u­larly a pos­si­ble extremely high cat­nip response rate in Japan). I use Google Sur­veys August-Sep­tem­ber 2017 to con­duct a brief 1-ques­tion online sur­vey of a pro­por­tional pop­u­la­tion sam­ple of 9 coun­tries about cat own­er­ship & cat­nip use, specifi­cal­ly: Canada, the USA, UK, Japan, Ger­many, Brazil, Spain, Aus­tralia, & Mex­i­co. in total, I sur­veyed n = 31,471 peo­ple, of whom n = 9,087 are cat own­ers, of whom n = 4,402 report hav­ing used cat­nip on their cat, and of whom n = 2996 report a cat­nip response.

The sur­vey yields cat­nip response rates of Canada (82%), USA (79%), UK (74%), Japan (71%), Ger­many (57%), Brazil (56%), Spain (54%), Aus­tralia (53%), and Mex­ico (52%). The differ­ences are sub­stan­tial and of high pos­te­rior prob­a­bil­i­ty, sup­port­ing the exis­tence of large cross-coun­try differ­ences. In addi­tional analy­sis, the other con­di­tional prob­a­bil­i­ties of cat own­er­ship and try­ing cat­nip with a cat appear to cor­re­late with cat­nip response rates; this inter­cor­re­la­tion sug­gests a “cat fac­tor” of some sort influ­enc­ing respons­es, although what causal rela­tion­ship there might be between pro­por­tion of cat own­ers and pro­por­tion of cat­nip-re­spon­der cats is unclear.

An addi­tional sur­vey of a con­ve­nience sam­ple of pri­mar­ily US Inter­net users about cat­nip is report­ed, although the improb­a­ble cat­nip response rates com­pared to the pop­u­la­tion sur­vey sug­gest the respon­dents are either highly unrep­re­sen­ta­tive or the ques­tions caused demand bias.

Main arti­cle:

Optimal catnip alternative selection: solving the MDP

Bol et al 2017 tested 4 cat stim­u­lants on a large (n > 100) sam­ple of cats, yield­ing with­in-in­di­vid­ual cor­re­la­tions of stim­u­lant respons­es. This allows pre­dic­tion of stim­u­lant response con­di­tional on observ­ing other stim­u­lant respons­es. I use this to demon­strate how to opti­mize stim­u­lant selec­tion as a sequen­tial test­ing prob­lem, yield­ing (for one set of real­is­tic pur­chase costs) a test sequence of cat­nip → hon­ey­suckle → sil­vervine → Vale­ri­an, which is differ­ent from the greedy pol­icy of pick­ing stim­u­lants by prior prob­a­bil­i­ty.

Bol et al 2017, as not­ed, pro­vides responses for 4 drugs (catnip/Valerian/silvervine/honeysuckle) in a large sam­ple of cats; responses turn out to be heav­ily inter­cor­re­lat­ed, per­mit­ting the abil­ity to bet­ter pre­dict responses to the cat­nip alter­na­tives based on a known response to one of the oth­ers. This becomes use­ful if we treat it as a drug selec­tion prob­lem where we would like to find at least one work­ing drug for a cat while sav­ing mon­ey, and adapt­ing our next test based on failed pre­vi­ous tests.

If they were not inter­cor­re­lat­ed, one would sim­ply min­i­mize expected loss in a greedy fash­ion, start­ing with cat­nip etc; but as they are inter­cor­re­lat­ed, now a drug has both direct value (if the cat responds) and value of infor­ma­tion (its fail­ure gives evi­dence about what other drugs that cat might respond to), which means the greedy pol­icy may no longer be the opti­mal pol­i­cy. The opti­mal sequence can be derived by con­sid­er­ing all pos­si­ble sequences of tests, updat­ing pre­dic­tions in a Bayesian fash­ion for each hypo­thet­i­cal sequence, cal­cu­lat­ing total expected losses based on the pos­te­rior prob­a­bil­i­ties, and min­i­miz­ing loss­es. For one set of costs and one cat response dataset, I derive an opti­mal sequence of: cat­nip, hon­ey­suck­le, sil­vervine, and valer­ian. Imple­men­ta­tion below.

