Primate diet notes
(World population of humans will increase from 6.9 billion in 2010 to 9.3 billion in 2050. World population of apes might be, I'd guess, maybe less than 50,000. Why the difference?)
- graphic overview of the evolution of human diet
- brain size and increasing energy costs
- Conjectural Overview of hominoid diet.
- Stanford chapter in TO
- Wrangham chapter in TO; cooking has a history. why cooking? (video)
- the excellent online summary
of primate brains and thought.-- note the comments on role of diet.
- Another factor in dietary change is cooking, which involves some control over fire. (See Wrangham reading.). New
research suggests human ancestors may have been cooking meat even 1.5
mya. (Cooking often makes nutrients more available to digestion -- external
rather than internal food processing.) This also is probably true for certain plants including roots, tubers, and other potato-like potential foods. Cooking would make these easier to eat and more importantly perhaps, enable our gut to get the most calories during digestion.
- This shift to higher calorie foods
and more readily available nutrients enabled the human gut to become smaller
and our brain larger for a primate our body size. Notice the large belly
on gorillas; this is probably a reflection of the large gut they need to process
a huge amount of low grade foods such as leaves, bark, and shoots.
- There's more discussion
on the dietary shift to meat by our ancestors abour 2.5mya. Meat-tolerant
genes offset high cholesterol and chronic diseases in human ancestors, according
to a new USC study. Without them, researchers say, the species could have
been ‘wiped out’ millions of years ago.
- Even more on eating meat in human evolution - a review!
- Can cooking be a biological trait of humans? This
is a follow-up on the Wrangham readng in TO. (above) There's an interview with Wrangham in the NYT regarding his new book on the topic, 4/21/09. .. W says :
- "Chimps spend most of their day finding and chewing extremely fibrous foods. Their diet is very unsatisfying to humans. But once our ancestors began eating cooked foods — approximately 1.8 million years ago — their diet became softer, safer and far more nutritious. And that’s what fueled the development of the upright body and large brain that we associate with modern humans. Earlier ancestors had a relatively big gut and apelike proportions."
of supplemental fatty acids (cod liver oil) in maternal diet on brain size
and cognitive abilities of her children. (This interesting article goes along
with the discussion of the role of meat iin diet (above), and interestingly
the speculative "Aquatic Ape" theory of human evolution which postulates
an intermediate group of ancestral hominids who lived along shores, with a
diet of seafood. Most scientists are skeptical of this but there are some
unexplained issues in human evolution including human fat layers, tear ducts,
and hair reduction. At the very least this illustrates the complex relationship
between reproduction, diet, brain size and cognition. Even though differences
in the study are not large, in terms of evolution, a small advantage in reproductive
fitness can multiply itself over generations resulting in a significant species
difference -- in this case perhaps brain size.) Perhaps even more important,
this susggests what a poor diet might to an infant's brain.
- The cod liver oil may relate to another issue -- the relation of vitamins
and exposure to sunlight, skin color, and the disease of rickets. It is not
a co-incidence that more northern latitude people tend to have lighter
skin -- as do chimpanzees. To much sun can lead to foliate deficits and neural
tube defects as well as sperm deficiency; while too little leads to vitamin
D deficits and rickets. These issues are complex yet it seems clear diet was
a critical element in human adaptation to northern and high latitude environments.
- Review abstract
on the topic.
- early tool find of 2.6 mya suggests tools->diet->>>brain
- There are striking differences in dependence on vertebrate meat between
human foragers and apes Humans get 30-80% from meat while apes (chimps) get
2%. See Kaplan, H. S., HIll, K., Lancaster, J. B., & Hurtado, A. M. (2000).
A theory of human life history evolution: diet, intelligence, and longevity.
Evolutionary anthropology, 9, 156-185.
- Lucy - relation between her Australopithecus afarensis teeth and Homo x
teeth suggests change
in diet to meat.
- A recent suggestion is that the huge molars
in robust austrolopithecus served to crunch shellfish. Analysis of carbon
molecules in their teeth suggests they were not vegetarians as previously
believed. This is consistent with finding these fossils in wetlands and similar
jaw-teeth structure in species of otter and marsh mongoose known to eat shellfish.
(Feb 06, Scientific American)
- Diet plays an obvious and not so obvious role
in developing intelligence in humans and possibly some non-human primates. Again fish oil seems to be a significant factor; here in adolescent male diets.
- Changes in availability of large amouts of fat and sugar in modern times
may turn a metabolism advantage when food is scarce into a great disadvantage
(diabetes) when food is abundant. (See Diamond, J (2003) ,The double puzzle
of diabetes, Nature, 423, 599-602.
- Gorillas eat decayed wood chips and lick rotten stumps to obtain sodium..
Sodium is of course necessary for mammals generally. Gorillas obtain 95% of
theirs from 4% of their food intake in these wood sources.
- Chimps and animals generally have dietary components that might be said to be "medicinal" in nature. This is certainly no surprise; what remains unknown is what leads animals to specific plants etc and under what conditions.
- Comparisons of several hundred orang skulls suggests their diet may have
affected brain size. It isn't clear to me if this is a genetic effect or
a developmental one. There are also some issues of sampling -- were these
representative of the regions involved (Sumatra with larger brains, areas
of Borneo with smalled brains.)?
- Genetic variation in contemporary humans concerning ability to convert starch to simple sugar may be as important as adaptation to meat diet in homo Sapiens. (See Wrangham above also on this topic).
- Check the News for items related to skin color and pigmentation. This one for example on Neanderthal's.
- The above and recent research on vitamin D suggest limited exposure to sunlight remains a problem.
- Loss of hair, uV exposure, and diet are a complex of interrelated topics.
- "In short, Jablonski and Chapel convincingly demonstrate that skin tone was naturally selected, via two different adaptations, to block just enough UV penetration to enable both folic acid and vitamin D synthesis. But their explanation alone does not suffice to explain this paper’s central puzzle. Two more points are necessary. The first focuses on dietary vitamin D to explain how and why Europeans became uniquely fair-complexioned, with lighter tone than any other group on earth, regardless of latitude. The second discusses the heredity of complexion to explain why equatorial Native Americans have not become as dark as equatorial Africans."