Reading Chris Stringer's Homo Britannicus is a bit like going down to the pub beer garden on a sunny Sunday afternoon and listening to an acquaintance who's fast becoming a friend setting out their life's work and passion – he wants you to grasp the excitement of the work, and understand what's going on, but he's also scrupulous in making clear in this fast-moving field what's now known fact, what's generally believed but could be overturned in a moment, and the theories he holds that run against the general view of the field.
What's more, Stringer wants you to understand why this is important, beyond the pure science, beyond the romance of history – for his study of the spread of 700,000 years of human occupation of Britain has a powerful lesson about just how difficult an environment this proved for multiple species Homo, and just how often the environment wiped them out, or forced them to flee.
Stringer is one of the leading lights in the Ancient Human Occupation of Britain project, which after centuries of amateur enthusiasm and chance discoveries has sought to bring planning and careful science to a field that's often been left to chance, amateur enthusiasm, and occasionally blighted, as with the Piltdown Man, by forgery, and more frequently by over-claim and media distortion.
He begins with a brisk skip through this often less than illustrious history, but the story properly begins 700,000 years ago – at a site in what is now East Anglia, where a species using only shaped stones for tools lived on a peninsula linked to western Europe. The site is Pakefield, and, Stringer explains, through a technique called amino-acid dating, human occupation here has been dated back this far – the oldest firmly dated site north of the Alps. The tools are very simple – but, he explains, they were made from water-worn pebbles, a material not suited to large flaked tools like handaxes. The flora and fauna of the time suggests a remarkably mild environment, and it is clear that Stringer inclines towards supporting the view that this "Costa del Cromer" was only a brief episode of migration under unusually favourable conditions, not real adaptation to anything like normal northern conditions.
There's then a gap to 500,000 years ago, when Homo heidelbergensis, a species that made very finely shaped handaxes, lived (and thought to be an ancestor of both Neaderthals and us) – best known through the much-reported Boxgrove site. It deserves its fame, for rare conditions of preservation mean that not only mere artefacts are preserved, but moments in real time – when a person crouched down to knap a flint tool, then walked off with it, leaving the debris spread around the worksite and their footprints visible. There are also butchery sites – the bones and the tools left there when the work was done.
But the evidence also shows more. On the bones of the big game being butchered here — rhinos, deer and horses — the human tool marks on the bones always precede the teeth marks of hyena or wolves, indicating that these people were either capable of hunting game for themselves, or at least fighting off the fiercest of scavengers until they'd got what they wanted from a carcass. Stringer explains that when this discovery was made in the 1990s it was a revelation – for while secondary scavenging and using tools for marrow extraction may have been enough to allow the first human expansion out of Africa about 2 million years ago, primary access, with intestines and offal, meant a much better quality and variety of food.
Very late in the work at Boxgrove, on one last throw of the dice, the investigators found one of the Boxgrove men – or at least his tibia and a couple of teeth. From this they were able to draw conclusions about the sort of individual this diet could produce – 1.8 metres (5' 11") tall, weighing about 90kg (200lb), and perhaps 40 years old when he died. What's more, they know he was righthanded from the marks on his teeth made when he used them as a "third hand" while slicing items with stone tools. (Reading this book, one often longs for a time machine – but with this level of science you almost have one.)
But their rather idyllic life beside a lake, with elephants, rhinos, horses and giant deer grazing the grasslands was to come to an abrupt end, with a huge ice cap advancing rapidly from the north. (In the process it pushed the Thames to its present course.) The heidelbergers must have fled, or died out.
By 400,000 years ago, however, kinder conditions had returned, even warmer than today, in the period known as the Hoxnian, when with them emerged a new species of human, recognisably an ancestor of the Neanderthals. Or — and this is one of the great mysteries yet to be solved — there might have been two species, for apparently contemporaneously there are two distinct types of tools in use.
Best represented at a site in Swanscombe, there were people making handaxes, but there was also a culture known as Clactonian, after Clacton-on-Sea in Essex, using tools made with the flakes taken from a flint core. It had been thought that maybe the same people were using different tools for different purposes — handaxes for butchering big mammals, flakes for finer work — but during excavations for the Channel Tunnel rail link in 2003, an elephant skeleton was found surrounded by about 100 Clactonian tools. Speculation suggests, Stringer says — and he obviously has some sympathy with it — that Clactonian culture was a pre-existing European one, eventually displaced by the Neanderthal handaxe culture.
