Stages of Human Evolution

As we know, humans make their own history – admittedly they do determine their history according to an individual whim, but according to circumstances derived from the past, in relation to the objective laws of social development. Humankind therefore have features of social life that are uniquely human and these include family structure, the fact that they have or still do live by hunting, their food-sharing, possession of a home camp. Furthermore, we can recognise other sharp delineations between humans and apes, these delineations being evidenced by qualitative breaks between the human species and all other forms, past or present, of monkeys and apes.

At this point we van envisage that at some time in the dim past of 500,000 to 1,000,000 years ago ancient hominids in the form of primitive varieties of the gens Homo appeared. Eons prior to this emergence, even more primitive hominid types had developed from the basic primate pattern. We can regard this happening, for the sake of clarity, in two stages. The first stage of hominisation took shape in the lower Pleistocene, which began about 2,000,000 years ago and merged with the middle Pleistocene some half-million years ago. The hominid representatives of this period were primitive variants of Australopithecines. These diminutive pre-men combined bipedal locomotion with an erect posture, though fossil evidence suggests a rather ore shuffling form of gait than a striding walk. Their brain capacity was small. Compared with modern man they had 600 cc in comparison with our average of 1500 cc. In so far as these various types of Australopithecines – or Southern Ape men – were concerned there is little evidence to indicate that their social organisation was much in advance of the Pleistocene apes, but they were it is now believed primitive tool makers and users.

Though they are still subject to conjecture, the Australopithecines were probably vegetarian rather than carnivorous, because it is doubtful whether they had the necessary level of social organisation to permit either organised hunting, or the weapons needed to kill large prey. Nothing precludes their scavenging from the prey of animal predators, and it is also likely that they would have foraged during the day in protective groups, but we cannot assume that they were internally organised by kinship relations. These speculations and conjectures mean that, if we are correct, the Australopithecines were only a little in advance of the chimpanzees. These Australopithecines are the first known hominid types who had developed an erect posture and had thus freed their hands for tool manipulation. Their teeth functioned as tools, despite their humanoid dental structure as opposed to that of the great ape, for eating roots and nuts and tearing natural materials. However, we can see that in these early hominids the basic rudiments of the trend towards the emergence of the ways of life exhibited by humans. The Australopithecines eventually became extinct during the lover Pleistocene era, and are today regarded by most serious anthropologists as a branch off the main evolutionary line of the hominid progression that culminated in Homo sapiens.

The second stage is found in the middle Pleistocene with the appearance of men – with large brains and much taller than the Australopithecines. I should be noted that these Australopithecine types were not directly ancestral to the middle Pleistocene hominids, but an offshoot away from the main line. The theory is that both types considered here had a common, more primitive progenitor. These middle Pleistocene hominids that had bypassed the Australopithecine blind alley, occurred about half a million years ago and are the various representatives of the ‘erectus’ species of the genus Homo. The first men!

These early men possessed and used complex tools and weapons, made from various types of stone, which they used to kill large animals and collect plants and roots. In may respects they thus led a recognisable human way of life. They had home bases and camps – many of their fossil remains being found in obviously continuously inhabited caves. It is at this period that there occurred the rapid development of the habits and modes of existence that are part of the cultural ancestry of the human species. This development in economic terms is known as the hunter-gatherer mode of life and subsistence – which became the universal mode of subsistence for the ensuing 500,000 years. The development of settled communities using cultivation, which led to the increasing complexity of human society, occurred only around 10,000 years ago.

One persistent problem concerns the stage during human evolution at which culture originated. The ‘critical point’ theory postulated that there occurred an ‘all or nothing’ quantum leap, and that the development of the capacity to acquire culture was of a sudden appearance. A ‘now you don’t  see it’ and ‘now you do see it’ concept. This particular theory argues therefore that at a certain historical moment in the progress of the hominid procession there suddenly occurred the ‘humanisation’ of a particular branch of the hominid stock. This great even was, in genetic and anatomical terms, only a minor alteration in the structure of the cerebral cortex. This suggests that the point of the appearance of Homo depends entirely on the random, chance occurrence of a mutation or mutations. This theory proceeds to outline the process in terms of a methodology. The portentous event of ‘humanisation’ is conceptualised as a ‘marginal’ quantitative change that gave rise to a radical qualitative difference, In other words this theory tries to explain each higher stage of human society as having its cause in a mutation affecting parts of the cerebral cortex. This is not quite the case however.

The critical point theory admits to the existence of leaps as the qualitative result of a series of quantitative events, but it does not seem to realise that the new qualitative stage is a higher stage. And certainly, the development of the cerebral cortex with its complex association areas and frontal development is not the result of some sudden mutation – but the qualitative result of ages of quantitative accumulations involving social labour, the use of the hand, and the formulation of symbolic signals expressed as language. Nonetheless, this theory does have some elements of reality, especially when compared to religious and idealist theories of anthropogenesis. The critical point theory claims there are three major considerations that give support to its position.

Firstly, the ‘critical point’ theorists note the enormous gulf between the mental abilities of humans and the great apes. This is certainly true, for as we know, man talks, conceptualises and makes tools. Secondly, it is shown that mankind uses a language, can think in abstractions, and can symbolise. Man has named his environment, given terms to describe and denote events, laws and matter. This is an arbitrary framework to enable man to classify, codify, and thereby modify., his environment. Further from this there has been the progress from simple reflex activity, through conditioned responses, to more complex signal behaviour which arrived eventually at conceptual thought. These processes are achieved as a series of quantum leaps, not as a result of a lineal development or continuum. Thirdly, there is the concept which has been termed the ‘psychic unity’ of mankind. This, quite truthfully, states that in regard to the living ‘races’ of mankind, no important differences in natural thought processes exist. This is supported by all the available empirical evidence from various ethnic groups. The support for the ‘psychic unity of mankind’ hypothesis is quite extensive, drawing evidence from psychology, semantics, ethnological studies, and linguistics. There is no critical brain size in relation to human intellect – palaeontological evidence proves that Neanderthals on average had larger brains than modern man. It is therefore unscientific to search for a ‘cerebral rubicon’ with regard to the relative size of the brain – it is the internal organisation of the brain that is the main criteria in determining the development of intellect.

