Nature 387, 173 - 176 (08 May 1997); doi:10.1038/387173a0

Body mass and encephalization in Pleistocene Homo

Christopher B. Ruff^*, Erik Trinkaus^† & Trenton W. Holliday^‡

^* Department of Cell Biology and Anatomy, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205, USA
^† Department of Anthropology, University of New Mexico, Albuquerque, New Mexico 87131, USA, and URA 376 du C.N.R.S., Universite de Bordeaux I, 33405 Talence, France
^‡ Department of Anthropology, College of William and Mary, Williamsburg, Virginia 23187-8795, USA

Many dramatic changes in morphology within the genus Homo have occurred over the past 2 million years or more, including large increases in absolute brain size and decreases in postcanine dental size and skeletal robusticity. Body mass, as the 'size' variable against which other morphological features are usually judged, has been important for assessing these changes^1–5. Yet past body mass estimates for Pleistocene Homo have varied greatly, sometimes by as much as 50% for the same individuals^2,3,6–12. Here we show that two independent methods of body-mass estimation yield concordant results when applied to Pleistocene Homo specimens. On the basis of an analysis of 163 individuals, body mass in Pleistocene Homo averaged significantly (about 10%) larger than a representative sample of living humans. Relative to body mass, brain mass in late archaic H. sapiens (Neanderthals) was slightly smaller than in early 'anatomically modern' humans, but the major increase in encephalization within Homo occurred earlier during the Middle Pleistocene (600–150 thousand years before present (kyr BP)), preceded by a long period of stasis extending through the Early Pleistocene (1,800 kyr BP).

1. Pilbeam, D. & Gould, S. J. Size and scaling in human evolution. Science 186, 892−901 (1974). | PubMed | ISI | ChemPort |
2. McHenry, H. M. Early hominid body weight and encaphalization. Am. J. Phys. Anthropol. 45, 77−84 (1976).
3. McHenry, H. M. in Evolutionary History of the "Robust" Australopithecines (ed. Grine, RE.) 133−148 (Aldine de Gruyter, New York, 1988).
4. McHenry, H. Behavioral ecological implications of early hominid body size. J. Hum. Evol. 27, 77−87 (1994). | Article |
5. Ruff, C. B., Trinkaus, E., Walker, A. & Larsen, C. S. Postcranial robusticity in Homo, 1: temporal trends and mechanical interpretaiton. Am. J. Phys. Antrhopol. 91, 21−53 (1993). | ChemPort |
6. McHenry, H. M. Body size and proportions in early hominids. Am. J. Phys. Anthropol. 87, 407−431 (1992). | PubMed | ISI | ChemPort |
7. Rightmire, G. P. Body size and encephalization in Homo erectus. Anthropos (Brno) 23, 139−149 (1986).
8. Gauld, S. C. Body size of Asian Homo erectus: estimation based on prediction models utilizing measures of cranial bone thickness (abstract). Am. J. Phys. Anthropol 16 (suppl.) 93 (1993).
9. Hartwig-Scherer, S. body weight prediction in fossil Homo. Cour. Forsch.-Inst. Senckenberg 171, 267−279 (1994).
10. Ruff, C. B. & Walker, A. in The Nariokotome Homo Erectus Skeleton (eds Walker, A. & Leakey, R.) 234−265 (Harvard Univ. Press, Cambridge, 1993).
11. Aiello, L. C. & Wood, B. A. Cranial variables as predictors of hominine body mass. Am. J. Phys. Anthropol. 95, 409−426 (1994). | PubMed | ChemPort |
12. Kappelman, J. The evolution of body mass and relative brain size in fossil hominids. J. Hum. Evol. 30, 243−276 (1996). | Article |
13. Ruff, C. B., Scott, W. W. & Liu, A. Y.-C. Articular and diaphyseal remodeling of the proximal femur with changes in body mass in adults. Am. J. Phys. Anthropol. 86, 397−413 (1991). | PubMed | ChemPort |
14. Trinkaus, E., Churchill, S. E. & Ruff, C. B. Postcranial robusticity in Homo, II: humeral bilateral asymmetry and bone plasticity. Am. J. Phys. Anthropol. 93, 1−34 (1994). | PubMed | ChemPort |
15. Grine, F. E., Jungers, W. L., Tobias, P. V. & Pearson, O. M. Fossil Homo femur from Berg Aukas, northern Namibia. Am. J. Phys. Anthropol. 97, 151−185 (1995). | PubMed | ChemPort |
16. Ruff, C. B. Morphological adaptation to climate in modern and fossil hominids. Yb. Phys. Anthropol. 37, 65−107 (1994).
17. Holliday, T. W. Body Size and Proportions in the Late Pleistocene Western Old World and the Origins of Modern Humans. (Thesis, Univ. New Mexico, Albuquerque, 1995).
18. Wood, B. Origin and evolution of the genus Homo. Nature 355, 783−790 (1992). | Article | PubMed | ISI | ChemPort |
19. Walker, A. in The Nariokotome Homo Erectus Skeleton (eds Walker, A. & Leakey, R.) 411−430 (Harvard Univ. Press, Cambridge, 1993). | ChemPort |
20. Rightmire, G. P. Patterns in the evolution of Homo erectus. Paleobiology 7, 241−246 (1981). | ISI |
21. Leigh, S. R. Cranial capacity evolution in Homo erectus and early Homo sapiens. Am. J. Phys. Anthropol. 87, 1−13 (1992). | PubMed | ChemPort |
22. Henneberg, M. Decrease of human skull size in the Holocene. Hum. Biol 60, 395−405 (1988). | PubMed | ChemPort |
23. Frayer, D. W. in The Origins of Modern Humans: A World Survey of the Fossil Evidence (eds Smith, F. H. & Spencer, F.) 211−250 (Liss, New York, 1984).
24. Tobias, P. V. The negative secular trend. J. Hum. Evol. 14, 347−356 (1985).
25. Brown, F., Harris, J., Leakey, R. & Walker, A. Early Homo erectus skeleton from West Lake Turkana, Kenya. Nature 316, 788−792 (1985). | Article | PubMed | ISI | ChemPort |
26. Martin, R. D. Primate Origins and Evolution (Princeton Univ. Press, Princeton, 1990).
27. Stephan, H., Bauchot, R. & Andy, O. J. in The Primate Brain (eds Noback, C. R. & Montague, W.) 289−297 (Appleton-Century-Crofts, New York, 1970).
28. Martin, R. D. Relative brain size and basal metabolic rate in terrestrial vertebrates. Nature 293, 57−60 (1981). | Article | PubMed | ISI | ChemPort |
29. Beals, K. L., Smith, C. L. & Dodd, S. M. Brain size, cranial morphology, climate, and time machines. Curr. Anthropol. 25, 301−330 (1984).
30. Hooton, E. A. The Indians of Pecos Pueblo. A Study of Their Skeletal Remains. Papers of the Phillips Acad. SW Exped., No. 4 (Yale Univ. Press, New Haven, 1930).