Load Bol et al 2017 for pre­dict­ing response to one drug based on responses to oth­ers:

bol2017 <- read.csv("")
bol2017[,5:8] <- (bol2017[,5:8] > 0) # treat '5'/'10' (weak/strong response) as binary
bol2017Responses <- subset(bol2017, select=c("Catnip", "Valerian", "Silver.vine", "Tatarian.honeysuckle"))
colnames(bol2017Responses) <- c("Catnip", "Valerian", "Silvervine", "Honeysuckle") # rename for consistency
#...  variable missing complete   n mean                   count
#       Catnip       1       99 100 0.68 TRU: 67, FAL: 32, NA: 1
#  Honeysuckle       3       97 100 0.53 TRU: 51, FAL: 46, NA: 3
#   Silvervine       0      100 100 0.79 TRU: 79, FAL: 21, NA: 0
#     Valerian       4       96 100 0.47 FAL: 51, TRU: 45, NA: 4

Greedy one-step pol­icy + sim­ple mar­ginal prob­a­bil­ity chooses a test sequence of catnip/valerian/silvervine/honeysuckle:

Drug Cost P Loss
Cat­nip 8.96 0.67 2.9568
Valer­ian 7.00 0.47 3.7100
Sil­vervine 17.77 0.79 3.7317
Hon­ey­suckle 7.99 0.53 3.7553
costs <- read.csv(stdin(), header=TRUE, colClasses=c("character", "numeric"))

Define a cat­nip test­ing MDP: we are test­ing 4 cat drugs with inter­cor­re­lated respons­es, we want to find 1 drug which works, and we want to min­i­mize the mon­e­tary loss (since we have to pay for each one as defined above). What is the opti­mal sequence, which min­i­mizes expected loss before find­ing 1 work­ing drug? We can solve by back­wards induc­tion on a deci­sion tree and using Bayesian lin­ear regres­sion to pre­dict pos­te­rior prob­a­bil­ity of each remain­ing drug’s suc­cess prob­a­bil­ity con­di­tional on pre­vi­ous drugs not work­ing (rather than using just the uncon­di­tion­al, mar­gin­al, prob­a­bil­ity of any cat respond­ing to each):


predictBayes <- memoize(function (action, observations, df) {
    formula <- as.formula(paste(action, paste(c(names(observations), "1"), collapse=" + "), sep=" ~ "))
    b <- stan_glm(formula, family=binomial(), algorithm="optimizing", data=bol2017Responses)
    if (length(observations)==0) { mean(inv.logit(predict(b))) } else { inv.logit(predict(b,[1]) } })

f <- memoize(function(observations) {
    allActions <- colnames(bol2017Responses)
    actions <- allActions[!allActions %in% (names(observations))] # untried drugs
    if (length(actions) == 0) { return(0) } else {

       actionCosts <- costs[costs$Drug %in% actions,]$Loss

       probabilities <- c(numeric())
       for (i in 1:length(actions)) {
          probabilities[i] <- predictBayes(actions[i], observations, bol2017Responses)
       lossActions <- c(numeric())

       for (i in 1:length(actions)) {
           # we pay the loss to test each action; if successful, we stop here, otherwise we add a FALSE observation and recurse
           obs <- list(a=FALSE); names(obs) <- actions[i]
           obs <- c(observations, obs)
           newHistory <- obs[order(unlist(obs), decreasing = TRUE)] # sort history to avoid unnecessarily different but equivalent calls
           # 1. incur cost of each drug; success means stopping; failure: augment history with failure observation, and look for an optimal path through remaining actions recursively by calling 'f' again
           lossActions[i] <- actionCosts[i] + probabilities[i]*0 + ((1-probabilities[i]) * (f(newHistory)))
       print(data.frame(Actions=actions, P=probabilities, Loss=lossActions))
       print(paste("Optimal action: ", actions[which.min(lossActions)], "; given observations: ", names(observations), observations))
       return(min(lossActions)) }
# f(list(Catnip=FALSE, Honeysuckle=FALSE, Silvervine=FALSE))

## No data, optimal choice is catnip:
#       Actions            P        Loss
# 1      Catnip 0.6810641502 15.79007271
# 2    Valerian 0.4731509696 16.92706363
# 3  Silvervine 0.7879218896 20.92153367
# 4 Honeysuckle 0.5276423201 16.51408849

## With catnip resistance, optimal choice is honeysuckle:
#       Actions            P        Loss
# 1    Valerian 0.2005122547 23.27730700
# 2  Silvervine 0.7202520977 21.49101933
# 3 Honeysuckle 0.3287608075 21.41519278

