The nature and origins of hominid intelligence is of natural interest to humans as the most successful and intelligent hominid species. As nearly a century of archaeological research has shown, the hominids evolved from earlier primates in eastern Africa. Like some non-primate tree-dwelling mammals, such as opossums, they evolved an opposable thumb, which enabled them to grasp and manipulate objects, such as fruit. They also possessed front-facing binocular vision.
Around 10 million years ago, the earth's climate entered a cooler and drier phase, which led eventually to the ice ages. This forced tree-dwelling animals to adapt to their new environment or die out. Some primates adapted to this challenge by adopting bipedalism: walking on their hind legs. The advantages of this development are widely disputed. It was once thought that this gave their eyes greater elevation and the ability to see approaching danger further off but as we now know that hominids developed in a forest environment this theory has little real basis. At some point the bipedal primates developed the ability to pick up sticks, bones and stones and use them as weapons, or as tools for tasks such as killing smaller animals or cutting up carcases. In other words, these primates developed the use of technology, an adaptation other animals have not attained to the same capacity as these hominids. Bipedal tool-using primates evolved in the class of hominids, of which the earliest species, such as Sahelanthropus tchadensis, are dated to about 7 million years ago although hominid-made tools were not developed until about 2 million years ago. Thus bipedal hominids existed for 5 million years before they started making tools. The advantage of bipedalism would have been simply to be able to carry anything with survival value from an unfavorable environment to a more favorable one. Anything too big or heavy would have to be broken or cut. This would be an insight that led early minds to develop tools for the purpose.
From about 5 million years ago, the hominid brain began to develop rapidly, some say this was because an evolutionary loop had been established between the hominid hand and brain. This theory says that the use of tools conferred a crucial evolutionary advantage on those hominids which had this skill. The use of tools required a larger and more sophisticated brain to co-ordinate the fine hand movements required for this task. However this theory has not been confirmed and many other theories have been developed based on scientific evidence. It is likely that a tool-using hominid would have made a formidable enemy and that surviving this new threat would have been the loop that increased brain size and mind power. By 2 million years ago Homo habilis had appeared in east Africa: the first hominid to make tools rather than merely use them. Several more species in the genus 'homo' appeared before fully modern humans developed, known as homo sapiens. These homo sapiens, which are the archaic version of the modern human, showed the first evidence of language, and the range of activities we call culture, including art and religion.
About 200,000 years ago in Europe and the Near East hominids known to us as Neanderthal man or Homo neanderthalensis appeared. They too had art, such as decorated tools for aesthetic pleasure, and culture, such as burying their dead in ways which suggest spiritual beliefs. Hotly debated in the scientific community is whether or not Homo sapiens developed from neanderthals or a combination of hominids. Some scientists say that the Neanderthals were wiped out by homo sapiens when they entered the region about 40,000 years ago. What is known is that by 25,000 years ago the Neanderthal was extinct. Between 120,000 to 165,000 years ago Homo sapiens reached their fully modern form. The first evidence of this was found in Africa, although once again the origins are widely debated between three theories, the Single-origin theory, the Multiregional model and the Assimilation model.
Sunday, October 25, 2009
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