An examination of his work in the light of modern scientific evidence and theory would perhaps refute this or that secondary detail of Engels' work, but would show that in broad outlines his arguments were correct. The pamphlet remains, in other words, a masterpiece of the dialectical method. What specific issues and questions led Engels to writing such an essay?

Marx and Engels had both arrived at the same philosophical method - dialectical materialism - although by different paths. Their outlook was materialist in the sense that they considered that all natural phenomena and social development to be firmly based, in the final analysis, on material processes, rather than spiritual or metaphysical (idealist) causes. At the same time, they considered that society and nature were in a constant process of dialectical change; that is, change through contradictions; everything was in a state of motion, of coming into being and passing away.

Both Marx and Engels applied their philosophical method particularly to social and political development, as historical materialism. Marx's greatest work, Capital, laid bare the general laws of motion of the capitalist system itself, but the two great founders of scientific socialism were at pains to explain that capitalism was only a single stage in social development. Just as the capitalist system came into being as a result of the social forces and contradictions within feudal society; so it would be overthrown by the contradictions it carried within itself; to be replaced by a socialist society.

The emphasis placed by Marx and Engels on the transitory nature of capitalism inevitably led them to a consideration of pre-capitalist societies. They sought to demonstrate that the method of historical materialism, just as it had revealed the inner mechanism and laws of capitalism would also find application in earlier societies, revealing their own special laws of social development. Casting an even wider net, they also sought to use contemporary scientific studies to show the general validity and applicability of dialectical materialism as a universal world outlook. As Engels explained in Dialectics of Nature,

''...it is precisely dialectics that constitutes the most important form of thinking for present day natural science, for it alone offers the analogue for and thereby the method of explaining the evolutionary processes occurring in nature, interconnections in general, and transitions from one field of investigation to another."

The notes of Marx and Engels on pre-capitalist societies were both used by the latter in his work The Origin of the Family, Private Property and the State published 100 years ago. Engels' own notes and essays on the relationship between science and dialectical materialism were only published in 1924, nearly 30 years after his death, in Dialectics of Nature.

There was a natural bridge, therefore, linking Marx and Engels ideas on political issues and Engels' interest in anthropology and the origins of humanity. Marx and Engels had hailed Darwin's theory of Natural Selection as a triumph for materialism because it provided a scientific foundation to human evolution from "lower" animals. After Darwin, the origin of the human species was firmly rooted in the natural material sciences rather than in theology or metaphysics.

But while Darwin emphasised the material continuities between the animal kingdom and homo sapiens, Engels stressed the dissimilarities arising as a result of material processes from the animal world; mankind was nevertheless unique, a social animal. Without ever leaving the high firm ground of materialism, Marx and Engels sought to explain how the quantitative evolutionary changes in apes had produced a qualitatively different species, a unique thinking, social animal. Man, Engels explained, was the only animal that undertook labour - a conscious interaction with nature, purposefully altering nature to Man's advantage, but altering Man also in the same process.

The central purpose of Engels' essay on the part played by labour was to show that human labour and social organisation were not the product, so much as the cause, of the development of the human hand and brain, those features most generally used to characterise human likeness. "Labour," Engels explained, "is the primary basic condition for all human existence, and this to such an extent that, in a sense, we have to say that labour created man himself." Engels' view was presented in direct opposition to those contemporaries of his who saw human development through the spectacles of "Civilisation", as a process motivated by ideas and thoughts. Engels explained:

"All merit for the swift advance of civilisation was ascribed to the mind, to the development and activity of the brain. Men became accustomed to explain their actions from their thoughts, instead of their needs…even the most materialistic natural scientists of the Darwinian school are still unable to form any clear idea of the origin of Man, because under this ideological influence they do not recognise the part that has been played therein by labour."

The idealistic notion of the origin of humanity found its expression in scientific circles in the generally held theory that mankind developed a large brain before the development of the hand and before bipedalism (erect walking). Hypnotised by the wonders of society, the scientists of Engels' day (and indeed very much later) pushed the more modest productions of the working hand into the background. With scarcely any direct and concrete scientific evidence, but using only the method of dialectical materialism, Engels was able to show that the common scientific theories of human development were in fact incorrect. His pamphlet explained that in early man the upright posture and bipedalism had freed the hands for the manipulation and manufacture of tools. The making of tools and their use led to a further refinement and development of the hand so that the hand was both the "organ" and the "product" of labour. The conscious interaction of man with nature - altering both at the same time - was an active process in contradistinction to other animals' interaction with nature which is entirely passive. Man is the only animal which engages in labour.

