How humans are still evolving
Human evolution is often thought of as a process that ended millennia ago, when our ape-like ancestors morphed into Homo sapiens. But a new study has found that the process of natural selection continues, gradually weeding out life-shortening traits in modern humans, including genes that predispose people to heart disease, Alzheimer’s, and heavy smoking. Geneticists examined the genomes of 210,000 people of European descent in search of mutations associated with greater or lesser longevity. Natural selection—a basic mechanism of Darwin’s theory of evolution—is based on the principle that organisms best suited to their environments tend to survive longer, making it more likely that they’ll pass their genes on to future generations. The researchers found that the ApoE4 gene linked to Alzheimer’s is becoming less common, particularly among women. A gene mutation associated with a strong addiction to cigarette smoking in men is also on the decline, ScienceDaily.com reports. “It may be that men who don’t carry these harmful mutations can have more children, or that men and women who live longer can help with their grandchildren, improving their chance of survival,” says the study’s co-author, Molly Przeworski. The analysis also reveals that genetic variants linked to heart disease, asthma, obesity, and high cholesterol all appear less frequently in people who live longer—an indication that humans may continue to adapt to a constantly changing environment.