Review Article

Humans: a not so modest affair

Don Brothwell
Department of Archaeology, University of York
King's Manor, York, YO1 7EP, UK

Books Reviewed

ROB DESALLE & IAN TATTERSALL. Human origins: what bones and genomes tell us about ourselves. 216 pages, 113 colour illustrations. 2008. College Station (TX): Texas A&M University Press; 978-1-58544-567-7 hardback £20.50.

PAUL MELLARS, KATIE BOYLE, OFER BAR-YOSEF & CHRIS STRINGER (ed.). Rethinking the human revolution: new behavioural and biological perspectives on the origin and dispersal of modern humans. xx+436 pages, 159 illustrations, 33 tables. 2007. Cambridge: McDonald Institute for Archaeological Research; 978-1-902937-46-5 hardback £35.

H. SCHUTKOWSKI. Human ecology: biocultural adaptations in human communities (Ecological Studies 182). xvi+304 pages, 36 figures, 7 tables. 2006. Berlin, Heidelberg & New York: Springer; 978-3-540-26085-1 hardback £91.

The three books reviewed here are all concerned with the most complex, most destructive, most adaptive, and probably the most thoughtful species living on our planet. The small amount of DNA which separates our genus Homo from that of the great apes has been enough to meet a variety of environmental and social challenges over the past few million years, and produce a complex patchwork of variation unseen in the previous history of any other mammal. The only success we are as yet a long way from claiming is in the longevity of our genus, which is but a blink of an eye in geological time, and a mere fraction of the millions of years occupied by the great adaptive range of dinosaurs. Admittedly, the prosimians, the first primates, had a good time in the Palaeocene and Eocene, and their adaptive radiations conquered many varied environments. But few of these genera lingered on, and most were extinct by the Oligocene. Those that remained, a few tarsiers, lorises and lemurs, could be viewed as a somewhat unprogressive lot, relative to the heyday of prosimian radiations. The worldwide spread and adaptation of monkeys had better luck and many species survive today. In contrast, the emergence of the hominoids, ancestors to the great apes and ourselves, was a modest affair centred in the Miocene. Viewing the surviving great apes today, chimps, gorillas, orangs, they display ponderous, thoughtful, and perhaps even philosophical qualities indicative of a superior range of controlling DNA. But the challenges in their lives, to secure food, protect territory and family, have not been sufficient to drive them to another plane of evolution. Viewing chimpanzees in particular, and their potential for language and conflict, one gets the feeling that their DNA just needed a little more variation and a selective evolutionary push, and they would have entered our family tree as a closer relative. Sadly, they haven't made it, and so we are left with our line, arrogantly called Homo sapiens, although wisdom seems to be in short supply.

Human origins

In the enjoyable text by DeSalle and Tattersall, we are introduced to our place in the evolution of life forms, in an excellent outline which uses skeletal, material-cultural and molecular evidence. For archaeologists with no previous knowledge of this field, the book will be both a pleasant read and a valuable source of information. In particular, all the details and discussions around DNA are well illustrated with informative diagrams. The palaeolontological evidence for the evolution of our species is generally known, but its links with the aDNA evidence is especially well presented. Inevitably I find myself asking questions. For instance, why use the species name Homo heidelbergensis (especially for an early skull from Bodo in Ethiopia), when the original fossil from Heidelberg was only a mandible? And why give names like Homo georgicus (from Dmanisi in Georgia) and Homo ergaster (from Kenya), when both can be sensibly viewed as Homo erectus? Such taxonomic labelling seems to me to represent acts of faith rather than good biology.

I enjoyed the molecular text especially, and it prompted me to think of evolutionary questions which had previously escaped me. For instance, if the DNA sequences for humans and chimpanzees are so very close, then why not place them both in the genus Homo, or at least in the same close evolutionary line? I can understand the recoil by the good citizens called Homo sapiens, and what a come-down and blow to our arrogance. More importantly, it raises the question of the degree of humanness of this hairy relative, and what our behaviour should be to this advanced primate with debatably complex thought processes.

The discussion on molecular aspects of the Neanderthals is of particular interest, to me at any rate. All too often are these Palaeolithic communities viewed as prehistoric luddites, because they refrained from significant tool kit changes. But why change if they do the job? They survived unpleasant climates, clearly thought about death in their tough world, and buried their dead. Of considerable importance is the fact that the aDNA signature of Neanderthals so far tested suggests very little, if any, interbreeding with the intrusive advanced Palaeolithic groups which entered Europe. Personally I don't believe this, and we need to test a far larger sample before a firmer conclusion can be reached. But the DNA evidence does suggest that language or cultural complexity, or both, tended to keep the two groups apart. Other evidence and conclusions from DNA studies reinforces the 'Out of Africa' theory concerning the regional origin of our species (but see below), with the differentiation of a number of lineages. Some remained in Africa, and others were involved in separate waves, peopling the world. The final population movement presented by the authors was between 30 000 and 10 000 years ago, with intrusions into the New World. DNA clearly produces nice stories, but inevitably there are serious questions lurking in the background. How sensitive would aDNA studies on a few fossils be to occasional miscegenation? And if the aDNA from Mungo 3 represents a lost genetic lineage of no relevance to the history of modern Australian Aborigines, then what other lost lineages might be there in our past? In sum, this is a highly readable broad review of human origins, which includes, apart from fossil finds and molecular aspects, the fascinating question of brain increase and evolution of language.

