Tuesday, August 4, 2009

The Emergence of Our Human Ancestors: The Appearance of Homo Habilis About 2.5 Million Years Ago


Approximately 2.5 million years ago, during the Miocene Epoch, a series of interrelated events took place that had a significant effect on the evolution of our ancestors. There was a dramatic change in climate which produced drying and cooler climatic conditions including glaciation. This was particularly true in Africa which was also being affected by the uplift of the mountains in eastern Africa. Much of the tropical forests were eliminated and replaced by grass lands. This meant that the Australopithecines lost much of their sources of food, the trees with fruit and berries.

The genus Homo, taken from the Latin, meaning "human being", or "person," evolved as a genus from Australopithecine ancestors with the initial appearance of Homo habilis. Commonly referred to as "handy man", Habilis was so called because of evidence of tools found with its remains. H. Habilis lived between 2.4 and 1.5 million years ago. As a genus, Habilis shared a number of similarities to the australopithecines. Habilis had a primitive looking face that bore many similarities to the australopithecines. The molars were small, but were still much larger than those found in modern humans. The average brain size, at 650 cc, is considerably larger than in australopithecines. The shape of Habilis' brain was also more humanlike. Habilis might have contained a form of a rudimentary Broca's area which is essential for speech, and habilis might of been capable of producing rudimentary speech. Habilis was about 5 foot tall, and weighed about 100 pounds at maturity, although females may have been smaller.

The appearance of the H. Habilis line of development coincides with the first evidence of stone tools with primary reference to the Oldowan toolkit which was made by H. Habilis from flint. "The technology is called 'Oldowan' because the first specimens were found by Louis and Mary Leakey at Olduvai Gorge. Oldowan tools have been described as 'crude but effective';... Most of the tools were made by a single blow of one stone against another, to produce a sharp-edged flake. But for some of them, a softer rounded hammer stone was needed to achieve the right effect."

Another distinguishing characteristic of the Oldowan Toolkit is that they were non-symmetrical as shown in this depiction by José-Manuel Benito, and from Wikipedia.


Evolutionary developments were combined with technological innovations and cultural forms that coalesced around human growth as a species. The result of technological and cultural changes which vastly sped up the development of intellect and resulted in a quickening pace of change for human development.We have already seen the effect of Oldowan Toolkits as early examples of technological developments and innovations are clearly demonstrated by the creation of established practices to create stone tools which pushed humans to constantly be innovative and to seek better and better refinements in the use of flint and the control of fire. Both flint tools and the control of fire pushed humanity forward as each provided protection and access to sources of sustenance. Flint and fire translated into human access to power and control over the environment.

The use of brain power or modes of behavior is a highly distinguishing characteristic of human ancestors beginning with H. Habilis' ability to create diets that consisted of higher nutritional components. And the inclusion of the high concentrations of protein, calories, and fat found in meat brought forth changes in dental structures and in the facial bones. A non-physical aspect of dietary change was witnessed in the continued refinement and use of tools. And of equal if not revolutionary importance was that the move to becoming carniverous meant that H. Habilis began to span across a wider geographic range than previous hominids as the search for new sources of meat drove Habilis farther away from a centrally based location to greater vistas.

H.Habilis also developed a focused spatial and temporal sense, commonly referred to as foresight that provided the means for producing tools. H. Habilis is known to have created stores of rock that were to be used for the creation of more tools in the future and also because H.Habilis saw the need for specialization, tools were produced with very specific tasks in mind. The use of forethought and the movement from general tools to specifically modified tools designed to accomplish a particular tasks directly reflects H.Habilis use of an expanding brain power.

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