Neanderthal brain size at birth provides insights into the evolution of human life history.
Level 4 - case-series / case-control
Comparative fossil case series (by design analogy, not clinical CEBM)
PubMed 18779579 · doi:10.1073/pnas.0803917105
What was done
Researchers performed virtual reconstructions of cranial morphology from three Neanderthal fossil specimens: one neonate from Mezmaiskaya Cave (Russia) and two infants from Dederiyeh Cave (Syria). These reconstructions were evaluated alongside modern human and chimpanzee data to infer neonatal brain size, postnatal growth rates, and evolutionary life history constraints.
What was found
The abstract reports background scaling values (human brains expand by a factor of 3.3 from birth to adulthood versus 2.5 in chimpanzees) but reports no specific numerical measurements or rates for the fossil specimens. The reconstructions indicated that Neanderthal neonatal brain size was similar to modern Homo sapiens, but Neanderthals exhibited higher brain growth rates during early infancy, resulting in larger adult brains without an earlier completion of growth.
Why it matters
This study provides evidence that modern-like neonatal brain size and related obstetric constraints were present in Neanderthals, suggesting their life history pace was as slow as, or slower than, modern humans.
Limits
The analysis is based on an extremely small sample of only three fossil specimens (one neonate, two infants), limiting population-level generalization. Brain volumes and trajectories are indirect estimates derived from virtual skeletal reconstructions rather than direct soft-tissue measurements.
Cited by
- supports Prior to birth, the rate of brain size increase compared to body size is approximately identical in humans and chimpanzees.