When, Where, and How Did the Genus Homo Develop?
Since the late 1960s, a number of sites in South and East Africa have produced the fossil remains of lightly built bipeds all but indistinguishable from the earlier gracile australopithecines, except that the teeth are smaller and the brain is significantly larger relative to body size. The earliest fossils to exhibit these trends appeared around 2.5 million years ago (mya), along with the earliest evidence of stone tool making. Homo habilis or “handy man” was the name given to the first members of the genus as a reflection of their toolmaking capacities. While paleoanthropologists debate the number of species of early Homo existing during this time period, most concur that the genus Homo developed from one of the smaller-brained bipedal australopithecines in Africa by 2.5 mya. By 1.8 mya, brain size along with cultural capabilities increased considerably, marking the appearance of the species Homo erectus, a fossil group that appears to have descended through variational change from H. habilis. Equipped with larger brains and more sophisticated tools, H. erectus spread from Africa into previously uninhabited regions of Eurasia and distinct regional features appear in the fossil record. Paleoanthropolo-gists debate whether this variation constitutes separate species and the relationship of these ancestral forms to modern Homo sapiens. The controversy intensifies when it comes to Neandertals, the large-brained, robust, muscular members of the genus Homo from Southwest Asia and Europe.
What Were the Cultural Capabilities of Our Ancestors?
The archaeological record, starting with the oldest known artifacts—stone tools dated to between 2.5 and 2.6 mya from Gona, Ethiopia—provides tangible evidence of H. habilis’ culture in the distant past. These mark the start of the Lower Paleolithic or Lower Stone Age. With the appearance of H. erectus, more sophisticated stone tools included the hand axe and other tools of the Acheulean industry along with innovations such as the controlled use of fire (for light, warmth, protection, and cooking), travel across bodies of water, and hunting with specialized tools. The Middle Paleolithic that followed is marked by a diversification of tool
Types and more sophisticated methods of fabrication. The best-known industry of this period, the Mousterian, began around 166,000 years ago and was used by all people—Neandertals as well as other members of the genus Homo said to possess more anatomically modern skulls—in Europe, North Africa, and Southwest Asia up until 40,000 years ago.
Paleoanthropologists are faced with evidence that is often scant, enigmatic, or full of misleading and even contradictory clues. The quest for the origin of modern humans from more ancient bipeds confronts mysteries, none of which has been completely resolved to this day.
Some of the mystery stems from the kind of evolutionary change that was set in motion with the appearance of the genus Homo. Beginning 2.5 mya, several million years after the appearance of bipedalism separated the human evolutionary line from those of the other African apes, brain size of our ancestors began to increase. Simultaneously, these early ancestors increased their cultural manipulation of the physical world through their use of stone tools. These new bipeds were the first members of the genus Homo. Over time, they increasingly relied on cultural adaptation as a rapid and effective way to adjust to the environment.
While the evolution of culture became critical for human survival, it was intricately tied to underlying biological capacities, specifically the evolution of the human brain. Over the course of the next 2.2 million years, increasing brain size and specialization of function (evidence preserved in fossilized skulls) permitted the development of language, planning, new technologies, and artistic expression. With the evolution of a brain that made versatile behavior possible, members of the genus Homo became biocultural beings.
Biological anthropologist Misia Landau has noted that the human being can be thought of as the hero in the narrative of human evolutionary history.1 The hero, or evolving human, is faced with a series of natural challenges that cannot be overcome from a strictly biological standpoint. Endowed with the gift of intelligence, the hero can meet these challenges and become fully human. In this narrative, cultural capabilities increasingly separate humans from other evolving animals. But biological change and cultural change are very different phenomena. Cultural equipment and techniques can develop rapidly with innovations occurring during the lifetime of individuals. By contrast, because it depends upon heritable traits, biological change requires many generations. 105
Paleoanthropologists consider whether an evident cultural change, such as a new type of stone tool, corresponds to a major biological change, such as the appearance of a new species. Reconciling the relation between biological and cultural change is often a source of debate within paleoanthropology.
World History