## With catnip/honeysuckle resistance, optimal choice is silvervine, and if silvervine doesn't work, only Valerian is left:
#      Actions            P        Loss
# 1   Valerian 0.1695397115 21.75727933
# 2 Silvervine 0.6813415396 20.00060922

## Final optimal policy: catnip, honeysuckle, silvervine, Valerian; aside from catnip, almost reverse of greedy policy.

Known cat stimulants

Fig­ure 1. “A cat on Christ­mas Island in an appar­ent drug-in­duced stu­por after chew­ing the roots of Aca­lypha indica.” (From .)
Fig­ure 7: bob­cat with sil­vervine (From .)

“Cat­nip, Vale­ri­an, Hon­ey­suckle and other cat-at­trac­tant plants”, Hartwell 2008:

  • : active ingre­di­ent nepeta­lac­tone

  • Lonicera Tatar­ica (Tatar­ian Hon­ey­suck­le) : nepeta­lac­tone TODO: that can’t be the only ingre­di­ent if cat­nip does­n’t work on Percy and hon­ey­suckle does?

  • Vale­ri­an:

    • Valer­ian offic­i­nalis : active ingre­di­ent actini­dine
    • Vale­ri­ana celtica : active ingre­di­ents nepeta­lac­tone (Bic­chi et al 1983)
  • Actini­dia Polygama (Japan­ese Cat­nip or Matatabi or Sil­vervine or sil­ver vine or cat pow­der) and Actini­dia macros­perma : active ingre­di­ent Actini­dine and dihy­droac­tini­d­i­olide

  • (In­dian acalypha/Indian net­tle), active ingre­di­ents: Isodi­hy­dronepeta­lac­tone, Isoiridomyrmecin (eg Scaffidi et al 2016)

  • cat thyme (teu­crium marum) : active ingre­di­ent TODO

  • Buck­bean (Menyan­thes tri­fo­li­ata): mit­sug­ashi­walac­tone

  • North­ern ground­cone (Bosch­ni­akia rossi­ca): bosch­ni­akine and bosch­nialac­tone

  • Yel­low­bells (Te­coma stan­s): bosch­ni­akine and actini­dine

  • Trum­pet Creeper (Camp­sis rad­i­can­s): may bosch­ni­akine

  • Guelder Rose (Vibur­num opu­lus, some­times called Cran­berry Bush and most com­monly found in cul­ti­va­tion as the Snow­ball Tree)

  • the peren­nial Dit­tany of Crete (Ori­g­anum dictamnus/Hop Mar­jo­ram)

  • the spring-flow­er­ing annual Baby Blue-eyes (Nemophila men­ziesii)

  • the Zim­bab­wean plant Zinz­iba (Lip­pia javan­ica aka Ver­bena javan­i­ca).


  • there are anec­do­tal reports that some cats are attracted to olive prod­ucts: olive wood, olive oil, and olive fruits them­selves

Local cat experiments

The cat­nip lit­er­a­ture has a good sam­ple of what the cat­nip fre­quency response is, but it’s clear that a lot of cats are immune and their own­ers need to use one of the many sub­sti­tutes. The lit­er­a­ture does not seem to have much, if any, cov­er­age of all the main alter­na­tives, so own­ers don’t know what to try after cat­nip. There’s also no infor­ma­tion on any cor­re­la­tions between respons­es: does cat­nip immu­nity cause sus­cep­ti­bil­ity to a differ­ent stim­u­lant? Are some cats more response to stim­u­lants in gen­er­al? If we know a cat is immune to, say, cat­nip and vale­ri­an, can we bet­ter pre­dict what a owner should try next?

Since cats are easy to come by and the stim­u­lants are cheap, I thought it might be inter­est­ing to assem­ble a col­lec­tion of stim­u­lants and sys­tem­at­i­cally try them out on each cat I should hap­pen to meet. Specifi­cal­ly, I’ll look at the most com­mon and easy to come by stim­u­lants, since it’s not use­ful to dis­cover that some extinct African flower is super-po­tent:

