By Richard Wrangham October 07, 2019 ⋅ 6 min read ⋅ Books
Introduction
What made us human was our control of fire and the advent of cooked meals.
Cooking increases the value of our food by
Making food safer
Making it tastier
Reducing spoilage
Breaking down tough foods
Some think that the greatest change in evolution was the eating of meat.
Habilines, the missing link between apes and humans, shows that there were two changes in the path from ape to human
One 2.5 million years ago.
One between 1.9 and 1.8 million years ago.
Meat eating accounts for the first transition.
The author believes cooking accounts for the second transition.
But the main advantage of cooking is that it increases the amount of energy our bodies obtain from our food.
The extra energy allows us to have more free time and to grow bigger brains.
Humans are cooking apes; creatures of the flame.
Chapter 1: Quest for Raw-Foodists
Are humans dependent on cooked foods or is it a random preference that we evolved?
An experiment was run where people ate from 70% to 100% raw food and the conclusion was that a strict raw food diet cannot guarantee an adequate energy supply.
The subjects of the experiment started losing weight even though they were healthy.
Maybe the difference was that they ate less meat?
Among people who eat cooked diets, there’s no difference in body weight between vegetarians and meat eaters.
Any system that reduces the size of food particles, such as grinding and crushing, leads to predictable increases in energy gain.
Everywhere we look, home cooking is the norm in all human cultures.
There’s abundant evidence and stories of people surviving on raw food but only temporarily or eating high quality raw foods that are highly processed.
There’s no long term evidence, such as longer than a year, that a person can survive on wild, raw food.
We are not like other animals in that we need cooked food to survive.
Chapter 2: The Cook’s Body
At some point in evolution, our ancestors must have been able to use raw foods effectively because our primate cousins do. So what changed?
Evolutionary trade-offs are common are in nature.
E.g. Long legs make it harder to climb but easier to walk. Long arms make it easier to climb but harder to walk.
Similarly, our poor effectiveness at digesting raw food lets us process cooked foods much better.
E.g. We have smaller digestive systems compared to our cousin apes which allows them to process raw foods better at the cost of more energy.
Cooked food offers two advantages
Spontaneous advantages that almost any species, when fed cooked food, can use by growing faster and more efficiently.
Evolutionary benefits such as the smaller mouths, weaker jaws, smaller guts, etc. that use less energy when compared to apes.
It also seems like our digestive systems evolved around cooked food but is this the case?
Maybe our digestive system evolved to handle meat and handling cooked food was a byproduct.
Evidence suggests that we didn’t evolved to eat raw meat as our teeth aren’t as sharp, compared to lions and dogs, and food passes our stomach too quickly.
Since cooking predictably destroys many toxins, we may have evolved a relatively sensitive palate.
We are cooks more than carnivores.
Chapter 3: The Energy Theory of Cooking
Cooking increases the amount of energy we get from food by
Gelantinizing starch
Denaturing proteins
Softening everything
Softer foods provide more energy because they are cheaper to digest.
The effects of grinding and cooking are independent as both methods can be used together to get even more energy out of food.
Chapter 4: When Cooking Began
While humans have been using fire for hundreds of thousands of years, archaeology doesn’t tell us when our ancestors began using fire.
With the inability to use archaeological evidence to tell us when humans started to control fire, we turn to biology.
There are two vital clues from biology
The fossil record paints a clear picture of the changes in human anatomy over the past two million years.
Our biology changes in response to our diet.
Chimpanzees, when presented with raw and cooked food, always pick the cooked over the raw.
Why do wild animals prefer cooked foods over raw foods?
This preference for cooked foods implies an innate mechanism for recognizing high-energy foods.
Cooked foods taste better by being sweeter and less bitter.
The species implicated with the start of cooking is Homo erectus at 1.8 million years ago.
There are two pieces of evidence that Homo erectus started cooking
Anatomical changes related to diet.
The loss of traits related to climbing.
Chapter 5: Brain Foods
Our exceptional intelligence is the defining feature of our species and yet its origins have long been a puzzle.
There appears to be a link between brain size and social relationships.
E.g. Dolphins, elephants, hyenas, crows, and ants.
This is also known as the social brain hypothesis: large brains evolved because intelligence is a vital component of social life.
It also explains why species with bigger brains tend to have more complex societies.
If social intelligence is so important, then why do some group-living species have smaller brains than others?
Diet provides a major part of the answer.
The first requirement for evolving a big brain is the ability to fuel it and to do so reliably.
We are physiologically similar to primates with the only exception being our gut size and brain.
Gut size is linked to the quality of the diet since high energy-dense foods require smaller guts to digest.
Our small gut size provides the answer to what body part was traded off for a larger brain.
Primates that spend less energy fueling their guts can afford to power more brain tissue.
This is also known as the expensive tissue hypothesis: big brains are made possible by reducing expensive tissue such as gut tissue.
The first increase in brain size is attributed to eating meat, and the second increase is attributed to cooking.
Chapter 6: How Cooking Frees Men
Cooking made possible the sexual division of labor.
Sexual division refers to how women and men perform different yet complementary tasks.
The gendered division of labor is universal among humans.
Women and men spend their days seeking different kinds of food, but the foods they obtain are eaten by both sexes which is unusual.
Other animals usually don’t share their food with others but we are an exception.
The human family is the result of the reciprocity of hunting and gathering as women share what they’ve gathered and men share what they’ve hunted.
Since women gather roots and fruits, they can guarantee that their will be food for dinner while men go hunt for more exquisite and energy-dense foods like meat.
Another benefit of cooking is that it frees up time that would’ve been spent eating.
Chimpanzees spend more than six hours a day chewing while humans spend less than an hour a day chewing.
This reduction in chewing time is due to cooked foods being softer.
E.g. Boiling potatoes makes them softer, slow cooking tough meat makes it more tender, and frying fish turns the meat flaky.
Cooking frees up time for us to do other things.
Chapter 7: The Married Cook
Data collected from 185 cultures around the world shows that women tend to cook for the household. There were only three exceptions where women didn’t do the majority of cooking.
The rule that cooking is women’s work is consistent across the vast majority of human societies.
Why is that? It’s because when women cook it solves a basic problem.
The problem is that women need protection to cook and men provide this protection.
Men also get the bonus of guaranteeing their own meal as the woman cooks for the both of them.
Cooking also has the cultural effect of preventing people from stealing as a man can expect food from his wife which means he won’t steal another woman’s meal.
Another interesting element of cooking is that if a single woman shares her food with a single man, they are regarded as married since she cooked for him.
While women are forced to cook by men, it isn’t completely one-sided.
Women feed men to reward them for behaving well.
Food seems to drive a man’s marriage decision more than the need for a sexual partner.
Chapter 8: The Cook’s Journey
Cooked foods being softer means mothers can wean their baby off earlier.
This leads to faster recovery for the mother, a faster growing baby, and faster baby turnover.
Fire also has the benefit of keeping us warm which might explain why we are naked compared to other primates.