So the theory goes, cooking allowed us to become the humans we are today.
As popularized by Richard Wrangham in his book entitled Cathing Fire: How Cooking Made Us Human, it is hypothesized that humans became the way they are today because of the discovery and utilization of fire.
Wrangham states that humans have used fire to make our food more rich and “valuable,” that it influenced the way our bodies look today, and it changed our social structures.
Between our ancestors, the australopithecines, and the next evolutionary primates the habilines, a change took place about 2.6 million years ago. In the book it states that at this point, the first signal of change is evidenced by markings in Ethiopian rock, signalling the first tool construction. The brains of the habilines was also about twice the size of nonhuman primates at this point.
Then, between 1.9 to 1.8 million years ago, the second step took place leading to the development of Homo erectus. At this point the book goes on to say that it was the eating of meat that caused humans to develop from these ancestors, and thus the use of fire that facilitated this change.
Fruit and Big Brains
In a recent study published in the journal Nature Ecology & Evolution, the authors have discovered that diet does play a larger role than previous theory of sociality in the production of a larger brain, and specifically a higher fruit diet.
Fruit-eating primates naturally had larger brains than did primates who primarily ate leaves. It is hypothesized that the complexity of having to find ripe fruit – remembering where trees are located, when to visit them, etc. – is what causes some primates to have significantly larger brains.
This new theory has trumped the previous theory that our social structures were the largest influence on our brain size.
It is proposed by researchers Tony Wright and Graham Gynn in their book Left In The Dark, that our brains have actually shrunk in size in the last while and that this may have to do with a change in our hormone system mediated by our food. This shrinkage has also been accompanied by a less intensive use of our brains, mainly to do with the right hemisphere.
In an interview, Tony Wright states that:
“The key components in fruit are the chemicals that give fruit its colour, many of which happen to be hormonally or neurochemically active. This is relevant to the real time functioning of the brain. However these effects are of much greater significance during the early development of the brain. Fruit is generally a ‘free lunch’, easy to digest and rich in simple sugars (rocket fuel for the brain). The possibility that humans became near specialist fruit eaters solves a lot of physiological enigmas without having to cobble together complicated theories based on hostile environments that have never produced such a large or complex brain for such a small species.”
Energy Rich Diet
There are many factors that influence brain growth. Karin Isler of the University of Zurich states in an article for Scientific American: “Diet composition is only one factor which correlates with relative brain size […] There is also seasonality, manipulative skills, extractive foraging, age at first reproduction, reproductive rate and longevity, to name a few. And it would be interesting to study how all of these factors [might work together.]”
However, a key factor in brain size development seems to be the richness of the diet. Although scientists have struggled to determine exactly what kind of diet that looks like. But perhaps that matter is irrelevant. Perhaps what is consumed can vary and it matters more that we obtain a greater amount of energy from the diet.
By this logic, we could get the same results with many different diets. And despite the fact that meat was consumed, it is irrelevant to the development of a larger brain.
The first mark of change in the australopithicines was the use of tools. This most likely allowed them to procure more energy from their foods, simply by being able to manipulate them without having to develop the physical bodily structures to do so. Think blending a food versus eating it whole. Many people find it easier to eat a food in large quantities when it is blended or especially juiced, as opposed to eating all of the elements whole.
Luckily in our modern society, food is in abundance for many people. This factor alone could result in more energy being absorbed with less effort (going to the store) allowing for a surplus. Pair that with processing food and you have even more energy available.
To sum it up, the vast number of conflicting studies could simply be the result of different solutions to the same problem – how to procure energy. Although there are many ways to do so, some ways are perhaps easier on the body and more beneficial than others. The use of fire and consumption of meat is just one way, as evidenced by the many individuals living healthful lives on vegan and raw vegan diets. Perhaps the question should be less about what foods a person eats and more about how they go about solving the same old problem our ancestors dealt with long long ago.