Did we evolve to eat meat?

[Approaching Infinity]

Chimps and gorillas eat bark as part of their diet. Luckily that is not on my menu, but I can imagine that a serious GI tract is necessary for digestion of such foods.

The point that a more robust GI tract is necessary to properly digest plant fiber is correct, although I'm not sure how much bark Chimps and Gorillas eat. It also helps to answer the question of why humans have a smaller GI tract. Chimps are omnivores, like humans, but their diet is primarily vegetarian.

I think one of Dirk's stumbling blocks is hinted at above. He's imagining a lot, but not looking at what is. Yeah, we COULD have evolved this way or that, but the evidence seems to show that at a certain time we started engaging in certain eating practices, and we are what we are as a result. What do we see when we look at things as they are? Well, a lot has been mentioned already, but among other things: veggies irritate our GI tract, meat and fats are easier on our system and they feed our brain efficiently, fruit wasn't likely a huge part of our evolutionary past. Even in equatorial regions, fruit availability varies. It's out of season more often than not. We certainly didn't evolve on an all fruit diet. Carbs were necessary in summer months to built up fat for the winter, during which time we ate primarily meat. Our bodies respond based on this cycle even when we try to go against it (read TS Wiley's Lights Out for the details).

As for the arguments against killing animals, yeah the turnover in slaughterhouses may be high, but I haven't heard of any hunter-gatherer tribes' hunters getting disgusted with hunting and going veg. It's seen as a part of life and accepted as such. And yeah, kids have to be taught how to hunt, just like they've got to be taught it's not cool to punch their sisters.

 

[Seamus]

I can look in a mirror and see that my meatsuit evolved to be carnivorous predator. I brush those "canine" fangs and sharp front teeth twice a day. I think they're called "canines" because my teeth don't look all that different from my dog's? Meat rippers in the front and bone crushers in the back. Then there are those predator eyes I'm looking into the mirror with, set in the front of my face, only about an inch or so apart and looking straight ahead. A herbivore's eyes are much further apart, set more to the sides of their heads...to watch for us.

Hi Guardian,

I agree with you that our eyes and teeth are well adapted to hunting and eating meat however, I think that they may have been factors that allowed us to evolve from herbivores into carnivores, not the other way around. I'm not sure about our fingernails. I know that some small primates have retractable claws that are similar to a cats claws, designed for grasping branches. It seems to me that this would be a much better offensive weapon than our weak fingernails. I think our primary offensive weapon is our brain.

Primates and apes like chimps and gorillas actually tend to have much larger canines, and they have binocular vision, even though they are primarily vegetarians. Monkeys probably evolved binocular vision to judge distances so that they were better at jumping from branch to branch, and apes, including humans, inherited this trait.

As far as canine teeth go, take a look at this fella:

And this guy:

As you can see, both species have HUGE canines and forward facing, close set eyes. Some primates have even larger canine teeth relative to their body size. These large canine teeth seem to serve a sexual function. The large canine teeth are used primarily by males in dominance and sexual displays and for fighting if need be. Like the way a rooster uses his spurs. He shows off with them and scrapes them against his wing when courting a hen or taunting another rooster, and if push comes to shove he tries to spear his adversary with them.

Primates, such as baboons, are well known for their highly sexually dimorphic canine teeth, with males possessing canines that are up to 4 times taller than those of females. Primate canine dimorphism has been extensively documented, with the consensus that large male primate canines serve as weapons for intrasexual competition, and some evidence that large female canines also have this function. Primate canine teeth are as large or larger as similarly sized carnivores; they also seem to have been selected for their strength and length does not necessarily impact on canine function.

This article is not particularly well written, but it discusses this in a bit more depth:

ScienceDaily (June 30, 2008) — Measuring and testing the teeth of living primates could provide a window into the behavior of the earliest human ancestors, based on their fossilized remains. Research funded by the National Science Foundation and led by University of Arkansas anthropologist Michael Plavcan takes us one step closer to understanding the relationship between canine teeth, body size and the lives of primates.

In an article published in American Journal of Physical Anthropology, Plavcan and colleague Christopher B. Ruff of Johns Hopkins School of Medicine report on an initial examination of the function of the shape of canine teeth in primates. This is the first published comparative analysis of canine strength for primates.

Understanding more about the function of canine teeth can lead to new models for understanding human evolution. Plavcan has been studying primate teeth and skulls for 24 years and spent four years collecting dental data for this analysis.

The researchers compared the size, shape and strength of canine teeth from 144 primates with similar measurements taken from 45 carnivores. They examined the relationship of the size of primates’ canines to body size and the relative strength of the teeth. This comparison could help answer the speculation about the function of male primates’ canine teeth in the competition for females. Are the canines used as weapons or simply for display?

