Evolution of Immunity in Invertebrates

The complex immune systems of humans and other mammals evolved over quite a long time - in some rather surprising ways. In 1982 a Russian zoologist named Elie Metchnikoff noticed a unique property of starfish larva. When he inserted a foreign object through it's membrane, tiny cells would try to ingest the invader through the process of phagocytosis. It was already known that phagocytosis occurred in specialized mammal cells but never in something less complex like a starfish. This discovery led him to understand that phagocytosis played a much broader role, it was a fundamental mechanism of protection in the animal kingdom. Metchnikoff's further studies showed that the host defense system of all animals today were present millions of years before when hey were just beginning to evolve. His studies opened up the new field of comparative immunology. Comparative immunologists studied the immune defenses of past and current creatures. They gained further insight into how immunity works.…