Comments on: Genetic neoteny – how delayed genes separate human brains from chimps

By: megan

megan — Fri, 11 Nov 2011 00:19:18 +0000

Only a MAN trying to be “intellectually curious”, you know study of Greeks and social norms, hmm yah. innocent curiosity needing pictures..proof…. could EVEN COME UP with a friggin pedophilia link to the topic of this article.

@Rob C. Says: – And we’d need to see just how young or how long neoteny is extended into sexual maturity and that you know males of the species are just programmed to test it out for primal fecundity reasons, it’s nature not self aware intelligent species controllable. I would like to submit my past research done in Thailand.

By: iain

iain — Sun, 29 Mar 2009 15:33:05 +0000

I think the Vila et al dog genetics study has been superseded by these papers:
Leonard, J. A., R. K. Wayne, J. Wheeler, R. Valadez, S. Guillen, and C. Vila. 2002. Ancient DNA evidence for Old World origin of New World dogs. Science 298:1613-1616.
Savolainen, P., Y.-p. Zhang, J. Luo, J. Lundeberg, and T. Leitner. 2002. Genetic Evidence for an East Asian Origin of Domestic Dogs. Science 298:1610-1613.
and the Aurigancian dog story can be found at:
Germonpré, M., M. V. Sablin, R. E. Stevens, R. E. M. Hedges, M. Hofreiter, M. Stiller, and V. R. Després. 2009. Fossil dogs and wolves from Palaeolithic sites in Belgium, the Ukraine and Russia: osteometry, ancient DNA and stable isotopes. Journal of Archaeological Science 36:473-490.
Of course these tend to depend on an assumption that the relationship between the humans and the dogs can be defined by either the genes or the morphology. Whereas (I think) the implication of the paper that is the subject of this blog is that there may be some subtler processes involved.

By: Rob C.

Rob C. — Fri, 27 Mar 2009 18:06:38 +0000

@Paper Hand
“What benefit would attraction to sexually immature mates have?”
None that I can think of offhand (perhaps one could invent some plausible just-so stories). It might arise accidentally as an extreme of a gradual shift towards younger (looking) mates (which I now realize is closer to Brin’s point), and the shift towards younger (looking) mates would be a self-reinforcing generational loop as per the standard theory of sexual selection (except in this case it’s a bit self-referential as the sexual selection would be for sexual preference itself).
The possible replacement of younger mates by younger “looking” mates would be the driver for neoteny that I was wondering about.
@doug
“younger and presumably more fertile”
Many species have clear markers as to when individuals become fertile. We do too, but they’re a bit blurry compared to many, I think. It’s just not true that younger = more fertile. The world’s youngest mother was 5 when she gave birth (! according to my old Guinness Book of Records) but that’s the absurd (and horrible) early end of the frequency distribution—one sees a ramp-up to higher fertility rates starting at near-zero when normal puberty begins, through a peak (the age of which depends strongly on individual life-history) and gradual diminishing till menopause. (Oldest mother, same Guinness Book, gave birth at age 69).
What I was wondering about was what role, if any, pedophilia, or its cousin ephebophilia, played in the gradual neotenization of ancestral apes to humans. It now seems to me that all you’d need for neoteny to arise was a slight preference, on average, for “younger than optimal” mates.
Why such a preference could arise, or what benefit it could have (or lack of penalty), is a different question. One could, again, imagine “just-so” stories for that, but I’d prefer first to see if it could happen that way at all.

By: doug l

doug l — Fri, 27 Mar 2009 11:16:47 +0000

The issue of paedophilia and neotony is interesting though recognizing/differentiating the sociopathic variety such as sometimes seen in certain genetic conditions (Kleinfelters syndrom) from the instinctual desire to mate with younger and presumably more fertile partners, would be essential if it’s to be considered at all. As to what advantage neotony might confer in our ancestors, questions of paedophilia aside, perhaps neotony would have helped early humans in overcoming some instinctual resistance to large and complex social structures and concomitant issues of dominance and aggressoion, which in turn allow for longer infant and adolescent stages and great degree of cooperative behaviors and instincts to become more prominent and integral to what makes us so social and so human.

By: Paper Hand

Paper Hand — Fri, 27 Mar 2009 04:11:37 +0000

@Rob C.
Hmm … that’s a fascinating idea. I’m not sure how plausible it is, though. What benefit would attraction to sexually immature mates have?

By: Stefan

Stefan — Thu, 26 Mar 2009 07:22:33 +0000

Assuming you’re the real Dr. Somel,
Wow, thanks for taking the time to answer my question! It’s very interesting research.
Stefan

By: brooks

brooks — Thu, 26 Mar 2009 01:48:50 +0000

henk, paul: there is some (debatable) fossil evidence for dog domestication during the aurignacian period: http://anthropology.net/2008/10/18/a-possible-domestication-of-dogs-during-the-aurignacian-31700-years-ago/ more widely known, there is also a paper on canine genetics by vila et al suggesting genotypic divergence back 100,000 kya or more: http://www.mnh.si.edu/GeneticsLab/StaffPage/MaldonadoJ/PublicationsCV/Science_Dog_Paper.pdf

By: Lilian Nattel

Lilian Nattel — Wed, 25 Mar 2009 20:00:51 +0000

The headline is fine. It caught my attention and fits the article, an interesting one as usual!

By: Mehmet Somel

Mehmet Somel — Wed, 25 Mar 2009 19:30:28 +0000

@Stephan
Thanks for raising this point. We indeed (have to) use brain tissue from dead individuals, so you are right to wonder how much gene expression in dead brains represents those in live brains. Previous work form our lab showed that the correlation is actually quite good (http://genomebiology.com/2005/6/13/R112).
In addition, the patterns of expression change we find with age also relate to specific biological functions, such as developmental processes, which gives us more confidence. Also note that, we are studying changes with development, so any expression pattern that occurs at or after death would need to occur in different ways between children and adults (as well as between humans and chimps). This could be the case if types of death (quick or slow) among individuals correlated with age. But that was not the case among the subjects in our study.
Hope this was clear.
And Ed, thanks for covering our work!
Mehmet Somel

By: Rob C.

Rob C. — Wed, 25 Mar 2009 16:19:37 +0000

I’ve been wondering for some time whether or not pedophilia was an evolutionary driver for human neoteny. It’s certainly plausible, and possibly testable using shorter-lived organisms as proxies. David Brin has an essay where he argues the connection goes the other way, i.e. neoteny enables pedophilia, but that seems less plausible to me.
Of course, this line of reasoning and experiment might not be terribly desirable to follow through on, because so many people think that just because something WAS so at one point in our evolutionary history then this makes it desirable or natural to BE so now. This is the “You can’t get an ought from an is (or was)” fallacy. And, while some places have gone overboard in the fight against pedophilia (one young man is serving a *ten year* jail sentence for having had sex with a 15 year old girl — when he was 17) it is absolutely clear that sex with people who cannot reasonably consent is fundamentally wrong. So, we don’t want to enable people to argue for pedophilia.
Still, I find I’d like to know the answer to this. Was, at some point in our history, pedophilia an important driver in making us neotenous apes? Some of the items on Stephen Jay Gould’s list of neotenous characteristics (from the work of Bolk) would seem to support the idea (vide 2, 9, and 12); others, not so much. Ed, do you know of any research on this idea? I doubt I’m the first to think of it.