“Near-chromosomal de novo assembly of Bengal tiger genome reveals genetic hallmarks of apex-predation”, (2022-05-17):
The tiger, a poster child for conservation, remains an endangered apex predator. Continued survival and recovery will require a comprehensive understanding of their genetic diversity and the use of such information for population management. A high-quality tiger genome assembly will be an important tool for conservation genetics, especially for the Indian tiger, the most abundant subspecies in the wild.
Here, we present high-quality near-chromosomal genome assemblies of a female and a male wild Indian tiger (Panthera tigris tigris). Our assemblies had a scaffold N50 of >140 Mb, with 19 scaffolds, corresponding to the 19 numbered chromosomes, containing 95% of the genome. Our assemblies also enabled detection of longer stretches of runs of homozygosity compared to previous genome assemblies which will improve estimates of genomic inbreeding. Comprehensive genome annotation identified 26,068 protein-coding genes, including several gene families involved in key morphological features such as the teeth, claws, vision, olfaction, taste and body stripes. We also identified 301 microRNAs, 365 small nucleolar RNAs, 632 tRNAs and other noncoding RNA elements, several of which are predicted to regulate key biological pathways that likely contribute to the tigers apex predatory traits. We identify signatures of positive selection in the tiger genome that are consistent with the Panthera lineage.
Our high-quality genome will enable use of non-invasive samples for comprehensive assessment of genetic diversity, thus supporting effective conservation and management of wild tiger populations.
“Cranial volume and palate length of cats, Felis spp., under domestication, hybridization and in wild populations”, (2022-01-26; similar):
Reduced brain size, compared with wild individuals, is argued to be a key characteristic of domesticated mammal species, and often cited as a key component of a putative ‘domestication syndrome’. However, brain size comparisons are often based on old, inaccessible literature and in some cases drew comparisons between domestic animals and wild species that are no longer thought to represent the true progenitor species of the domestic species in question.
Here we replicate studies on cranial volumes in domestic cats that were published in the 1960s and 1970s, comparing wildcats, domestic cats and their hybrids.
Our data indicate that domestic cats indeed, have smaller cranial volumes (implying smaller brains) relative to both European wildcats (Felis silvestris) and the wild ancestors of domestic cats, the African wildcats (Felis lybica), verifying older results. We further found that hybrids of domestic cats and European wildcats have cranial volumes that cluster between those of the 2 parent species. Apart from replicating these studies, we also present new data on palate length in Felis cat skulls, showing that domestic cat palates are shorter than those of European wildcats but longer than those of African wildcats.
Our data are relevant to current discussions of the causes and consequences of the ‘domestication syndrome’ in domesticated mammals.
“Complex feline disease mapping using a dense genotyping array”, (2021-08-09; similar):
The current feline genotyping array of 63k single nucleotide polymorphisms has proven its utility within breeds, and its use has led to the identification of variants associated with Mendelian traits in purebred cats. However, compared to single gene disorders, association studies of complex diseases, especially with the inclusion of random bred cats with relatively low linkage disequilibrium, require a denser genotyping array and an increased sample size to provide statistically-significant associations. Here, we undertook a multi-breed study of 1,122 cats, most of which were admitted and phenotyped for nine common complex feline diseases at the Cornell University Hospital for Animals. Using a proprietary 340k single nucleotide polymorphism mapping array, we identified significant genome-wide associations with hyperthyroidism, diabetes mellitus, and eosinophilic keratoconjunctivitis. These results provide genomic locations for variant discovery and candidate gene screening for these important complex feline diseases, which are relevant not only to feline health, but also to the development of disease models for comparative studies.
“CC, world’s first cloned cat, turns 18 years old”, (2020-01-02; ; backlinks; similar):
The first of her kind, CC the cloned cat is breaking more boundaries as she turns 18 years old. There are no big plans locally to mark the day, but CC—Carbon Copy or Copy Cat—will be the focus of a Dutch cartoon set for release today to celebrate her birthday, researcher and owner Duane Kraemer said.
