The Real Fuel of Brain Expansion: Cooking
Brain expansion almost certainly could not have occurred until hominids adopted a diet rich enough in calories and nutrients to meet the associated energy costs. And cooking food does just that. Once plants foods are cooked, they become easier to bite and chew. This means that more energy (calories) can be obtained per minute of eating, and hence more calories can be gained per day. This is particularly true for starchy tubers such as potatoes.
There are nutritional advantages, too. Cooking breaks down the cell walls of vegetables, releasing more vitamins, minerals, protein and carbohydrates. Cooking also makes some poisonous tubers safe, thus widening the range of food available.
Cooking is widely accepted to have occurred at least 250,000 years ago (Ragir, 2000). Other evidence points to the control of fire by hominids even earlier – it is suggested that vegetables were being cooked 1.9 million years ago (Wrangham et al., 1999) as primitive chefs learnt to control and work with fire as a weapon and a tool.
And researchers based at the universities of Minnesota and Harvard in the USA believe that boiling vegetables, such as carrots, poached potatoes and boiled beets was exactly what sparked the development of bigger, human-like brains. This also boosted the availability of food, allowing females to grow almost as big as males.
This contradicts the popular view that eating meat triggered the evolution of hominids into Homo erectus, the ancestor of modern man. It is also backed by Chris Stringer of the Natural History Museum in London, who says: “You have equally nutritious food in roots and tubers but these could not be unlocked until they were cooked” (The Times, 1999).
Scientists Wrangham and Conklin-Brittain state: “Over evolutionary history the adoption of cooking should probably be regarded as one of the largest ever improvements in dietary quality... enabling humans to maintain a more effective immune system and perhaps contributing to the evolution of reduced mortality” (Wrangham and Conklin-Brittain, 1999).