The origin of the species

THE Incredible Human Journey is the book accompanying the BBC television series of the same name. It’s written by Alice Roberts, who also presented the series, and investigates how human beings colonised the planet.

Roberts travels to far-flung places and examines the archaeological record, the genetic evidence, even folklore and ancient climates, to assemble the pieces of a complex jigsaw puzzle. Her approach means that this is a travel book as well as a book of popular science. It’s a clever idea, because the exciting travel to exotic places livens up the science and gives the book a second story.

Alice Roberts is by no means a scientific light weight. She’s a qualified medical doctor, on a sabbatical from her job as a lecturer in anatomy at Bristol University. She has an interest in evolutionary anatomy, the study of how the human body came to be the shape it is today, and she’s not afraid of expressing her own opinion.

There are several schools of thought on how we evolved as a species and then spread out to colonise practically the entire world (we can’t really claim to have inhabited Antarctica).

The mainstream theory is that modern humans are descended from a small band of people who emigrated from Africa between 50,000 and 80,000 years ago. This makes us all closely related. The genetic evidence suggests that all modern humans share one common ancestor, a many-times-great grandmother who lived in Africa 200,000 years ago.

There are other theories. The orthodox view among Chinese scientists is that human beings evolved separately from more primitive forms in their country, and that the Chinese people have no African forebears. Alice Roberts doesn’t agree with this, and I suspect she’s right.

The book also has wonderful information about other ‘human’ species that are now extinct. I’ve always been fascinated by Neanderthals. They migrated out of Africa long before modern humans and they were already in Europe when our ancestors arrived there.

They seem, in many ways, to have been superior to us. They had bigger brains, strong bodies that were better adapted to the northern climate, and they made very sophisticated tools. But after our arrival they rapidly became extinct, and nobody knows why. Genetics has shown that there was no significant inbreeding between Neanderthals and modern humans, so the two populations didn’t merge. The Neanderthals just dwindled away, apparently making a last stand on the Rock of Gibraltar 25,000 years ago.

The story of the ‘Hobbits’ of Flores is even more extraordinary. The skeletons of tiny, human-like creatures were discovered on the Indonesian island of Flores in 2003. The discovery made newspaper headlines round the world and upset the apple-cart as far as orthodox scientific theory is concerned. The Flores Hobbits are an impossibility. They seem to have lived there for a very long time and survived until as recently as 12,000 years ago. Because Flores has been an island surrounded by deep sea for hundreds of millions of years, they must have got there in some kind of boat. This, along with tools the archaeologists unearthed, suggests a quite sophisticated human culture. But anatomically they are totally different to us, with much smaller brains. They resemble the very early African australopithecines, which approximate to the old-fashioned idea of a missing link between humans and anthropoid apes. The mystery has not yet been solved.

Leaving these extinct (presumably!) ‘human’ species to one side, the story of modern humans is also astonishing. We are so incredibly adaptable that within a relatively short space of time the descendants of that small band of African pioneers had colonised the frozen wastes of Siberia during an Ice Age, the burning deserts of central Australia, and both North and South America.

The obstacles they overcame were not just climatic. There was asteroid bombardment, the eruption of massive super-volcanoes, and an array of monstrous animals that are now extinct. It’s miraculous that we are here today.

The book and the TV series are quite different. There is far more hard science in the book, though it’s written in a clear, simple manner. With a book, you control the speed at which you take in the information, so books are better than TV at communicating complex ideas.

There’s also more detail in the travel stories in the book. In one episode of the TV series, Roberts travels with a nomadic tribe of reindeer hunters and herders, the Evenki, in northern Siberia. These people are dependent on a combination of wild and domesticated reindeer. They eat practically nothing else and make their tents and most of their clothing from the hides of the animals. Alice Roberts lived with them for a while.

The Evenki are completely carnivorous and spend a lot of their time killing reindeer and then, amongst other things, drinking steaming cups of the fresh blood. What is revealed in the book but not, I think, in the television programme, is that Alice Roberts is a life-long vegetarian, adding a new dimension to the story.

The TV series is also, by its nature, episodic. The book does a better job of linking the various locations, and the different strands of the story, into one coherent narrative.

I found it altogether fascinating and I learnt a lot about who I am and where I came from.