“The reason we wanted to use the carnivores is that we know carnivores use their canines for killing,” Plavcan said. “If primates’ canines are too weak to function as weapons, then they’re all just for show.”

Among anthropoid primates, it is well known that the canine teeth of males are up to four times as long as those of females. The researchers compared the canine teeth of male and female primates.

“If the male’s canines are stronger than the female’s canines that would imply there is sexual selection for strength and that the tooth is actually used as a weapon,” Plavcan said. “Female’s canines are short, and shorter, stubbier objects are harder to break. So, if the long, thin male canines are as strong or stronger than those of the female, that would also suggest they are capable of being used for fighting.”

The results were mixed in an interesting way.

“We found that the primate canines are generally as strong as or stronger than carnivore canines," Plavcan said. “But they are not associated with any sort of estimate of sexual selection.”

Generally the canines of males and females were equally strong. Given that primates have such strong teeth in general, the researchers suggested a couple of possible explanations. It could be that all primate males have strong teeth because of a significant risk to reproductive success for any male who breaks a canine tooth. Or it could be that the strong teeth are due to basic inherited design.

Hominids – the primate family that produced humans – retain body mass sexual dimorphism; that is, males typically have a greater body mass size than females. At the same time, the difference in size in canine teeth between males and females is lost.

“This goes back to the earliest hominids,” Plavcan said. “In fact, one of the few diagnostic characteristics of hominid evolution is reduction in canine size dimorphism while maintaining strong body mass dimorphism.”

For example, gorillas have chunky teeth set in massive bodies. To have canines proportionately as long as other primates, a male gorilla’s canines would have to be 25 centimeters long, and the teeth at the base would then be too wide for his jaw.

“This suggests that there may be an upper limit on canine size in primates simply due to spatial constraints on fitting such teeth in the jaws,” the researchers wrote.

The difference in body size between male and female hominids has been the subject of study because it is an obvious and important trait. Yet there are drawbacks to using body size to understand sexual selection. A change in body size can impact many other aspects of life, including metabolism, feeding patterns and vulnerability to predators. Canine teeth, on the other hand, are a far simpler system.

“With canines, we can go in and effectively construct an experiment that allows us to control for all these other variables and look at only one thing,” Plavcan said. “The same phenomenon that works on the canines, we can translate into the body mass and then into behavioral models for the fossil record.”

Plavcan is an associate professor of anthropology in the J. William Fulbright College of Arts and Sciences at the University of Arkansas. He and Ruff are authors of “Canine Size, Shape, and Bending Strength in Primates and Carnivores” in the May issue of American Journal of Physical Anthropology.

Their research indicates that primate canines are as strong as carnivore canines, so again I think that we inherited our teeth from our herbivorous ancestors and they happily adapted to a carnivorous diet.

Its interesting to note that in most primates the males have larger canines, but in humans this difference is lost. Perhaps, as Laura wrote earlier, we sacrificed our large, sexy teeth for larger, sexier brains.

 

[Seamus]

Yeah, we COULD have evolved this way or that, but the evidence seems to show that at a certain time we started engaging in certain eating practices, and we are what we are as a result. What do we see when we look at things as they are? Well, a lot has been mentioned already, but among other things: veggies irritate our GI tract, meat and fats are easier on our system and they feed our brain efficiently, fruit wasn't likely a huge part of our evolutionary past. Even in equatorial regions, fruit availability varies. It's out of season more often than not.

I think the most recent research suggests that our distant primate ancestors were quite similar to chimpanzees, or that we may share a common ancestor. In either case, what happens to a chimp-like ape's omnivorous diet consisting of fruits, leaves, nuts, seeds, tubers, miscellaneous vegetation and the occasional monkey if the climate changes from jungle to savanah? Or if an overhead cometary bombardment burns his forest to the ground? If most of the vegetation is dead, what will he eat? Well, luckily he is an omnivore and even has a little experience hunting monkeys. So he eats what is available: meat. Maybe only the craftiest hunters survive this period, which could last generations as the forests slowly grow back. In the meantime they begin to adapt to eating more meat, and when the fruit they used to eat is once again available, they are no longer as interested in it. Soon they start walking around on two legs more often, they get taller, their brains keep getting better as they develop more efficient hunting tools, fire cooking, etc.

I'm not saying that this is definitely what happened, but I agree with AI that the evidence supports this hypothesis.

As for the arguments against killing animals, yeah the turnover in slaughterhouses may be high, but I haven't heard of any hunter-gatherer tribes' hunters getting disgusted with hunting and going veg. It's seen as a part of life and accepted as such. And yeah, kids have to be taught how to hunt, just like they've got to be taught it's not cool to punch their sisters.

