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Humans and Primates

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Brain Squeeze
Teacher Contributed

Brain Squeeze

Sure the baby is small but look at that head! What do you think that head would look like if it wasn't born by a cesarean operation?

Why Does My Little Brother Have A Conehead?

Have you ever seen a baby born by vaginal childbirth? Not everyone has, but many who have are surprised and even concerned about the shape of the baby's head. The symmetry which we see in adults is...well, not quite there, and the babies head can look a little squished. It's okay though and is really quite normal. All babies' heads used to look like that. As a matter of fact, not only is it "normal", but it seems that we humans have shared this trait with our ancestors for quite awhile--for 2.5 million years!

Extension Investigation

Use the resources below to answer the following questions:

  1. How does a baby's flexible skull make the birthing process safer for the mother? What sort of potential problems are eased?
  2. What is possible after the birth of a human that is not possible for primates with fused skulls at birth?
  3. How did changes in the pelvis that promoted bipedalism (walking on two feet) affect the birthing process? Was this change beneficial to the mother?
  4. Which do you think came first for early humans: a bigger brain or walking upright? Think carefully about the benefits of both and the physical changes that were necessary? Explain your thinking. Does the finding that some primates had flexible skulls 2.5 MYA support your thinking?

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