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Consider the apparently simple task of cooking two fried eggs, over easy. First, obtain two eggs. Then have some oil or butter ready to fry them in, and salt and pepper handy to apply when the eggs are cooked. Next, gather together all the cooking and serving ware that you will need: a non-stick pan, a spatula, and a plate for serving the eggs on and a fork for eating them. Place the pan on the burner and set it to high to warm the pan up, and then turn the heat down to low. Place a small quantity of the fat in the pan; while it heats up, swirl it around in the pan to cover the surface. Break the eggs into the pan. Watch them as they cook until the whites start to set. After a minute or two, but while the yolks are still runny, use the spatula to flip them over, taking care not to break open the yolks. Cook long enough for the surface of the yolk to solidify, but leave most of the yolk runny. Use the spatula to lift the eggs out of the pan and on to a plate. Season with salt and pepper. What could be more simple?
Well, actually, a lot of things could be more simple. Cooking two eggs over easy requires a number of steps, the employment of various materials, tools, and senses, and the ability to assess the progress of a food as it is transformed by temperature. The mind of the cook juggles these various concerns more or less effortlessly to produce eggs of a desired doneness. In order to accomplish this feat of cognitive juggling, the cook uses what psychologists call working memory.
Working memory refers to the ability to draw on and manipulate information over short periods of time, and to use this information to accomplish tasks of various kinds. In his cognitive model of working memory, Alan Baddeley hypothesizes the existence of a "central executive" that oversees the various processes that go into accomplishing a complex task. This executive control is based in the part of the brain called the prefrontal cortex.
Anthropologists and psychologists have long pointed to the enhancement of prefrontal executive control as one of the hallmarks of human behavioral and cognitive evolution. Thomas Wynn and Frederick Coolidge have even more specifically argued that an enhanced working memory is one of the cornerstones of the "modern" mind (see the special issue on working memory and human evolution in Current Anthropology, volume 51, 2010). They suggest that this may have been a recent development, well within the timeframe of modern Homo sapiens (200,000 years or less). However, archaeologists such as Philip Beaman and Miriam Haidle have compared the kinds of tools that chimpanzees make with the kind of stone tools our ancestors made 1.5 - 2.0 million years ago. Their (separate) analyses indicate that advances in working memory, compared to that seen in the great apes, were already present in our earlier Homo ancestors.
The timeframe of 1.5 million years ago is also important for the possibility that this may have been the period when early humans started to use fire to cook food. As Richard Wrangham and his colleagues have argued, cooking food may have been a critical development in human evolution, allowing our ancestors to expand their diets and gain access to the nutrients present in meat derived from muscle tissue (as opposed to soft organs) and calorie-rich tubers. This enhanced diet supported the growth and maintenance of a brain much larger than those seen in early hominins or the great apes.
As I suggest in the first paragraph, cooking food is a task that draws heavily on working memory. One risk involved with cooking food, and which would have increased the selection pressure for better working memory in the past, is that if food is cooked too long, its nutritional value can be destroyed. Given the energetic investment involved in obtaining foods that need cooking, wasting that food in the preparation process would have been a double-disaster for our ancestors. I think it is therefore likely that food preparation, especially if it involved cooking, was a major factor in the natural selection of enhanced working memory in hominins living 1-2 million years ago.
So enhanced working memory was likely an important factor in human cognitive evolution, but what does that have to do with brain health today? Researchers have shown that declines in working memory are an important component of general cognitive decline associated with aging. Based on the "use-it-or-lose-it" hypothesis, numerous studies have shown that keeping cognitively active can improve brain health and function in aging. Such cognitive enhancements can be obtained by maintaining activity in both social and intellectual realms. In either case, working memory is exercised. Food preparation, extending to meal planning and cooking, is another potential realm for cognitive enrichment. The deep evolutionary roots of how people think about food, which is as important as social or technological cognition, suggest that keeping the food-related working memory pathways in the brain active in aging may also keep them healthy (see my book The Omnivorous Mind for context and a discussion).
In the interest of promoting brain health via recipes, I am going to mention my three favorite, lesser-known cookbooks for everyday cooking. First is The Heritage of Southern Cooking by Camille Glenn (Workman, 1986, be wary of abridged additions), a book we have given to many friends. Worth it for the pancakes and waffles section alone. Second, is The Quick and Easy Japanese Cookbook by Katsuyo Kobayashi (Kodansha, 2000). This books shows how a few simple ingredients and flavors, incorporated into very basic dishes, can evoke an entire cuisine. Last, Cooking the Roman Way by David Downie (HarperCollins, 2002), a book that is essential for anyone who likes eating the Roman way. I have used these books often to keep my working memory in working order.