"Animals in the narrower sense also have tools, but only as limbs of their bodies…Man alone has succeeded in impressing his stamp on nature."

But the use and manufacturing of tools, Engels explained, also increases the usefulness and purposefulness of joint activity, of social labour. Both tool production - and social labour raised the question of language and speech.

"First comes labour, after it and side by side with it, articulate speech. These were the two most essential stimuli under the influence of which the brain of the ape gradually changed into that of man."

The further development of the brain, of course, would interact with labour processes and social intercourse to develop greater capacity for language, for reflection, judgement and abstract thought. The accumulated effects of these interacting processes led to human evolution.

"By the combined functioning of hands, organs of speech and brain, not only in each individual but also in society, human beings became capable of executing more complicated operations…"

The social accumulation of knowledge, skill and expertise would mean that these things could be passed on by speech from one generation to another - a cultural evolution is thereby set in train.

A re-examination of Engels' ideas in the light of modern discoveries shows their complete validity. If he could be alive today, he would no doubt immerse himself in the mass of accumulated detail, facts and knowledge, and after studying them in his normal meticulous fashion, he would rewrite The Part Played by Labour in the Transition from Ape to Man with fundamentally the same view.

The great weight of material evidence on the origin of the human species comes from palaeontology - the collection of fossils, and stone tools. The earliest stone tools are between 2.5 and 3 million years old. These hominid (human-like) artefacts include tools used to make other tools and they mark a clear distinction with the present day apes, who though they make and use tools of soft materials (twigs and leaves), never use them to manufacture other tools.

The hominid tools, often associated with particular sites where they were manufactured or used. were relatively simple to begin with, but over a period of a million years or so increased in complexity and sophistication. The simple Oldowan stone culture, named after the Olduvai Gorge in Tanzania where the implements were found, became transformed between 1.5 and 2.5 million years ago into the Acheulian, a more refined, stone culture. But of course stone tools are preserved, while others that may have been made of bone, wood or hide could not be. It is generally assumed that such tools were made and used before progress was made on to stone materials which are much harder to shape and to adapt to a particular use.

Even extremely simple tools would be the product of a long period of experimentation, experience, observation, reflection and recollection. The simplest tools like sharpened sticks to dig roots, or hide bags to carry food, would represent almost a revolution in human development - they would give any early hominid species a huge advantage for survival, yet none of these soft artefacts would be preserved. Long before the 2.5 million year old Oldowan stone culture, therefore, it is likely that early hominids were using tools, although of perishable materials.

This scenario fits in with recent fossil discoveries made in East Africa by the American palaeo-anthropologist Johanson, notably the female skeleton, nick-named Lucy, which belongs to the species he describes as Australopithecus Afarensis (around 3.5 to 3.75 million years old), which demonstrated a number of remarkable facts:

1. Lucy and her cousins were fully bipedal, they walked upright. The configuration of the hip, thigh and knee bones pointed to a capacity for an upright gait no less efficient than that of modern humans.

2. The hand had a fully opposable thumb, was capable of a strong grip, and capable of good manipulation. It was a very human-like hand, capable of making and using tools, but not a completely human hand.

3. The cranial capacity, a measure of the brain-size of the species, was only marginally larger than that for comparable apes of the same body weight. The cranial capacity of a chimpanzee is 300 or 400 ml, Specimens of Australopithecus Afarensis had cranial capacities of between 380 or 450 ml. (The average cranial capacity for homo sapiens is 1400 ml.)

These fossil remains therefore pointed to an apparently small brained but upright hominid with clear manipulative ability. These discoveries were complemented by those of another palaeontologist, Mary Leakey, who discovered in Laetoli, in Northern Tanzania, two sets of remarkable footprints fossilised in ash. Examination of these footprints, between 3.5 and 3.75 million years old, shows unmistakably that they made by a hominid. Once again, to use Mary Leakey's words, "A fully-upright, bipedal and free-striding species."

Both Johanson and Leakey have suggested that the finds at Hadar in Ethiopia and Laetoli in Tanzania are related, the former even suggesting that they represent remains of the same species. What these finds do show is that a highly developed manipulative skill, indicative of tool use, and a fully upright gait clearly preceded the full human brain development.

Stone tools have not been associated with these fossils, they are normally associated with a later, different species of fossil (although some palaeontologists would argue a later development of this same species) Homo Habilis with, among other things, a slightly larger cranial capacity and other more human characteristics. These finds would seem to confirm the dawning realisation among modern anthropologists, that tool use and upright walking anticipated the development of the human brain. Ten years before these discoveries, an American anthropologist Napier had written:

"It is now becoming clear that this important cultural phase in evolution (the use and manufacture of tools) had its inception at a much earlier stage in the biological evolution of man, that it existed for a much longer period of time and that it was set in motion by a much less advanced hominid and a much less specialised hand than was previously believed."

