Morphological variation con Homo erectus and the origins of developmental plasticity Leave a comment

Morphological variation durante 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 preciso technological, energetic and foraging shifts. The temporal and regional anatomical variation in H. erectus suggests that per high level of developmental plasticity, a key factor per the ability of H. sapiens puro occupy a variety of habitats, ental plasticity, the ability sicuro modify development per response puro environmental conditions, results con differences durante 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 sopra instances of resource scarcity and high predator load. We consider the metric variation sopra 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 durante differing patterns by sex across populations. The fossil samples esibizione less evidence of variation than expected, although H. erectus varies more than Neandertals.

1. Introduction

Homo erectus was the first hominin onesto exhibit extensive range expansion. Much like recent humans, this long-lived and widely dispersed species inhabited environments mediante equatorial Africa and more temperate Eurasia. As such, considerable work has been framed around understanding what made dispersal possible and what the broad geographic and temporal trends con variation might mean biologically for H. erectus. Recently, the regional variation sopra 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 per response preciso environmental conditions, resulting in variation in adult anatomy that is not genetically canalized . Taxa with a high degree of plasticity should be able puro respond on short-term time scales to 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 a broad range of environments . A high degree of developmental plasticity is considered an important aspect of the human ability puro occupy multiple different environmental niches.

Related puro this plasticity, differences in body size, shape and dimorphism across human populations con part reflect levels of resource sufficiency and extrinsic mortality [5–8]. Preciso be sure, body size, shape and sexual dimorphism have multifactorial causes: there is a genetic component to 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 to body size outcomes. Resource sufficiency includes any variable that influences the nutritional luogo, 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 durante recent human environments, factors like homicide . The theory that links shifts per body size and age at first reproduction puro 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 durante resources lead onesto slow growth rate and small adult size, whereas increases per mortality favour early maturation usually leading esatto small body size. Extrinsic mortality related to predator load may differ somewhat from this expectation per instances when larger body size is advantageous for predator control or survival . In these è arablounge gratis instances, early maturation but faster growth may favour the retention of large size, particularly in males. Per humans, males and females are often argued preciso be differentially influenced especially by resource sufficiency, with human females being more strongly buffered from environmental vicissitudes and human males responding more dramatically esatto both resource excess and insufficiency. This difference is thought esatto be related sicuro female buffering of infant brain size and to be marked durante 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 record of H. erectus should show 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 .