Free Lone Survivors by Chris Stringer Page B

conditions, serious enough to affect plant and animal life on land and sea, but perhaps not totally devastating. On the other hand, new analyses of land sediments and pollen in a core from the Bay of Bengal, involving the leading proponent of the Toba effect on early humans, Stanley Ambrose, did find signs of a long period of desiccation in India at the time of the Toba eruption. Unfortunately for simple scenarios, the apparent extinction of the South African Still Bay people after a short florescence came about 2,000 years after Toba, if the present dating evidence is accurate, although some might argue that their innovations were an outcome forced by the environmental degradation that the eruption brought about.
    Now let’s move on about 35,000 years to the environments and time scales around the time of the extinction of the last Neanderthals. Of course, if the Neanderthals passed on their genes to modern humans, as we will discuss in chapter 7, they did not become entirely extinct, since some of their DNA lives on within us. Nevertheless, as a population with their own distinctive bodily characteristics they vanished, and there are many scenarios constructed around what may have happened to them. Explanations have ranged widely from suggestions of imported diseases to which they had little natural immunity, through to economic competition from, or even conflict with, early modern humans. Until recently the view of climate change in Europe at this time was rather simplistic, leading to climate being ignored as a factor in Neanderthal extinction: they became extinct before the peak of the last Ice Age, they had survived cold conditions before, and they were adapted physically, and probably culturally, to cope with climatic downturns. Many explanations (including my own) had instead focused on the direct impact of modern humans on the Neanderthals, and the inherent superiority of people like the Cro-Magnons. But rich paleoclimatic records from cores in ice caps, the sea floor, and lake beds now reveal a startling complexity in climatic change at this time, with many rapid oscillations. This led to new ideas about their extinction, including those of two of my friends, Clive Finlayson and John Stewart, who consider that the Neanderthals were probably on the way to extinction anyway, and that moderns had little or nothing to do with their demise. For example, Clive thinks that early moderns had honed their adaptations on the plains of Africa, a very different environment from that to which the Neanderthals were adapted in Europe; hence the two species had different ecological preferences and never really overlapped, competed with each other, or interbred. According to this view, the Neanderthals faded away about 30,000 years ago as their preferred mixed habitats finally vanished from their last outposts, in places like Gibraltar.
    In my own case, around the year 2000, I took part in a collaboration called the Stage 3 Project (Marine Isotope Stage 3 lasted from about 30,000 to 60,000 years ago), led by Tjeerd van Andel and based in Cambridge. We used fluctuations in temperature recorded in a Greenland ice core and a lake core in central Italy to reconstruct hypothetical “stress curves” for Europe, based on two factors of equal weight, both of which were assumed to be bad for humans, whether Neanderthal or Cro-Magnon: low temperatures and rapid destabilizing fluctuations in temperatures in either direction—higher or lower. The approach was simplistic in that it did not attempt to model other factors such as changes in rainfall, snow, and wind chill, which would also have had important impacts on the human population of Europe and their survival prospects. The stress curves we generated showed a mild climatic phase around 45,000 years ago, which perhaps correlated with the migration of moderns into Europe, but the “climatic stress” peaked at around 30,000 years, rather than the subsequent glacial