Becoming Human: Birth of Humanity: Part 2 of the three-part series airs tonight on PBS.
Becoming Human: Birth of Humanity: Part 2 of the three-part series airs tonight on PBS.Courtesy NOVA
In case you missed it last week, TPT 2 aired the first of a 3-part Nova series entitled Becoming Human. The next episode will air tonight at 7 pm on TPT 2 and, in my humble opinion, is worth your time to watch.

Tonight's episode is Becoming Human: Birth of Humanity

"Part 2 of the three-part look at the evolutionary arc of humans focuses on the first discovered skeleton that looks like a modern human---"Turkana Boy," a complete Homo erectus specimen that dates back some 1.5 million years."

For those of you who missed last weeks episode, I took notes for you:
Becoming Human: First Steps

  • Africa used to be a lush rain forest, but over time climate change caused widespread changes to the terrain including the emergence of wide plains and deserts.
  • A new theory of how bipedalism emerged suggests that it was the result of deforestation and the need to travel further between food sources.
  • From the time that bipedalism emerged in our chimp ancestors, changes in the brain began to occur. While brain size remained relatively constant, two major changes occurred:
    1. Brain development slowed: the average chimp brain is fully developed by the age of three while human brains require 20 years to fully develop. By studying the size of the brain case molds of children and adults, scientists determined that hominid brains began to develop more slowly over the several million years after bipedalism first appeared.
    2. The lunate sulcus became less prominent. The lunate sulcus is a groove in chimps' brains that marks the separation of the visual cortex from the rest of the neocortex. Through the study of brain case molds, scientists found that the lunate sulcus moved further back allowing for a larger neocortex.
  • As stated previously, brain size remained relatively constant of the next several million years after the emergence of bipedalism. However, approximately two million years ago, brain size began to increase as evidenced by brain case molds and wider foreheads in hominid species.
    • Two million years ago marked a period of rapid climate change wherein a large lake could emerge, become barren, and reemerge in the space of 1000 years.
    • Some scientists are now suggesting that this rapid climate change spurred the increase in brain size as an adaptation to the rapid changes.

You can watch the full First Steps episode here to get caught up for tonight's episode. Also, check out NOVA's evolution website for some great information on evolution including news stories, links, and videos.

Your Comments, Thoughts, Questions, Ideas

JGordon's picture
JGordon says:

If you're interested in human evolution, be sure to check out Science Buzz's Human Spark feature too!

posted on Tue, 11/10/2009 - 2:06pm

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