Tag Archives: Speciation

The meaning of Neandertal skeletal morphology

The meaning of Neandertal skeletal morphology

Timothy D. Weaver

The take home from these papers is that human/Neandertal skeletal changes are mainly through genetic drift, the idea of ecological adaption is strong but the authors found no evidence. Maybe more skeletons, more power will help. Much more interesting are the papers about birth and the birth canal (2,3,4). The last common ancestor of both subspecies had an ape type birth canal much larger than the head while both have a canal equal to the head size at birth. This was done by an amazing reconstruction from fragments of a Neandertal pelvis (3). This reconstruction does make some fairly loose assumptions, especially about Neandertal sexual dimorphism. Nevertheless, there is this: both humans and Neanderthals experienced a burst of brain growth since the MCA. Thus both had to get a large brain through a small space. In addition, the human fetus spirals around as it goes through the birth canal.  Neandertals don’t show this. Assisted birth would have a huge fitness advantage, this also means the cognitive use of memory and passed culture. Whether Neandertals required assisted birth is unknown but the added “twist” in humans made giving birth without knowledgeable assistance a dangerous undertaking. Human brain growth has ended and our brains are getting slightly smaller under stabilizing selection. No brainiacs yet. What further intervention in the birthing process in the form of C-sections will do remains to be seen.

  1. The Neandertal type site revisited: Interdisciplinary investigations of skeletal remains from the Neander Valley, GermanyRalf W. Schmitz, David Serre, Georges Bonani, Susanne Feine, Felix Hillgruber, Heike Krainitzki, Svante Pääbo, and Fred H. Smith

  2. Neanderthal brain size at birth provides insights into the evolution of human life history – Marcia S. Ponce de León, Lubov Golovanova, Vladimir Doronichev, Galina Romanova, Takeru Akazawa, Osamu Kondo, Hajime Ishida, and Christoph P. E. Zollikofer

  3. When did the modern human pattern of childbirth arise? New insights from an old Neandertal pelvis - Robert G. Franciscus

  4. Neandertal birth canal shape and the evolution of human childbirth -  Timothy D. Weaver, and Jean-Jacques Hublin