This episode of National Geographic's Naked Science series examines one of humanity's greatest unanswered questions - when exactly was the transitional moment in our evolutionary history in which we became men?
Experts examine the fossils of three of our predecessor species - Australopithecus afarensis, Homo erectus and early Homo sapiens - while asking which traits qualify as essentially human. Citing bipedalism as one of the primary identifying traits, Australopithecus afarensis (nicknamed "Lucy"), stood erect and walked on two feet some 4 million years ago. Noting the small brain and protruding jaw, archaeological researchers and makeup artists construct a mask that mimics what they believe Lucy may have looked like.
In a rather comical sequence, the researcher tasked with modeling the scientifically accurate Lucy mask and matching full-body suit brings this ancient ancestor to life by walking the streets of London, interacting with people, and merging our distant past with the modern world.
1.8 million years ago Homo erectus emerged, also bipedal but sporting a larger brain, albeit still only 2/3 the size of that of Homo sapiens. Homo erectus is noteworthy for having discovered toolmaking and mastering the control of fire. Again, the filmmakers send a model Homo erectus into the modern world to interact with the public, and in yet another demonstration of bringing the past into the present they ask butchers to attempt to use the simple tools of the Homo erectus era with less than stellar results.
Homo sapiens are distinct from these earlier species due to their large brains, as well as creativity and an ability to problem solve. The film suggests that climate change, specifically an ice age, played a vital role in "survival of the fittest" by reducing the population of early Homo sapiens, requiring a change in the way the surviving population used tools, approached problems, and communicated, paving the way for modern humanity and developed society.
Through a series of interviews and creative demonstrations, this installment of Naked Science asks what it was about earlier hominid species that allowed them to survive a near-extinction and progress into the intelligent, advanced human beings of today.