The handaxe was, Stringer says, the Paleolithic equivalent of the Swiss Army knife. "They sat easily in the hand, they had a point at one end (or a chisel-like surface if broken across), a cutting or scraping edge down one side, and a ticker butt for use as a hammer. … Microscopic studies of used handaxe edges suggest that they were employed for a variety of tasks including butchery, working wood and chopping plant materials…" But Stringer adds, there is a mystery, for to do all of these things they didn't need to be as finely made as many are. He's obviously attracted to Mithen and Kohn's theory, that making these was in effect a mating ritual, a way of displaying your attractiveness as a mate, just like a peacock's tail. But it's one of the pleasures of this book that he asks these sorts of questions, as well as charting the attractive, practical tale.
Again, however, the ice returned, then it went, but in one of the other great mysteries, the Neanderthals were never really able to establish themselves as a population. Even when Britain was a hunters' paradise of warmth and big game, there were no humans – although they were well established in neighbouring France and Belgium. (The possibility that for some of this time it was an island isn't, Stringer says, sufficient to explain the situation.)
By about 60,000 years ago, however, they had definitively returned, and a rich site in Norfolk, at Lynford, shows them thriving in a climate of warm summers, although Arctic winters. But then we arrived – whether we were the villains of the piece, whether we interbred with them, or whether we simply witnessed a tragedy (and all of the recent science seems to rule out the middle possibility – at least on any significant scale).
Stringer identifies as one of the most important difference between us and the Neanderthal a social reach across the landscape. "Whereas virtually all Neanderthal stone tools were made from raw materials sourced within an hour's walk from their sites, Cro-Magnons were either much more mobile or had exchange networks for resources covering hundreds of miles." But while with anatomically modern humans there arrived new uses of clay, of bone, and of pigments (in cave paintings), he makes the important point that they did bury their dead, sometimes with burial objects such as food, they knew about pigments (some have suggested that they used their bodies as canvas), and they clearly used materials such as wood that almost never survive.
We, however, did hardly better than the Neanderthals at clinging on in Britain, arriving about 30,000 years ago, but gone by 25,000; back about 15,000 years ago to produce some fine art on Creswall Crags in Derbyshire, although in Somerset's Gorge a confusing but unpleasant looking picture of cannibalism appears about the same time. But again came the ice, and again we went, and it was only about 11,500 years ago that permanent occupation began.
It's this period that brings Homo britannicus into its really modern significance – looking at climate change between 45,000 and 12,000 years ago. Much of that variability was down to the Gulf Stream, but "on many occasions in the past 100,000 years, for reasons that are still not fully understood, the Gulf Stream has completely shut down and the conveyor has rapidly swung into reverse, surrounding Britain with the freezing waters its latitudinal position would otherwise dictate. The polar front migrated towards the Equator, often lying as far south as the coast of Portugal, and even feeding icebergs into the Mediterranean … Astonishingly, some of these extreme oscillations happened over only about ten years." (p.148)
Against this description, Stringer's account of a climate change finds Britain by the end of this century growing oranges, lemons, avocados, grapes and olives. But he points out, if the well-known feedback mechanisms kick in — permafrost melting, icecaps melting — we could see massive sea level rises: one metre "would threaten not only London, but Hull, Liverpool, the south coasts of England and Wales, and East Anglia, as well as the Netherlands…"
Stringer asks what the human species that came before us, and our own ancestors, tell us about the possibility of surviving such rapid, dangerous change. Good old ancient Homo erectus — the first out of Africa, who lasted over a million years and spread across the entire tropical and sub-tropical Old World (think Java man) — puts our history as a footnote in terms of length, but they only ever had a limited ecological niche.
The most successful were, he says, the Gravettians of some 27,000 years ago, who were "able to switch mobility patterns, at times settling in large camps with stable supplies, at other rimes dispersing and diversifying to gather scattered and varied food resources … the extensive spread of the so-called Venus figures at the time across Europe and Asia, as far east as Lake Baikal, gives a further clue to the success … their wide social networks … all important when local resources were unpredictable and it might be necessary at times to rely on the support of neighbours to bail you out."
Studying hundreds of thousands of years of human history — imagining not just all of those species, but all of those small bands of individuals who battled, and eventually fell, imagining the last surviving individual from thousands and thousands of cases of human failure, cowering before a lion, simply lying down to die, alone and defeated, or even resorting to the last desperate option of cannibalism — has obviously had an impact on Stringer and his team. And you'd hardly be human if it didn't move you, too. But, by extension, its a peak at the past that certainly gives you a broader perspective on the problems of today.