I was intrigued by reports last week on the discovery of a previously unknown extinct human species, Homo luzonensis, in a cave in the Phillipines. It’s the fourth new human species – genus Homo – discovered in the past twenty years. All are extinct, and much clearly remains to be revealed, but it’s nonetheless clear that older ideas about the nature of human evolution as a one-species ‘ascent’ are long gone.
That journey of discovery has been a wild ride – one I’ve been following closely. I did the sciences before focusing on history, and one of my undergrad degrees is in anthropology. Back in the early 1980s, when I was at university, human evolution was simple; we’d always been a single species, with maybe a couple of dead-end side branches, now gone, and that was that. Paleo-anthropology consisted of putting the prior forms into the right order. It stood to reason: there were many species of other animal, but only one of human.
By the mid-twentieth century this notion was being quietly questioned in the academy – not least because it implied that humans were exempt from the processes known to apply to everything else when it came to evolution. But the idea was effectively still mainstream even in academic circles. It was popularly given weight through an influential infographic by Rudolph Zallinger, the ‘march of progress’, published by Time-Life in 1966. This became a trope, presenting human evolution as a linear ascent from crouching and primitive ape to upstanding and sophisticated modernity.
The particular point of debate by the 1980s was over how modern humans had somehow emerged in every part of the planet when there was also evidence of prior forms – such as Homo erectus – across a wide swathe of the globe. Either humans had come ‘out of Africa’ and migrated more than once, each new form supplanting the last. Or there had been parallel evolution. From this emerged ‘multi-regionalism’, which argued that in defiance of the way evolution worked for everything else, isolated erectus populations simultaneously became identical modern humans in different environments, some as diverse as Java and England.
The thing is that modern humans are a single species. Indeed, we’re unusually close, biologically – if we were dogs, we’d be a single breed (labradors, I hope). It indicates there was a population bottleneck in the not-too-distant past, maybe 70,000 years back. This ultra-close relationship within Homo sapiens meant it wasn’t plausible for every H. erectus, everywhere, to have suddenly become an identical form of modern human. And yet evidence for multiple exits from Africa was non-existent at the time.
As a result there was an apocalyptic academic struggle between the ‘out of Africa’ camps and the ‘multi-regionalists’. By the 1980s, paleo-anthropologists were screaming at each other, desperately trying to prove to the world how ignorant and incompetent any colleagues were who followed the ‘other’ theory. Much pivoted on the implicit assumption that humans were a special case, further driven by the fact that, at the time, the total physical evidence of ancestral human species and locations amounted to just a few dozen specimens. The fact that ‘multi-regionalism’ flew in the face of accepted mechanisms of allopatric speciation (to use the technical term) was met by sophistries such as assumed back-migration, none of which had any evidence behind them.
Since then those arguments have been put to rest by a flood of new evidence. Humans seem to have emerged in a habitation range stretching from modern Ethiopia perhaps into the Middle East, spreading both out of – and, in a curious reversal of old thinking, in to Africa. It happened multiple times. Humans also speciated like every other animal – meaning that each new form did not replace the old, but that multiple species of human lived simultaneously, shaped by genetic drift and by environmental pressures. And we’re finding the examples. The question is how to understand what’s been discovered. Given what I know about human nature and academia, I can’t help thinking this will trigger yet another shit-fight in the paleo-anthropological community (it’s an ape thing, weaponising one’s own ordure, and the fact that humans do it intellectually rather than literally doesn’t reduce the symbolism).
So – it’s clear now that we, H. sapiens, are the last humans out of at least half a dozen species in our family. The very last. Aside from the obvious responsibilities now resting on our shoulders, that begs another question. Why did our species survive, alone of all humans? It’s not, I suspect, because we have anything special. We may not even have been smartest; there’s evidence that Denisovan and Neandertal stone-age tech was better than ours, and they had bigger brains than we do, on average. Remember, Neandertals invented epoxy resin about 40,000 years before we did. They were also physically at least twice as strong as we are.
For all that, old tropes have died hard. For a long time the idea was that the modern body form emerged about 1.5 million years ago with H. erectus and that our evolution after that consisted purely of the relentless expansion of a single body part – and yes, I mean the brain – although nothing else changed. And there was a supposition that eyebrow ridges and low forehead implied stupidity. It’s still widely held outside the science community. The first news I read of the new find, in a general news website, described Neandertals as ‘thick-browed yet sophisticated’. But hey – how did Neandertals think of us? Flat-faced children? H. sapiens adults have the same facial structure as Neandertal kids did, pre-puberty (which came earlier for Neandertals than for us) – and we’re physical weaklings by their standards. The technical term is neotony.
Of course, Neandertals have always had a bad rap, thanks to old social tropes of directional evolution. In this vision, dripping in ethnocentric culturalism, Neandertals were the ‘missing link’ with apes. They spoke in deep grunts, lacked intellect, had names such as Thog, and went extinct for no better reason than that they were stupid and out-competed by Homo sapiens, aka Man The Wise. Apparently.
The notion that Neandertals were just different, like lions are different from tigers, took time to emerge. They lived in ice-age Europe, and their anatomy was well-adapted to cold; their protruding face (technically, ‘prognathic’) meant they had long nostrils to pre-warm the air. Their brains were bigger than ours, and analysis of endo-casts indicates that although differently shaped, they were not less than ours in functionality. In short, Neandertals were just as sophisticated as us in their own way, and perhaps superior. Oh – analysis of their vocal tract and hyoid bone structure implies they probably had high-pitched voices.
But even once this had begun to emerge, the notion that H. sapiens was somehow exceptional among human species remained implicit within the science community. I’ve got a book in my collection, penned by a couple of academics from the University of Colorado, How to think like a Neandertal. They essentially argued that sure, Neandertals were smart, had brains bigger than ours, made clothes, had epoxy resin, and so on. But they were still broadly static and uninventive. The authors suggested the difference was H. sapiens social-group size and abstract creativity, painting a scenario of small Neandertal families sitting huddled around a fire in near-silence, while across the valley the bands of H. sapiens are socialising in large groups, story-telling, singing and so forth. The implication is that Neandertals were not in the league of their more creative cousins and, variously, succumbed to a combination of sapiens’ success and environmental pressures to which they could not adapt swiftly enough.
The thing is that, just now, the long-held paleo-anthropological idea of all humanity living in a kind of intellectual fog, and the light suddenly going on for H. sapiens alone, about 40,000 years ago, is a bit shaky. Since that book was written, archaeologists have found Neandertal-made cave art, jewellery and musical instruments. It’s also been discovered that they threw spears – another thing reserved as an H. sapiens achievement and decisive advantage for hunters. Meanwhile, the story of another close cousin, the Denisovans, is just beginning to unfold. And guess what – their mesolithic tech was also superior to H. sapiens, and they made jewellery – and there’s doubtless more to come.
Still, the idea that H. sapiens is exceptional refuses to die, despite mounting evidence that we’re not. That’s in part because we, alone, survived. But was this simply accident? The great age of apes was the Miocene, which ended five million years ago. Since then, the number of all ape species have declined sharply. Most are extinct. All that’s left of the so-called ‘great’ apes are one species of human, two of chimp, two of gorilla, and three of orang-utan (one was recently discovered). Time has not been kind to family Hominidae. The behaviours that characterise this family – chimps and humans especially – are not, it seems, a long-term recipe for survival. There is good reason to suppose that our sole surviving human species is around only by chance. Luck, not exceptionalism, left us alone to carry the human torch forwards. Thoughts?
Copyright © Matthew Wright 2019