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Going Ape over Chimp Diets

Dispensing with Fruitarian Monkey Business

by Ward Nicholson
Copyright © 1997 by Ward Nicholson. All rights reserved.
Contact author for permission to republish.

The following debate took place on the Raw-Food listgroup in December of 1996, and is an actual example illustrating the unsubstantiated claims and distortions often made by fruitarians in denial about the realities of chimp diet. In this exchange, poster AA begins the thread with a question about chimps. Fruitarian XYZ is the advocate for fruitarianism who took up the thread in response. My replies are abbreviated here as WN, with supporting references provided at the end. Fruitarian XYZ chose not to reply further.

Editorial note: Spelling errors and other glitches typical of online conversation have here been corrected. Comments in brackets [ ] have been added to the original for clarity and to provide context where necessary. Extraneous material in the postings was edited out where not germane to the thread being focused on here.

Also, I have here paraphrased the statements of the other two posters to steer clear of possible copyright infringement problems. Since I wanted to extend some degree of anonymity and privacy to the other posters, I was unsure of the propriety of quoting them word-for-word without attribution. Whether it would have been permitted under "fair use" provisions of copyright law to have quoted verbatim the comments of the other two posters, even as "literary criticism," was not clear to me, given that I would have been quoting their comments without identifying them. Those wishing to go so far as to check up on the accuracy of my paraphrases or the identity of the other posters are of course free to perform a search on the Raw-Food archives, if they want to go to the trouble.

Poster AA (bystander): Fruitarian XYZ claims on their website that with the exception of one known "tribe" that eats meat, all chimps are vegetarians, and that those in the meat-eating "tribe" are much weaker and live only half as long. I thought all chimps ate meat, as Jane Goodall reports.

Fruitarian XYZ: Your impression of Goodall's reports is wrong. Re-read them or read our comments below.

Poster AA continues: When you refer to "tribe," what does that mean? Does it mean you think there are sociological bonds that can cause chimps to form tribes that fall into practices such as eating meat against their genetic predisposition?

Fruitarian XYZ continues: Here is the passage from our book which contains more detail than what is on our web page.... [additional side commentary snipped]

Response by WN: I am not exhaustively familiar with all the chimp literature, but I have paged or scanned through or seriously studied probably anywhere from 6 to 8 to 10 different field study reports in the last few years. In that time, I do not recall running across the term "tribe" used to describe chimps. Those conversant with the literature normally use the term "community" most frequently or perhaps "population" or "group." [for example see Wrangham 1992; Tutin 1992, Goodall 1986] "Tribe" is normally used to refer to human beings.

Fruitarian XYZ: Cooked-foodists and instinctos are in denial. They say humans are carnivores since chimps hunt and eat meat, and we are their closest evolutionary relatives, but six million years of evolution separates us from them. It's time this kind of logic was seriously re-examined.

Response by WN: Without even the need to consider chimpanzees for supporting evidence, hominids are known through archaeological evidence to been have been eating meat since long before Homo sapiens arrived on the scene. Australopithecus, from around 2.5 to 3.7 million years ago, one of our ancestors, is known to have eaten some meat as determined by strontium-calcium ratios in bone and scanning electron microscope studies of teeth microwear [Walker 1996; Sillen 1992]. Homo habilis ate meat 1.8 million years ago as determined by the presence of hammerstone percussion marks and other stone tool cut marks on animal bones [Blumenschine 1992; Megarry 1995]. Meat-eating increased with Homo erectus beginning approximately 1.5 million years ago [Walker 1996]. Homo sapiens evolved approximately 100,000 to 200,000 years ago [Foley 1995; Groves 1993]; thus the human line had been eating meat by that time for already 3 million years.

Fruitarian XYZ: To begin with, it is only forest-dwelling and not savannah chimps who hunt, and they do so only once a week or slightly more often. The single kill is shared by every adult in the tribe, demonstrating that their diet contains only a small percentage of raw meat.

Response by WN: I would appreciate seeing a reference for the statement only forest-dwelling chimps engage in hunting behavior, as I want to track it down to verify. Raw meat does comprise a small percentage of chimp diet, approximately 1-2% or so according to tables and charts I have seen, but these estimates are inexact. On the other hand, animal food in total comprises somewhere in the neighborhood of 5%, maybe 6%, of chimp diet, most of which is insects. [McGrew 1992, Tutin 1992, Wrangham 1992] At this time, I have heard of only one chimp community (the Kibale population) that does not eat insects, though there may be one or two others; however the Kibale population eats meat. [Wrangham 1992]

Fruitarian XYZ: As a second point, vast amounts of physiological research shows both humans and chimpanzees are biological frugivores, as can be seen in our book's appendix.

