Timewalkers: The Prehistory of Global Colonization

The central theme of Gamble's book is the spreading out of early humans from their evolutionary place of origin in Africa. Gamble argues that the fact that our ancestors came to occupy virtually the entire globe is the key to understanding our humanity.

There are some good things about the book. For example, Gamble argues that there are few genetic rules for behaviour in humans. Human nature is not fixed, it is flexible: we are cultural beings.

But I found myself disagreeing with one of his main arguments. This concerns the origins of human consciousness and intelligence, and of the 'purpose' which he says motivated the human colonisation of the globe.

Most writers agree that an interaction of three factors stimulated the development of show more the large human brain: tool making (labour), social life and language. But there is disagreement about which of these factors was the key one in getting the ball rolling.

Many scientists, for example Kathy Schick and Nicholas Toth in their book, "Making Silent Stones Speak", argue (as did Frederick Engels, incidentally!) that tool making was the initial spark. But Gamble supports a currently trendy argument which plays down the importance to tool making and claims that social skills were the crucial element.

He claims that 'Machiavellian' social interaction was the main cause of the growth of human intelligence. Competition within the social group (for example, for mates) led to the need to form alliances, to try to look into opponents' minds, and to use devious tricks to outwit them.

This is a view of social interaction which is strongly tainted by the ideology of capitalism. His focus is on competition. But in early human societies and, for example, in the case of our nearest living relatives the bonobo ('pygmy') chimpanzees, the key social element seems to be cooperation, not competition.

Then there is the fact, as Schick and Toth point out, that upright stance evolved long before the brain grew large. And what did upright stance crucially do? It released the hands for the later development of tool making.

Of course, social life is an important factor. Tool making took place in a social context and there was a feedback loop between labour, language and social skills. But it seems to me that tool making was the crucial element which enabled humans not only to occupy the entire world but also to transform it.

The leading evolutionary biologist John Maynard Smith is quite impressed by the 'social skills' argument. But he has also pointed out that it is not clear why humans should have evolved a higher level of intelligence than other social animals, such as dogs, if it had not been for the tool use made possible by grasping hands.

It is this theme of the central importance of tool making in human evolution which runs throughout Schick and Toth's book. I would recommend it much more than Gamble's. show less

In the preface of this book, the author states that the question he will investigate is: why were people everywhere? In other words, why and how did homo sapiens and her cousin species populate almost the entire planet in prehistoric times? This is a fascinatingly broad question and the author certainly has the expertise to seek answers in the global archeological and paleontological evidence, which he reviews at a suitable level for a non-specialist audience.

However, I didn't quite find his presentation and his answers intellectually satisfying. It is to some extent understandable that no very definite answers can be given. The prehistoric evidence would probably be overinterpreted if one was to give only one reason for all prehistoric show more migrations. But in the concluding chapter, titled "why people were everywhere", the author resorts to the rather placid explanation that "humans went everywhere because humans have purpose". I found this puzzling since "purpose" had not been discussed at all in the earlier chapters, and simply concluding that migration and settlement were deliberate hardly explains why it was successful.

Intriguingly, on several occasions in the book the author actually points toward a more informative answer: increased social interaction. He mentions in passing that the extension of range was the product of more complicated social organization, that social relationships are a form of storage, and that similarities in archeological items indicate increasing scale in social systems as prehistoric colonization proceeded. This seems to make intuitive sense. Wider, peaceful social networks and trade would have multiplied the knowledge and resources available to prehistoric humans, which presumably would have aided migration and settlement.

Unfortunately it is hard to say to what extent these claims of expanding social networks are just unwarranted speculation on the part of the author, or actually supported by evidence. The author does not pursue questions of social scale consistently. Perhaps such questions cannot be reliably investigated by paleontological means, but then he could have written so explicitly.

In summary, the present conclusion, which bears little resemblance to the preceding presentation, would probably have been better left unstated. Since the author set out to answer a general question, he could have re-examined his entire argument more critically to find the archeological and paleontological tracks which could lead to general conclusions with real interest. show less

Great, but a tad complicated. Excellent analysis of a wide-spread characteristic