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Lecture 19: New theories of human evolution: The cooking ape hypothesis

Terms in this set (15)

• So, the old theory was that only meat could explain how human beings get so intelligent; only meat could explain how we get this gigantic jelly field heads, swollen fat heads.
• Our brain is very unusual; they are extremely large. We are very different because of our brains.
• Meat was considered to be the cause of this.
• But meat eating goes way way back, way way back before all these changes took place. Walking came first. Small brain creatures walked around and eat meat and they stayed small brain for quite a while.
• What is the proper food for a particular animal? Fleas-suck blood. Giraffe-leaves. Dolphins-fish. But what is the natural, original food of humans? Fruits (so do chimps) and meat and other food.
• The closest thing we could go by, aside from archaeological evidence, is what modern hunter gatherers have done since they were being observed for the last 100-150 years, not many are left now. Many modern hunter gatherer societies have been observed. They were considered the 'original' people because they are still living as hunter gatherers. But it is actually a mistake, they are not ancient people, they are modern people. They are people alive in the present and they just have many years of history behind their society as we do. So, one has to careful in equating them as the same that modern hunter gatherers are exactly the way ancient hunter gatherers were 100000 years ago. But they are the closet thing we got to observe and how ancient humans lived and ate.
· We cook food because we can.
· Cooking food is one of the very few things that is universal about human beings. Human societies around the world are so diverse that they are very few things that you can say that it is universal.
· Even religions and belief in supernatural beings are not universal. There are societies in the world that have no gods. But in Darwin's day, this(having gods) is thought to be universal; every tribes and race in the world believe in god, so there must surely be a god. This is what people believed during those days. But this wasn't true.
· One thing that is very crystal clear Is that cooking is universal. All human groups ever encountered in the history of the world and those exist today all eat cooked food.
· But what about eskimos who eat raw seals and sushi? Sashimi?
· All those cases that you can think are delicacies.
· Sushi is primarily cooked rice. Most of the food matter is cooked with a bit of raw fish. But nobody lives on sashimi. They live on cooked food. Eskimos who supposedly live on raw seals only eat raw meat in special circumstances when they are out hunting in the ice. When they are out hunting on the ice, they could not start the fire so they would eat raw meat during the day. All the travelers who saw this always reported this. But Eskimos do not live on raw meat. They lived on a diet of cooked food. The men went home at night and the womenfolk would have a cooked meal for them. If Eskimo hunters went home to the igloo and if there wasn't a hot meal waiting for him, he would have kicked her (wife) out of the snow and tell her to get lost and throw her things out. It is essential that after a long day hunting in the snow, they would come home to cooked food. Their meal is primarily cooked.
· But the fire evidence doesn't seem to go back far and that is where Wrangham's critics are hitting him.
· On the other hand, one has to say that when the evidence of the fire vanishes is also consistent simply to the deterioration of the evidence of fire. (this sentence don't make sense). The further back you go, 200-300 thousand years, a million to 3 million years, the evidence for anything gets much much less because they are washed by floods and erosions and things change. Evidence tends to be eroded with time, so we don't know how way back fire goes. We know fire goes way way back, but we don't know how far back the evidence for cooking goes. We know that these creatures had fire, so they probably used it for warmth, chase animals away but we don't know when did that figure out that they could cook food with it. It seems like the kind of thing that could be stumbled across easily. For example, you brought back a dead rabbit from your hunt and threw them around in front of the camp fire and you suddenly you rabbit is all scorched and it is softer now and it tastes better. Wranghan found out that other animals, species preferred cooked food if you offer it to them, even wild animals. Whether it is meat or plant material, the animals preferred cooked food.
· With processed food we get fat, same thing with pets.
· We are evolutionary adapted to live only cooked food, but not with cats and dogs.
· Cats and dogs have the materials, the sharp claws and teeth to eat raw food, supposedly it is healthier for them. Not sure whether it is true.
· Summary. Wrangham wants to contradict the old fashion view that cooking has no real effect, it is just an epiphenomenon.
· Cooking is universal, we need it. We have smaller gut. Eating meat does not explain that it makes us humans.
· There are people who don't eat mean and they are just as human as we are, they are just as fit and smart and everything.
· His conclusion is that humans are biologically adapted to eat cooked food. Just like how the flea is adapted to drink blood and the giraffe eat leaves on top of trees and so forth.
· What are human adapted for? Nobody can really answer this question. Fruits, yes. Meat, yes. But what we have been missing is cooked food. We all eat cooked food and we have to.
· The old test, which is the atwater of digestibility, was based on the idea of what comes out of your rear end, basically all the calories that you eat are gone by the time it gets out on the other end.. Therefore, you must have got all those calories. This turns out to be wrong. It turns out that all of the calorie information on the food that you buy and eat is in a way wrong, it is misleading. Because that calorie information is based on burning the food. But it says nothing about the calorie information based on whether it is cooked or not or how it is cooked. If you eat a cooked sausage and a raw sausage, the amount of energy that you get out of the same sausage is vastly different. Why? Because your body has to do work that cause energy to digest the food. There is a calorie cost in whatever you eat vs the calorie benefit in whatever you eat.
· Cooked food has vastly higher energy than raw.
· Body can't get the same amount of nutrients from raw food.
· Cooked food is basically pre-digested.
· Cooked food makes it easy for animal guts to digest. We get loads of calories from smaller amount.
· Human don't spend a lot of time chewing every day. We lose the big jaw, teeth and muscle. We don't need them.
· Used to be believe that raw eggs are the perfect food.
· But it turns out you get very little energy from raw egg. Because your body need to work more to digest.
• He starts off by observing that only human beings, of all the living things in the world, can recognize tracks on the ground. Other animals can recognize scent but smudges on the grounds mean nothing to other animals, only humans recognize the tracks because we are so clever and can understand what the marks on the ground mean. We used them to chase animals down.
• Hand signs indicate that one of them had found the tracks of a group of animals.
• The persistence hunt - the most ancient hunting technique in the world. The tribe people run down their prey.
• They feel the rhythm of the animal's movement through the spacing in their tracks.
• Concentrate on the animal which carry a heavy set of horns à the animals will get tired more easily.
• They separate their target prey from the herd so that its track won't be confused by other animals.
• After hours of tracking, they go into a trance like state of concentration.
• If they could not see the tracks of animal, the hunters have to imagine the path the animal would have taken.
• Next stage of the hunt -the chase. Only one man will undertake the chase - the runner.
• This is how a man hunted without weapons, he hunted with physical endurance.
• Running on 2 feet is more efficient in longer distance than running on four. With hands, the man carry water to replenish himself the liquid which he loses as sweat
• The moment of the animal's death, the hunter shared his pain.
• He rubbed his legs with the animal's saliva to relief the agony of his burning muscle and gives thanks the life he has taken to sustain the lives of his family., waiting for him back in the settlement.
• These are modern people living in the current society. And this kind of hunting is very likely the earliest form of hunting where they had no weapons, simply their bodies are enough to hunt, having 2 legs to run rapidly.
• We usually underappreciate our bodies to run long distances with 2 legs. We can run really far with 2 legs, unlike animals.
• If we chase animals long enough, the animals would die.