User:Rrami052/Homo erectus

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Homo erectus is believed to have changing plasticity in its body which is deemed to be different from non human primates and situational through a list of factors. Regional variants among Homo erectus is to be expected as changes in resources and the idea of scarcity will affect the sexual dimorphism of Homo erectus.

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Like modern humans, H. erectus varied widely in size, ranging from 146–185 cm (4 ft 9 in – 6 ft 1 in) in height and 40–68 kg (88–150 lb) in weight, thought to be due to regional differences in climate, mortality rates, and nutrition. Some of these factors are mutually exclusive such as nutrition or resource scarcity fluctuating due to climate changes ranging from rainfall or seasonality of resources. The reasoning behind the fluctuating body sizes is the idea of plasticity which is unique primarily to human-like species versus their non-primate counterparts. Plasticity details that the difference in body size is due to two factors: Resource sufficiency and extrinsic morality. Like modern humans and unlike other great apes, there does not seem to have been a great size disparity between H. erectus men and women (size-specific sexual dimorphism), though there is not much fossil data regarding this. Brain size in two adults from Koobi Fora measured 848 and 804 cc (51.7 and 49.1 cu in), and another significantly smaller adult measured 691 cc (42.2 cu in), which could possibly indicate sexual dimorphism, though sex was undetermined. Another case that depicts the difficulty of assigning sex to the fossil record is a few samples taken in Olduvai Gorge. In 1960, in Olduvai Gorge two skulls identified OH12 and OH9, were found to be that of H. erectus with a cranial capacities of 1000cc and 700cc. The interesting part was that both skull samples were noted to be full adults and possibly represent a male and female. Sexual dimorphism was deemed a factor in the varying cranial capacity and hinted that H. erectus showed possible signs of sexual dimorphism, but was hard to prove further as the samples deemed fragmented. The sex of certain H. erectus variations are identified to not be either on the basis that the assemblage of certain fossil records are incomplete In the Olduvai H. erectus samples found in Olduvai Gorge, it is seen that certain fragments of the body's structure make it difficult to identify sex and more less if H. erectus depicted sexual dimorphism. If H. erectus did not exhibit sexual dimorphism, then it is possible that they were the first in the human line to do so, though the fragmentary fossil record for earlier species makes this unclear. If yes, then there was a substantial and sudden increase in female height. Certain features of sexual dimorphism are often identified in the possibility of determining sex such as lack of muscle marking.

H. erectus had about the same limb configurations and proportions as modern humans, implying humanlike locomotion. H. erectus and H. sapiens have similar body types that both are considered to have plasticity, but H. erectus is considered the first of the lineage to have express plasticity. The human attributes of H.erectus are theorized to be the starting point for plasticity because of the multiple types of H. erectus found throughout Asia, Europe, and Africa The adaptability of H. erectus to its environment provides a more rapid response to plasticity and explains the differences of body types throughout the fossil record. H. erectus tracks near Ileret, Kenya, also indicate a human gait. A humanlike shoulder suggests an ability for high speed throwing. It was once thought that Turkana boy had 6 lumbar vertebra instead of the 5 seen in modern humans and 11 instead of 12 thoracic vertebrae, but this has since been revised, and the specimen is now considered to have exhibited a humanlike curvature of the spine (lordosis) and the same number of respective vertebrae. (This is the paragraphs I will be improving with my sources)