MARY KILBOURNE MATOSSIAN
From Hominids to Human Beings
Mary Kilbourne Matossian, "From Hominids to Human Beings," in Shaping World History (Armonk, NY: M. E. Sharpe, 1997),9-14. excerpted in Kevin Reilly's Worlds of History

This selection is part of a chapter from a recent world history book. How is the subject of this chapter different from the previous article? How is this time period different?
  What, according to the author, happened in East Africa around 15 million years ago? What happened as a long-term result of this change around 4.5 million years ago? What happened about 2.5 million years ago? 200,000 years ago? 35,000 years ago? 27,000 years ago?
  What happens if you try to place the dates in this selection on the time line you drew for the previous article?
  Draw a time line specific to this selection. Mark the left-most notch " 5 million years ago," then add ten equally spaced notches, ending with "today" on the far right. Label notches in increments of 0.5 million years. Now plot the major dates referred to in the article, indicating to what the dates refer.
  If you were to extend this time line to include 15 million years ago -using the same incremental scale -how many pages more would you need? If you wanted to include the dates mentioned in this chapter's first selection by Carl Sagan, how many pages more would you need?
  To understand the geography of this selection, locate the Great Rift Valley on a topographic map, which will show the rift in relief. 
  The article follows:

Anthropologists have named us Homo sapiens sapiens, the clever, clever hominid. Over a century ago certain scientists abandoned the Western creation myth and began to seek human origins in nature among the primates (apes and monkeys). If apes and people had many resemblances, what kind of creatures linked the two species? When and where did this linking happen?
  The discoveries of physical anthropologists and geneticists have indeed established that we belong to the primate family. The line of hominids (bipedal apes, apes who walk on two legs) differentiated from that of other apes about five million years ago. We share with chimpanzees and bonabos (pygmy chimpanzees) between 98 percent and 99 percent of our structural genes. Who can watch primates in a zoo without experiencing a shock of recognition?
  In December 1992 in Ethiopia, Tim White, an anthropologist from the University of California at Berkeley, and his team discovered the earliest hominid yet known. They announced their discovery in September 1994. Anthropologists believe that the bones discovered are almost 4.5 million years old. These hominids walked upright, were four feet tall, and lived in a woodland setting. Their skull capacity was about one third that of ours. They lived very close to the time of separation between hominids and apes estimated by geneticists -'-- five million years ago.
  In August 1995 Mary Leakey and her team discovered in Kenya similar hominids that were 4.1 million years old. These hominids are estimated to have weighed between 101 and 121 pounds. This is the most recent of a long sequence of discoveries. It now seems likely that hominids differentiated from apes in northeast Africa, in or near the Great Rift Valley of Ethiopia, Kenya, and Tanzania. Hominids had habitually upright posture and walked on two legs. They lived mainly on the ground, not in trees. These attributes appeared long before their brain expanded and they began to make tools.
  About fifteen million years ago the environment in East Africa was changing. The earth's crust was splitting apart in places, while highland domes of up to nine thousand feet formed in Ethiopia and Kenya. These domes blocked the west-to-east airflow and threw the land to the east into rain shadow. Lacking moisture, the continuous forests in the east fragmented into patches of forest, woodland, and shrub-land. About twelve million years ago the Great Rift Valley , running north to south, appeared in East Africa.
  This development had two major biological consequences. First, the Great Rift Valley was an east-west barrier to the migration of animal populations. Second, although the apes in the dense jungle on the west side of the valley were already adapted to a humid climate and thus were not forced to adjust to a new environment, in the east a rich mosaic of ecological conditions emerged. Biologists believe that mosaic environments drive evolutionary innovation, since competing successfully in such an environment requires new adaptations. The hominids -bipedal apes -developed in such a place. This is the first example of the influence of climatic change on prehistory.
  According to Peter Rodman and Henry McHenry, on the east side of the Great Rift Valley, where woodlands were scattered, a bipedal ape had an advantage. It could move more easily from one grove of food-bearing trees to a more distant grove. An ape who walked habitually on two legs was more energy-efficient than an ape who walked on four. Upright posture was also more efficient for cooling the body in thc daytime heat. Other anatomical changes made it easier for hominids to stride and to run. The beginning of brain expansion in hominids began in Africa around 2.5 million years ago with Homo-habilis and was associated with the appearance of the earliest stone tools. By 1.8 million years ago a more advanced hominid, Homo erectus, was making sharp-edged tools. The process involved knocking one rock against another, chipping off a sharp flake from the "core" stone and using the flake as a knife. Hominids could use this knife to cut through the hides of most animals and get to the meat quickly. Evidence shows that with this innovation hominid meat eating soon increased.
  There was probably a positive feedback loop between the expansion of the hominid brain and meat eating. The hominid brain is three times as big as that of an a pc of similar body size. Meat is an excellent source of protein and, because of its fat content, is high in calories; this helps to support the larger brain. At the same time the growth of the brain in relation to body weight favored the improvement of human hunting skills and higher meat consumption. In hominid females, the pelvic opening widened to compensate for the increased brain size of the hominid infant. However, that was not enough, and any greater widening would reduce bipedal mobility. A solution to the problem of increased hominid brain size was the natural selection of those hominids that produced children born "too early," with brain size only one third that of an adult. These infants are slow to mature and so depend on their parents for a longer period. This extends the time that parents can transmit culture (patterns of behavior) to their offspring. In contrast, baby apes are born with a brain one half the size of that of an adult ape. They mature more quickly than hominids do, but have fewer years of dependency to learn from their parents.
  What sort of culture did prehistoric humans transmit? Cultural anthropologists who have studied the way of life of foragers (hunter-gatherers) today say that the usual size of a human band is twenty-five persons, including children and adults. A larger unit, the dialectical tribe, includes about five hundred persons. Foragers use only temporary camps and move about on their range. Since longevity was usually only twenty-five to thirty years, many children were raised by relatives, their parents being dead. The band, not the nuclear family, was the principal social unit. A band acquires food cooperatively, by hunting and gathering, and shares it. Adults teach their children, who are born self-centered, to become sensitive to the needs of others and to share food.
  Is such sharing, social behavior unique to humans? Frans de Waal, a researcher at the Yerkes Primate Research Center in Atlanta, Georgia, discovered that chimpanzee groups consist of caring, sharing individuals who form self-policing networks. He believes that the roots of morality may be far older than we are. A chimpanzee seems to realize that social disorder is a threat to its individual well-being. When rivals embrace, signaling an end to their fight, the whole colony may break into loud, joyous celebration.
  However, chimpanzees share food and other treasures only when it is to their advantage. They cheat when they can get away with it by hiding a private stock of food. When cheating, they try to deceive other members of the group. Fortunately, they live in groups of less than a hundred, so they can watch each other and identify the cheaters. Older chimpanzees deny food to young cheaters by excluding them from sharing in the next windfall.
  It appears that both our moral and immoral tendencies are part of the natural order. Both "good" and "evil" are aspects of our adaptive and competitive strategies. We can imagine that human goodness developed out of the need to adjust to a cooperative group. By belonging to such a group an individual had a major advantage in the struggle to survive and reproduce.
  No more can we think of stone-tool making and sharing behavior as unique to our species. Nor are we unique in our capacity for tactical deception and savagery. Rather, we have a place in a natural mammalian continuum.
  The only behavior unique to humans appears to be the ability to communicate quickly with a large number of phonemes ( discrete sounds). We can make fifty phonemes; apes can make only twelve. Humans can speak more quickly and articulately than any other species. The placement of our vocal organs makes this possible. When did our ancestors acquire spoken language involving more than twelve phonemes? Some anthropologists think it was as far back as 2.5 million years ago (the time of Homo habilis). Most agree that complex spoken language goes back at least thirty-five thousand years to the time of the cave paintings in Europe. They think that language evolved as a means of social interaction, allowing individuals to prevent fights or settle them more easily.
  Recent discoveries in the Pavlov Hills of the Czech Republic indicate that ceramics and weaving go back twenty-seven thousand years -to before the beginning of settled life. These skills were probably the innovations of women, because women could make pots and weave while they took care of children.
  When did people exactly like us, anatomically speaking, appear?
  Many anthropologists think that our species (Homo sapiens sapiens) differentiated around two hundred thousand years ago in either south or northeast Africa. From northeast Africa people spread across the earth. They went to the Near East, Europe, China, Southeast Asia, Australia, the Pacific Islands, and the Americas. Lucky humans settled on lands suited to agriculture. Only they could look forward to sustained population growth and civilization.
  They were especially lucky if the relationship between Land and water in their region was favorable for water transportation, as the cost of moving bulk goods by water for a given distance was one eighth to one twentieth that of moving them by land. Waterborne commerce may have been just as fundamental as the development of farming for the birth of civilization.

