Humans Are Still Evolving — and Your Genes Prove It
Many think civilization stopped human evolution. Genes tell a different story: milk, mountains and malaria changed us in the last 10,000 years.
It is easy to believe that evolution is finished with us. We have medicine, heating, supermarkets — the weak no longer die young, so why would our genes keep changing? But geneticists who read human DNA see the opposite. Evolution never had a finish line. It simply keeps adjusting living things to the world they live in, and our world has changed faster in the last 10,000 years than ever before.
In 2007 a team of scientists compared the genomes of people from different continents and found that human adaptive evolution actually sped up over the last 40,000 years, and especially after farming began — more people meant more new mutations for nature to choose from https://pubmed.ncbi.nlm.nih.gov/18087044/. Ten thousand years is a blink in the history of life, yet it was enough to leave clear marks in our DNA.
The milk mutation
Almost every mammal loses the ability to digest milk after it stops nursing: the gene that makes lactase, the enzyme that breaks down milk sugar, switches off. Then people began keeping cows, goats and camels. In Europe, a small change near the lactase gene kept it switched on in adults https://doi.org/10.1038/ng826. In East Africa, herders developed different mutations with the same effect — nature found the same answer twice, independently https://pubmed.ncbi.nlm.nih.gov/17159977/ Today in parts of Northern Europe around nine in ten adults can drink milk without trouble, while in much of the world most adults cannot.
Living on the roof of the world
At 4,000 metres above sea level every breath brings in far less oxygen. Most visitors respond by making too much haemoglobin, which thickens the blood and can make them ill. Tibetans do not. Their genomes carry variants of the genes EPAS1 and EGLN1 that keep haemoglobin at a normal level even in thin air https://pmc.ncbi.nlm.nih.gov/articles/PMC3711608/ https://doi.org/10.1126/science.1189406. Researchers called EPAS1 one of the fastest changes ever seen in a human gene.
Genes against disease
• Malaria. In regions where malaria killed children for thousands of years, one copy of the sickle-cell gene variant became common because it strongly protects against severe malaria https://pubmed.ncbi.nlm.nih.gov/15942909/
• Starch. Peoples whose traditional diet is rich in starchy food tend to carry more copies of the amylase gene, which helps digest starch https://pubmed.ncbi.nlm.nih.gov/17828263/
Still happening now
Evolution did not stop with farming. A 2016 study of thousands of modern British genomes found traces of natural selection over just the past 2,000 years https://dspace.mit.edu/handle/1721.1/124745 Today's pressures are different — less hunger and fewer predators, more sitting, more calories, more screen light. How our genes will answer them is something only future geneticists will be able to read. But one thing is clear: the human body is not a finished product. It is a work in progress — and so are we.