Um... it did? Our guts shrank relative to body size, and our teeth and jaws shrank considerably.
Both of these are likely adaptations to cooking our food, which makes it more digestible and easily chewed. Our colons and ceca are much smaller than our relatives as well because we don't rely nutritionally on fermentation of greens for our caloric needs. Granted these examples are not support for carnivory
Yet more stories and no data to support meat eating.
It's easy to establish to which diet an animal is adapted by feeding it to the animal. Humans fed exlcusively on cooked food do not thrive. Humans fed on raw fruits and some greens thrive. I lived this way for years, so have many others. Some day perhaps science will spend more time exploring this phenomena (i.e. being healthy). But for now I am happy to be one of those in the know and beyond a need to read fictional accounts about what humans might be adapted to and how we may of evolved.
They don't, if you adjust for all the other confounding factors that typically go along with meat eating vs vegetarianism in Western diets. Tobacco use, smoking, and sedentarism are all more prevalent among Western meat-eaters than they are among vegetarians because vegetarianism is perceived as a "health" practice, and also as unpleasant--so vegetarians tend to be pre-selected for health consciousness.
You are probably familiar with the Seventh-day Adventists study? They are vegetarians and have one of the longest life spans of any group studied (of course they also have serious confounders like an insular community, strong family ties, very low drug and alcohol use, etc.).
The point with the SDA data is that it compares like with like accept for the variable under study, meat eating. That is why the SDA data is compelling, they provide their own control group. Most vegetarian data is confounded by multiple variables in lifestyle. The SDA data is not.
But guess what? Certain Mormon communities share many of these characteristics, with one key difference: they are not prohibited from eating meat, and tend to eat it regularly. And they live even longer than the JWs do.
JWs? Genetics play a bigger part in longevity than diet, that is why you can find smokers who still outlive the average vegetarian adventists. Also Mormons are mainly white whereas SDAs are a significantly black group, and race plays a part in longevity to, so I reject the comparison you suggest.
You are probably familiar with the China Study if you're advancing the veg*an argument, so I'd be interested to know if you've read these critiques.
Yes, I have read D Mingers articles, she has her critics too (google them, and see below), but unlike Minger they understand statistics.
I am aware that a selective pressure is also necessary; I assumed it went without saying that if, as you are claiming, eating meat causes heart disease and early death, that would represent a significant-enough selective pressure to cause some adaptation over the course of 500k-1M years. My mistake for not clarifying.
Death from meat eating occurs well after the reproductive years, it does not provide such a selective pressure.
But the key point is that herbivores get cardiovascular disease and meat eating species do not (see below).
Is the whole text of that paper available anywhere? I'd like to read it if it's available free; the abstract was interesting.
You can either buy it like I did, or if you are lucky beg a copy from the author. Research is expensive and time consuming, one has to actually obtain quality text books and papers and then read them and put the picture together.
Here are some quotes:
"Extant and fossil humans possess lower incisors that are similar to those of most Miocene apes, and their incisor-molar relation is close to that of Miocene apes."
"It is interesting to note that the more carnivorous common chimpanzee (Pan troglodytes) has the most elongated and most procumbent incisive cutting edge of all known hominoids, whether extant or fossil, and the pygmy chimpanzee which seldom eats meat has less"
"The question naturally arises about the function of enlarged and spatuliform lower incisors with permanently sharp cutting edges that occur in chimpanzees. If frugivory is not the complete answer, then what are chimpanzees consuming that requires a long, sharp cutting incisive edge? A possible answer is meat."
"It has been said on many occasions that the enlarged incisor battery of chimpanzees is functionally related to their frugivorous diet (Pilbeam 1969). However, a moment’s thought will show that this hypothesis is incomplete, because there is good reason to consider that most of the Miocene apes were frugivores, as are most extant apes, yet not a single one of them possesses enlarged spatulate procumbent lower incisors such as those present in chimpanzees. There is thus no correlation between frugivory in hominoids and the presence of enlarged spatulate procumbent lower incisors."
"Observations on meat-eating in chimpanzees reveal that they use their incisors a great deal, especially to rip and tear skin from the cadaver."
"The molars of chimpanzees appear to show some features that could be related to meat consumption."
"In summary, not only do chimpanzee canines show features that enhance prey procurement, but also their incisors possess features that increase the efficiency of meat ingestion, and their molars have morphology that increases the efficiency of meat chewing. The canines are frequently used to kill prey, the incisors function as carnassials, albeit poorly when compared to the carnassials of most carnivores, and the molars are employed in chewing the flesh before it is swallowed."
"It seems probable that hominids only started to include meat in their diet on a regular basis once they could prepare it by cutting it into small pieces while it was still outside the mouth. This extra-oral meat preparation was possible only after sharp-edged tools had been invented, from which it follows that regular meat-eating among hominids may have started as late as the Upper Pliocene. Naturally, if sharp-edged tools are found earlier that 2.6–3 Mya, then this would push back the date of the onset of meat consumption by early hominids. Furthermore, meat consumption in extant humans is overwhelmingly accompanied by cooking. Unlike chimpanzees, humans do not generally obtain much nutritional benefit from eating raw meat (Wrangham 2002)."
Humans have very generalized and miniaturized teeth.
The dental pattern is common to frugivores, see above. Try eating fruit, our teeth excell at it. Further it is not enough to assume that our reduced dental features are a (genetic) adaptation, when they could just be developmental abnormalities.
It's consistent with eating cooked foods of all kinds
Dental problems occur in people who eat too much cooked food, we are evidently not well adapted to it.
, plant and animal, which is what you see in literally every free-living hunter-gatherer society on the planet (except marginal cases like the Inuit, who don't have plant matter available to them and traditionally eat a diet composed mostly of animal fat by calories--and who were, by all accounts, largely free of disease with a long natural life span until they abandoned their traditional diets for Western convenience foods).
Free of disease, I'd like to see that data.
Is building aeroplanes a "behavioural adaptation" to fly? Come on, there's something very wrong with this idea. Software and hardware are 2 very different things.
If I am going to eat a lot of meat or cooked food, I want to know that I have the hardware for it, not just that I can learn to do it!
that allows us to get away with small teeth, small muscles, small bones, and small guts. Fire/tool use is one of the most important behavioral adaptations in the history of life. We are well-adapted to meat consumption digestively/metabolically--our metabolism utilizes animal tissue for fuel and protein readily.
Can you explain these observations:
1) From Harpers Biochemcistry, 4th Ed.: "The rabbit, pig, monkey and humans are species in which atherosclerosis can be induced by feeding cholesterol. The rat, dog, and cat are resistant."
2) "Diets rich in palmitate inhibit the conversion of cholesterol to bile acids." [Meat is a rich source of palmitate.]
3) According to Lucas humans chew at a rate of 1.3 per second. In contrast pigs and dogs (real omnivores), chew at a rate of 3.03 and 3.16 per second respectively, whereas mountain goats chew at a rate of 1.28 per second
Care to give even the briefest of summaries of a hypothesis you find more convincing, that I might be able to learn more about?
From "The Symbolic Species". Humans are desomatized, we have a small body not a large head. Our head and thus brain grows at just the same rate as say a pig or cow.
What humans have acheived by cooking is to make indigestable vegetables softer and more digetsable like fruit. This is not adaptation, it is making the best of an ecological catastrophe to survive.
Some 400yo Innuit mummies were found, they ate the traditional "Paleo" diet and they had atherosclerosis. Another Paleo failure. http://www.youtube.com/watch?v=x6j75BDq6DQ