Altruism has long been a contentious issue in evolutionary biology as it is a counter-intuitive fit in the Darwinian theory of natural selection. While altruistic behaviour has been studied in colonies of bacteria, a recently published paper indicates that it can also occur at a cellular level. Bikul Das, a researcher at the Stanford University School of Medicine has shown that certain human embryonic stem cells, in times of stress, produce molecules that not only benefit themselves, but also help nearby cells survive.
So how does altruism work in cells? "Darwin's theory of natural selection applies to cells, too — the fittest survive and the rest die. Stem cells, however, have an additional burden — they not only have to survive but also retain their identity of 'stemness'. The latter is a crucial task.
External factors could force stem cells to 'differentiate' and turn into nerve cells, heart cells, skin cells or any other cells. Therefore, in times of crisis, they transform to a higher degree of stemness and then secrete chemicals that not only help them but also other cells survive threat. "This is altruism," Das explained.