Twice a year, arctic terns make an epic journey. They travel the length of the Earth, from breeding grounds in the high Arctic to their southern habitat in Antarctica and back—a one-way distance of almost 20,000 kilometres[1]. This migratory pattern allows terns to follow their food, and escape extreme winters at both ends of the globe. They also avoid the central latitudes, where the predators are. They have every reason to make the trip, but how do they manage the navigation? One popular suggestion is that the Earth’s natural magnetic poles help to guide birds in their migrations[2]. How they…

Though Darwin’s original theory of evolution and natural selection stresses the role of selective forces acting on individuals of varying fitness, group-oriented ‘altruistic’ behaviours within the animal kingdom, such as worker castes in social insects and alarm cries in bird flocks, have been documented repeatedly which at a glance appear to completely contradict traditional evolutionary theory (Williams, 1971). They pose a challenge to evolutionary biologists, because the theory of natural selection in its simplest form favours selfish individual behaviours over altruistic ones: Individuals who invest the most effort into their own reproduction and survival should leave the most offspring and…