Body mass estimates of hominin fossils and the evolution of human body size
Mark Grabowski et al. in Journal of Human Evolution
How an animal interacts with the natural world - its energy requirements, home-range size, social organization, relative brain size, locomotion, and many other characteristics - is directly related to its body size. Thus, understanding the biology and evolution of extinct organisms, including species in our own lineage, requires accurate estimates of body size. The last major review of hominin body size based on postcranial traits was more than 20 years ago. Since that time, numerous fossils have been discovered, fossil attributions have been clarified, and methods improved. Understanding the evolution of hominin body size is particularly pertinent at this time as a number of recent high- profile papers on the origins of our genus are based on estimates of body size that directly or indirectly draw from that 20 year old analysis.
Here, we present the most comprehensive and thoroughly vetted set of body mass estimates, species averages, and species averages by sex for fossil hominins to date. Our results show early hominins were generally smaller-bodied than previously thought, but also that some Au. afarensis reached body masses equivalent to that of large H. erectus - findings that challenge numerous evolutionary hypotheses on the origins of our genus based on an increase in body size. In addition, our results suggest it is very unlikely that early H. erectus had a level of dimorphism comparable to that seen in modern humans Thus, evolutionary models based on a significant reduction in dimorphism in this taxon should be reevaluated.