Humans Are Still Evolving, and It Shows in Surprising Traits
Humans are still evolving, with recent genetic adaptations linked to free-diving, high-altitude living, disease resistance, and digesting milk as adults.
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Human evolution did not stop in the distant past. Populations of modern humans have continued to develop genetic differences as they encountered new foods, diseases, climates, and ways of life. Examples include adaptations associated with long breath-hold diving, life at high altitude, resistance to some infectious diseases, and lactase persistence, which allows some adults to keep producing the enzyme needed to digest lactose in milk. These changes can become common when a genetic trait provides an advantage in a particular environment, but they do not happen in exactly the same way everywhere. Lactase persistence is especially interesting because several different genetic variants are associated with the trait in different populations, alongside the spread of dairying cultures. Research on diving populations has also found genetic signals associated with larger spleens, which can provide a larger reserve of oxygenated red blood cells during breath-hold diving. High-altitude populations have developed different genetic and physiological strategies for dealing with low oxygen. Modern genetic research continues to uncover evidence that natural selection has shaped human populations during relatively recent periods, while the exact history and significance of individual traits can remain an active area of research.
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