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(Humanity's Evolutionary Prehistoric Diet and Ape Diets--continued, Part H)

P O S T S C R I P T :   S I G N I F I C A N T   R E S E A R C H   U P D A T E S   ( c o n t .)

(EDITORIAL NOTE: Triple-asterisked items in boldface below refer to passages in the interview as originally published, which are followed by updated comments based on additional observations or more recent scientific research.)

Research updates relating to diet
and health late in human evolution

*** "...but widespread global use [of seafoods] in the fossil record is not seen until around 20,000 years ago and since. For the most part, seafoods should probably not be considered a major departure, however, as the composition of fish, shellfish, and poultry more closely resembles the wild land-game animals many of these same ancestors ate than any other source today except for commercial game farms that attempt to mimic ancient meat."

It may be that the fact fish is one of the foods some people are allergic to is an indicator evolutionary adaptation to this food may well not be complete, or is at least still problematic for some genetic subgroups, though compared to grains and dairy, there is of course a far better case for including it in a Paleolithic diet. Strictly speaking, meat from land animals is the primary flesh-food adaptation for humans. (The small minority of researchers promoting the very controversial "aquatic ape" theory of human evolution presently considered fringe science--which proposes a brief formative phase of human evolution taking place in coastal waters--might disagree, of course.) To this date, I have not myself seen or heard convincing research either way on how well adapted the human species overall may be to fish consumption compared with land game animals.

*** "35,000 B.C. to 15-10,000 B.C.: The Cro-Magnons (fully modern pre-Europeans) thrive in the cold climate of Europe via big-game hunting, with meat consumption rising to as much as 50% of the diet."

At least one researcher has voiced the opinion that given Ice-Age Europe in many areas was not too dissimilar from the arctic climate that modern-day Eskimos inhabit [i.e., very little plant food available], meat consumption in Europe during the last Ice Age may have approached similar levels--that is, considerably more than 50%, up to as high as 90% in some areas.

*** "Wild grasses and cereals began flourishing [around 10,000 B.C.] making them prime candidates for the staple foods to be domesticated, given our previous familiarity with them."

This statement could be construed as giving the impression that wild grasses and cereals may have been flourishing in many places around the globe. While it is true that environmental conditions at this time became considerably more favorable to wild grasses and cereals, I have since learned that the ones which thrived naturally and lent themselves best to the development of agriculture (wheat, barley, etc.) were indigenous only to a limited number of locales around the globe, the most notable of which, of course, was the Near East, where agriculture got its earliest start. A more accurate statement would be that peoples in the locations where these grasses and cereals began flourishing indigenously took advantage of the improved weather and environment to exploit them even further. The grasses and cereals would not have flourished to the extent they did, nor--most importantly--spread as widely as they came to do (virtually around the globe), were it not for proactive human intervention.

*** "During the time since the beginning of the Neolithic, the ratio of plant-to-animal foods in the diet has sharply increased from an average of probably 65%/35% during Paleolithic times to as high as 90%/10% since the advent of agriculture."

As stated above, the average animal food consumption during the Paleolithic was more likely in the 50-65% range than 35%. This makes the decrease down to 10% of the diet in many places even more noteworthy in terms of suggesting the possible nutritional repercussions of modern-day diets.

*** "Skeletal remains show that height decreased by four inches from the Late Paleolithic to the early Neolithic..."

Various sources I've seen since say as much as six inches decrease in height. It is worth noting in this connection that vegetarians will often argue that the extra growth animal foods promote is "pathological" hypergrowth; leads to premature aging, etc. It should be noted, however, that recent studies show that the reduced growth sometimes seen in infants on vegan diets can lead to failure to meet accepted benchmarks for health status during the growth period. In refuting the common claim of vegetarians that the rebound in adult heights of modern populations eating more animal food is nothing but "pathological hypergrowth," it is also worth repeating that the historical decrease in height noted in skeletal remains after the Neolithic (when animal food consumption began plunging) was accompanied by skeletal signs of disease-stress, as mentioned in Part 1 of the interview. Also, longevity of Neolithic peoples, who ate diets higher in plant food (particularly grains) and lower in animal food, was in general a bit shorter than that of Paleolithic peoples. [Angel 1984]

Clarifications regarding
chimpanzee diet

*** "The argument made is very similar to the "comparative anatomy" argument: Look at the rest of the animals, and especially look at the ones we are most similar to, the apes."

