Morphological variation sopra Homo erectus and the origins of developmental plasticity

Morphological variation mediante Homo erectus and the origins of developmental plasticity

Homo erectus was the first hominin sicuro exhibit extensive range expansion. This extraordinary departure from Africa, especially into more temperate climates of Eurasia, has been variously related puro technological, energetic and foraging shifts. The temporal and regional anatomical variation mediante H. erectus suggests that per high level of developmental plasticity, verso key factor durante the ability of H. sapiens to occupy a variety of habitats, ental plasticity, the ability puro modify development durante response onesto environmental conditions, results durante differences con size, shape and dimorphism across populations that relate con part sicuro 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 per instances of resource scarcity and high predator load. We consider the metric variation mediante 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 durante differing patterns by sex across populations. The fossil samples show less evidence of variation than expected, although H. erectus varies more than Neandertals.

1. Introduction

Homo erectus was the first hominin esatto exhibit extensive range expansion. Much like recent humans, this long-lived and widely dispersed species inhabited environments sopra equatorial Africa and more temperate Eurasia. As such, considerable rete di emittenti has been framed around understanding what made dispersal possible and what the broad geographic and temporal trends durante variation might mean biologically for H. erectus. Recently, the regional variation durante H. erectus has been described as ‘human-like’ , and by extension we have suggested that the dispersal and evolutionary longevity of the species ental (phenotypic) plasticity [2,3].

Developmental (phenotypic) plasticity is the ability sicuro modify development con response sicuro environmental conditions, resulting durante variation per adult anatomy that is not genetically canalized . Taxa with a high degree of plasticity should be able puro respond on short-term time scales onesto individual environmental or maternal environmental signals. Arguably this ability may also play an important role per moderating environmental influences too chronic for short-term accommodation and too short for genetic adaptation, as well as providing real advantages for occupying a broad range of environments . A high degree of developmental plasticity is considered an important aspect of the human ability to occupy multiple different environmental niches.

Related onesto this plasticity, differences sopra body size, shape and dimorphism across human populations in part reflect levels of resource sufficiency and extrinsic mortality [5–8]. Onesto be sure, body size, shape and sexual dimorphism have multifactorial causes: there is a genetic component preciso size and variation, and other environmental conditions such as temperature also influence the attainment of adult size. The latter is reasonably well understood, allowing consideration of other contributions puro body size outcomes. Resource sufficiency includes any variable that influences the nutritional base, some of which are co-correlated with aspects of climate such as rainfall and seasonality. Extrinsic mortality can be defined generally as the external risks of mortality such as predator and parasite load, or in recent human environments, factors like homicide . The theory that links shifts per body size and age at first reproduction preciso resource sufficiency and extrinsic mortality is relatively clear . Resource sufficiency is positively correlated with extrinsic mortality and negatively correlated with adult body size; that is, decreases sopra resources lead esatto slow growth rate and small adult size, whereas increases sopra mortality favour early maturation usually leading esatto small body size. Extrinsic mortality related to predator load may differ somewhat from www.datingranking.net/it/seekingarrangement-review/ this expectation in instances when larger body size is advantageous for predator control or survival . Con these instances, early maturation but faster growth may favour the retention of large size, particularly sopra males. In humans, males and females are often argued sicuro be differentially influenced especially by resource sufficiency, with human females being more strongly buffered from environmental vicissitudes and human males responding more dramatically onesto both resource excess and insufficiency. This difference is thought onesto be related preciso female buffering of infant brain size and to be marked per humans for this reason . Such differential influence can alter dimorphism values if the female size change differs from that of males . Extrapolating from living humans, this logic predicts that the skeletal superiorita of H. erectus should spettacolo not only regional variations, but also overall smaller adult body sizes and lower levels of dimorphism in populations experiencing resource scarcity and high extrinsic mortality if the species shows human-like levels of plasticity .