  • Cat­nip (ob­vi­ous­ly)
  • Tatar­ian hon­ey­suckle (one of the most fre­quently men­tioned alter­na­tives)
  • Valer­ian (not as com­monly men­tioned, but very cheap due to its pop­u­lar­ity as a herbal sup­ple­ment for sleep & anx­i­ety)
  • Sil­vervine (rarer & more expen­sive but still acces­si­ble, and reput­edly quite effec­tive)
  • Cat thyme
  • Olive oil/wood (cats’ react­ing to olive-re­lated things is an obscure & anec­do­tal claim; but both are easy to get and included for the sake of com­pre­hen­sive­ness)


For each stim­u­lant, one clean nev­er-used feather was put into a clean jar along with a good help­ing of the rel­e­vant stim­u­lant, and shaken and left to sit. The olive wood would not fit into a jar, so I sawed it in half, saved the saw­dust, and put the two wood blocks, saw­dust, and feather into a lit­tle ziplock bag. The wand lets the feath­ers be added or removed eas­ily so I can test each feather one at a time by switch­ing feath­ers, play­ing with the cat for 5 min­utes, and wait­ing for any response or indi­ca­tion of inter­est beyond reg­u­lar chase. This works well, aside from the sil­vervine pow­der where inevitably some of the pow­der falls off or blows out of the con­tain­er, so it’s best to do the sil­vervine last.


Cat Sex Age Fixed Color Kind Cat­nip Valer­ian Hon­ey­suckle Sil­vervine Olive wood Olive oil
My cat M 1.5 1 black Domes­tic long 0 1 0 1 0 0
Percy M 3 1 brown Tabby 0 0 1 1 0 0
Kiki M 2 1 grey Tabby 1
Stormy M 10 1 grey Russ­ian Blue
Sara F 10 1 brown Tabby 1
Whitey F 5 1 white Domes­tic short 1
Sassy F 12 1 orange Domes­tic short 0 0 0 1 0 0

Descrip­tion of effects:

  • Cat­nip: too well known to need much descrip­tion. Cat­nip respon­der cats become ‘hyper’, unin­hib­it­ed, play­ful, inter­ested in the cat­nip toy.

    Test­ing it in my 2 non-re­spon­der cats in Decem­ber 2014, Percy and my cat ini­tially sniffed it for a few sec­onds and then ignored it after­wards, regard­less of whether I shook a quar­ter kilo­gram of cat­nip leaf under their nose or let the open jar sit next to them. Like­wise, attempts to inter­est them in the cat­nip extract spray in Novem­ber 2015 also failed. In Octo­ber 2016, I pur­chased ~100g of dried cat­nip leaves at a local Renais­sance fes­ti­val to have a backup for the cat­nip extract spray and per­haps try out “cat­nip tea” myself (and if I can’t find any use for it, I can always exper­i­ment with home steam dis­til­la­tion of cat­nip oil from cat­nip leaves!). Retest­ing Percy/my cat with the new leaves, Percy remained unin­ter­ested but this time my cat was inter­ested in the plas­tic bag con­tain­ing the cat­nip leaves, try­ing to claw and chew it, so I put ~10g into a lit­tle cot­ton bag and give it to him, which he began to chew and claw and even laid down to hold it in his paws and kick at it - how­ev­er, despite resem­bling the cat­nip respon­se, he was not hyper, and he did not repeat the reac­tion on 4 sub­se­quent occa­sions I tried to inter­est him in the cat­nip bag (spray­ing it with the cat­nip extract did not help). This makes me won­der if cat­nip response might have some ultra­-long tol­er­ance like some drugs in humans which take weeks or months for tol­er­ance to be restored, or if the cat­nip response is not bimodal after all (cat­nip being an dom­i­nant gene would cer­tainly seem like it almost has to pro­duce a bimodal/binary trait, but we have only Todd 1962 as evi­dence for it being dom­i­nant, and he used a sin­gle small breed­ing colony and no one has ever fol­lowed up & tried to repli­cate it that I know of). Per­haps the issue of mea­sure­ment error has been under­es­ti­mated in past stud­ies and many cats will only dis­play a cat­nip response occa­sion­ally or under ideal con­di­tions, and so the esti­mates of cat­nip immu­nity are heav­ily biased upwards?

  • Vale­ri­an: on my cat, pro­duces an inter­est­ing mix of pas­sive­ness and pos­ses­sive­ness - after onset and a long , he mostly lays on the floor pas­sive­ly, occa­sion­ally pulling him­self across it towards the toy, but gen­er­ally mak­ing lit­tle effort to hunt; if the toy comes within reach, though, then he seizes it ener­get­i­cally and abruptly begins clasp­ing it to his face, chew­ing it, curl­ing up around it and kick­ing at the toy with his hind legs. Even­tu­ally he can be coaxed into play­ing chase nor­mal­ly, with his usual level of com­pe­tence and inter­est. Actively repelled Sassy.

