Synopsis

What is the purpose of sex? Surprisingly, it may be protection from disease. Brian Leith explores the complex question of sexual reproduction and discovers a startling truth: males appear, at first glance, almost superfluous – many thriving plants and animals (like the common weeds we battle in our gardens) manage perfectly well without them! Yet, larger creatures, from polar bears to humans, invariably possess both male and female individuals, and for a compelling reason. The key to understandi