The turnover in slaughterhouses is probably high because the working conditions are notoriously bad. Turnover is high in microchip factories as well, but its not because the workers are Luddites. Read Upton Sinclair's The Jungle, or if you feel that's outdated or you'd rather watch a short documentary take a look at Food Inc.. That movie is one of the saddest things I've ever seen. Workers in slaughterhouses aren't treated much better than the animals, as far as I can tell. If you want moral reasons to swear off meat, or at least factory farm meat, Food, Inc. will give you plenty.

 

[mcb]

Re: Questions

...Joe, what do your INSTINCTS tell you? Put a child in a room with meat and fruit and he'll eat the fruit. If he is young enough at least. The thought of hunting an animal down is disgusting to me and I would certainly prefer fruit if one of them has to be sacrificed. That said, if I need to survive, yes I will hunt the animal down, but only in circumstances of utter need and it requires me to shut out my conscience.

I don't think this is about instinct at all, although it does have something to do with what a person finds "disgusting." I was not raised to hunt, and it's not something I especially want to do. I would, like the child and for the same reason, go for the fruit, lacking someone else to do the hunting and butchering. But many people do hunt, and they would go for the meat. I knew this even as a child, from reading, though I found it a little strange at the time that a character in a novel would "salivate" at the sight of a live animal suitable for eating--but I understood it as a different way of looking at things than what I was used to. And under different circumstances, given the opportunity to learn how to do everything (and a younger body better suited to hunting), I would go for the meat too.

As a simpler example, I grew up thinking seaweed was "disgusting," but now I eat it regularly. Did my instincts change? Hardly. So what is so "disgusting" about hunting an animal down? That sounds like a position to me. So take that position if it suits you, but notice that there are other valid ways of looking at it, and that it has nothing to do with "instinct."

What would your conscience tell you about hunting animals if no one had ever taught you that it was wrong? If it were simply the prevailing way of life where you found yourself?

 

[Richs]

If you haven't yet read the transcript of the latest session with the C's (Session 13 Feb 2011) there is this segment of it which relates to diet:

"Q: (Andromeda) Are veggies not really good for us as we have begun to suspect from our research?

A: Pretty much.

Q: (L) Why?

A: Every living thing has a protective life preserving mechanism. For animals it is their ability to run and hide or fight. For living things that do not have those capacities nature has still not abandoned them.

Q: (Ailen) Basically lectins... (Psyche) And anti-nutrients. (Ailen) Geez... between that and the low-fat propaganda, most people are dead.

A: Yes.

Q: (Perceval) Is it possible for us to get all of our nutrients from animals without taking supplements?

A: It would be better if they were "wild fed" but you are able to figure this out."

 

[Laura]

Chimps, our allegedly closest primate relative, actually eat a lot more protein than is generally widely known. They would probably eat a lot more if they were good hunters. They do eat a lot of termites - meat type protein.

Anyway, fruit as the year-round alternative is very bad for most people - if not all people - because it causes insulin resistance. But fruit is, indeed, intended by nature to be eaten as opposed to many vegetables that have built in protection in the form of anti-nutrients that are harmful to the human system. Herbivores can generally deal with these problems because they have multiple stomachs and digestive tracts designed to do so.

The most important factor in all of this is, I think, the fact that we need lots of animal fats to build and insulate our brains as well as all the other cells of our bodies. Not only that, but a high fat diet helps to balance hormones in the body, including neurotransmitters, and aids in the body's ability to communicate with all its parts. A high animal fat diet is also very satisfying - you get hungry less often, your stamina increases, your metabolism balances and you are warmer, etc.

Then, there is the big one: eating a lot of animal fat keeps the liver active and that aids detoxification. People who have been accustomed in Western society to eat low fat, high veggie/grain diets need a period of readjustment, a period of kick-starting sluggish livers to get them back online. But once they do, things begin to run like a humming top. The main thing is to avoid too many carbs though some are beneficial though I won't say necessary.

If you are keeping your liver active with fats, not irritating your digestive tract with too many veggies, avoiding too much sugar (as in fruits) so that your insulin and other hormones are not going nuts, you feel a whole lot better.

 

[Ollie]

People who have been accustomed in Western society to eat low fat, high veggie/grain diets need a period of readjustment, a period of kick-starting sluggish livers to get them back online. But once they do, things begin to run like a humming top.

I've been taking supplements to get my sluggish liver back on track since the Christmas break. Whilst everyone is individual and times will vary, approximately how long does it take to get the sluggish liver back online? How will a person know?

