Monday, January 29, 2007

Argument against "Aquatic Ape"

Basically, according to them, there is evidence that we could have obtained sufficient amounts of good brain fats from a terrestrial ecosystem. Not sure what this evidence consists of -- I don't have access to the full-text of this paper.

Docosahexaenoic acid, the aquatic diet, and hominin encephalization: Difficulties in establishing evolutionary links

Bryce A. Carlson, John D. Kingston

American Journal of Human Biology Volume 19, Issue 1 , Pages 132 - 141
Abstract: Distinctive characteristics of modern humans, including language, tool manufacture and use, culture, and behavioral plasticity, are linked to changes in the organization and size of the brain during hominin evolution. As brain tissue is metabolically and nutritionally costly to develop and maintain, early hominin encephalization has been linked to a release of energetic and nutritional constraints. One such nutrient-based approach has focused on the n-3 long-chained polyunsaturated fatty acid docosahexaenoic acid (DHA), which is a primary constituent of membrane phospholipids within the synaptic networks of the brain essential for optimal cognitive functioning. As biosynthesis of DHA from n-3 dietary precursors (alpha-linolenic acid, LNA) is relatively inefficient, it has been suggested that preformed DHA must have been an integral dietary constituent during evolution of the genus Homo to facilitate the growth and development of an encephalizing brain. Furthermore, preformed DHA has only been identified to an appreciable extent within aquatic resources (marine and freshwater), leading to speculation that hominin encephalization is linked specifically to access and consumption of aquatic resources. The key premise of this perspective is that biosynthesis of DHA from LNA is not only inefficient but also insufficient for the growth and maturation demands of an encephalized brain. However, this assumption is not well-supported, and much evidence instead suggests that consumption of LNA, available in a wider variety of sources within a number of terrestrial ecosystems, is sufficient for normal brain development and maintenance in modern humans and presumably our ancestors.

4 comments:

anthrosciguy said...

That also backs up what I've previously seen and reported on my web site critiquing the AAT/H (you may have seen it; it's Aquatic Ape Theory: Sink or Swim?).

From my site:
"the purportedly required shore-based diet is far lower in energy (also required of course) than the terrestrial diet (Loren Cordain, Janette Brand Miller, S Boyd Eaton, and Neil Mann, American Journal of Clinical Nutrition, Vol. 72, No. 6, 1585-1586, December 2000)." and Katharine Milton, pg. 1587 American Journal of Clinical Nutrition, Vol. 72, No. 6, 1586-1588, December 2000.

Just found your blog through a Google alert; I'll have to read more of your posts when I get a chance.

Yann Klimentidis said...

Thanks for the link and references. I'm surprised, although by no means disappointed, that aquatic ape is still under debate, at least according to this latest paper in AJHB.

anthrosciguy said...

Well, the debate is largely one-sided; that is, every time someone who knows anything about evolutionary theory looks at it, they determine it doesn't make sense. But the appearance of a theory with something to say is maintained by PR on the part of Morgan and some other proponents, and by the nutrition people (Cunnane, Crawford, et al.) who make elementray mistakes in evolutionary theory. It's outside their discipline, but nothing stops them from learning before they speak up; I've got a page on them specifically on my site.

BTW, I also recently wrote an entry on it in the Sage Encyclopedia of Anthropology (which is unfortunately so expensive I can't afford it, and who knows how many libraries US$800 or thereabouts).

aquape said...

Nice to see AAT discussed. AAT = sea/lake/riverside adaptations of human ancestors after the human/chimp divergence c.5 Ma. For recent views please see
http://groups.yahoo.com/group/AAT
http://users.ugent.be/~mvaneech/outthere.htm or google "aquarboreal"

 
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