The human species

‘Man is a tool-using animal… Without tools he is nothing, with tools he is all.’ – Thomas Carlyle. Like all other species of plants and animals the large primate we call human, Homo sapiens (’wise man’), evolved from a minuscule mass of living matter that appeared in the Earth’s seas over 3,000 million years ago. Human beings are currently the dominant mammals in the Age of Mammals; they dominate the Earth and are even moving into space. What is it about Homo sapiens that sets this species apart from all others?

Of course we should begin by acknowledging our animal ancestry and our enormous similarity to other animals, particularly the mammals and especially the great apes such as gorillas and chimpanzees. When the structures of very complex molecules in the body are studied, such as haemoglobin in the blood, the difference between us and the apes is found to be very small, in some cases non-existent. Scientists no longer devise ‘evolutionary trees’ with worms at the bottom of the tree and Homo sapiens at the top, representing the highest, most advanced and most specialized organism yet produced by evolution. In fact, in terms of physical make-up, human beings are remarkably unremarkable primates with a fairly primitive structure. What sets us apart in the end is our brain.

Natural selection

In order to understand our origins we must look at the process that has shaped all life on Earth – evolution. In this process small genetic changes occur from one generation to the next, so that over many generations organisms gradually change. The mechanism that determines the character of the change is natural selection, first described by the English naturalist Charles Robert Darwin (1809-1882) in his momentous book ‘On The Origin of Species’ (1859). We can do no better than quote Darwin’s conclusion to his other major work “The Descent of Man’ where he contrasts man’s physical form with his towering intellect: ‘Man with all his noble qualities, with sympathy that feels for the most debased…with his god-like intellect…still bears in his bodily frame the indelible stamp of his lowly origin.’

In evolution by natural selection, a species that is able to compete has a better chance in the struggle for existence. Animals with special features that are well suited to their environment and give them an advantage over others are the ones that will survive and reproduce. If the advantageous feature is inherited by offspring they will be similarly better suited. Natural selection makes use of mutation. This is a spontaneous alteration in the structure of the genes -the DNA carried in the chromosomes of every cell. If the mutation is unfavourable it could wipe out the species; if favourable it could ensure survival of the species at the expense of other, less well adapted organisms. Mutations have occurred regularly throughout the immense time span that evolution has had to operate – over 3,000 million years. The cumulative effects of evolution have created the huge variety of modern plants and animals.

Evidence from fossils

One major source of evidence supporting the theory evolution, which allows us to conjecture about the past, is the fossil record. Complicated chemical processes over millions of years have turned the remains of dead animals into rock, creating fossils. Fossils have enabled us to put together the story of man’s development; an exciting story, probably the greatest detective novel of all time. There are still gaps in the record, but from thousands of bone fragments palaeontologists have been able to recreate the past and trace the development of Homo sapiens. In the process of evolution, as animals develop they tend to become more specialized. Unfortunately, the environment tends to change also, so that very specialized species cannot cope and die out, to be overtaken by less specialized types. The human species has explored numerous pathways of development, many of them evolutionary dead-ends, while cousins – not ancestors – evolved simultaneously along other paths. Completely opposed to the theory of evolution is the religious theory of Creation, which maintains that life and man in his present form were created by God in a short period of time. Fossils are considered as by-products of the Deluge (the flood that Noah built his ark to escape), and the scientific attractiveness of the evolution theory is regarded as being the devil’s work. Whatever the case may be, from a purely scientific point of view it is difficult to discredit evolution.

Evidence from living organisms

A second major source of evidence for the theory of evolution is derived from living animals. The standard system of biological classification reflects the evolutionary trends of animals: from simple to complex, small to large, coarse to sophisticated. By comparing various extant species comparative biologists can devise evolutionary ‘maps’ and predict which characteristics possessed by an organism are primitive, which are advanced, and where evolution is leading.

Man’s early ancestors

About 60 million years ago the Age of the Dinosaurs abruptly ended and the mammals took over. About 20 million years ago a primitive ape-like creature, Dryo-pithecus, lived in the world’s forests. As the climate changed this species left the jungle and possibly evolved into Ramapithecus, a creature that dwelt on the plains about 15 million years ago. Ramapithecus searched for roots, seeds and possibly meat to eat. On the plains, the ability to climb trees became less important; those creatures which could stand upright and run stood the best chance of survival.