Human revolution

Rethinking the human revolution provides a broader and multi-authored view of the past, especially of later Pleistocene times. Attention is concentrated on behaviour and biocultural adaptations of our species. The introduction, by Paul Mellars, usefully discusses what is meant by 'revolution' in relation to the long time-depth of our prehistory, and if it is appropriate to talk of revolutions in our distant past; can we identify them, and the processes involved? His succinct review, drawing on information from sub-Saharan Africa through to the Eurasian Palaeolithic, sets the stage nicely for the following 33 chapters, sensibly assembled into seven parts. Ultimately of course, biocultural evolution must inevitably be a mixture of 'gradualism' (I would prefer the word 'bumblingism') and periods of accelerated change. Variation in 'complexity' is perhaps the most difficult notion for me to grasp, as what we see at a material culture level may not be well correlated with the extent of brain and thought complexity. Need a Plato be a super-technologist?

In part 1, as in the previous volume, we are again concerned with fossil and aDNA aspects of human origins, but here with special reference to the emergence of modern humans. Chris Stringer, the éminence grise of Upper Pleistocene human evolution studies, provides a brief but valuable update, followed by supporting DNA and Y-chromosome haplogroup studies. Although I remain stubbornly resistant to the 'Out of Africa' hypothesis, for the emergence of our own species, the evidence seems to be stacking up against me. Kivisild is persuasive as regards the later Pleistocene expansion and spread of peoples from Africa, initially into western Asia and then beyond. So Europeans are really Africans or Afro-Asians, or could it yet be that Africans are really Near Eastern people who expanded (back?) into the least healthy of the continents? The additional information from Y-chromosome Haplogroup l Variation contributes especially on the phylogeography and prehistory of European groups (note the maps in Figure 3.4) and shows again how molecular studies are a new force for understanding the demography of the past.

Part 2, concerned with cognitive perspectives, changes gear. Beads are considered 'elements of technologies for transmitting information', the earliest finds being 100 000 BP (from Mount Carmel, Israel). 'Culture' and 'acculturation' are discussed at some length. It is argued that the relationship between culture and evolved intelligence is complicated and not self-evident. There is also the question of the possible different order of phenomena - blades and worked bone versus symbolism and 'art'. The evolution of human mental capacities is bravely considered by Kathleen Gibson. Was there a 'major genetic mutation' which resulted in' modern intellectual and linguistic capacities'? There is always a danger that such questions will be rendered too simplistic when dealing with our complex brains and minds; nevertheless the chapter provides a detailed review of the problem, and this is amplified in the next chapter, which asks if our modern thinking capacity is the result of a specific change in our working memory potential, a question rightly treated with caution. Problem solving abilities could have improved over our evolution, but the mess we have made of urban and industrial development and failure to control population, argues against it. However, Dunbar's contribution makes a good case for critical changes to the human mind at the earliest differentiation of our species some 200 000 years ago. Yet another point of view, presented by Derek Bickerton, is that syntax was a major trigger to a human revolution. Mithen considers music, and argues that, long before compositional language had evolved, communication would have made extensive use of rhythm and melody. Indeed, what are the calls of higher primates other than proto-music?

Part 3 of this stimulating volume is dedicated to regions of Africa, with special attention to the finds from Blombos Cave, South Africa, the Omo Kibish Formation in Ethiopia, Taforat in Morocco, and the Nile valley. Geographic extensions include the Levant and Eurasia. The final parts of this volume continue to emphasise geographic areas. In various contributions, Neanderthalers are discussed in relation to the replacing advanced Palaeolithic communities. Personally, I don't think the evidence is yet sufficient to suggest a major divide between these groups in terms of intellect or linguistic complexity. I am not sure why other contemporary groups were not discussed; they should certainly not be ignored. Africa could have had a significant population of Rhodesian-Saldanha people, unrelated to the Neanderthalers. And Asia similarly had different pre-sapiens people. As a whole, there is much to contemplate from this collection of papers. Whether there ever was a 'human revolution' is still a matter for further debate. Some themes of prehistory, such as modifications to tool technologies or increasing carnivory and eventual domestication, are well visited topics. To me at least, language and art especially demand more debate, as does the question of rates of change. The nature of the mind remains as elusive and as challenging as ever.

Human ecology

The third volume, Human ecology, discusses in more general terms human populations with their environments, and this through time. But, as the sub-title indicates, biocultural adaptations are the main theme. While many mammal groups have successfully adapted to highly variable environments, our species has been supremely creative in terms of adapting by cultural innovations. In this respect we are ecologically unique. Human ecology has considerable breadth, and Schutkowski has wisely limited this volume to a detailed consideration of human subsistence through time, from Upper Pleistocene foragers to recent exploitation of domesticated food species. Linked with such changes have been population increases and adapting social organisations. There has, of course, also been the emergence of warfare and militarism related to resource needs and their protection. The potential for population increase depends on resource availability and carrying capacity, and when these factors are not balanced, numbers crash and diseases may sweep in. Have numbers been regulated in the past? It seems debatable, and this aspect has certainly been one of the failures, rather than adaptive successes, of our species. Two children per family should perhaps have been the general rule by the Bronze Age in the Old World. Social status and privilege also got in the way and thwarted any early egalitarian aspirations of a Neolithic Plato. All of this is well discussed in Human ecology. I believe it is a successful attempt to review a complex of strategies to exploit and manage our planet's resources through time.

Human future?

While at first sight the titles of the books under review seem to diverge to the point of not having a common theme, I think that there is indeed a common message. We have evolved over a few million years by using our wits and competing for resources. Some peoples may have gone to the wall in this survivorship game, and, as part of the strategy to live on, cultural creativity has spun out a range of material evidence which includes decoration and art. And to perpetuate this acquired knowledge through the generations, language has been deemed a good thing. The final question, deserving perhaps another look, is whether we are much more than simply resource exploiters and slick creative adaptors to our basic needs. With global warming, religious extremism, ultra-destructive weaponry, population mushrooming and finite resources, our species will have to become smarter than that.