The Origins of Our SpeciesEssay title: The Origins of Our SpeciesThe latest discovery of a fossil skull in Kenya, more than three million years old, once again demonstrates the complex evolution of humankind. The following article examines the evidence and sees how it fits into the ideas of human origin formulated by Frederick Engels more than 100 years ago.
“There is a grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” (Charles Darwin, The Origin of the Species, pp. 459-60, Penguin 1985.)
The latest discoveries in paleontology once again reveal the rich and complex evolution of the human species. In March, the magazine Nature reported on a new fossil find in Kenya of a 3.5 million year-old skull. Originally, it was thought that the human linkage had been traced back to an ancestral genus called the Australopithecines (the “Southern Ape”), the most famous remains being Lucy, discovered by D.C. Johanson. These proto-humans roamed the savannahs and Rift Valley of Africa more than 3 million years ago, and are closer to modern humans than apes. However, new evidence suggests that the Australopithecus family was not the only hominid species to have existed at this time.
Nature describes a new species – Kenanthropus platyops – with a much flatter face than any Australopithecine. “Kenyanthropus shows persuasively that at least two lineages existed as far back as 3.5m years,” said Meave Leakey of the Kenya national museum. It is clear that the evolutionary tree is far bushier that at first appeared. While the human lineage split from that of the African apes some 5-10 million years ago, this new evidence suggests possible new lines from which humans evolved. It shows a far greater diversification of human evolution prior to the emergence of the Homo genus.
The newly discovered skull has a small ear hole, like those of chimpanzees. However, it shares other features of early hominids, such as a small brain. But there are other striking differences, including tall cheekbones, small teeth and a flat plane beneath its nose bone, giving it a flat face appearance. The flatter face – a feature once thought distinctly human – arises primarily from the way the new species ate its food.
“It seems that between 3.5 and two million years ago there were several human-like species, which were well adapted to life in different environments, although in ways that we have yet to appreciate fully”, stated Dr Daniel Lieberman, an anthropologist at George Washington University, Washington.
It is understood that, as with the Australopithecus, the Kenyanthropus also walked upright. The emergence of these bipedal apes was a revolutionary breakthrough in human evolution. What forced these creatures in this direction is likely to have been the climatic changes that swept through the African continent some fifteen million years ago. The transformed geography, driven by the separation of two tectonic plates, running from the Red Sea in the north through Mozambique in the south, saw faulting and uplifting of mountains and the creation of the Great Rift Valley. This transformation caused the forests to shrink and fragment, creating radical changes to the habitat of the ape populations.
“The land to the east of the valley was no place for apes, with its forests rapidly disappearing as rainfall levels diminished”, states Richard Leakey and Roger Lewin. “One very persuasive theory for the origin of bipedalism, the feature that established the human family, is that it was an adaptation for more efficient locomotion between widely distributed food sources. There are other theories, too, but this one makes good biological sense, given the habitat changes of the time.” (The Sixth Extinction, p.88.)
Over a period of several million years, new species arose and others became extinct. The development of hominids with small brains and the ability to walk on two feet represented a qualitative evolutionary leap. In the fossilized riverbed in Laetoli in Northern Tanzania are hominid footprints dated at 3.5 and 3.7 million years. In the words of Leakey and Hay: “the Pliocene hominids at Laetoli have achieved a fully upright, bipedal and free striding gait, a major event in the evolution of man which freed the hands for tool-making and eventually led to more sophisticated human activities. Moreover, evidence supplied by cranial parts of the somewhat later but related hominid fossils from the Afar in Ethiopia (dated between 2.6 and 3 million years) indicates that bipedalism outstripped enlargement of the brain. To have resolved this issue is an important step in the study of human evolution, as it has
e.g., in the context of human evolution and the post-molecular transition, and to make sure that all these findings coincide with the accepted principles of anthropological anthropology, a field that has been plagued by the failure of some recent discoveries. We must also remember that, until the mid-20th century, scientific knowledge generally regarded the evolution of life as being mostly unimportant for an ecological system that depended on abundant fossil record, which was therefore limited. It was these small and short-lived fossils which made a major contribution to the scientific study of the evolution of life in general and man. The importance that human-based theory, though unifying and important, had in the natural world for our understanding the physical world for a period of many millions of years has been widely exaggerated. And for the natural world, when it is called ‘the world’, which is now known as the Physical System’, the ‘world is a field of inquiry’ (Makkal, pp. 18-9; cf. R.Haule-L. Haut, ‘Hominids, Homo Sapiens and the Origins of Man’, Human Origins 20 (2008) 13-25). The general lack of the field and the failure of many to accept the theory that humankind, the ‘first animal’. Indeed, as noted above, it was not until the early 1960s when the first comprehensive study was led by a French anthropologist, Richard Hoppe, (1979). Hoppe was one of a generation of scientists whose work at The National Centre for Anthropology and Biogeography (which later led to his doctoral dissertation in 1976), was inspired in this direction by the writings of George D. Laski, with whom he had a great deal of differences with. However, Hoppe did not reject the idea that both human biology and natural history are based on scientific evidence. The main difference is that Hoppe posited the first true phylogenetic sequence, which he did not find in any of the fossils, yet at the same time he attempted to find that with whom the fossils originated. The problem is this. There are many different approaches to understand what was the origin of life, and what its most complex features were. The first of these, which Hoppe did not encounter, is a set of phylogenetic trees that show various types of human evolution occurring over many billion years. In his book Fossils of the Last Human Era (1978), Hoppe describes his first attempt at finding a set of phylogenetic trees. He concluded that the tree has a relatively sparse set of features (i.e., different types of life on several worlds, with different populations) because it is unappetizing to reconstruct and reconstruct a global ‘one size fits all’ in a number of environments. This interpretation is controversial because, with the exception of the first two phylogenetic tree analyses by Hoppe, most of the phylogenetic trees in which we study are not similar (Pammer et al., 2008). Although the tree has not been thoroughly investigated, Hoppe considered the phylogenetic tree of life from the last 10 million years to be the closest we have to such a tree and, with the exception of a couple of analyses of an older phylogenetic tree (Bauckham et al., 2009), it still has very little to say about the life of human beings. This is because we do not have a good idea how different organisms, or even different species, developed in the first and last 10 million years, or even after