There is no doubt that the 3.5 million year old Lucy would have had sufficient manipulative skill to have made and used implements, perhaps of materials like wood and skin - which were not preserved along with her own bones. Moreover, she had an upright gait as developed as that of modern humans, allowing her the full freedom to use her hands to make, use and carry implements or food. Indeed, there is no other explanation for the shape of Lucy's hands except that she was a regular and habitual user of tools. As Engels says:

"It stands to reason that if erect gait among our hairy ancestors became first the rule and then, a necessity, other diverse functions must in the meantime have developed upon the hands."

Whereas with modern apes, tool use is casual and not passed on in any way from one generation to the next, in a species beginning to learn social organisation, including communicative speech, expertise in tool use is cumulative from one generation to the next. Lucy's hand would already suggest a dexterity qualitatively superior to modern apes, but without a brain very much bigger. Yet the continuous and regular manufacture and use of tools would tend to lead, as Engels explained, to an even greater development and refinement of human characteristics, especially the hand and brain. That, in later hominid species, appears to be exactly what happened. The hand, to use Engels' expression, becomes therefore both the organ of labour and also the product of labour.

"One sees the great gulf between the undeveloped hand of even the most manlike apes and the human hand that has been highly perfected by hundreds of thousands of years of labour…The hand is not only the organ of labour, it is also the product of labour. Labour, adaption to ever new operations, the inheritance of muscles, ligaments and, over large periods of time, bones that had undergone special development and the ever renewed employment of this inherited finesse in new more and more complicated operations, have given the human hand the high degree of perfection required to conjure into being the pictures of Raphael, the statues of Thorwaldsen, and the music of Paginini." (Dialectics of Nature)

Lucy, the large brained ape, was capable of the use and manufacture of tools, but by the performance of labour, she also thereby capable of pushing primate development on to the road of the perfecting of the human hand and brain. Scientific disputes about the precise relationship of Lucy's species to the human lineage do not alter the fundamental fact of bipedalism and hand development preceding the large growth of the brain.

As Richard Leakey, son of Mary, explained:

"As the fossils from Africa illustrate, the hominids were ape-like in size. Presumably the hominids were living very differently from their ape relatives because they were also walking around on two legs. But whatever their lifestyle, it does not seem to have demanded a significantly expanded brain. Not until 2 million years ago is there firm evidence of Homo Habilis whose cranial capacity was close to 800 ml.

"This creature had a brain nearly twice as big as Lucy, but without being any bigger in stature. The next step in hominid development, Homo Erectus showed an even greater brain development, reaching 1000 ml."

Marx and Engels' emphasis on the social character of human development is now repeated almost universally by modern palaeo-anthropologists. Concrete evidence of social behaviour does not exist and could never be preserved, but there are enough indications pointing in that direction. Stone tools, for example, are not found at random, but often in particular sites whose functions seem to vary. One 2 million year old site at Koobi-Fora, in Kenya, is associated with hippopotamus bones and it is clear from the stones and flakes found there that tools must have been made and used on the spot. But the materials used to make the tools (hammer stones and smaller stones) did not originate in that area but must have been carried there from some 3 or 4 kilometres distance. Apart from this "butchering" site, others have been discovered with apparently different special functions - as living places, as sites used purely for the preparation of tools to be used elsewhere. In addition to these preserved tools, as has been said, it is likely that there were, over an extended earlier period, tools of materials that were not preserved.

Even without any further evidence, the manufacture and use of tools would suggest already some form of cooperative organisation. The collection of stones, their selection, preparation, transport, use and retention are all operations that would be inconceivable without social labour. No modern ape collects and transports food to be eaten elsewhere, and although hunting occasionally, no ape will ever persevere in a hunt for a long period of time.

The early hominids, in collecting food, carrying it and storing it, had already taken a qualitative evolutionary leap. But all these operations suggest that there would be sharing, cooperation and a division of labour, and therefore a more or less well established pattern of social relationships and behaviour.