…CC is not only enjoying life as the Kraemers’ pet, but she has her own condo called the “kitty house” behind the Kraemers’ house where she lives with her three offspring, sired by a cat named Smokey. Those offspring, just by existing, helped CC make headlines in the scientific community. There had not been much research done in the reproduction success of clones—and none had been done with a cat. Tim, Zip and Tess were born Sept. 1, 2006, along with a fourth kitten that was stillborn. Not knowing CC’s reaction would be to her kittens, Kraemer said, they found CC was “the perfect mother” and had the innate maternal instincts they were hoping she would exhibit. Besides proving clones can successfully reproduce, CC also proved not all clones die young. “Dolly the sheep, that was the first of the mammals to be cloned by nuclear transfer, had died at, I think, at 6 years of age”, Kraemer said. “So the fact that CC didn’t die young was news.” About 20% of cloned animals have developmental abnormalities of some kind, he said, with some being serious enough to result in the animal’s death at a young age or at birth. However, the other 80% born without those conditions “would probably live to a normal variation of ages.”
“Throwing the Baby Out With the Bath Water: Could Widespread Neutering of Companion Dogs Cause Problems at a Population Level?”, (2019-07-22; ; backlinks; similar):
In many countries where companion dogs are popular, owners are strongly encouraged to neuter their dogs. Consequently, millions of dogs are neutered each year. In recent times considerable attention has been paid to the possible effects of such procedures on canine health and welfare. Less scrutinized are the potential ramifications of widespread neutering on the breeding of dogs and their continued success as human companions. This paper summarizes research investigating factors influencing the breeding and rearing of dogs most suited to companionship roles in contemporary, typically high-density, communities, and briefly reviews current breeder practices. It then argues that a fundamental shift to promote inclusion of “proven” companion dogs in the gene pool, as opposed to dogs meeting conformation or working/sporting standards, is required to successfully meet the needs of modern urban dog owners. A new model is proposed, whereby responsible owners and breeders work together to produce dogs most suited for life as human companions.
…The demonstrated importance of genetics and early environment in determining behavioral predispositions makes it imperative to consider where companion dogs come from. Prior to the widespread introduction of neutering practices, dogs often bred indiscriminately, and people typically obtained their dogs for free from neighbors whose bitch had produced a litter (47). While this was problematic in terms of creating dog overpopulation, it meant that most of the dogs who produced offspring were well suited to the demands of the lives they were expected to lead. Those who weren’t well-suited were disposed of. Today, strong demand for companion dogs, coupled with rapid urbanization, increased concern regarding the welfare of animals, particularly companion dogs, and high neutering rates, has resulted in a multimillion-dollar industry involving the selective breeding and selling of puppies (48). Widespread neutering means that humans intentionally control nearly all dog breeding in developed countries…As described previously, in many developed countries, neutering companion dogs is considered an important aspect of responsible ownership. Hence, the very best companion dogs in the general community, those owned by responsible citizens who choose their dogs carefully and ensure they are reared correctly, are almost certainly those most likely to be neutered. Conversely, it is those companion dog owners who fail to perform the “responsible” behavior of neutering their dog who are perhaps most likely to breed. These “breeders” may also choose not to perform other “responsible” behaviors, such as selecting their dog carefully, testing it for genetic disorders, or evaluating the dog’s suitability as a companion prior to allowing it to reproduce. In other words, they may not thoroughly consider the genetic and environmental factors known to be critical to optimal puppy development.
Second, we advocate that all dogs should be independently tested for suitability before being bred—much as breeders now advertise that their puppies’ parents are successful show dogs, or that they are free from known genetic disorders, so they should be encouraged to advertise that independent testing has shown their breeding dogs to be well-suited behaviourally to life as human companions. We anticipate that responsible breeders would be willing to pay for this independent certification, much as they presently pay for genetic tests, eye screening and tests for hip dysplasia. Several behavioral tests exist to measure specific traits, such as the Socially Acceptable Behavior test (64), which measures aggression, or the Dog Mentality Assessment test (65), which examines levels of playfulness, curiosity, aggression, sociability, and chase-proneness. In the USA, the Canine Good Citizen program, administered by the American Kennel Club, takes <30 min to administer and is designed to identify dogs that meet ten objectives consistent with being a good companion dog. Any one of these tests could be used as a basis for developing an assessment suited to breeding dogs—dogs that are not themselves good companions are less likely to produce puppies able to excel at this role.
