The author claims 20 generations would be enough to breed the powers shown and thousands is unrealistic:
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even the most pessimistic estimates of how many generations it might take to drastically increase average human intelligence or almost entirely eliminate a nasty recessive by R.A. Fisher might be 20 generations .
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But some of the powers, like remembering ancestors memories barely even exist in humans today. The field of epigenetics has proven that a starving parent can alter how the genetics of even grandchildren express themselves. So some basic functions like wrapping DNA tighter or loser and adding a methyl chemical group exist to pass information across generations, but this is like an extra bit or two per gene. To extend the functionality to the level of recording memories would take almost as long as it took for DNA to become as fancy as it did from the original RNA molecules that could produce more of themselves without any enzymes or DNA having developed yet. So almost as long again as life itself has taken, not 20 years.
> But some of the powers, like remembering ancestors memories barely even exist in humans today.
That would be a valid point... except why are they still breeding for things like intelligence? That was my point. Thousands of generations later, they're still breeding for basic stuff like enhanced intelligence, which makes little sense under pretty much everything we know about intelligence's genetics.
> The field of epigenetics has proven that a starving parent can alter how the genetics of even grandchildren express themselves.
The extent to which transgenerational heritable epigenetics matters in humans has been wildly exaggerated by the media and the field is rife with overinterpretations, small samples, and non-replication.
Not to mention, even that hype didn't exist when Herbert was writing it, so he couldn't've been thinking of it. I am fairly sure he was gesturing towards a more Akashi-Records-style psi mechanism with access granted by ancestry, not actual encoding of memories into spare DNA (which among other things would mean no ancestor would remember anything after having a kid).
> To extend the functionality to the level of recording memories would take almost as long as it took for DNA to become as fancy as it did from the original RNA molecules that could produce more of themselves without any enzymes or DNA having developed yet.
Neurons already re-edit and splice their chromosomal DNA, so the mechanisms are already there for at least part of it.
I always assumed that the BG were directing genetic averages across whole populations, and/or had such a deep understanding of genetics that they could predict the exact result of two peoples genes mixing.
If you could determine with 99% accuracy the exact genome of a child by their parents genomes alone, would you be able to optimize humans across given a relatively small set?
But in Dune there are mechanisms beyond genetics at work - that's why artificial insemination is prohibited - the BG believe the emotional act of copulation influences traits in the offspring.
Also "wild genes" - particularly those of the Fremen - producing unexpected results (ex: Leto II).
The Bene Tleilax though, they're probably making solid genetic projections.
No. Not even with that degree of knowledge could one effectively engineer towards a goal. Or, rather, one could engineer towards a goal but only by either accepting or ignoring profound weaknesses and drawbacks. Look at something like Golden Retrievers, for example. They were effectively developed into a distinct breed... and suffer tremendous health complications from it. It's not a matter of the breeders slipping up. It's a matter of genes and genetic activity being complex enough that all 'pure' traits are paired with 'pure' flaws. You cannot acquire one without the other.
This leaves aside the more important question raised by the scope of the Dune universe, which is defining what 'optimal' would even mean in such a world. Traits are only optimal or sub-optimal relative to an environment. Being smart and not able to move heavy objects would doom a medieval man, but being stupid but strong would hamper a modern man. That's a facile example and you'd be more likely talking about weakness to certain pathogens, dependence upon particular physical environmental needs (oxygen level, caloric availability, body temperature control efficiency, etc) though, really. If you're going to be planet-hopping and galavanting across the universe, what is optimal in one place can kill you in another and vice versa. The myth that there is a 'strongest' state is just that, a myth.
In genetics, diversity always wins. Flexibility and complexity always wins. Being mediocre at everything is a far greater survival trait than being a master at one is if it means you are a total failure on another count. Living things can only fail once.
It is a little handwavy, but perhaps the BG worked for generations to achieve key areas of hybrid superiority by honing pure breeding lines in these two families? Does not seem to be what the BG are doing, though.
Furthermore, one can now ask if the more perfect specimen for a given environment might be a chimera: this genome for nervous system, that genome for leg muscles, this other genome for internal organs, etc.
But your main point stands. The Dune series presumes that such a thing as breeding a superior human is not very difficult to manage on the scale of mere centuries. I am not sure how even define such a thing. And I rather doubt such a specimen would breed true with a similarly superior specimen.
Except that gene mixing is a highly quantum mechanical process, and so we are precluded from predicting the result of a single event. We can only predict the probability of a particular mix of genes. They could direct averages, but not individual events.
Of course with the spice and mentats, they could probably use some limited form of prescience to explore possible avenues the future was likely to take. It is a universe in which magic, by another name, works.
Once you accept that premise, throw rationalizations out the window. There's no point theorycrafting, just make up anything you like. Whether or not something is possible is a function of what is needed for the story. The answer to any such question is, "Do you want it to be?"
The best science fiction and fantasy begins by taking a few specific assumptions, which may be fantastical, but then exploring the consequences of those assumptions in a disciplined way. For example having one form of FTL travel with known limitations in an SF setting and exploring the possibilities within those rules.
Writers that take your approach - it’s all made up so I’ll just make up new rules whenever so feel like it - are rarely satisfying because the reader can’t trust anything or reason about the setting or the characters choices.
This is the problem with J.J. Abrams approach Star Trek and Star Wars. He seemed to take a special glee in arbitrarily violating established conventions in the settings with respect to things like how Warp Drive and Transporter technology work in Star Trek.
