On Wed, 1 Jul 2009 18:43:49 -0400, [log in to unmask] wrote:

>> My co-worker asked me to explain why our teeth do not appear more like a
>> "carnivore's".  

The short answer is because we are omnivores--so we have teeth for both meat
and plant foods. 

The carnivorous aspects of our omnivorous teeth tend to be ignored by
vegetarians. The teeth of all carnivores and of humans consist of canine and
brachydont (low-crowned) teeth. Brachydont teeth erupt once and do not grow
or get replaced and they have a continuous, fairly uniform enamel that coats
the external surface of the crown of brachydont teeth.

Herbivores' teeth tend to have rough surfaces spiked with ridges of enamel
(lophs), better enabling grinding. Strict herbivores have aradicular
(without roots) hypsodont (high-crowned) molars that grow continuously,
which prevents their disappearance as they are worn down by the frequent
grinding. Most of the enamel in hypsodont teeth lies beneath a layer of
cementum. Even omnivores whose diets are plant-heavy, such as rodents, have
hypsodont teeth, whereas we have none. 

We have canine teeth, whereas some animals whose diets are plant
heavy--again such as rodents--lack them. Our jaws can move up-and-down when
chewing, whereas strict herbivore jaws move only side-to-side. Like other
omnivores we have bunodont teeth in which the cusps are rounded hills and
the entire tooth is covered in enamel.

People who eat a flesh-based diet tend to have few or no dental caries,
whereas people who eat grain-based diets tend to be riddled with them.
Vilhjalmur Stefansson wrote: "Henry B. Collins, Jr., Director of the Wartime
Ethnogeographic Board, and ethnologist on the staff of the Smithsonian
Institution, considers that if archaeologists discover anywhere a group of
several skeletons, of no matter what probable antiquity, they may be sure
that if the teeth have cavities in them, signs of dental caries, then those
are the skeletons of a people who had lived under a fairly well developed
agriculture."

>It's a Frequently Asked Question, and the answer is simple enough.  Our
>evolutionary path was different from the wolf's.  Although our ape
>ancestors no doubt ate some meat, as modern apes do, our path was to go
>from that low-meat diet to a meat-dominated diet, and instead of using our

True, and also throughout all of that evolution, some sort of meat (muscle
meat, fat, organs, eggs, insects, grubs, worms, etc.) was always part of the
diet, in every primate species and in every human society and even tribe.
There has never, to my knowledge, been a single tribe of humans that was
exclusively vegetarian. 

The importance of nonplant foods among primates has historically been
underestimated. All primates were once thought to be herbivorous and some
vegetarian propagandists still claim that some or all primates are naturally
strict vegetarians, but scientists now recognize that chimpanzees are
omnivorous and that all primates eat at least some meat--even mountain
gorillas, who eat some termites, ants, slugs, grubs, etc. Unless one counts
insects, slugs, grubs, worms, lizards and small eggs as "plants," no primate
is exclusively vegetarian. Flesh food even seems to be crucial in the
fertility of female chimps. One of the reasons given in support of
vegetarianism by prominent promoters like John Harvey Kellogg was that it
reduced the "sinful" sex drive.

When large game (such as mammoths, mastodons, aurochs, Eurasian bison,
rhinos, musk ox) was more prevalent, the diet of ancient Eurasian, North
African and North American Homo sapiens was much more dominated by meat than
it is today. Even Homo erectus hunted mastodon as early as 1.8 million years
ago. Carnivores are animals whose diet is dominated by animal tissue, not
necessarily exclusively so. So on the basis of diet alone there was an
extended period in human history when many people were effectively
carnivores. Some argue weakly that plant foods don't leave as much
archaeological evidence and their contribution to ancient diets is therefore
underestimated, but the overall weight of the evidence is that the diets of
early homo sapiens tended to be dominated by nonplant foods.

Plus, one hypothesis is that the omega 3 fats from either the bone marrow
and brains of land mammals or from fish was the key food that spurred the
development of larger brains in humans. In other words, without meats and
animal fats--especially animal fats--homo sapiens may never have come into
being, though it's a matter of controversy.

>our hands.  This, incidentally, may have been driven by the need to use
>our mouths for something more specialized: speech.  That's speculative, of
>course, but there's no question that language would have made hunting in
>groups much more effective, because language enables the communication of
>plans.

Other primates, such as chimpanzees also hunt in teams (mainly for monkees)
and communicate before and during the hunt and then loudly screech their
ecstatic pleasure when the prey is caught and the booty is shared (sometimes
followed by ecstatic sex, btw ;-) -- see "Wild Chimpanzees Exchange Meat for
Sex on a Long-Term Basis,"
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0005116 ).
Better communications do improve hunting effectiveness, but some scientists
reverse the order, claiming that increased hunting by pre-humans led to the
development of better speech more than the reverse (though they are both
reinforcing of each other, of course).

Nonhuman primates have been found to use gesture and verbal communications
and some scientists who are not fans of hunting have ironically added
further credence to the language-from-hunting hypothesis with research
supporting gestural language as the prime original means of human
communications, with complex verbal speech language developing after the
evolution of the human species (see 'The "gestural" origin of language in
humans,' at http://www.koko.org/friends/significance.koko.html ).

>Note that hominids, and then humans, have been using tools in this way for
>at least 2.5 million years.  See Craig Stanford's book _The Hunting Ape_.

Yes, and even vultures use stones as tools to crack open ostrich eggs.
Different groups of chimps have developed different specialized tools and
passed down how to use them for generations.