You may have heard science has reconsidered its view of Neanderthals but did you know human hybrid species played a key role in our evolution?
Scientific study of human evolution historically reassured us of a comforting order to things. It has painted humans as as cleverer, more intellectual and caring than our ancestral predecessors.
From archaeological reconstructions of Neanderthals as stooped, hairy and brutish, to “cavemen” movies, our ancient ancestors got a bad press.
Over the last five years discoveries have upended this unbalanced view. In my recent book, Hidden Depths: The Origins of Human Connection, I argue that this matters for how we see ourselves today and so how we imagine our futures, as much as for our understanding of our past.
Six revelations stand out.
1. There are more human species than we ever imagined
In the last few years we have realised that our Homo sapiensancestors may have met as many as eight of these different types of human, from robust and stocky species including Neanderthals and their close relatives Denisovans, to the short (less than 5ft tall) and small-brained humans such as Homo naledi.
But Homo sapiens weren’t the inevitable evolutionary destination. Nor do they fit into any simple linear progression or ladder of progress. Homo naledi‘s brain may have been smaller than that of a chimpanzee but there is evidence they were culturally complex and mourned their dead.
2. Hybrid humans are part of our history
Hybrid species of human, once seen by experts as science fiction, may have played a key role in our evolution. Evidence of the importance of hybrids comes from genetics. The trail is not only in the DNA of our own species (which often includes important genes inherited from Neanderthals) but also skeletons of hybrids.
3. We got lucky
Our evolutionary past is messier than scientists used to think. Have you ever been troubled with backache? Or stared jealously after your dog as it lolloped across an uneven landscape?
That should have been enough to show you we are far from perfectly adapted. We have known for some time that evolution cobbles together solutions in response to an ecosystem which may already have changed. However, many of the changes in our human evolutionary lineage maybe the result of chance.
For example, where isolated populations have a characteristic, such as some aspect of their appearance, which doesn’t make much difference to their survival and this form continues to change in descendants. Features of Neanderthals’ faces (such as their pronounced brows) or body (including large rib cages) might have resulted simply from genetic drift.
Epigenetics, which is where genes are only activated in specific environments, complicate things too. Genes might predispose someone to depression or schizophrenia for example. Yet they may only develop the condition if triggered by things that happen to them.
4. Our fate is intertwined with nature
We may like to imagine ourselves as masters of the environment. But it is increasingly clear ecological changes moulded us.
The origins of our own species coincided with major shifts in climate as we became more distinct from other species at these points in time. All other species of human seem to have died outas a result of climate change.[…]
A socialised wolf enjoying affectionate contact. Vilmos Vincze / Wikimedia Commons:, CC BY
Professor of the Archaeology of Human Origins, University of York