title: Body mass estimates of hominin fossils and the evolution of human body size.
abstract: Body size directly influences an animal's place in the natural world, including its energy requirements, home range size, relative brain size, locomotion, diet, life history, and behavior. Thus, an understanding of the biology of extinct organisms, including species in our own lineage, requires accurate estimates of body size. Since the last major review of hominin body size based on postcranial morphology over 20 years ago, new fossils have been discovered, species attributions have been clarified, and methods improved. Here, we present the most comprehensive and thoroughly vetted set of individual fossil hominin body mass predictions to date, and estimation equations based on a large (n = 220) sample of modern humans of known body masses. We also present species averages based exclusively on fossils with reliable taxonomic attributions, estimates of species averages by sex, and a metric for levels of sexual dimorphism. Finally, we identify individual traits that appear to be the most reliable for mass estimation for each fossil species, for use when only one measurement is available for a fossil. Our results show that many early hominins were generally smaller-bodied than previously thought, an outcome likely due to larger estimates in previous studies resulting from the use of large-bodied modern human reference samples. Current evidence indicates that modern human-like large size first appeared by at least 3-3.5 Ma in some Australopithecus afarensis individuals. Our results challenge an evolutionary model arguing that body size increased from Australopithecus to early Homo. Instead, we show that there is no reliable evidence that the body size of non-erectus early Homo differed from that of australopiths, and confirm that Homo erectus evolved larger average body size than earlier hominins.
authors.affiliation: Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, 800 22nd St., NW Suite 6000, Washington, DC 20052, USA; Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, 0316 Oslo, Norway. Electronic address: mgrabowski@email.gwu.edu.
authors.forename: Mark
authors.initials: M
authors.lastname: Grabowski
authors.affiliation: Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, 800 22nd St., NW Suite 6000, Washington, DC 20052, USA; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103, Leipzig, Germany.
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Hatala
authors.affiliation: Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794, USA.
authors.forename: William L
authors.initials: WL
authors.lastname: Jungers
authors.affiliation: Division of Anthropology, American Museum of Natural History, New York 10024, USA.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Richmond
mesh_terms: D000818:Animals; D005075:Biological Evolution; D049628:Body Size / Q000502:physiology*; D005260:Female; D005580:Fossils; D015186:Hominidae / Q000502:physiology*; D006801:Humans; D008297:Male; D015233:Models, Statistical; D010163:Paleontology
keywords: Australopithecus; Homo; Human evolution; Paleoanthropology