Friday, April 24, 2009

Neandertal Birth: No Rotation?

According to a story in Science, Neandertal neonates likely did not turn in their mother's womb before birth. The story, by Ann Gibbons states the case this way:
Collaborating with Jean-Jacques Hublin at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, Weaver got permission to make computed tomography-scans of the pelvis, which is kept at the British Museum in London. The two researchers were able to refit the pieces of the pubis, ischium, and ilium together in a three-dimensional, virtual reconstruction. They also used landmarks on the pelvic fragments to compare the pelvis to those of modern humans--and to predict the size and shape of the missing pieces, such as the sacrum and dimensions of the pelvic outlet.

The reconstruction suggests that the pelvis of the Tabun Neandertal was widest from side to side all the way down the birth canal, more like that of Homo erectus or australopithecines than modern humans. And that means that although Neandertal mothers still had difficult births because of their babies' large heads, their babies did not rotate in the womb, the team reports online today in the Proceedings of the National Academy of Sciences.

Getting smaller is not always a good thing.


  1. Is birth in humans uncommonly difficult? For example, do the great apes have it easier? Quadropedal mammals? Birds (in laying eggs, I mean)?

  2. As you move up the primate ladder, there is a higher brain weight/body size ratio, and some primates find it easier than others. Modern humans have reached equilibrium, and have a very tightly constrained birthweight for normal term delivery, but, as medical technology continues to raid the evolutionary game, that is relaxing a bit and will continue to do so. Although Neandertals had larger brains than ours are, the female Neandertals had wider hips than we do—ours are more streamlined. All the same, it seems as though some adjustments were necessary.

    Then, on the other hand, there is the "ooh ooh ahhh" bird.