  • Hon­ey­suck­le: on Per­cy, had a gen­eral stim­u­lant effect; despite being fat, lazy, and usu­ally entirely unin­ter­ested in chase, he will make an effort to play after sniffing a hon­ey­suck­le-im­preg­nated toy. This stim­u­lat­ing effect does not pro­duce the un-in­hi­bi­tion of cat­nip, and seems fairly mild. Actively repelled Sassy.

  • Sil­vervine:

    1. on my cat, a gen­eral stim­u­lat­ing effect with con­sid­er­able inter­est in play­ing chase or watch­ing the toy, but curi­ous­ly, he makes many fewer attempts at attack­ing or chas­ing and when he does, he is dis­tinctly slower (and thus, less effec­tive) than usu­al. His coor­di­na­tion is fine - he’s not clumsy or falling over - but he’s just not as effec­tive (in a way hard to pin down specifi­cal­ly).
    2. On Per­cy, like­wise a gen­eral stim­u­lat­ing effect but far more effec­tive than the hon­ey­suckle in induc­ing chase play, with him even try­ing out jumps when coaxed appro­pri­ate­ly; he may be less effec­tive, like my cat when affect­ed, but he plays chase so lit­tle that it’s impos­si­ble for me to make any com­par­isons with his ‘nor­mal’ chase behav­ior.
    3. Sassy: sim­i­lar. More time on back while play­ing chase than usu­al.
  • Olive oil/wood: all cats showed brief inter­est in smell, then ignored entire­ly.


Breeding cats to increase frequency of catnip response

I sketch out a thresh­old selec­tion breed­ing pro­gram for increas­ing cat­nip response fre­quen­cy. Based on Vil­lani 2011’s mea­sured her­i­tabil­i­ties of cat­nip response (cor­rected for mea­sure­ment error), select­ing exclu­sively respon­ders would result in cat­nip response becom­ing nearly uni­ver­sal (~95%) within ~7 gen­er­a­tions or poten­tially less than a decade.

Given the ben­e­fits of cat­nip for behav­ioral enrich­ment, it’s unfor­tu­nate that cat breed­ers have not used a lit­tle selec­tion pres­sure to make cat­nip response uni­ver­sal. There are 3 major sce­nar­ios for cat­nip breed­ing:

  1. Mendelian auto­so­mal dom­i­nant: mark­er-as­sisted genetic selec­tion: 1 gen­er­a­tion to fix­a­tion

    A genetic test for cat­nip response is not avail­able as of July 2017, since the allele has not even been local­ized to any chro­mo­somes, much less iden­ti­fied, and given the small niche of cat genet­ics research, large-s­cale GWAS would almost cer­tainly be very expen­sive (eg the 99 Lives Cat Genome Sequenc­ing Ini­tia­tive requires, as of July 2017, ~$7000 to sequence 1 cat genome, which is >7x more than it would cost to sequence a human genome via Ver­i­tas, and they have sequenced 53 cats, increas­ing to 131 by Feb­ru­ary 2019 as their 30x WGS cost has appar­ently dropped to ~$1500; to sequence “”, tar­geted $6500 in May 2015). As cat­nip response appears some­what sim­i­lar across the felids, a suc­cess­ful find of a cat­nip gene in another species might make it much eas­ier to find it in cats, reduc­ing the sam­ple size require­ment.

    For­tu­nate­ly, cats are oth­er­wise not expen­sive to test, as a num­ber of suc­cess­ful exist­ing feline sali­va-based genetic tests indi­cate (Lyons 2009, , ): as of August 2017, the UC Davis Vet­eri­nary Genet­ics Lab­o­ra­tory offers coat col­or, ances­try, parent­age, blood group, genetic dis­eases (Pro­gres­sive Reti­nal Atrophy/PRA-PK Defi­cien­cy, Glyco­gen Stor­age Dis­ease Type IV, GM1 & GM2 Korat Gan­gliosi­do­sis, Poly­cys­tic Kid­ney Dis­ease etc) for prices rang­ing $40-$120; the UK Lang­ford Vets (Uni­ver­sity of Bris­tol) offers a sim­i­lar list of tests start­ing at £36.60/$48; the US ’s offers a more lim­ited selec­tion but again all for $45. The Mor­ris Ani­mal Foun­da­tion spon­sored devel­op­ment of an Illu­mina feline SNP array (the “Illu­mina Infinium iSe­lect 63K Cat DNA Array”) start­ing around 2011 (with unfor­tu­nately a lim­ited selec­tion of only 70k SNPs as opposed to the 500k+ stan­dard in human SNP arrays), and as of 2014, was offer­ing it for$100 to researchers. Hence, it is plau­si­ble that after dis­cov­er­ing the cat­nip allele, the cost of test­ing a sin­gle cat might be <$50.

