It stands tall in the semi-arid desert of the Kalahari, giving its inhabitants much-needed shade during summer days, large pods when food is scarce, and a foundation for one of the most remarkable constructions built by a colony of birds. It's the camelthorn, one of only a handful of large trees that can take root in the Kalahari's deficient soil. Discover the evolutionary secrets that allow it to tower as a master of survival in the vast expanses of these African plains, where living is an often unthinkable challenge.