How else would it be possible to transmit the large accumulation of experience and practice from one generation to the next, except through some form of social organisation? Cooperative behaviour is even suggested by the anatomical development of hominids. Lucy herself had not apparently developed a hip sufficiently well adapted to give birth to large brained infants. As the size of the brain expanded from one species to the next, however, problems would have arisen with birth because of the size of the infant's brain. But evolutionary development found a way around this problem by delaying certain aspects of growth until after the birth. At birth the brain of a Rhesus monkey is 65% of its final size, a chimpanzee's is 40% and that of a human child only 23%. Consequently, compared with the nearest ape relatives, human children have to have an extremely long and protracted childhood, something that would be inconceivable without some social mechanism to provide the necessary care and attention. Moreover, such a social organisation and a prolonged childhood would be the only way to give the child time to absorb the tradition of labour to which it would be heir.

In evolution in general the development of a particular physical attribute (colour, size, shape, etc) can give a selective advantage to a particular species or strain of organism; therefore that attribute is likely to be passed on from one generation to the next. But in the development of humankind, tool use and social behaviour can themselves become adaptive, carried from one generation to the next by the teaching of these cultural skills to the young.

The constant social use of implements - as Engels would have said, the labour - becomes more and more a necessary part of the hominid lifestyle, without which it would perish. But having the faculty of labour imparts to the hominid an enormous selective advantage over any other species that lacks it altogether, or over one that may possess the same faculty in a crude and rudimentary form. Biological evolution - change through genes - is not eliminated, but a powerful impetus is given to cultural evolution - the accumulation, generation by generation, of a vast store of skill, knowledge, expertise, and language.

There are a variety of modern theories dealing with the specific environmental conditions of development of the human species. The most generally held view is that humankind began to develop in an environment of semi-open savanna land at a time, 4 or 5 million years ago, when there was a shrinking of the large forests, particularly in what is now East Africa. Such an environmental pressure - moving out from a forest to a more open environment - could also correspond to the development of an upright posture described by Engels as "the decisive step in the transition from ape to man."

Even within this general framework, however, there are differences of emphasis, for example on the relative importance of gathering vegetable foods compared to hunting for meat. Studies of modern hunter-gatherer communities would indicate that for the amount of time per person spent on each activity, gathering food is nearly 70% more productive of calories than hunting. In addition, whilst modern apes like baboons and chimpanzees do hunt from time to time, their meat consumption represents only a tiny proportion of their diet.

The evidence of hominid development, especially the use of stone tools with special butchering sites, shows that at some stage there must have been a big increase in the incidence of hunting as compared to apes, moving perhaps from small to larger prey, something also commented upon by Engels, who also pointed out that meat had a higher nutritional value than vegetable matter. But nevertheless vegetables would probably have remained the main part of the diet and the implements most likely associated with their production and collection - digging sticks or carrying sacks, would have perished.

But the characteristic common to all modern theories of human evolution is that they all recognise the essential role of social organisation and behaviour. Early hominids were adept at hunting, gathering, collection, transportation, tool manufacture and use - these as has been said would suggest sharing, cooperation and division of labour. None of these are even conceivable without well developed social rules and practices.

Another important element in the evolution of Man, intertwined with social labour and tool use, is the development of speech, of language.

"The development of labour," Engels pointed out, "necessarily helped to bring the members of society closer together by increasing cases of mutual support and joint activity and by making clear the advantage of this joint activity to each individual. In short, men in the making arrived at the point where they had something to say to each other. Necessity created the organ…this explanation of the origin of language from and in the process of labour is the only correct one."

It would follow from Engels' view, despite the eccentric references to parrots in his own essay, that man, being the only animal able to perform labour, would be the only animal capable of language. This is in fact the case. Repeated attempts have been made, especially by American anthropologists, to teach sign language to chimpanzees. But after years of learning, there is no evidence that the chimpanzees have achieved anything more than complex rote learning, involving variations of signs, each of which in its own right is meaningless to the animal. In individual chimpanzees, even the most celebrated, the learning of sign language, even where it apparently increases in vocabulary, is qualitatively different to learning in human infants. Chimpanzees simply learn to mimic longer strings of sign words, whereas a human child learns a deeper and more complex use of words and concepts as it grows older.

Key elements of human language are completely absent in apes, Man's nearest relative in the animal kingdom. With apes, communication is entirely emotional and always concerns the immediate environment. Human language is necessarily associated with the development of human cognitive processes and both are necessarily associated with labour.

None of the processes mentioned earlier - tool making and social labour - would have been possible without a parallel development of thought processes. Man must have developed the faculty of mental "displacement", that is, the capacity to have a mental picture of a situation removed in time and place from the immediate surroundings. The manufacture of tools would be impossible without a preconceived idea of what the implement would look like, what its function would be and where it would be used, and these faculties are way beyond even the most intelligent ape.