    Once a genetic test does become avail­able at suffi­ciently low cost, it offers by far the fastest and most pow­er­ful selec­tion method. Given a genetic test for the cat­nip allele (as a com­mon vari­ant, it is likely eas­ily tested for), breed­ing could be con­ducted in 1 gen­er­a­tion: test the pop­u­la­tion of cat­nip respon­ders, and breed only the homozy­gous dom­i­nant cats (ie the cats with 2 copies), who make will make up ~ of the pop­u­la­tion. All off­spring will then also be homozy­gous dom­i­nant & thus cat­nip respon­ders, and cat­nip response rates will be 100% bar­ring any fur­ther intro­duc­tion from out­side the breed­ing pop­u­la­tion of reces­sive car­ri­ers. This sort of sin­gle-gen­er­a­tion selec­tion would be doable at fairly mod­est total cost, <$100k (eg start with 1000 cats, test for cat­nip respon­se; about half will respond, and test­ing each at $50 would cost ~$25k, of which about half will be homozy­gous rather than het­erozy­gous, giv­ing a large found­ing pop­u­la­tion of ~250 cats all of whose descen­dants will be cat­nip respon­der­s).

  2. Mendelian auto­so­mal dom­i­nant: phe­no­typic selec­tion: ~9 gen­er­a­tions to near-u­ni­ver­sal­ity (>=99%)

    Assum­ing there is no genetic test, one can instead breed based on the observed phe­no­type of cat­nip respon­se; this will be slower and less effi­cient because het­erozy­gous and homozy­gous can­not be dis­tin­guished.

    But if Todd is cor­rect about the allele being dom­i­nant, cat­nip response is still eas­ily bred, since selec­tion against a reces­sive pro­ceeds fast when start­ing from a high fre­quen­cy. Under the Mendelian auto­so­mal dom­i­nant the­o­ry, if the cat­nip reces­sive is present at per Todd 1962, and we would like to decrease the rate of cat­nip resis­tance in a breed to <=1%, then we need to decrease the fre­quency to . If we breed only cat­nip respon­ders (which for­tu­nately are the major­ity already), this cor­re­sponds to a s=1, and the num­ber of gen­er­a­tions has the sim­ple equa­tion (more gen­eral treat­ments: 1, 2) or gen­er­a­tions. Cats mature repro­duc­tively at 18 months & preg­nancy is around 2 months, so 8.2 gen­er­a­tions would take ~14 years (). So a phe­no­typic cat­nip breed­ing pro­gram need not take an infea­si­ble amount of time based on Todd 1962’s esti­mates.

  3. poly­genic lia­bil­i­ty-thresh­old: phe­no­typic selec­tion: ~25 gen­er­a­tions to near-u­ni­ver­sal­ity

    Alter­na­tive­ly, if Todd is incor­rect about cat­nip being Mendelian dom­i­nant con­trolled trait, it still appears to run in fam­i­lies & species and thus have a genetic basis, so, since the trait appears bina­ry, the true genetic archi­tec­ture might then be a trait. Phe­no­typic selec­tion in the lia­bil­ity thresh­old trait depends on the pop­u­la­tion fre­quency of the trait (which defines the unob­served latent thresh­old’s start­ing point, and effi­cacy slows at the extremes of 0 and 1) and on the her­i­tabil­ity of the trait (which defines the genetic response to each gen­er­a­tion of selec­tion; unfor­tu­nate­ly, unknown for cat­s). Large-s­cale human twin stud­ies such as Pol­d­er­man et al 2015 turn in a grand mean across all stud­ied human traits of ~50% her­i­tabil­i­ty, and the largest mul­ti­-be­hav­ioral-trait cat her­i­tabil­ity study I know of, , like­wise obtains tight esti­mates of 50–50% her­i­tabil­i­ty, so a pri­ori one would expect a rea­son­ably high her­i­tabil­i­ty, and Vil­lani 2011’s large cat­nip results indi­cate, con­sid­er­ing the mea­sure­ment error, a her­i­tabil­ity of at least 0.7, so we will con­sider that sce­nar­io:

