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The Homo Lineage

The earliest secure evidence of the genus Homo is piece of upper jaw recently discovered at Hadar, in the Awash Valley, Ethiopia, dated at 2.33 million years. This maxilla was found washing out of a steep slope by members of Don Johanson's field expedition, and is associated with stone tools. The size and shape of the teeth and the shape of the palate closely resemble those of Homo habilis from Olduvai and East Turkana, but the Hadar specimen is too incomplete to tell if this is actually Homo habilis. The first evidence of stone tools is also from Ethiopia and dated at 2.5 million years. The earliest occurrence of stone artifacts may eventually be found to coincide with the earliest appearance of Homo.

Whereas it was originally believed that there was a single lineage of Homo sapiens ancestors, with one species giving rise to another, recent discoveries have indicated a more complex picture. The earliest species of Homo was believed to be Homo habilis, the first tool maker, which is known from Olduvai Gorge and East Turkana almost 2 million years old. But the discovery of the skull KNM-ER 1470, also dated at almost 2 million years old, and the recognition that it represented a separate species, now known as Homo rudolphensis, changed this interpretation. These two species of Homo lived contemporaneously in the same area. Similarly it was believed that a single exodus of Homo erectus from Africa led to the emergence of Homo neanderthalensis, which later gave rise to Homo sapiens. Recent discoveries and new dating techniques have shown that the Neanderthals lived contemporaneously with Homo sapiens for several thousand years indicating again that the single line interpretation is incorrect.

Tool use
The Homo lineage is characterised by the development of technology, from the initial manufacture of stone tools for specific purposes 2.5 million years ago to the rapid and exponential technological advances that we see today. The earliest and simplest stone tool technology, the Oldowan, remained unchanged for a million years until the appearance of the Acheulian Industry 1.5 million years ago. This too varied very little for a little less than a million years until the appearance of archaic Homo sapiens about 600,000 years ago. It was not until the development of agriculture about 10,000 years ago that technological innovations began to appear with increasing rapidity to the point that we see today when new inventions are replaced almost as soon as they are built. The main reason that this has become possible is that modern humans have increasingly sophisticated means of communication The evolution of our means of communication is one of the most significant and unique characters of modern humans. It is the basis of our exponentially developing technology.

Due to the increased size of the brain, Homo sapiens has an ability to learn unequaled in the animal kingdom. To allow time for the assimilation of knowledge, our species has an extended childhood, and during this time knowledge is assimilated by the young, not only through experience but also through teaching by the older generation. Communication is an essential tool for human learning.

The development of speech was a major milestone in human history, and the discovery that events and facts could be recorded permanently by the written word was another major breakthrough. Radios, telephones, and more recently televisions, videos and CD-ROMs have enormously increased our capacity to communicate, and in the last few years the internet has opened another even greater dimension to our communicative abilities. This means that we can now record an infinitely large bank of knowledge gained by previous generations, and we can make this knowledge more easily accessible for future generations to build on and expand than ever before. The learning opportunities for Homo sapiens are greater than they have ever been.

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