One of the hominids finds an animal carcass and recalls the black monolith he previously saw. He makes a connection and realizes that he can use the bone as a tool. He uses the bone to destroy the carcass and eventually uses it to kill other animals for food. The hominids change from herbivores to omnivores and use tools for war.
Beakman explains what a microscope does and then dresses up like Zacharias Janssen, the compound microscope inventor. He shows how Leewenhoek basically created a magnifying glass but Janssen expanded upon it by adding the second lense to make a compound microscope. Beakman then shows a variety of slide samples under the microscope and explains it's an important scientific tool.