Body mass and encephalization in Pleistocene Homo

Abstract

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. Yet past body mass estimates for Pleistocene Homo have varied greatly, sometimes by as much as 50% for the same individuals. 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).

Empirical approaches to the study of language evolution

“…Another increase in brain size and cognitive sophistication is represented by a suite of fossils often referred to as Homo heidelbergensis in a broad sense (Ruff, Trinkaus, & Holiday, 1997). These hominins produced excellently balanced wooden throwing spears (Thieme, 1997), and are thought to be close to the common ancestor of Neanderthals and modern humans (debate still rages over whether H. antecessor may be the more suitable moniker; Bermúdez de Castro et al, 1997;Endicott, Ho, & Stringer, 2010).…”

The energetic significance of cooking

“…The unflared, barrel shape of the thoracic cage and the narrow dimension of the pelvis in H. erectus also indicate a small gut (Aiello and Wheeler, 1995), suggesting a diet of higher digestibility. Despite these anatomical constraints, H. erectus shows signals of increased energy use compared to Homo (Australopithecus) habilis, including larger body and relative brain size (Leonard and Robertson, 1994;Ruff et al, 1997;Aiello and Wells, 2002), a suite of locomotor adaptations that improve the human capacity for long-distance running (Bramble and Lieberman, 2004), and possibly reduced interbirth intervals (Aiello and Key, 2002). The apparently softer, more digestible and higher energy diet of H. erectus is consistent with the expected effects of cooking (Wrangham, 2006).…”

Stature estimation from complete long bones in the Middle Pleistocene humans from the Sima de los Huesos, Sierra de Atapuerca (Spain)

“…However, the relationship between stature and long bone length may differ among populations and, as a consequence, populationspecific regression equations are often used for individuals from different populations. For example, many attempts at stature reconstruction from fossil human long bone specimens generally involve the use of regression analysis based on the Trotter and Gleser equations (Trinkaus, 1983;Vandermeersch and Trinkaus, 1995;Ruff et al, 1997;Carretero et al, 1997Carretero et al, , 1999Rosenberg et al, 2006).…”

“…To combat these problems, researchers derived alternate procedures involving the use of reference populations that are more similar in size to the fossil specimens (Lovejoy and Heiple, 1970;McHenry, 1974McHenry, , 1991McHenry, , 1992Olivier, 1976;Trinkaus, 1981Trinkaus, , 1983Leakey and Walker, 1985;Geissmann, 1986;Ruff et al, 1997). These studies suggest that stature estimations for fossil hominins should be based on equations derived from modern populations with similar body proportions.…”