Response by WN: Could you please publish at least a few of your citations that we can look up to see this evidence without having to buy your book to get the appendix? In studies I have seen, chimpanzees are indeed primarily frugivorous (eating about 2/3 fruit for common chimps; 80% for bonobo chimps [no ref. for this factoid, going by memory]); but chimpologists and other observers do not intend the term to indicate exclusivity in fruit. Common chimps also eat approximately 20% leaves in their diet, and about 5% animal as noted above, along with fractions of other non-fruit plant items making up the other 10% or so. [Goodall 1986, McGrew 1992, Tutin 1992, Wrangham 1992]

Fruitarian XYZ: When finished eating raw meat, chimpanzees immediately consume leaves that have bactericidal action, which combats the ill effects that such unnatural raw-meat-eating has on them.

Response by WN: I have not heard this in regard to the consumption of the bacterial leaves immediately after meat, so again, I would like to see a literature reference I can track down to verify the statement. The recent reference I have seen from 1990 [Sears 1990] on the eating of Aspilia leaves (which have high concentrations of the antibiotic thiarubrine-A) by chimps makes no mention of these leaves eaten in conjunction with meat, as noted by three of the most famous of the chimp-watchers: Jane Goodall and Richard Wrangham, observing chimpanzees in Gombe; and Toshisada Nishida at the Mahale Mountains site.

Goodall noted the behavior as far back as 1964, but at the time could not figure out why the chimps were swallowing these leaves that they did not chew like other leaves, and it took a long time before it was discovered the chimps' selection of three different kinds of these leaves coincided with the ones that local human populations also were found to be using for their medicinal properties. The hypothesis is that chimps are, incredibly, aware that the leaves can relieve symptoms of diarrhea. In this report, after intensive investigation, the only connection the researchers could make was that they seemed to seek out the leaves when they were sick or when they were suffering bouts of diarrhea.

Unrelated to the Aspilia leaves, there is in fact a behavior of chimps whereby they eat leaves with meat, but it is the practice known as "wadging," where the leaves are wadded and stuffed into their palate which is adapted for this purpose to form a press to suck the juices out of the meat. This technique is not exclusive to raw meat, being used on fruits as well, and other soft foods.

Fruitarian XYZ: Chimps are the victims of parasitic diseases due to their flesh-eating, which runs contrary to their design as biological frugivores.

Response by WN: Chimps do fall victim to parasites, but attributing it solely to meat-eating is a logical leap I would again like to see references for. Regarding the "biological design" in regard to frugivorousness and other "comparative anatomy" arguments used to support arguments for exclusive fruit-eating or vegetarianism, John McArdle, Ph.D., a primatologist and anatomist, refutes a number of popular myths about it [McArdle 1996]: The basic point of misunderstanding among those using correspondences among anatomies of different animals is that there is not always a one-to-one correspondence between form and function. "Individual anatomical structures can serve one or more functions and similar functions can be served by several different forms."

Examples from McArdle:

It is not so simple to draw hard-and-fast conclusions about a species' diet based on oversimplified abstractions about its rough digestive anatomy.

Fruitarian XYZ: Chimps should live to the age of between 42 and 56 years since it takes seven years for them to reach maturity.

Response by WN: "Should" according to whom? If you choose to answer, please give a literature reference I can track down to verify. I don't know that much yet about chimp longevity but I would like to learn more.

Fruitarian XYZ: Chimps who are meat-eaters never live beyond age 35.

Response by WN: Goodall [1986], in a discussion of mortality rates among the chimps of Gombe (one of the heavier meat-eating communities of chimps, I believe) notes several chimps who were well past the age of 35 at the time of their deaths. Although exact age is not always possible to determine, condition of teeth (how worn down they are) is one indication that can be used. On page 104 of this reference, there is a picture of a chimp with the caption, "Flo in 1968, four years before her death. She was certainly over 40 years old at the time. Note her very worn teeth."

Because age sometimes must be estimated, Goodall has classified some of her data on mortality into a chart [p.112], with the rough age categories for chimps who have reached independence as "young adult" (15-20 years), "prime" (21-26), "middle-aged" (27-33), and "old" (over 33). Although there is no specific listing of ages at time of death in this chart, Goodall does mention a few things in the narrative, stating about "really old" chimps that males may have a tendency to outlive females: "During the entire study period, I have seen only three females (Flo, Sprout, and Wilhelmina) who looked really old [Flo was earlier noted to have died at at least the age of 44], compared to 6 ancient-seeming males (McGregor, Hugo, Mike, Goliath, Dracula, and Hubert)." [p. 113] This sounds to me like we have at least 9 of the Gombe chimps who lived past the age of 40, and if that is the case, there must be a considerable number of others who lived past age 35.

Fruitarian XYZ: As a third point, the innate muscular strength of chimpanzees enables them to hunt without the need of even natural weaponry like claws, sharp teeth, or poisonous venom. Humans are not naturally equipped in this way to catch or kill anything, and need tools to do so. Ask yourself if on your own you could take down a wild animal, naked, without shoes or tools, or if it is in your psychological capacity to kill with your bare hands. Humans--who existed for millions of years without technology--could simply not have done so.