“Breed differences of heritable behaviour traits in cats”, (2019-05-28; ; backlinks; similar):
Cat domestication and selective breeding have resulted in tens of breeds with major morphological differences. These breeds may also show distinctive behaviour differences; which, however, have been poorly studied. To improve the understanding of feline behaviour, we examined whether behavioural differences exist among cat breeds and whether behaviour is heritable. For these aims, we utilized our extensive health and behaviour questionnaire directed to cat owners and collected a survey data of 5726 cats. Firstly, for studying breed differences, we utilized logistic regression models with multiple environmental factors and discovered behaviour differences in 19 breeds and breed groups in ten different behaviour traits. Secondly, the studied cat breeds grouped into four clusters, with the Turkish Van and Angora cats alone forming one of them. These findings indicate that cat breeds have diverged not only morphologically but also behaviourally. Thirdly, we estimated heritability in three breeds and obtained moderate heritability estimates in seven studied traits, varying from 0.4 to 0.53, as well as phenotypic and genetic correlations for several trait pairs. Our results show that it is possible to partition the observed variation in behaviour traits into genetic and environmental components, and that substantial genetic variation exists within breed populations.
Cat-Sense: “Cat Psychology & Domestication: Are We Good Owners?”, (2018-11-03; ; backlinks; similar):
Extended book review of Bradshaw 2013 (Cat Sense) on the connections between cat psychology, evolution/genetics, history of domestication or lack thereof, & possible dysgenics, highlighting modern maladaptivity of cat psychology, with fulltext bibliography of key references.
I review John Bradshaw’s book on domestic cat psychology, Cat Sense, after difficulties dealing with my own cat. Bradshaw reviews the history of domestic cats from their apparent Middle Eastern origins as a small solitary desert predator to their domestication in Ancient Egypt where breeding millions of cats for sacrifice may have played a critical role (as opposed to any unique role as a vermin exterminator) through to the modern day and psychological studies of the learning abilities and personalities of cats, with particular emphasis on cat social skills in “cat colonies” & plasticity in kittenhood. As Bradshaw diagnoses it, these are responsible for what ability they have to modern pet life, even though they are not bred for this like dogs; every tame cat still has the feral cat in them, and are in many ways unsuited for contemporary living, with disturbing hints that human lack of selective breeding plus recent large-scale spay/neuter population control efforts may be producing a subtle dysgenic effect on domestication, and this double neglect & backfire may be responsible for disturbingly high rates of cat maladaptation & chronic stress diseases.
Clone: “Dog Cloning For Special Forces: Breed All You Can Breed”, (2018-09-18; ; backlinks; similar):
Decision analysis of whether cloning the most elite Special Forces dogs is a profitable improvement over standard selection procedures. Unless training is extremely cheap or heritability is extremely low, dog cloning is hypothetically profitable.
Cloning is widely used in animal & plant breeding despite steep costs due to its advantages; more unusual recent applications include creating entire polo horse teams and reported trials of cloning in elite police/Special Forces war dogs. Given the cost of dog cloning, however, can this ever make more sense than standard screening methods for selecting from working dog breeds, or would the increase in successful dog training be too low under all reasonable models to turn a profit?
I model the question as one of expected cost per dog with the trait of successfully passing training, success in training being a dichotomous liability threshold with a polygenic genetic architecture; given the extreme level of selection possible in selecting the best among already-elite Special Forces dogs and a range of heritabilities, this predicts clones’ success probabilities. To approximate the relevant parameters, I look at some reported training costs and success rates for regular dog candidates, broad dog heritabilities, and the few current dog cloning case studies reported in the media.
Since none of the relevant parameters are known with confidence, I run the cost-benefit equation for many hypothetical scenarios, and find that in a large fraction of them covering most plausible values, dog cloning would improve training yields enough to be profitable (in addition to its other advantages).
As further illustration of the use-case of screening for an extreme outcome based on a partial predictor, I consider the question of whether height PGSes could be used to screen the US population for people of NBA height, which turns out to be reasonably doable with current & future PGSes.
2017-ottoni.pdf: “The palaeogenetics of cat dispersal in the ancient world”, (2017-06-19; backlinks):
The cat has long been important to human societies as a pest-control agent, object of symbolic value and companion animal, but little is known about its domestication process and early anthropogenic dispersal.
Here we show, using ancient DNA analysis of geographically and temporally widespread archaeological cat remains, that both the Near Eastern and Egyptian populations of Felis silvestris lybica contributed to the gene pool of the domestic cat at different historical times.
While the cat’s worldwide conquest began during the Neolithic period in the Near East, its dispersal gained momentum during the Classical period, when the Egyptian cat successfully spread throughout the Old World. The expansion patterns and ranges suggest dispersal along human maritime and terrestrial routes of trade and connectivity. A coat-colour variant was found at high frequency only after the Middle Ages, suggesting that directed breeding of cats occurred later than with most other domesticated animals.