The great variety of possible time lines reminds us that history can focus on different time periods. Any history must make some judgment about how things have changed over time, and these changes can be measured only within an appropriate framework. Consider, for instance, what type of time line you would use if you wanted to compare the publication dates of each selection in this chapter. And, again, what time line would you use to plot your life as well as your parents' and grandparents' lives?
  Thinking of time in a linear way can be quite useful, but there are many things a time line cannot do. It does not, for instance, establish a definitive relationship between two events except within the context of time. Assume time relationships to be coincidental unless there is reason to believe otherwise. The fact that one event occurred before another cannot, by itself, establish causation. Determining cause and effect is a complex process that begins with knowledge of when things happened.
  Recognize, too, that a linear way of thinking about time is not the only way. Time might also be thought of as recurring cycles, a vast continuum. Seasons, holidays, even birthdays bring us back to familiar times: They become our touchstones. Recurring dreams, images, feelings, and smells can make the past the present, if only for a moment. Ecstatic experiences eliminate time entirely- time does fly when you're having fun.
  Culturally speaking, linear time is a Western (European and American) concept. In ancient India, by contrast, philosophers imagined time as an endless series of cycles rather than a straight line. If you envisioned time as a cycle, how would you chart it? If you thought of time as a never-ending cycle, would history matter?