The science of episode three: Savage Family First true Homo species: Homo ergaster / Homo erectus The presumed tool making abilities of habilis were not enough to convince many anthropologists that they should be named ‘Homo’. The species of the genus Homo have large brains, a more modern skeleton, a significant reduction in tooth and jaw size and, importantly, culture. Overall, these hominids departed from the ape-like body plan of our early evolution and were rapidly approaching the body and brain size that characterise modern humans. The Kenyan fossil skeleton called 'Nariokotome Boy,' belongs to a species of early Homo called Homo ergaster. It is the most complete skeleton of an early hominid found to date. The skeleton was that of an adolescent boy who was tall and thin in body shape and had already reached a height of 1.5 meters. This species had a narrow pelvis, which was much more efficient for walking and running than our own. Naked skin Professor Peter Wheeler of Liverpool John Moores University has done much work on thermoregulatory selection pressure on human evolution. His research suggests that naked skin with highly developed sweat glands enabled ergaster to lose heat by evaporation at a rate between 10 and 100 times faster than they could using their respiratory systems alone. Language The evidence of fossil brains provides clues that Homo ergaster may have had spoken language, but this evidence is not very strong. Hence there is controversy as to the extent to which ergaster would have been able to master language. The throats of ergaster suggest that they could have articulated a larger range of vowel sounds than apes. It has been suggested that they would have had a proto-language. The human eye Work by Japanese researchers Hiromi Kobayashi and Shiro Kohshima show that the human eye has exceptional features. Human eyes differ in the following ways from those of apes: 1) The exposed white sclera lacks any pigmentation, and 2) humans posses the largest ratio of exposed white sclera in the eye outline and 3) the eye outline is extraordinarily elongated in the horizontal direction. Humans, with their more sophisticated societies, need to be able to know who they can trust and who they can’t. Reading a person’s gaze is crucial for this. Many scientists think that this new eye design evolved at the time of ergaster. Acheulean tools The tools first appeared around 1.4 million years ago, and are found alongside ergaster remains. It took great skill and strength to master the making of Acheulean tools. At around a million years ago the tools became dominated by symmetrical axes called bifaces. The production team trained the ergaster actors in how to accurately manufacture and use these stone tools, and they even had to learn how to butcher a real deer carcass with the stone axes they’d made. Homo erectus and the exodus from Africa. The first hominid fossil found outside of Africa was the ergaster Trinil2 type specimen, known as Java Man. Further discoveries in Java have turned up remains from a total of about 40 individuals, and an equal number have come from Zhoukoudian in China. It seems the first humans ventured out of Africa via the Middle East with Oldowan tools close to two million years ago, but they do not appear to have ventured into Europe. Perhaps they were prevented in doing so by climate and geography. Instead they dispersed east, taking a southern route to China and on to the island of Java in South-East Asia. Dr Geoffrey Pope believes bamboo would have been an important resource for these first Asians. Evidence of hominid use of fire It is important to distinguish between opportunistic use and direct control of fire. It’s very difficult to prove hominid control of fire without a hearth. Archaeologists use clues like burnt animal bones, charcoal, heat-stained stone tools and baked clay, as well as the colour of the deposits and the presence of hominid remains, to determine the likelihood that hominids were involved in or responsible for the fire. But bush fires and lightning strikes can produce the same effects. This makes determining the earliest use of fire difficult. Next: Episode four - The Survivors
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