Response by WN: Humans have lived with technology (beginning with stone tools) for processing animals for food (whether scavenging or hunting is a focus of debate in the archaeological community right now when you go back to Homo erectus and beyond) at least 1.8 million years, perhaps 2.5 million. [Blumenchine 1992; Megarry 1995] Tool use is an integral part of the definition of humans that evolutionary biologists have used for a long time (along with bipedalism, large brain size, extremely extended infanthood-to-maturity due to the large brain size which takes many years to develop, and other characteristics I do not currently remember).

Fruitarian XYZ: We must consider that chimpanzees' level of intelligence has enabled them to violate their instinctive nature by hunting, just as humans have.

Response by WN: Is this simply your personal opinion, or can you supply us with a reference to substantiate the statement? If you can supply a reference, I will attempt to track it down when I have spare time, and if it is from reputable scientific literature, I will report back to this listgroup whether it agrees or disagrees with your statement.

Fruitarian XYZ: With cooking, however, humans have gone another step beyond what chimps do. Even chimpanzees are intelligent enough not to cook meat.

Response by WN: I would like to hear your scientific criteria for "having enough sense not to cook flesh." Widespread cooking by humans has been around for approximately 125,000 years [James 1989; Davidson and Noble 1993] and at least 230,000 to 460,000 years since first use [Megarry 1995; Wu and Lin 1983; Patel 1995]--more than likely enough time for genetic adaptation to have taken place to for the foods that were cooked. The Cavalli-Sforza research team who has helped pioneer the field of population team states based on their survey, The History and Geography of Human Genes, that 50,000-100,000 years is probably representative of the time span over which most current human polymorphisms (variants) of human genes have evolved [Cavalli-Sforza 1994].

[Editorial note: As discussed in the updates to Part 2 of the Health & Beyond interviews on Paleodiet vs. Natural Hygiene on this site, I have since learned that fire use for cooking may, more likely, not have been employed consistently until about 40,000-60,000 years ago.]

--Ward Nicholson

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Literature Cited:

Blumenschine, Robert (1992) "Hominid carnivory and foraging strategies, and the socio-economic function of early archaeological sites." In: Whiten and Widdowson (1992), pp. 51-61.

Burenhult, Goran (ed.) (1993) The First Humans: Human Origins and History to 10,000 B.C. New York: Harper-Collins Publishers.

Cavalli-Sforza, et al (1994) The History and Geography of Human Genes. Princeton, NJ: Princeton University Press.

Davidson and Noble (1993) "When did language begin?" In: Burenhult (1993), p. 46.

Foley, Robert (1995) Humans Before Humanity. Cambridge, Mass: Blackwell Publishers.

Goodall, Jane (1986) The Chimpanzees of Gombe: Patterns of Behavior. Cambridge, Mass: The Belknap Press of Harvard University Press.

Groves (1993) "Our earliest ancestors." In: Burenhult (1993), pp. 33-40, 42-45, 47-52.

James, Steven (1989) "Hominid use of fire in the lower and middle Pleistocene. A review of the evidence." Current Anthropology, vol. 30, pp. 1-26.

McArdle, John (1996), "Humans are omnivores" In: Vegetarian Resource Group (ed.), The Vegan Handbook, Vegetarian Resource Group, P.O. Box 1463, Baltimore, MD 21203.

McGrew W.C. (1992) Chimpanzee Material Culture: Implications for Human Evolution. Cambridge, England: Cambridge University Press.

Megarry, Tim (1995) Society in Prehistory: The Origins of Human Culture. New York: New York University Press.

Sears, Cathy (1990) "The chimpanzee's medicine chest." New Scientist, vol. 127 (Aug. 4, 1990), pp. 42-44.

Sillen, A. (1992) Strontium-calcium (Sr/Ca) ratios of Australopithecus robustus and associated fauna from Swartkrans." Journal of Human Evolution, vol. 23, pp. 495-516.

Tutin, et al (1992) "Foraging profiles of sympatric lowland gorillas and chimpanzees in the Lope Reserve, Gabon. In Whiten and Widdowson (1992), pp. 19-26.

Walker, Alan and Shipman, Pat (1996), The Wisdom of the Bones: In Search of Human Origins. New York: Alfred A. Knopf.

Whiten A. and Widdowson E.M. (eds.) (1992) Foraging Strategies and Natural Diet of Monkeys, Apes, and Humans. Oxford, England: Clarendon Press, pp. 51-61.

Wrangham et al (1992) "The significance of fibrous foods for Kibale Forest chimpanzees." In Whiten and Widdowson (1992), pp. 11-18.

Wu Rukang and Lin Shenglong (1983) "Peking man." Scientific American, June 1983, vol. 248, no. 6, pp. 86-94.

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