The Australopithecines were called ‘man-apes’ and lived around 750,000 to 1,750,000 years ago in southern and eastern Africa – and what is so striking about them is their combination of both primitive and advanced anatomical features. Firstly, their pelves and bones of the lower limb exhibit a structure similar to modern man (hence the idea that they were upright and bipedal in gait). Yet, the capacity of their crania was only slightly larger than that of a gorilla. We can therefore assume that even if they were not directly ancestral to the genus Homo, they do represent an initial form in the evolutionary path that eventually arrived at sapiens man. It is generally accepted that the Australopithecines branched off from the main line of development and became extinct after failing to develop further. Additional evidence of occasional hunting and primitive implement fabrication indicates that these Australopithecines were capable of mastering some rudimentary elements of culture, and in such a ‘proto-culture’ we may be able to conclude that some form of early communication existed between them.

The ‘critical point’ viewpoint believes that the major period of cortical development followed, and did not precede, the development of culture. The ‘critical point’ theorists therefore regard man as more less complete in terms of his neural compositions before cultural development started. Therefore their view develops from the proposition that cultural expansion and improvement was occurring prior to the cessation of human organic evolution. In certain respects this is true of a number of anatomical and morphological structures, but it is not true in respect of the human intellect. The development of mans’ cerebral capacity surely arose in an inter-related and inter-dependent context of social labour and increasing technological expertise?

Why should ‘brain’ precede culture? Are we not more correct when stating that the development of mans’ brain was an inter-related process, that included the use of his hands and the development of articulate speech, in conjunction with the unique and crucial criteria of social labour? This returns us to the main flaw in the ‘critical point’ theory’s position, and that is their conception of a ‘before and after’ situation with regard to the origin of culture. In terms of millions of years we can certainly say that man is today what he was not yesterday – but can we claim that, because man developed rapidly in society, his biological evolution has ceased? Certainly we can admit that man evolved biologically further than Homo erectus who was a primitive cultured hominid. We must conclude that in reality the neurological development of man’s brain was the result of culture – it became the ‘human’ brain precisely because of social labour. Social labour of necessity requires speech and language, as well as the necessarily indispensable hands and tools.

If man makes himself, and we accept this, then we cannot agree that man had developed cortical structures of a highly specialised type with all the attendant association areas and neural ramifications, prior to requiring them or before he even knew he would need them. Man, as these theorists point out quite correctly, is not just a producer of culture and technology, he is also the product of that culture.

Up to now we have considered the biological and social evolution of modern Homo sapiens from or pre-sapient ancestors and precursors. It remains to analyse the crucial element that enabled man to become Homo sapiens, and this unique factor, which has to be understood in relation to human society, is the development of the hand and its role in social labour. It is this factor which adds to man’s uniqueness and his true nature – man evolved as a worker! We cannot try to analyse the origin and development of the human family, or attempt to appreciate its role in modern society, until we recognise mans’ origin and subsequent development in terms of labour, in terms of his production of the material conditions of life.

Man is a tool fabricating organism – his implements are intelligently organised modifications of naturally existing objects or materials. Furthermore, man’s concepts of his tools are based upon his accumulated experience and knowledge of past effects of such implements. The use of tools depends completely upon the necessary evolution of the human hand, the hand not only being itself an organ of labour but also the manipulator of tools which are ‘extensions’ of the hand. With other animals their own body extensions function as their sole implements – and as such are specialised and adapted and inseparable, usually unalterable part of the animal anatomy. Obviously this is not the case with man, whose tools are extraneous and his hand as a universal tool. The human hand is an exquisite piece of organised and sensitive anatomy compared with even that of a great ape. Only the human hand could be so well developed because unlike apes, only human hands have had the benefit of hundreds of thousands of years of determined labour to perfect them.

The hand is the ‘organ of labour’, and more especially the hand is the product of labour, but the hand did not arise on its own. Therefore we must of necessity consider the hand in relation to the material organ of thought – the brain. As has been stressed, man can foresee the future action of his implements and this underlines the fact that complete use of the hand implies an enormous level of developed intellect. One needs to see to make or use tools and this again implies the necessity of conscious thinking and conceptualisation, as well as showing that the use of implements reacts back upon man and enhances his thinking and knowledge of his environment.

We can summarise the comparative study of man and other animals. Man either excels or at least equals all other specialised species of animals and this is because other animals are adapted by natural selection to their own particular ecological niches. In this respect man is, and had to be in order to achieve his sapient state, a relatively unspecialised animal. Unlike most animals, man goes where he will or may, often accompanied by those erstwhile camp-followers – the dog, the rat, and the cockroach.

The brain of Homo sapiens has taken epochs to reach its highly evolved state – the difference between the animal and human brain is not merely one of quantitative sixe or complexity, it is at a qualitatively higher level of organisation. The human brain and its property, consciousness, is the highest form of organised matter. The human brain in terms of cells is not merely bigger, it is endowed with cerebral structures and interconnections not possessed by other animals. Examples that easily come to mind are the association areas concerned with speech and language, motor areas connected with manual dexterity and control, and the all important expanded cortical development. Mans possibilities are enhanced by the fact that his brain can make and remake, constantly, new connections and inter-connections – and it is within these patterns that we find the accumulated experience and knowledge, not only of the individual, but of the species.


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