*In the past, changes in the food environment have led to measurable changes in human biology over time. A recent study found that populations eating a high-starch diet have more copies of a gene coding for amylase, the enzyme needed to break down starch. The authors of the study suggest that natural selection has favored the gene in those populations that began eating cereal grains after the birth of agriculture. George H. Perry, et al., “Diet and the Evolution of Human Amylase Gene Copy Number Variation,” Nature Genetics published online September 9, 2007; doi:10.1038/ng2123.