Catnip: “Catnip immunity and alternatives”, (2015-11-07; ; backlinks; similar):
Estimation of catnip immunity rates by country with meta-analysis and surveys, and discussion of catnip alternatives.
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 Cat Sense review.
2014-montague.pdf: “Comparative analysis of the domestic cat genome reveals genetic signatures underlying feline biology and domestication”, (2014-10-03; ; backlinks; similar):
Little is known about the genetic changes that distinguish domestic cat populations from their wild progenitors. Here we describe a high-quality domestic cat reference genome assembly and comparative inferences made with other cat breeds, wildcats, and other mammals. Based upon these comparisons, we identified positively selected genes enriched for genes involved in lipid metabolism that underpin adaptations to a hypercarnivorous diet. We also found positive selection signals within genes underlying sensory processes, especially those affecting vision and hearing in the carnivore lineage. We observed an evolutionary tradeoff between functional olfactory and vomeronasal receptor gene repertoires in the cat and dog genomes, with an expansion of the feline chemosensory system for detecting pheromones at the expense of odorant detection. Genomic regions harboring signatures of natural selection that distinguish domestic cats from their wild congeners are enriched in neural crest-related genes associated with behavior and reward in mouse models, as predicted by the domestication syndrome hypothesis. Our description of a previously unidentified allele for the gloving pigmentation pattern found in the Birman breed supports the hypothesis that cat breeds experienced strong selection on specific mutations drawn from random bred populations. Collectively, these findings provide insight into how the process of domestication altered the ancestral wildcat genome and build a resource for future disease mapping and phylogenomic studies across all members of the Felidae.
2011-villani.pdf: “Heritability and Characteristics of Catnip Response in Two Domestic Cat Populations”, (2011; ; backlinks; similar):
The domestic cat response to catnip is unique in nature as it represents a repeatable, recognizable behavioral response to an olfactory stimulus that appears to have little evolutionary importance. There is clear variation in response between cats and this has been attributed to genetic factors in the past.
These factors are explored in this study using behavioral observation after presenting of catnip to cats in two different research colonies with different environmental and genetic backgrounds. The response trait is defined [as a liability-threshold model trait] and [Bayesian] Gibbs sampling methods are used to explore a mixed model for the trait to determine genetic effects.
Heritabilities obtained in the two colonies for the most important response behaviors, the head over roll and cheek rub, were 0.511 and 0.794 using catnip spray and dried catnip respectively. No clear Mendelian mode of inheritance was ascertained in either colony.
The variation in response behaviors and intensity seen in the two colonies reflects the complex nature of expression of the catnip response, but there is a clear genetic influence on the feline predisposition to responding.
“Interspecies Implantation and Mitochondria Fate of Panda-Rabbit Cloned Embryos”, (2002-08-01; ; similar):
Somatic cell nuclei of giant pandas can dedifferentiate in enucleated rabbit ooplasm, and the reconstructed eggs can develop to blastocysts.
In order to observe whether these interspecies cloned embryos can implant in the uterus of an animal other than the panda, we transferred approximately 2,300 panda-rabbit cloned embryos into 100 synchronized rabbit recipients, and none became pregnant. In another approach, we co-transferred both panda-rabbit and cat-rabbit interspecies cloned embryos into the oviducts of 21 cat recipients. 14 recipients exhibited estrus within 35 days; 5 recipients exhibited estrus 43–48 days after embryo transfer; and the other 2 recipients died of pneumonia, one of which was found to be pregnant with 6 early fetuses when an autopsy was performed.
Microsatellite DNA analysis of these early fetuses confirmed that 2 were from giant panda-rabbit cloned embryos. The results demonstrated that panda-rabbit cloned embryos can implant in the uterus of a third species, the domestic cat. By using mitochondrial-specific probes of panda and rabbit, we found that mitochondria from both panda somatic cells and rabbit ooplasm coexisted in early blastocysts, but mitochondria from rabbit ooplasm decreased, and those from panda donor cells dominated in early fetuses after implantation.
Our results reveal that mitochondria from donor cells may substitute those from recipient oocytes in post-implanted, interspecies cloned embryos.
2000-ruizgarcia.pdf: “Is there really natural selection affecting the I frequencies (long hair) in the Brazilian cat populations?”, (2000; ; similar):
The scientific literature on cat genetics contains a presumed typical example of natural selection affecting I frequencies (long hair) in 16 Brazilian cat populations. It has been observed that the hotter and more tropical the climate in Brazil, the lower the values of I frequencies in the cat populations.