 

[Laura]

People who have been accustomed in Western society to eat low fat, high veggie/grain diets need a period of readjustment, a period of kick-starting sluggish livers to get them back online. But once they do, things begin to run like a humming top.

I've been taking supplements to get my sluggish liver back on track since the Christmas break. Whilst everyone is individual and times will vary, approximately how long does it take to get the sluggish liver back online? How will a person know?

It took me about 6 to 8 months of accompanying my high fat foods with ox bile and megazymes. Now, I only occasionally take an enzyme - usually only if I've eaten some carbs with the fat which makes a sometimes unpleasant combination.

 

[Joe]

Chimpanzees do eat meat. Here's a video you might find interesting.

http://www.youtube.com/watch?v=KTPkmH4hWCs

So the idea that we evolved to eat plants and fruits or that that is an optimal diet for humans is simply not true.

 

[Ollie]

People who have been accustomed in Western society to eat low fat, high veggie/grain diets need a period of readjustment, a period of kick-starting sluggish livers to get them back online. But once they do, things begin to run like a humming top.

I've been taking supplements to get my sluggish liver back on track since the Christmas break. Whilst everyone is individual and times will vary, approximately how long does it take to get the sluggish liver back online? How will a person know?

It took me about 6 to 8 months of accompanying my high fat foods with ox bile and megazymes. Now, I only occasionally take an enzyme - usually only if I've eaten some carbs with the fat which makes a sometimes unpleasant combination.

Thanks Laura, I've a while to go yet then! :) Perseverence is the key then.

 

[Laura]

Thanks Laura, I've a while to go yet then! :) Perseverence is the key then.

When you have been starving your body of necessary fats for a long time, that means that all your cells are constructed of the inadequate or even dangerous fats that you have been eating - like trans fats or, worse, vegetable fats. It takes time for the body to replace all the cell surfaces and other fat mediated structures, including all the cells of the liver itself! This isn't going to happen in a month or two! It could take up to a year or longer. You just have to get the right fats in there and do whatever is necessary to assist a fat-disabled body in processing them. It's like bootstrapping.

 

[go2]

...Joe, what do your INSTINCTS tell you? Put a child in a room with meat and fruit and he'll eat the fruit. If he is young enough at least. The thought of hunting an animal down is disgusting to me and I would certainly prefer fruit if one of them has to be sacrificed. That said, if I need to survive, yes I will hunt the animal down, but only in circumstances of utter need and it requires me to shut out my conscience.

I don't think this is about instinct at all, although it does have something to do with what a person finds "disgusting." I was not raised to hunt, and it's not something I especially want to do. I would, like the child and for the same reason, go for the fruit, lacking someone else to do the hunting and butchering. But many people do hunt, and they would go for the meat. I knew this even as a child, from reading, though I found it a little strange at the time that a character in a novel would "salivate" at the sight of a live animal suitable for eating--but I understood it as a different way of looking at things than what I was used to. And under different circumstances, given the opportunity to learn how to do everything (and a younger body better suited to hunting), I would go for the meat too.

As a simpler example, I grew up thinking seaweed was "disgusting," but now I eat it regularly. Did my instincts change? Hardly. So what is so "disgusting" about hunting an animal down? That sounds like a position to me. So take that position if it suits you, but notice that there are other valid ways of looking at it, and that it has nothing to do with "instinct."

What would your conscience tell you about hunting animals if no one had ever taught you that it was wrong? If it were simply the prevailing way of life where you found yourself?

Does anyone have evidence from experiment to back up the statement that children will choose to eat a banana or apple before eating barbecued beef ribs or baked rosemary chicken? My observation is that children nearly always prefer cooked meat to fruit salad. I think children salivate over cooked meats and not the living animal and loading the question in this manner betrays the writer's agenda.

 

[Seamus]

Chimpanzees do eat meat. Here's a video you might find interesting.

http://www.youtube.com/watch?v=KTPkmH4hWCs

So the idea that we evolved to eat plants and fruits or that that is an optimal diet for humans is simply not true.

Thanks for the video Perceval. As an aside, the narrator kind of looks like Jon Voight from Anaconda.

Chimps, our allegedly closest primate relative, actually eat a lot more protein than is generally widely known. They would probably eat a lot more if they were good hunters. They do eat a lot of termites - meat type protein.

Maybe the idea that chimps are "primarily vegetarians", as wikipedia says, is disinformation or based on faulty or old research?

If they were better hunters and ate more meat, maybe they would be more like humans? Maybe they would have to become more like humans to be better hunters.

As far as termites go, evidence suggests that Early Humans Ate Termites, just like Chimps.

