The Same Gene Tells Different Stories in Cities and Villages

Scientists have long scratched their heads over a gene variant called APOE ε4. It is linked to heart disease and brain decline in modern societies. Yet it has been around for a very long time. That suggests it once helped people survive in older environments. The idea is that what makes a gene risky today might not have been risky back then.

To test this, researchers studied two Indigenous groups. The Turkana in Kenya and the Orang Asli in Malaysia include people with shared roots living in different ways. Some follow traditional lifestyles. Others live in cities with modern habits. This setup let the team ask whether the same gene acts differently depending on lifestyle.

The results confirmed some known patterns. More copies of APOE ε4 meant higher total cholesterol and higher LDL cholesterol. It also meant lower HDL cholesterol. These effects showed up across lifestyles. But lifestyle mattered for other traits. In the Orang Asli, the gene changed certain innate immune markers depending on how people lived. The same interaction did not appear in the Turkana.

There was also a link between APOE ε4 and a longer reproductive lifespan. But the link was weak. It was not consistent across populations. And it did not lead to more children overall. So the gene is not a clear win in non-industrial settings. Local conditions seem to shape whether it helps or hurts. The same genetic variant can have very different biological effects depending on where and how someone lives.