Summer Rylander in Nautilus:
Few animals are more synonymous with the African savannah than the lion. With its muscular stride and ferocious roar, it has long been a symbol of strength, courage, and nobility. As an apex predator, it sits at the top of the food chain—the only real predator it must fear is the human. But recently, one of the savannah’s tiniest inhabitants, one that is barely visible, has fundamentally reshaped the fortunes of the lion, as well as those of a number of other magnificent beasts: zebras, elephants, and buffalo.
This real-life fable begins with the iconic umbrella-shaped acacia tree, also known as the whistling thorn tree. Graceful and resilient, the acacia tree dominates the savannah landscape and often provides most of the tree cover for thousands of square miles. Hidden in the branches of this tree are great numbers of tiny acacia ants, which make their home there and act as protectors. With their painful stings and bites, the ants ward off large herbivores such as elephants and giraffes, and allow the trees to thrive.
More here.