Though not a popular item in Western cuisine, termites are prized in other cultures. And with good reason: they represent a valuable source of protein and fat. In fact, a 100-gram serving of these insects provides 75 percent more calories than an equivalent amount of rump steak. Chimpanzees, too, feed on termites, as Jane Goodall first noted 40 years ago in Tanzania, when she watched a nearby chimpanzee pluck a blade of grass, trim it with care and dip the modified stem into a termite mound to fish for the insects. Now it appears that ancient hominids also had a taste for termites. According to a report published today in the Proceedings of the National Academy of Sciences, modified bones dated to between 1.8 and 1.1 million years old that were thought to represent tools for digging up tubers were instead used to dig into termite mounds.

Francesco d'Errico of the University of Bordeaux and Lucinda Backwell of the University of the Witwatersrand analyzed more than 23,000 animal bone fragments from two South African hominid fossil localities known as Swartkrans and Sterkfontein. Earlier studies had identified 69 of these bones as putative tools, but the new work added 16 others to the list. Comparing these 85 specimens at the microscopic level with bones known to have been altered by natural agencies like animal gnawing, water, wind and so forth, the team confirmed that the markings on the purported tools did not match those of the naturally modified examples. Moreover, turning to modern examples, d'Errico and Backwell showed that the orientation of the marks on tools used for digging tubers differed significantly from that seen on tools used for breaking into termite mounds. The wear pattern on the fossil bone tools, they observed, closely resembles the modern termiting tool pattern.

Two kinds of hominid remains have been reported from these South African sites: a robust form of Australopithecus and an early member of our own genus, Homo. Homo is generally thought to have consumed more meat than Australopithecus robustus, whose large, flat teeth would appear to reflect a vegetarian diet. But recent chemical analyses of the A. robustus remains from Swartkrans have revealed a surprisingly high level of so-called C4 dietary carbon, which indicates an unusually sizeable protein intake for a vegetarian species. Termite consumption might explain this find. Indeed, Pennsylvania State University researcher Pat Shipman points out in a commentary accompanying the PNAS report that the termite-eating aardvark has a carbon-isotopic signal rather similar to that for A. robustus. For now the identity of the tool users remains unknown. Only further research will reveal whether one or both of these early hominids dined on termites.

Its interesting to note the author's speculation that it was Australopithecus robustus "whose large, flat teeth would appear to reflect a vegetarian diet" that seemed to be the one eating more termites, based on chemical analyses of their remains. Perhaps, like Chimpanzees, they weren't as good at hunting so they had to settle for termites? Even though termites are a good source of protein and fat, they are pretty tiny, so maybe there's a better return on energy spent hunting and hilling larger prey? Or maybe insects are harder to digest than cooked meat?

 

[Dirk]

Anyway, fruit as the year-round alternative is very bad for most people - if not all people - because it causes insulin resistance.

Do you have a source of that statement?

No references, but just from personal experience, you are right, if I eat a lot of fruit I generally feel very spacy, which signals that my blood sugar is too high and that the insulin cannot effectively remove the sugar from the blood into the cells.

However, if I eat no overt fats at all (as in the 80/10/10 diet) I can eat all the sugar I want, without the spacy feeling. Is there something to the combination of fats and fruits that is the culprit instead of fruit being solely the culprit?

 

[Dirk]

Maybe you could answer a few questions that I have.

I'll give it a shot.

Dogs can survive on dog food made primarily from grain, does that mean that meat is unnecessary for them?

I don't know, but yes, it said that dogs can live on vegan diets, where cats cannot. I don't know details about the consequences.

If fruit is such great brain food, why aren't chimps as smart or smarter than us?

Kleiber's law? They also eat bark, which requires them to have large digestive tracts and thus smaller brains? Just a guess, but according to the research this seems logical?

They probably eat more fruit than most humans.

No, my point is that an optimal diet of humans consists of more fruit than an optimal diet for chimps.

If fruit is as good as meat, why did the ancestors of humans ever start hunting and eating meat?

Climate changes maybe? Where fruit was there before, now it wasn't there anymore and they needed another source of food?

If fruit is as good as meat, why do chimps eat insects and sometimes hunt monkeys?

Because they have other digestive tracts then we do. Fruit is not 'as good' as meat, just different.

If fruit is as good as meat, why do tropical peoples eat meat, when they can have all the fruit they want?

We can have all the fruit we want to do, it's right there in the supermarket. But we don't either. So the answer lies in the habits.

Why go through all the trouble of hunting for or raising meat?

Why do people go through the trouble to get drugs? Because it stimulates the body, like meat, and temporarily alters one's state of consciousness.