A pioneering team of zoologists and botanists, in search of new creatures and plants, gets rare access to Brazil's highest and most isolated mountain, the Pico da Neblina.
This programme surveys mammal herbivores and their predators. The herbivores began to populate the forests when the dinosaurs disappeared, and many took to gathering food at night. To prepare for winter, some store it in vast quantities, some hibernate and others make do as best they can. However, the carnivores joined them, and when a drying climate triggered the spread of grass, they followed their prey out on to the plains. Grass is not easily digestible and most animals that eat it have to regurgitate it and chew the cud. Out in the open, the leaf-eaters had to develop means of protection.
Traveling is extremely arduous for microscopic sperm -- think of a human trying to swim in a pool made of...other humans.