Cousins: How big is the human family tree?

By Nick

One question I suspect most people ask themselves is “are we alone in the universe”. And while I’m not going to attempt to answer that (see here for the best explanation I can find), I’m going to pose another similar question, one which we might have an answer to: “How long have we been alone?”

What has happened to our family, our cousins, the other humans? When we think of human evolution we tend to think of things like Australopithecus living three or four million years ago, when we (early humans) would have been pretty similar – we cannot be certain if Australopithecus is actually in the human lineage (like a parent or grand-parent) or a side branch (like an uncle or great-uncle). But our human lineage is much more interesting and diverse than just cave-men and ape-like creatures.

We also know lots about Neanderthals, our ice-age, cold-loving, European dwelling cousins. They lived quite recently, up to at least 30,000 years ago, and maybe 24,000. We think Neanderthals probably interbred with humans.

But there are a couple of contenders for species that survived even more recently than 24,000 years ago. Human species that survived until 12,000 years ago.

What’s so special about 12,000 years ago? By 12,000 years ago we were beginning to farm, make pottery, build temples and were starting to domesticate animals. Homo sapiens then were essentially the same as they are now. We weren’t dumb animals back then, we were conscious, dreamers, builders, planners, very, very smart, with the beginnings of culture. Yet the more we look back at the history of human evolution, the more we discover that the traits we think of as special to us (symbolism, fire, language),  are actually found in other species of humans. And we could have lived alongside our quite well developed cousins.

One of these species is Homo floresiensis, also known as the Hobbit. Standing in at just over a 1m tall, with disproportionately long arms and big feet, skeletons of the Hobbit were discovered in 2004 on the island of Flores, in Indonesia. They have been discovered nowhere else. The Hobbit is known to have survived to at least 17,100 years ago. They could well have survived to 12,200 years ago. And if you believe local mythology, then the tales told in the villages of Flores, detail a group of small people that might have survived as recently as a few hundred years ago.

New research has been published this week (in PloS One, so you don’t need to pay for it) which could even trump the 12,200 years of the Hobbit. This week the discovery of the Red Deer People was announced. In a cave in South-West China, five skeletons of a potentially new human species were unearthed. They have an interesting mixture of primitive physical features and more advanced ones. They had short flat faces with big teeth and thick skulls. The work was co-led by Darren Curnoe of the University of New South Wales.

The Red Deer People could have survived to just 11,500 years ago.

But they’re urging caution with this new discovery. They may be a new species, or they may not be. Two other theories postulate that they might be an early population of Homo sapiens who were later replaced, or they could represent hybrids, a mixed population formed by the breeding of Homo sapiens and other Homo species. More work is needed, but without a doubt, this is a big discovery. Over the past few years we have discovered new Homo species (Hobbits, Denisovans, Red Deer People) that our changing our view on how long we have been alone for.

Of course, once we know how long we have been alone, it opens up a whole new raft of questions, including why did these species die out? But such is the journey of science. We’ll just have to wait and see.

A lot of my work relates to Homo floresiensis (the Hobbit). My samples come from a cave just a few hundred meters away from where Homo floresiensis was discovered. Whilst Human evolution itself may not be Earth Sciences, it does provide some fabulous context. I study the history of the monsoon in Indonesia, which I find pretty exciting on its own. But it adds something extra special to know that I am detailing what the climate was like when the Hobbit was around. And maybe my work will help to discover why the Hobbit died out, and why we are the last human standing.

If you’re interested in learning more about human evolution then SBS had a tremendous documentary on on Sunday night called Becoming Human: Last Human Standing. Well worth a look.

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