Diet produces significant changes in our body-shape, immune systems, and possibly even skin colour over time. "Diet," says anthropologist John Hawks, of the University of Wisconsin-Madison, "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." What we eat does, however, impact our evolutionary track over many generations.
Milk, Wheat, Starch and Alcohol
It's not unusual to see a whole grocery store lane dedicated to gluten-free cookies, bread, and crackers these days. Gluten intolerance, the major protein present in wheat, is another relatively recent stumbling block in human evolution. Humans didn't begin regularly storing and eating grains until roughly 20,000 years ago, and wheat domestication didn't commence in earnest until roughly 10,000 years ago.
However, since wheat and rye became prominent in human diets, celiac disease has become more prevalent. "You look at this and say how did it happen?" asks Hawks. "That's something that natural selection shouldn't have done."
Our immune response holds the key. The human leukocyte antigens system is involved in the fight against disease, and it produces new variations on a regular basis to combat ever-changing diseases. Unfortunately, this system misreads the human digestive system as a disease and targets the gut lining in those with celiac disease.