    threshold_select <- function(fraction_0, heritability) {
        fraction_probit_0 = qnorm(fraction_0)
        ## threshold for not manifesting schizophrenia:
        s_0 = dnorm(fraction_probit_0) / fraction_0
        ## new rate of schizophrenia after one selection where 100% of schizophrenics never reproduce:
        fraction_probit_1 = fraction_probit_0 + heritability * s_0
        fraction_1 = pnorm(fraction_probit_1)
        ## how much did we reduce schizophrenia in percentage terms?
        print(paste0("Start: population fraction: ", fraction_0, "; liability threshold: ", fraction_probit_0, "; Selection intensity: ", s_0))
        print(paste0("End: liability threshold: ", fraction_probit_1, "; population fraction: ", fraction_1, "; Total population reduction: ",
            fraction_0 - fraction_1, "; Percentage reduction: ", (1-((1-fraction_1) / (1-fraction_0)))*100))
    heritability <- 0.70; frac <- 0.61
    threshold_select(frac, heritability)
    # ...
    # [1] 0.7641164429
    generations <- 0;
    while (frac < 0.99) { frac <- threshold_select(frac, heritability); generations <- generations+1 }
    # ...
    # [1] 25

    Pro­gress, while ini­tially swift (eg get­ting to 95% only takes ~7 gen­er­a­tions), slows down rapidly towards the tar­get of 99% response rates. The selec­tion, espe­cially towards the end, could be improved by tak­ing into account genetic infor­ma­tion such as pedi­gree or GWAS-based poly­genic scores in order to select against cats with a high lia­bil­ity for cat­nip resis­tance but who do not dis­play the phe­no­type; mod­el­ing that, how­ev­er, would be diffi­cult with­out more data.

  1. For exam­ple, Todd 1962’s genetic analy­sis was based on just 34 cats of which 7 cats’ response were unknown; as far as I can tell, another pedi­gree analy­sis has never been done since then, much less extended to newer genetic meth­ods like or GWASes, although it con­tin­ues to be cited as the jus­ti­fi­ca­tion for treat­ing cat­nip response as an auto­so­mal dom­i­nant genetic trait.↩︎

  2. An exam­ple of founder effects in cat pop­u­la­tions are the feral cats of , whose fur col­ors are >95% black (or black with white spot­s): Dreux 1970, Todd 1971, Dreux 1974, Pas­cal 1994, Pon­tier et al 2004 ↩︎

  3. If cat­nip sen­si­tiv­ity fre­quency was 70% in 1950, and for the sake of argu­ment we accepted that the pro­por­tion had decreased ~0.0024 per year and was 54.16% in 2016, and we also accept Todd 1962’s analy­sis that cat­nip sen­si­tiv­ity is a dom­i­nant gene, then that implies that the fre­quency of the gene in 1950 was and so in 1950 p = 0.45; sim­i­lar­ly, , and so in 2016 p = 0.30, so the gene fre­quency would’ve fallen by 0.15 from 1950 to 2016. If a domes­tic or wild cat gen­er­a­tion is 3 years, then that 66 years is >22 cat gen­er­a­tions, and divid­ing a total fall of 15% over that peri­od, the gene fre­quency would be falling ~0.68% per gen­er­a­tion.

    While this could be caused by fairly weak selec­tion against cat­nip respon­ders, it’s hard to imag­ine what could cause that selec­tion or how it is con­sis­tent with the con­tin­ued exis­tence of cat­nip respon­ders given that: cat­nip has no known ill effects on cats, is rarely found in the wild, most cats are never exposed, those cats which are exposed at all tend to be pets which are spayed/neutered, no solid sex or breed cor­re­la­tion has been observed, and the exis­tence of cat­nip respon­ders has been doc­u­mented for cen­turies (ac­cord­ing to Tucker & Tucker 1988, , died 1705, was the first, and Gary Lock­hart attrib­utes the first men­tion of cats/catnip to , died 1048).↩︎