A brief note: the original article noted that humans are most genetically similar to chimpanzees. If more space had been available, I would have made the further distinction that we are equally as genetically close to the bonobo chimpanzee. However, since the common chimpanzee has been more closely studied than the rare bonobo chimp, the research from these studies has (until recently, perhaps) provided more wide-ranging insights.

So far as I am aware, the main observed differences between the common chimp and the bonobo, diet-wise, are that bonobos eat a higher percentage of fruit in the diet (approx. 80% vs. up to 60%-65% for the common chimp); and apparently insect and flesh consumption is less. Interestingly reminiscent of human behavior, the bonobos' highly sexual behavior in many common social situations seems to serve a communication function both as a social "glue" and as a conciliatory mechanism between individuals in potentially divisive situations. (Examples: bonobos will often engage in sex-play upon coming onto a major food source--sensory excitation often turns in sexual excitation, which is then discharged in fraternization with others in the group and seems to promote group cohesiveness. Also, when spats occur between bonobos, sexual engagement afterwards may serve as a way to smooth the incident over and reestablish normal relations.)

*** " would probably be fair to estimate that most populations of chimpanzees are getting somewhere in the neighborhood of 5% of their diet on average in most cases (as a baseline) to perhaps 8-10%..."

While the 5% figure was the best guess I could make at the time based on the difficulty in finding any research with precise figures, it does appear to be fairly close to the mark. I have since seen figures quoted in the 4% to 7% range for chimp animal-food consumption. 8-10% is in all likelihood too high as an average, though could plausibly reach that high at the height of the termite season or during the peak months for red colobus monkey kills.

*** "An important observation that cannot be overlooked is the wide-ranging omnivorousness and the predilection for tremendous variety in chimpanzees' diet, which can include up to 184 species of foods..."

Something I overlooked in this factoid taken from Goodall's The Chimpanzees of Gombe was that 26 out of the 184 items were observed to be eaten only once. Nevertheless, the 158 remaining items still constitute a remarkable variety of food items. That the additional items would still be sought out, on top of an already high level of variety, can be looked at as an interesting indicator of the "opportunistic" nature of chimpanzees in taking advantage of whatever food they can find and utilize. (In other words, as a "model" for the kind of dietary behavior that vegetarians sometimes hold up that humans ought to be compared to, chimps' opportunism suggests they are not particularly constrained by arbitrary food categories in deciding what is appropriate or not to eat.)

*** "...there is some suggestion chimps seem not to prefer extra-high roughage volumes, at least compared to the gorilla. Certainly they do not seem to be able to physiologically tolerate as much cellulose from vegetative matter in their diet."

This could be a bit misleading if construed to mean chimps don't have a lot of roughage in their diet, because they certainly do. It remains true, however, that chimps do not possess the requisite kind of symbiotic intestinal fauna (bacteria) to subsist on diets as high in leafy vegetative matter as gorillas do. The subsequent discussion on wadging was meant to show two things: that chimp behavior is inventive toward meeting their needs, and also that wadging can be a way of exploiting the part of fibrous foods they could otherwise not eat freely of due to the limitations of their gut.

The relevance of these observations for human diet would be that the first hominids went much further in the direction of less fibrous foods than chimpanzees were to go after the divergence from our common ape ancestor, and toward a much more concentrated diet higher in animal foods containing denser nutrients of higher bioavailability, as we discussed above regarding the increasing size of the human brain that occurred concomitantly with a reduction in the size of the gut.

This concludes Part 1. In Part 2, we'll look into such things as fire and cooking in human evolution, rates of genetic adaptation to change, modern hunter/gatherers, diseases in the wild, and then turn to "the psychology of idealistic diets."


(Fire and Cooking in Human Evolution)

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