Body mass and encephalization in Pleistocene Homo

Area of Science:

• Paleoanthropology
• Human Evolution
• Comparative Anatomy

Background:

• The genus Homo has undergone significant morphological changes over millions of years.
• Accurate body mass estimation is crucial for understanding these evolutionary changes.
• Previous body mass estimates for Pleistocene Homo have shown considerable variability.

Purpose of the Study:

• To reconcile discrepancies in past body mass estimations for Pleistocene Homo.
• To establish reliable body mass averages for early human species.
• To analyze brain size evolution in relation to body mass.

Main Methods:

• Utilized two independent body-mass estimation methods on Pleistocene Homo fossils.
• Analyzed a sample of 163 individuals from the Pleistocene epoch.
• Compared body mass and brain mass data with modern human samples.

Main Results:

• Two distinct body-mass estimation methods produced concordant results for Pleistocene Homo.
• Pleistocene Homo individuals averaged approximately 10% greater body mass than modern humans.
• Encephalization (brain size increase relative to body mass) peaked in the Middle Pleistocene, following a period of stasis.

Conclusions:

• Established reliable body mass estimates for Pleistocene Homo, indicating larger body sizes than present-day humans.
• The primary increase in brain size within the Homo genus occurred earlier than previously thought, during the Middle Pleistocene.
• Neanderthals (late archaic H. sapiens) exhibited slightly lower brain mass relative to body mass compared to early anatomically modern humans.