Nevertheless, this study of some new cat populations in Latin America showed that all of them, independent of the climate, had high or very high I frequencies.
I postulate that an alternative migrational-historical hypothesis exists that explains the correlation between the I frequencies and climate characteristics (which are correlated with the latitude) without using natural selection explanations concerning the appearance of the I allele in Brazil.
1999-bradshaw.pdf: “Feral cats: their role in the population dynamics of Felis catus”, (1999-12; ; backlinks):
The so-called domestic cat occupies an unique position within the truly domestic animals since it freely interbreeds with feral populations, and there is considerable gene flow in both directions. This is possible because the likelihood of an individual cat forming a relationship with people is strongly affected by its experiences during the socialisation period (3–8 weeks of age), although this does not preclude differences between owned and feral populations in the relative frequencies of alleles which affect social behaviour towards humans.
We suggest a hitherto unconsidered reason why a separate domesticated population of cats (apart from pedigree breeds) has not yet emerged: the unusual and stringent nutrient requirements of the cat may historically have militated against successful breeding on a completely human-provided diet, and led to the retention of the ability to achieve a nutritionally complete diet by scavenging and/or hunting. More recently, the widespread availability of nutritionally complete manufactured foods and veterinary care in western countries appears to be leading towards a rapid change in the population dynamics and population genetics of both owned and feral cats.
[Keywords: domestication, feral populations, population dynamics, cat]
“Early Canid Domestication: The Farm-Fox Experiment: Foxes bred for tamability in a 40-year experiment exhibit remarkable transformations that suggest an interplay between behavioral genetics and development”, (1999-03; ; backlinks; similar):
[Popular review of the domesticated red fox by the lead researcher. Trut gives the history of Belyaev’s founding of the experiment in 1959, and how the results gradually proved his theory about ‘domestication syndrome’: that domestication produces multiple simultaneous effects like floppy ears despite the foxes being bred solely for being willing to approach a strange human, suggesting an underlying common genetic mechanism]
Forty years into our unique lifelong experiment, we believe that Dmitry Belyaev would be pleased with its progress. By intense selective breeding, we have compressed into a few decades an ancient process that originally unfolded over thousands of years. Before our eyes, “the Beast” has turned into “Beauty”, as the aggressive behavior of our herd’s wild progenitors entirely disappeared. We have watched new morphological traits emerge, a process previously known only from archaeological evidence. Now we know that these changes can burst into a population early in domestication, triggered by the stresses of captivity, and that many of them result from changes in the timing of developmental processes. In some cases the changes in timing, such as earlier sexual maturity or retarded growth of somatic characters, resemble pedomorphosis. Some long-standing puzzles remain. We believed at the start that foxes could be made to reproduce twice a year and all year round, like dogs. We would like to understand why this has turned out not to be quite so. We are also curious about how the vocal repertoire of foxes changes under domestication. Some of the calls of our adult foxes resemble those of dogs and, like those of dogs, appear to be holdovers from puppyhood, but only further study will reveal the details. The biggest unanswered question is just how much further our selective-breeding experiment can go. The domestic fox is not a domestic dog, but we believe that it has the genetic potential to become more and more doglike.
1991-tomkies-wildcats.pdf: “Wildcats”, Mike Tomkies, Denys Ovenden (1991-01-01)
1989-mellen.pdf: “Reproductive behavior of small captive exotic cats (Felis spp.)”, (1989):
The focus of this dissertation was on species in the genus, Felis, maintained in captivity. With the exception of the domestic cat, all species of small cats (Felis) are threatened or endangered in at least some portion of their original range and although captive propagation of some groups of animals has facilitated their preservation, zoos have not been particularly successful in breeding small cats. These felids reproduce inconsistently, at best, in captivity. The purpose of this dissertation research was to examine behavioral aspects of reproduction of small cats (Felis) in a captive environment, to determine why reproductive success is limited, and to offer suggestions for improving their reproductive potential.
- Part I of the dissertation examined whether or not estrus could be detected and monitored solely through systematic behavioral observations. The behavior of 61 individuals representing 15 species of felids housed at 7 zoological institutions was systematically recorded for a total of 485 hours. Estrus was detectable using behavioral observations. In addition, it was found that compatibility of a pair and specific behavioral indicators of estrus could be determined through behavioral observations. Other reproductive parameters, eg. length of estrus and gestation, birth season, litter size, and age at maturity, were gleaned from zoo records. Information on size of captive populations and level of inbreeding for these species was also collected and analyzed.
