The Origin of Humankind Read Online Free
Author: Richard Leakey
other features indicated that it was a species of primitive ape (the jaw of modern apes is U-shaped). Ramapithecus had lived a life in the trees, like its later relative the orangutan, and was not a bipedal ape, still less a primitive hunter-gatherer. Even diehard Rama-pithecus-dLS-hommid anthropologists were persuaded by the new evidence that they had been wrong and Wilson and Sarich had been right: the first species of bipedal ape, the founding member of the human family, had evolved relatively recently and not in the deep past.
Although in their original publication Wilson and Sarich had proposed a date of 5 million years ago for this event, the consensus of molecular evidence these days pushes it back to close to 7 million years ago. There has, however, been no retreat from the proposed biological intimacy between humans and African apes. If anything, that relationship may be even more intimate than had been supposed. Although some geneticists believe that the molecular data still implies an equal three-way split between humans, chimpanzees, and gorillas, others see it differently. In their view, humans and chimpanzees are each other’s closest relatives, with gorillas at the greater evolutionary distance.
FIGURE 1.1
Molecular evidence. Before 1967, anthropologists interpreted fossil evidence as indicating an ancient evolutionary divergence between humans and apes: at least 15 million years ago. But in that year, molecular evidence was presented that showed the divergence to be much more recent: close to 5 million years ago. Anthropologists were reluctant to accept the new evidence but eventually did so.
The Ramapithecus affair changed anthropology in two ways. First, it demonstrated the perils of inferring a shared evolutionary relationship from shared anatomical features. Second, it exposed the folly of a slavish adherence to the Darwinian “package.” Simons and Pilbeam had imputed a complete lifestyle to Ramapithecus , based on the shape of the canine teeth: if one hominid feature was there, all such features were assumed to be present. As a result of the undermining of the hominid status of Ramapithecus , anthropologists began to be uncertain about the Darwinian package.
Before we follow the course of this anthropological revolution, we should look briefly at some of the hypotheses that over the years have been proposed to explain how the first hominid species might have arisen. It is interesting that as each new hypothesis gained popularity, it often reflected something of the social climate of the time. For instance, Darwin saw the elaboration of stone weapons as important in initiating the evolutionary package of technology, bipedalism, and expanded brain size. The hypothesis surely reflected the prevailing notion that life was a battle and progress was won by initiative and effort. This Victorian ethos permeated science, and shaped the way the process of evolution, including human evolution, was viewed.
In the early decades of this century, the heyday of Edwardian optimism, the brain and its higher thoughts were said to have made us what we are. Within anthropology, this prevailing social worldview was expressed in the notion that human evolution had been propelled initially not by bipedalism but by an expanding brain. By the 1940s, the world was in thrall to the magic and power of technology, and the “Man the Toolmaker” hypothesis became popular. Proposed by Kenneth Oakley of the Natural History Museum, London, this hypothesis held that the making and using of stone tools—not weapons—provided the impulse for our evolution. And when the world was in the shadow of the Second World War, a darker differentiation of humans from apes was emphasized—that of violence against one’s fellows. The notion of “Man the Killer Ape,” first proposed by the Australian anatomist Raymond Dart, gained wide adherence, possibly because it seemed to explain (or even excuse) the horrible events of the war.
Later,
Although in their original publication Wilson and Sarich had proposed a date of 5 million years ago for this event, the consensus of molecular evidence these days pushes it back to close to 7 million years ago. There has, however, been no retreat from the proposed biological intimacy between humans and African apes. If anything, that relationship may be even more intimate than had been supposed. Although some geneticists believe that the molecular data still implies an equal three-way split between humans, chimpanzees, and gorillas, others see it differently. In their view, humans and chimpanzees are each other’s closest relatives, with gorillas at the greater evolutionary distance.
FIGURE 1.1
Molecular evidence. Before 1967, anthropologists interpreted fossil evidence as indicating an ancient evolutionary divergence between humans and apes: at least 15 million years ago. But in that year, molecular evidence was presented that showed the divergence to be much more recent: close to 5 million years ago. Anthropologists were reluctant to accept the new evidence but eventually did so.
The Ramapithecus affair changed anthropology in two ways. First, it demonstrated the perils of inferring a shared evolutionary relationship from shared anatomical features. Second, it exposed the folly of a slavish adherence to the Darwinian “package.” Simons and Pilbeam had imputed a complete lifestyle to Ramapithecus , based on the shape of the canine teeth: if one hominid feature was there, all such features were assumed to be present. As a result of the undermining of the hominid status of Ramapithecus , anthropologists began to be uncertain about the Darwinian package.
Before we follow the course of this anthropological revolution, we should look briefly at some of the hypotheses that over the years have been proposed to explain how the first hominid species might have arisen. It is interesting that as each new hypothesis gained popularity, it often reflected something of the social climate of the time. For instance, Darwin saw the elaboration of stone weapons as important in initiating the evolutionary package of technology, bipedalism, and expanded brain size. The hypothesis surely reflected the prevailing notion that life was a battle and progress was won by initiative and effort. This Victorian ethos permeated science, and shaped the way the process of evolution, including human evolution, was viewed.
In the early decades of this century, the heyday of Edwardian optimism, the brain and its higher thoughts were said to have made us what we are. Within anthropology, this prevailing social worldview was expressed in the notion that human evolution had been propelled initially not by bipedalism but by an expanding brain. By the 1940s, the world was in thrall to the magic and power of technology, and the “Man the Toolmaker” hypothesis became popular. Proposed by Kenneth Oakley of the Natural History Museum, London, this hypothesis held that the making and using of stone tools—not weapons—provided the impulse for our evolution. And when the world was in the shadow of the Second World War, a darker differentiation of humans from apes was emphasized—that of violence against one’s fellows. The notion of “Man the Killer Ape,” first proposed by the Australian anatomist Raymond Dart, gained wide adherence, possibly because it seemed to explain (or even excuse) the horrible events of the war.
Later,