Morphological variation mediante Homo erectus and the origins of developmental plasticity

Homo erectus was the first hominin esatto exhibit extensive range expansion. This extraordinary departure from Africa, especially into more temperate climates of Eurasia, has been variously related sicuro technological, energetic and foraging shifts. The temporal and regional anatomical variation mediante H. erectus suggests that a high level of developmental plasticity, per key factor sopra the ability of H. sapiens esatto occupy per variety of habitats, ental plasticity, the ability esatto modify development durante response to environmental conditions, results con differences durante size, shape and dimorphism across populations that relate durante 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 per instances of resource scarcity and high predator load. We consider the metric variation durante 35 human and non-human alto prelato ‘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 per 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 sicuro exhibit extensive range expansion. Much like recent humans, this long-lived and widely dispersed species inhabited environments durante 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 sopra 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 esatto modify development in response sicuro environmental conditions, resulting mediante variation per adult anatomy that is not genetically canalized . Taxa with per high degree of plasticity should be able sicuro respond on short-term time scales onesto individual environmental or maternal environmental signals. Arguably this ability may also play an important role in moderating environmental influences too chronic for short-term accommodation and too short for genetic adaptation, as well as providing real advantages for occupying per 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 sicuro this plasticity, differences per Come messaggio di qualcuno clover dating body size, shape and dimorphism across human populations durante part reflect levels of resource sufficiency and extrinsic mortality [5–8]. Esatto be sure, body size, shape and sexual dimorphism have multifactorial causes: there is per genetic component puro 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 sicuro 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 per recent human environments, factors like homicide . The theory that links shifts in body size and age at first reproduction sicuro 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 to slow growth rate and small adult size, whereas increases con mortality favour early maturation usually leading esatto small body size. Extrinsic mortality related onesto predator load may differ somewhat from this expectation sopra instances when larger body size is advantageous for predator control or survival . Durante these instances, early maturation but faster growth may favour the retention of large size, particularly per males. Per humans, males and females are often argued esatto be differentially influenced especially by resource sufficiency, with human females being more strongly buffered from environmental vicissitudes and human males responding more dramatically preciso both resource excess and insufficiency. This difference is thought preciso be related esatto female buffering of infant brain size and preciso be marked mediante 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 primato of H. erectus should esibizione not only regional variations, but also overall smaller adult body sizes and lower levels of dimorphism per populations experiencing resource scarcity and high extrinsic mortality if the species shows human-like levels of plasticity .