- In Part II of this dissertation, the effects of early rearing experience on subsequent adult sexual behavior were examined. It is a pervasive opinion among zoo professionals that hand/human-raised felids are less likely to reproduce than are maternally-raised cats. However, numerous exceptions, ie. hand-raised cats, have reproduced. An experiment was conducted to examine the effects of hand-rearing on adult sexual behavior, using domestic cats as a model for captive small exotic cats. Results from this experiment demonstrate that hand-rearing substantially reduces the cats’ ability to reproduce. Implications for rearing techniques in zoo nurseries are discussed.
- Part III of this dissertation presents suggestions for the management of these cats in captivity, both at the level of the individual (husbandry protocol) and at the level of the captive population (population management).
1965-scott-geneticsandthesocialbehaviorofthedog.pdf: “Genetics and the Social Behavior of the Dog [Dog Behavior: The Genetic Basis]”, (1965; ):
Classic study of dog behavior, the authoritative information from 20 years of research at the Jackson Laboratory. The authors synthesize developmental problems and canine genetics, based on study of 470 dogs. Central to the book is the role heredity plays in the development of behavior. Giving puppies an environment designed on the principles of a well-run school, Scott and Fuller tested five breeds representing the major dog groups and carried out a Mendelian experiment with two of the most different breeds: The basenji and the cocker spaniel. They found that heredity affects almost every trait tested; that gender affects aggressiveness and the dominance order, but not trainability and problem-solving; that emotional traits profoundly influence performance; that, although breeds differ widely in emotional and motivational characteristics, none shows distinct superiority in problem solving; and that detailed statistical analyses indicate a highly complex pathway between primary gene action and its final effect on behavior. Includes important information on rearing methods, the origin and history of dog breeds, basic behavior patterns and the psychological and behavioral development of puppies. Their careful scientific work demonstrated the importance and existence of time limited phases in the early life of dogs within which certain experiences need to occur or the dogs may be forever deficient. Their work (with that of Eckhard Hess’s on ducks and geese) demonstrated that these critical or sensitive periods in early development could be scientifically studied in ways compatible with a scientific psychology. This book will always be especially valuable to dog breeders and trainers; its last chapters summarize in very clear terms the particular phases in early development and experiences the dog needs to be adequately socialized. The reader can refer back to earlier chapters to get more information on how the experiments were conducted and the distribution of results. It answers questions on proper age that puppies can be separated from their mothers, what experiences are important to provide at what age, etc. Originally published in 1965. [ISBN: 0–226–74335–7]
1962-todd.pdf: “Inheritance of the catnip response in domestic cats”, (1962; ; backlinks; similar):
Four behavioral components of the catnip response are described briefly. The analysis of a pedigree indicates that responding is inherited as an autosomal dominant. Other aspects of inheritance of the catnip response are discussed.
An essential oil, nepetalactone, was isolated from the catnip plant (Nepeta cataria) by McElvain et al 1941/1942/1955 2, 3, 4 and Meinwald 5. McElvain2 demonstrated with lions that the oil is the substance which is responsible for the attraction of cats to the plant and the only constituent capable of inducing a response. This familiar response has been broken down into four components, viz, 1. sniffing, 2. licking and chewing with head shaking, 3. chin and cheek rubbing and 4. head-over roll and body rubbing. None of these automatisms is unique to catnip, each of them apparently belonging normally to sexual or ingestive behavior1. These components almost invariably appear in the above sequence. In fact, among 58 responding cats, all tested with dried leaves, only 3 individuals deviated from this sequence and omitted the licking and chewing with head shaking. These animals went immediately into the rolling phase, which seemed to be exceptionally violent. Component four may last from three to six minutes before all response is extinguished. Additional behavior patterns noted occasionally are claw sharpening and washing, both of which occur as displacement activities in the ethological sense in sexual behavior1.
Among responding animals the response may occasionally be inhibited for obscure reasons, necessitating repeated testing of non-responders before drawing conclusions. Also, the response is not manifested in kittens under 6 to 8 weeks of age and may not develop fully until three months of age. In fact, catnip often produces a distinct avoidance response in young kittens which is gradually replaced by indifference in non-responders and by heightened curiosity in responders. Whether nursing is in any way connected with inhibiting the response has not yet been determined. In one case a 6- to 7-week-old nursing kitten gave a total response, but this seems exceptional. A distressed or enraged animal may still respond, and neutering appears to have no effect on behavior towards catnip.