Around 10 millions years ago the evolutionary line seems to have split, so that several species of hominids (the family that includes Homo) were around. One was Australopithecus africanus, living around 4 to 1.5 million years ago. It was about 1.2m high, walked erect, had a relatively large brain, and the evidence indicates it used tools and stored food for future use. Other species were Australopithecus afarensis, a small cousin, and Australopithecus robustus, heavier and bigger than its cousins but possibly also a tool-user. Living alongside the australopithecines about 2 million years ago was the species suspected to be our direct ancestor, Homo habilis (’handy man’). This species had a still larger brain, used tools and made them with much more sophistication, and is now generally regarded as the first human. At this point, we come upon the first recognizable human attribute and a sign of the hominids’ increasing intelligence. Other creatures use tools; a few make tools; but no other species makes tools and uses them to make more tools, with such precision and complexity and forethought as the hominids. Closely linked to this development is the evolution of the human hand from its tree-swinging days, to one with an opposable grip that allows for precise and delicate manipulation of objects. Once an upright stance had been adopted the hand was less necessary for mobility and became increasingly important in its new role of tool-handler. About 1.7 million years ago a new, more advanced species appeared on the scene: Homo erectus. Fossils of this creature have been found over much of the Old World, and have been named ‘Peking Man’, ‘Solo (or Java) Man’, and so on. At first these fossils were thought to come from different species but now it is recognized that Homo erectus was a widespread and geographically variable species, just like Homo sapiens today.

Homo habiiis and Homo erectus both showed signs of a developing intellect. They used fire to cook food and for certain ceremonies; they hunted in groups; and had fixed dwellings where tools and implements were kept. However, because of technical reasons, in connection with the shape of the skull. Homo erectus is not considered to be our direct ancestor, whereas Homo habiiis may well have been. Numerous remains of human creatures alive during the last Ice Age, some 100,000 to 50,000 years ago, have been found, particularly in Europe. From this period two types have been distinguished: Neanderthal and Cro-Magnon man. With both groups the resemblences to present-day human beings are more notable than the differences. They are therefore classified within the same species as ‘modern’ man, Homo sapiens. Neanderthal man – named after the valley of Neander, near Diisseldorf, where fossils were first discovered – had a rather flat skull, crude and strongly developed facial features, with heavy eyebrows. The brain-volume of this man who stood a metre-and-a-half tall, was around 1,350-1,700 cm’. Cro-Magnon man, named after the cave near Les Eyzies in south-western France where the first skeletons were found in 1868, resembles modern man even more, especially the flatness of the skull, and the shape of the chin. That Cro-Magnon man was culturally on a higher level than Neanderthal man, is evident from paintings found, among other places, in the caves at Lascaux, France, and at Altamira, Spain. Around 30,000 years ago, ‘modern’ man had spread out to almost every corner of the earth. Physically, he very much resembled present-day man. He used language and symbols; he could paint and sculpt; he now conducted ceremonies, and showed all the signs of a high intelligence.

Around 15,000 years ago, different races developed as a result of adaptations made in response to various environmental factors such as the climate, the plants and animals available and geological upheavals. One could say that the ‘biological evolution’ of man was completed at that time. After this, a new ‘cultural’ stage commenced in the development of man. 11,000 years ago the world was still populated by tribes of hunters and gatherers, but during the period 9,000-5,000 BC, man gradually evolved into farmer and stock-keeper. He lived in a fixed dwelling, burned and cut down forests, cultivated the land and grew plants. The oldest domesticated animals are the sheep and the pig (c. 8,500 BC), and the goat (c. 8,000 BC). Larger communities developed, so it became possible to specialize oneself in certain activities. The number of people increased more rapidly during the following period. If there were around 3 million people on Earth in 10,000 BC, then by 3,000 BC the world population had increased to 100 million. At that time, the balance between population and food supply was affected by changing or new environmental conditions; and aggression between different races competing for food began to play a major role in the story of man’s history and development.