“If there has been no spiritual change of kind / Within our species since Cro-Magnon Man . . .” The poet Louis MacNeice was voicing a commonplace that was accepted by most experts on human evolution until very recently – actually still is by some. The evolutionary biologist Stephen Gould put it like this: “There’s been no biological change in humans in 40,000 or 50,000 years. Everything we call culture and civilization we’ve built with an equivalent body and brain.”
The Cro-Magnons were the creators of the cave paintings at Lascaux and Altamira – the glacial period hunter-gatherers whose art astounds us (“We have learned nothing,” said Picasso, after seeing Lascaux). They were modern humans who entered Europe only about 40,000 years ago, and there, despite the hostile glacial period environment, created the primary artistically sophisticated culture. But that wasn’t the top of human evolution. Modern genomics has now shown us that biological evolution actually accelerated from now on, especially since the start of farming 10,000 years ago.
The wealth of cross-referring evidence now available from fossils, archaeology, and genomics has made the study of human evolution itself a rapidly evolving topic, and Chris Stringer is within the thick of this ferment. he’s Britain’s foremost expert on human evolution and, as a paleontologist at the explanation Museum, has been involved in much of the crucial research. This probably accounts for the very fact that in scripting this popular account he cannot altogether wrench himself far away from the tutorial arena during which one authority is forever contesting the findings of another. Such wrangling is, unfortunately, necessary because if recorded history has, as Eliot wrote, “many cunning passages”, that’s as nothing compared to the waxing and waning of human fortunes, battling with ice ages and natural catastrophes over many thousands of years of evolution. and therefore the evidence, of course, is indirect and has got to be pieced together from analyses of mineralized fragments of the past.
Stringer is most concerned with the amount from the emergence of Homo sapiens in Africa, around 195,000 years ago, to their arrival in Europe and therefore the subsequent demise of the Neanderthals (who had left Africa many thousands of years before). The archaeological record shows Homo sapiens in Africa several times on the verge of a cultural breakthrough, but this is often not consolidated until their arrival in Europe. Stringer writes: “It is as if the candle glow of modernity was intermittent, repeatedly flickering on and off again.”
The introduction of farming, first in Iraq and Turkey, was the only greatest event within the evolution of Homo sapiens since its emergence. From farming flowed, in an incredibly short time, increase, craft, art, religion, and technology.
New cultural practices led to radical genetic changes, the power of northern Europeans to digest cow’s milk being the foremost dramatic. This followed the adoption of cattle rearing and reverses the thought that genetic mutations have initiated innovation. even as often, it seems, it’s been a culture that has led, genes that have followed.
Although new fossil and archaeological evidence continue to mount, the drive-in understanding human evolution today, as Chris Stringer emphasizes, is genomic. it’s now possible to match the genomes of Neanderthals with modern humans and with chimpanzees. This work will continue for several years – the genome consists of 3bn letters, anybody of which could mutate – but already dramatic results are emerging.
Stringer has been a robust advocate of the dominant Out-of-Africa theory that modern humans emerged from that continent and completely replaced earlier human types like Homo erectus, Heidelberg man, and therefore the Neanderthals. But while Out-of-Africa still holds sway, the image is losing a number of its classical simplicity. Last year, the Neanderthal Genome Project, led by the Swedish biologist Svante Pääbo, finally established that modern humans in Europe and Asia (but not Africa) have some admixture of Neanderthal genes, thus ending decades of speculation. And in December last year, an equivalent team produced a complete surprise: a genomic analysis of human remains from a subside Denisova, southern Siberia, which proved to be genetically distinct from all known human types. The team declined at this stage to offer the find a Linnean species name, but, by analogy with the Neanderthals, named it Denisovan after the situation. the particular Denisovan specimens in Siberia were 30-50,000 years old, and therefore the type predated both modern humans and Neanderthals.
Apart from having what’s probably a replacement species to suit into the pattern of human evolution, the large shock of the Denisovans is that they even have contributed something to the fashionable human stock in Melanesia (the islands north of Australia that include Papua New Guinea). We now see a pattern emerging of interbreeding between modern humans and earlier types: Neanderthals in Europe and Asia and Denisovans in Melanesia. there’ll surely be further found. Especially interesting is East Asia, first peopled by Homo erectus as long as 1.7m years ago.