Morphological variation inHomo erectusand the origins of developmental plasticity

Abstract

One contribution of 17 to a discussion meeting issue 'Major transitions in human evolution'. Homo erectus was the first hominin to exhibit extensive range expansion. This extraordinary departure from Africa, especially into more temperate climates of Eurasia, has been variously related to technological, energetic and foraging shifts. The temporal and regional anatomical variation in H. erectus suggests that a high level of developmental plasticity, a key factor in the ability of H. sapiens to occupy a variety of habitats, may also have been present in H. erectus. Developmental plasticity, the ability to modify development in response to environmental conditions, results in differences in size, shape and dimorphism across populations that relate in part to levels of resource sufficiency and extrinsic mortality. These differences predict not only regional variations but also overall smaller adult sizes and lower levels of dimorphism in instances of resource scarcity and high predator load. We consider the metric variation in 35 human and non-human primate 'populations' from known environmental contexts and 14 time-and space-restricted paleodemes of H. erectus and other fossil Homo. Human and non-human primates exhibit more similar patterns of variation than expected, with plasticity evident, but in differing patterns by sex across populations. The fossil samples show less evidence of variation than expected, although H. erectus varies more than Neandertals.This article is part of the themed issue 'Major transitions in human evolution'.

Major transitions in human evolution

“…This mirrors the high level of diversity that is known from the succeeding Plio-Pleistocene [15]. Even within the Pleistocene, as Antó n [9] discusses for H. erectus, and Stringer [10] and Mirazó n Lahr [11] for H. sapiens and its contemporaries, there is considerable diversity, and clearly not a unilinear pattern.…”

“…Dean's [4] presentation of maturation patterns shows that shifts in lifehistory are likely to be equally important, and underlie many of the behavioural and cultural adaptations, while Antón [9] reminds us that the gap between genetics and culture is filled by many other possibilities, of which phenotypic plasticity in response to variable environments is an important one.…”

“…Antó n et al [9] show that H. erectus is highly variable, not just in body size (see [3]), but also in other aspects of its morphology. The appearance of modern humans is seen at about 195 Ka at Omo Kibish in Ethiopia (figure 3), but Stringer [10] argues that the lineage leading to it shows derived traits earlier than this, and so the transition is spread over several hundred thousand years, and that it is likely archaic populations persisted across the African continent, some until into the late Pleistocene [11].…”

“…We are now aware that there is much greater overlap and complexity. Stone tools may effectively be under some level of genetic control (see Collard [27]), and as Antó n et al discussed [9], morphological variation can reflect various levels of plasticity. But this in turn raises questions about the genetic basis for plastic responses and reaction norms.…”

Network analysis of the hominin origin of Herpes Simplex virus 2 from fossil data

“…Both Homo erectus and Paranthropus boisei are known from sites around Lake Turkana in Kenya that are contiguous in age (Anton et al, 2016;Wood and Constantino, 2007) and it is likely that close contact between the species would have been relatively common especially around water sources. The appearance of Homo erectus 2.0 MYA is accompanied by evidence of active hunting and butchery, and from 1.76 MYA increasingly sophisticated stone tools (Cachel and Harris, 1998).…”