HUMANS ARE STILL EVOLVING

EVOLUTION IS STILL SHAPING US AND SCIENTISTS DON’T KNOW WHY

Modern medicine’s ability to keep us alive makes it tempting to think human evolution may have stopped. Better healthcare disrupts a key driving force of evolution by keeping some people alive longer, making them more likely to pass on their genes. But if we look at the rate of our DNA’S evolution, we can see that human evolution hasn’t stopped — it may even be happening faster than before.

Evolution is a gradual change to the DNA of a species over many generations. It can occur by natural selection, when certain traits created by genetic mutations help an organism survive or reproduce. Such mutations are thus more likely to be passed on to the next generation, so they increase in frequency in a population. Gradually, these mutations and their associated traits become more common among the whole group.

By looking at global studies of our DNA, we can see evidence that natural selection has recently made changes and continues to do so. Though modern healthcare frees us from many causes of death, in countries without access to good healthcare, populations are continuing to evolve. Survivors of infectious disease outbreaks drive natural selection by giving their genetic resistance to offspring. Our DNA shows evidence for recent selection for resistance of killer diseases like Lassa fever and malaria. Selection in response to