Paranthropus boisei, also known as "the Nutcracker man", "the Zinj man" and other nicknames, was a cousin of the human ancestors, that lived during the Pliocene epoch, roughly about 2,000,000 years ago.
Although Paranthropus was related to the more famous and ancient Australopithecus, (initially some scientists thought that it was even another species of Australopithecus), it wasn't a direct ancestor to the modern humans, but only their more distant cousin. This is shown primarily by their teeth, jaws and skulls: the brain cavity was quite small, but the sagittal crest on the skull was quite large, showing that the head and jaw muscles of Paranthropus had also been quite large and also their jaws were shaped more closely like the plant-eating modern gorilla than the carnivorous, or and omnivorous members of the Homo genus.
However, just like Australopithecus, Paranthropus females traveled from one family group to another, in order to prevent inbreeding, as shown on the WWC. It had a bite 4 times that of a human as evidenced by the sagittal crest.
In Walking With... series
Paranthropus was one of the species shown in the second episode of Walking with Cavemen. In that episode, it initially flourished, eating hard plant roots and dry acacia pods (supplemented by termites) during the dry season in Africa, while the less specialized Homo habilis couldn't do that and had a harder time surviving, but at the end of the episode, when Earth's climate began to change, it died out alongside many other prehistoric mammals, yet unlike the more adaptable and generalized Homo habilis, who later evolved into Homo erectus instead.