How diets shape human evolution

Humans in their lifespan may not see the effect of their diets, habits and environmental factors on evolution

If you are Darwinian, you are one to believe in the theory of evolution of humans, but did you know that what we eat and drink, such as cheese, milk, wheat and alcohol, have an impact on human evolution?

"Diet has been a fundamental story throughout our evolutionary history. Over the last million years, there have been changes in human anatomy, teeth and the skull, that we think are probably related to changes in diet," John Hawks, an anthropologist at the University of Wisconsin-Madison told Smithsonian Magazine.

Studies show that humans continue to evolve and the process is impacting our lives in several ways from changes in Alzheimer's disease, skin colour to changes to menarche. These studies also show that diets will influence the future evolution of humans.

Lactose intolerance is not new

A study on ancient DNA shows that all human adults were lactose intolerant, but, over 20,000 years, one-third of humans are tolerant to lactose. In some geographies, lactose intolerance is lower than others. “In at least different five cases, populations have tweaked the gene responsible for digesting that sugar so that it remains active in adults,” Hawks said, adding that those from Europe, the Middle East and East Africa tolerance is most common.

A hard drop to digest

The scientist also says that one-third of the population from Japan, China and Koreans have a flushing reaction when metabolising alcohol. The process of metabolisation produces a higher than the optimal quantity of toxic acetaldehyde enzymes in these populations and there is evidence to show that this has come up only in the last 20,000 years.

A lot more people have trouble with gluten than you'd think

Humans started consuming wheat and rye in full swing only about 10,000 years ago, however, since then humans have also witnessed a high occurrence of celiac disease which attacks the lining of the gut. Genes known as human leukocyte antigens help in fighting disease and these antigens keep evolving to fight diseases that keep changing from time to time. But for those with celiac disease, the antigens mistake the human digestive system for a disease and hence the ill effects.

Evolution though in the larger scheme of things is quick, a human in their lifespan may not see the effect of their diets, habits and environmental factors on evolution. However, genome sequencing, databases and massive computing power helps spot small genetic tweaks that over time and generations contribute to massive shifts in evolution.