An exciting early man discovery published today in Nature may hopefully reverse the insane tide of opinion that hominin evolution is singular and linear.
Clearly we, homo sapiens sapiens, are the end game in a multi-million year evolution that moved step by step from one ancient creature to another, a “linear” evolution into ourselves.
But that doesn’t mean that the “family” of early men wasn’t much broader, with all sorts of other linear evolutions going hither and yon, all dead-ending but us.
I refer to doubters as “insane” because while there are wondrous moments in science where intuitive notions prove wrong, in this case intuitive is really all we need.
All the Kings of The Ecological Hills, sharks, elephants, lions, super viruses, so-called “invasive species” like garlic mustard, and yes, even cock roaches … all of these “kings” did not arrive on a singular path from times long ago.
They all had multiple ancestors, many of which evolved into dead-ends. It’s just totally counter intuitive that we – the “King of Kings” – didn’t arrive on our throne the same way.
Early early man scientists, however, had so little to work with that it really didn’t even occur to them that there could have been other post-ape, post-preman creatures, just like there’s a whole lot of birds. The few discoveries in hand spanned a period of time that could, indeed, suggest one evolved into the other: that all of them seemed in one evolutionary track.
With more and more discoveries, however, this became less plausible, particularly among the post-Australopithecine hominins.
Australopithecine creatures predate homo creatures, and the principal morphological differences are the teeth and brain size. Whether or not some Australopithecine is ancestral to some homo, both are considered incapable of having evolved into modern apes or orangutans … but they are definitely ancestors to us, or to other hominins that went extinct.
That’s the controversy: which is it? Are there other early hominins that went extinct, or is every individual early man fossil we’ve found so far a certain step in the evolutionary ladder to us?
The question really died about 15 years ago when virtually every early man scientist back then espoused a “branching” or multiple ladders theory. Those other ladders never made it to the top: their final species went extinct. We made it.
Homo erectus, in particular, was often cited as one of those dead-ends that got pretty close biologically and socially to us. He migrated all over the earth. He made tools and recent discoveries suggest he used fire.
Then he disappeared hundreds of thousands of years before we appeared.
Meanwhile, all sorts of varied homo hominins more recent than any Austraolipithecine were being discovered: heidelbergensis, floresiensis, habilis, rudolfensis and neanderthalensis. Add us (homo sapiens) and erectus and you have 7 different species, none of which were presumed ancestral to the other.
(Some scientists added others like ergaster and gautengensis, making it 9 or more.)
And then (!) there were some other early manlike creature discoveries, post Australopithecine, that were so taxonomically different they were marginalized as hominins that might even be something else:
Orrorin tugenensis, Paranthropus aethiopicus, Paranthropus boisei and perhaps the most controversial of all, Paranthropus robustus.
If you considered these to be hominin, then there were at least 11-13 or more different hominin species, none of which was ancestral to the other.
That sounded, and still sounds, right to me. As I’ve often said, with time I imagine we’ll add to this list.
Then come these scientists who find some discoveries in Georgia a few years ago which were striking for being among the most complete skulls, and for so many skulls.
The scientists’ assessment at the time was that everything that they had found was a homo erectus and they extrapolated from other details of their discovery that really homo erectus was the only hominin species predating homo sapiens!
The old question was ressurrected.
Well, time has passed and criticism has mounted and basically the consensus that has emerged is that yes, probably there are fewer different hominin species than many once suggested, but that the Georgia finds are woefully insufficient to suggest there weren’t at least some different simultaneous homo species!
And today’s publication in Nature really helps return to this belief: Scientists working in Ethiopia report the discovery of an Australopithecine (remember, the homin creature that predates homo) that was contemporary with “Lucy” (Australopithecus afarensis) but way too different to be like Lucy, so a completely new species of Australopithecine!
Since Austraolopithecine predate homo this suggests that if there are multiple Australopithecine then it’s completely plausible there are multiple homo.
Done for the moment. (Hardly for the term: Stay tuned!)