Just as tools are a product of labour, so also human mental processes and language develop from labour, from an active interaction with nature. Mental reflection is not a passive but an active process and language or speech becomes integral to it. Words and language, to use Lenin's expression, help humankind make the transition from elementary sense perception to generalised abstract thinking. Modern anthropologists, of course, have no concrete evidence, like fossil evidence, upon which to base their theories of language development, but most link the origin of language with tool use and the social labour of the early hominids for example.

"Developing hominids, at the australopithecine stare and perhaps even before, were able to predict the utility of a hand held tool beyond the period of immediate use, beyond immediate relationships to ones expanded in time and place." (Montagu, 1976)

Thus the practical labour is interwoven with speech, the development of tools with cognitive abilities and language. "Language," to use the even briefer expression of Karl Marx, "is practical consciousness."

Another anthropologist explains:

"The capacity to form and operate with abstract ideas is correlated in evolution if not in physiology, with the capacity to use human language. Here too the product grows with the instrument and vice versa. And these capacities in turn are correlated with tool making." (Dobzhansky)

Certain biological conditions must have been present for early hominids to begin to develop and interweave the processes of speech, tool making and social labour. But Engels makes it clear that in his view the fully human brain was a product of labour, not its originator. "First labour, after it and then with it, speech - these were the two most essential stimuli under the influence of which the brain of the ape gradually changed to that of man."

This view is fully endorsed by the modern fossil evidence, not only by the growth of brain capacity, but also by examination of the cranial casts to show which parts of the brain developed from the earlier man-apes. Referring to the very earliest hominid brains, the American anthropologist Washburn makes it clear: "From the immediate point of view this brain makes culture [i.e. labour - JP] possible. But from the long term evolutionary point of view, it is culture which creates the human brain."

With a co-worker, Lancaster, Washburn explains:

"It appears that the form of the human hand, the large area of the brain directly related to the hand, the much larger areas of the cortex related to skilful motor activity, and a greatly expanded cerebellum, also related to skilful activity, all evolved long after initial tool use and in response to new selection pressures arising from the success of implements of many kinds."

All the modern evidence, therefore, more than there is scope to mention here, supports the basic theme of Engels' essay: and confirms the materialist explanation for the origin of mankind. Engels perceived more than one hundred years ago, the dialectical relationship between language, intelligence, brain size, manual dexterity and their common denominator - labour.

It was the capacity to form labour in the pursuit of the basic necessities of life that catapulted some ape-like species onto the road of becoming a humanlike species. Labour became the basis of human development.

Engels succeeded in showing the dialectical relationship between biological and cultural development. Once it became a part of mankind's necessary lifestyle, labour perfected the human hand and brain. But labour, or social production, also achieved an impetus of its own - an extension of, but a qualitative development from, biological evolution.

Thus, social phenomena or the development of labour, cannot be crudely explained by genetic or biological factors - they can only be described in terms of their own separate laws. But they nevertheless have their foundation in the last analysis on material processes. In a sense, the capacity to labour became a means of transcending the blind process of biological change. As Engels said,

"…the more human beings became removed from animals, in the narrower sense of the word, the more they make their history themselves, consciously, the less becomes the influence of unforeseen effects and uncontrolled forces…The animal merely uses its environment, and brings about changes in it simply by its presence. Man by his changes makes it to serve his ends, masters it. This is the final essential distinction between man and other animals, and once again it is labour that brings about this distinction."

The enormous achievements of science and technique have all been made in what seems to be the twinkling of an eye compared to the millions of years of primate evolution - all the 2.5 to 3 million years during which culture, or labour was being created and was creating mankind. Yet none of the enormous cultural achievements of the last 10,000 years - civilisation, science, etc - have been due in any significant way to biological change, they have all been achieved by labour.

"Man alone," Engels explained, "has succeeded in impressing his stamp upon nature, not only by shifting plant and animal species from one place to another, but also by so altering the aspect and climate of his dwelling place, and even the plants and animals themselves, that the consequences of his activity can disappear only with the general extinction of the terrestrial globe. And he has accomplished this, primarily and essentially by means of the hand."

But Marx and Engels were not passive commentators on human development. They also understood that real human development, the real culture of humanity, would only succeed and flourish when society itself was changed appropriately. The rise of social classes, they recognised, was a necessary stage in social development, corresponding to changes in the mode of production, of labour. But a further stage of production could only be achieved by the abolition of classes and the social organisation of labour on a new and higher level, in other words, by socialism. "Only conscious organisation of social production, in which production is carried on in a planned way, can lift mankind in the specifically biological aspect." (Dialectics of Nature)