There is "hard" and "soft" magic in fantasy, just as there's "hard" and "soft" science in SF. A story with magic in the premise still needs that magic to have rules and limitations, even if they're not communicated to the reader - even the soft magic of myth and fairy tales needs to have some sense of internal logic.
Very interesting, but fantastic genetic traits like precognition and ancestral memories are (in fiction) a traditional good fit for the Mendelian inheritance pattern of few and high impact mutations.
I've idly wondered how you could interpret all the mutations in X-Men, but I don't know enough about the families or inheritance to make any reasonable guesses (I've seen a few cartoons and movies and that's about it). I know mutants generally have mutant kids but don't the powers differ? Which doesn't make much sense and I can't retcon it.
I have noticed, however, that in _My Little Pony_ (which I've finally gotten around to watching), it seems like earth/pegasus/unicorn traits are not races or subspecies analogous to human races but instead likely follow a polytomous liability threshold pattern. Why? Because we see the Cakes, two earth ponies, manage to have a pair of pegasus and unicorn fraternal twins, and when queried, mention they have some pegasus/unicorn ancestry. Since the pony type is mutually exclusive (we never see any pony who is both pegasus and unicorn, aside from the alicorns who are special magically-created cases), I don't know of any kind of common Mendelian trait pattern which would give a single type, normally breed true, and allow two earth pony parents with mixed ancestry to have kids who are both unicorns and pegasi (one non-earth-pony offspring would be fine as it would simply indicate a recessive discrete trait, but two different others? I don't see how that works unless you postulate some sort of multi-locus Mendelian trait with dominance of earth trait by both unicorn and pegasus, I guess?). Whereas if it's polytomous liability threshold, then that would be possible albeit unlikely, since they could inherit different fractions of ancestry and get pushed across different type thresholds.
Mendelian ponies could have a single gene with 3 alleles, E/U/P, with EE, EU and EP earth, UU and PP respectively unicorn and pegasus and UP either unicorn or pegasus at random (i.e. depending on other genes). If the two parents are EU and EP they are earth but offspring of all three types is possible.
An even simpler model: one gene with two alleles, earth and fancy, earth dominant, fancy ponies become unicorns or pegasi depending on rainbow intensity or other non-genetic factors.
In the Dune case a very Mendelian concern with preserving a few important mutations in very narrow bloodlines could be combined with a secondary requirement for high IQ, physical fitness etc. that could be (inefficiently) satisfied by focusing on "well bred" aristocracy that benefits from marrying genetically far above average people.
I feel stupid saying this, but it was explained to me as being like light through a filter, like for spider man, Parker was always going to get powers (all things being equal) but because the trigger was spider related the powers \ way he manifests them are "spider colored", like light through a keyhole, different keyhole, different image, but same light source.
With regard to the X-Men, I think they imply the "present day" is a Cambrian explosion, that then settles down in the far future into the most useful powers becoming common if less godlike levels: immortality, psi, telekinesis, and any other boring wish fulfillment.
As far as the X-Men go, very often children have similar (if not enhanced) powers compared to their parents c.f. Jean Grey and her multiple-universe-spanning offspring with some variation on tele{pathy,kinesis}.
However, in the cases where the mutation seems to not be directly inherited, the explanation lies in the "implementation details", as it were. When the X-gene activates (due to puberty, stress, etc.), it releases a protein that goes on to cause mutations in surrounding genes, seemingly at-random but not so random that you have "mutant" teens dropping dead of sudden protein deficiencies.
Why not two traits? One that determines if (Earth || !Earth) (call it the "Magic" gene) and one that determines (Pegasus || Unicorn) but only if the other gene is active.
I don't really like some of the mechanisms like dominance because it implies something for which we have no canon evidence: biases in discordant offspring towards particular types. And requires some rather specific patterns: in that case, it would require Mr and Mrs Cake to both have exactly 1 Earth/!Earth allele pair (so they become Earth but have a !Earth which can be passed on) and then each has a different Pegasus or Unicorn allele, which then also separately get passed on so they have two kids with !Earth/Pegasus and !Earth/Unicorn pairs. And it seems like if that were how it worked, you would expect way more discordant families to show up. (While polytomous threshold model can accommodate any level of rarity or stochasticness quite easily and naturally.)
This is the best write-up of Dune that I’ve ever read. Some of gwern’s stuff is kind of overcooked to a fault, and with intense focus, misses the broader prevailing drift of the topic at hand, but gwern’s got me on this one. It’s a good read.
Children of Dune and Dune Messiah are, imo, the weakest of Frank Herbert's Dune series. Persevere through those and you'll be rewarded in his later books.
It probably doesn't bear repeating at this point, but Brian Herbert's dreary offerings are pretty dismal and should be avoided by all but the most ardent Dune aficionados jonesing for a spice-fix and/or sci-fi masochists hoping to negate any enjoyment they derived from the Herbert novels.
Full disclosure: I didn't enjoy the Brian Herbert stuff.
But some of the powers, like remembering ancestors memories barely even exist in humans today. The field of epigenetics has proven that a starving parent can alter how the genetics of even grandchildren express themselves. So some basic functions like wrapping DNA tighter or loser and adding a methyl chemical group exist to pass information across generations, but this is like an extra bit or two per gene. To extend the functionality to the level of recording memories would take almost as long as it took for DNA to become as fancy as it did from the original RNA molecules that could produce more of themselves without any enzymes or DNA having developed yet. So almost as long again as life itself has taken, not 20 years.