Many factors—including genes, sex, ancestry, foetal and childhood conditions—influence how we digest foods and store fat. Physiological stress in mothers can leave lingering imprints on descendants for generations. So although it’s true that humans evolved to eat a diet relatively high in protein and low in carbohydrates and fat, it appears there’s no single Paleolithic prescription for better health.
There isn’t a perfect diet that is the same for everyone. The nature of our success is to find and make a meal in virtually any environment. But our different responses are structured by the basic biology we bring to the table.It seems that the internal working of our bodies have an important role to play including the genetic expressions controlled or at least influenced by our bacterial commensals—how genes are expressed and how you started off in life are powerful influences. Of course genes do not change during a lifetime, or even many lifetimes, but the way they express themselves can be changes quite quickly depending on environmental and other pressures brought to bear on their host.
Whilst our earliest ancestors may have had a meat prevalent diet due to the expansion of tools and fire by the time modern humans swept into Europe about 40,000 years ago, these hunter-gatherers were adept at hunting large game and had also expanded their palates to dine regularly on small animals and freshwater fish as well as roots, berries and other plant based foods.
The next big dietary shift came about 10,000 years ago, when humans began to domesticate plants and, later, animals. The move to agriculture introduced staples of the Western diet: cereal grains, sugars, and milk after weaning. For most of human evolution, our ancestors seldom ate these foods and they still represent a modernised approach to foods.
These foods favoured those whose genes allowed easy digestion of grains, alcohol and milk, just as those communities relient on meat as their staple developed gene associated improvements in meat digestion.
But when ethnic groups abandon traditional lifestyles and rapidly adopt Western diets, they often suffer. Researchers have known for more than a decade that the Pima of the southwestern United States have “thrifty phenotypes”: sluggish metabolisms that store fat efficiently and boost survival on low-calorie diets. That’s probably because their ancestors in Mexico underwent frequent famine. When they eat the calorie-rich Western diet, the Pima develop high rates of obesity, diabetes, and high cholesterol, although their blood pressure stays relatively low.
The bottom line, is that although some diets are better than others, there isn’t a perfect diet that is the same for everyone. The nature of our success is to find and make a meal in virtually any environment. But our different responses are structured by our basic biology. This requires an individualised approach to ensure the optimal intake of food groups and quantities are ingested to ensure the best health to weight ratio.
Gibbons A. Human evolution. What’s for dinner? Researchers seek our ancestors’ answers. Science. 2009 Dec 11;326(5959):1478-9. View Abstract