Hand axes were the first, rather than knives, although you’re correct in the general sense of cutting edges.
There has been a lot of new data an discoveries in these areas in the last few years. Partially new discoveries, but also because advances in genetic analysis are allowing massively increased resolution when we look at ancient bones.
Our genus moved out of Africa several times. Erectus and possibly Australopithecus millions of years ago. Neanderthals and Denisovans maybe 650 - 750 000 years ago. Probably in the form of Heidelbergensis. Recent discoveries are pushing that back, could be as far back as 1 million years ago. They interacted with other archaics when doing so.
The first remains we have of anatomically modern man are from northern Africa, Jebel Irhoud in Morocco, and 300 000 years old. At the time western Africa contained an unknown archaic about as divergent from us as Neanderthals were. We actually made other out-of-Africa attempts that were unsuccessful. At least on in the previous interglacial. When the weather cooled, better adapted species of Homo Sapiens drove us extinct. We did interbreed with at least one line of Neanderthals at the time The Levant may just as well be seen as a part of Africa here, we probably fluctuated into and out of places like Arabia.
Then, about 70 000 years back, very roughly, something happened. We don’t know what but we just exploded out of Africa in the middle of an Ice Age that we were totally wrong for. We overlapped with the previous inhabitants for 0 - 10 000 years in places. Neanderthals in Europe, Asia and the Middle East, Denisovans in Asia. We didn’t interbreed with most of them. We bread several times over thousands of years with one specific line of Neanderthals that split from the other Neanderthals about 70 000 years ago. We’ve never found physical remains of them. We interbred with something else along the edge of the Indian Ocean, and with the Denisovans probably long, long after the Neanderthals went extinct. Maybe a few others. Not every human line in the out-of-Africa lot outcrossed with the natives.
Bu there was always competition. All the way back to Erectus or further. Something just happened that let us wipe out the competition. Something that wasn’t genetic.
Can you explain a little further please:
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How do we know there was an unknown archaic species in Western Africa?
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How do we know that humans interbred with a “branch” line of Neanderthals whose remains have never been found?
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How do we know Sapiens interbred with “something else along the edge of the Indian Ocean”?
I assume the answers lie in genetic analysis but wondering if you can lay it out in a little more detail.
The general thinking (can’t know for sure, of course) is that we were mostly scavengers before being mostly hunters. And if so, tool use would have centered more around cutting up already dead animals than in killing them.
Stone tools figure prominently in the archeological record but probably because wooden tools don’t fossilize well. It’s almost certain that we used wooden tools before stone. Chimps not only use tools (stone and wood), but make them (wood) as well, so it’s likely that our common ancestor did the same.
Hand axes are very sophisticated stone tools and came long after the first, simpler stone tools appear in the fossil record. They were a remarkable innovation, but oddly stayed stagnant for hundreds of thousands of years.
Mostly, the increased sensitivity of genetic analysis lets us spot genes that do not track back to the base African population, and are deeply divergent from their counterparts in our line. On number 2, we can compare the Neanderthal genes we have found in our own species to those of the Neanderthal genomes we have sequenced and see that the genes diverge more from them than they do from each other. I’ll link to some of the papers tomorrow. I am, in all honesty a bit too far behind the times to be totally up on the techincal side of it.
The African population of archaic Homo is often called the “ghost species” because we only know of them through genetics, not through any fossils or DNA from fossils.
John Mace, thanks for that link about the “ghost species.” I supposed that answers my question 3 above as well.
I’m still wondering about the Neanderthal thing though–I would have assumed that we know today’s humans have NDNA by comparing our genome to that of a Neanderthal, and that the duplicate sequences are what we get from our stocky brethren. If the current thinking is that we have NDNA from a sequence for which we don’t have remains, how can that be inferred? Still not quite getting that one.
I’m not sure where that claim about Neanderthals is coming from. The research is still evolving (hah!) on this and new data is leading to new conclusions fairly frequently. I believe that Neanderthal and Denisovan hybrid conclusion came from direct comparison of modern DNA with DNA extracted from fossils of those two species. I’m not sure if this is still the consensus on Neanderthals, but evidence has been presented that the interbreeding took place in a fairly narrow time frame and geography. That is, it does not appear that modern humans interbred with Neanderthals all over Europe as they spread out thought that continent. Seems counterintuitive, but more data may produce newer conclusions.
It’s also believe that there was some remnant Erectus population in Southeast Asia with which the ancestors of modern humans in that area interbred. Whether you called them Erectus or Heidelbergensis is more a matter of terminology than anything else. I believe that genetic conclusion is made based on an analysis similar to the “ghost species” analysis and not direct species-to-species DNA comparison. AFAIK, there isn’t any DNA that’s been recovered from that that remnant Homo population.
This is all really earth-shattering stuff for those of us who grew up with the “no evidence of hybridization” hypothesis that was so common just a decade or so ago (and earlier).
Basically, you can compare the NDNA sequences in us with the NDNA in Neanderthal remains and see how it diverges. As well as compare the NDNA from Croatian Neanderthals with that of Altai ones, and see how close they are to each other and to the NDNA we carry.
Ok, here are some references: Neanderthals introgressing with humans only came from one population of Neanderthals: Reconstructing the genetic history of late
Neanderthals. The letter uses phrases like “We find that the bulk of Neanderthal gene flow into early modern humans originated from** one or more** source populations that diverged from the Neanderthals that were studied here at least 70,000 years ago, but after they split from a previously sequenced Neanderthal from Siberia around 150,000 years ago.” emphasis mine. But they seem to be covering themselves here, because if you read the letter there does not seem to be any evidence for gene flow from other lines of Neanderthals.
This is really a “Whoah” discovery. I mean we overlapped with Neanderthals for thousands of years in many places. And at the time, our own species was really variable in how friendly it was with outsiders. Some populations were exchanging genes across vast distances, others seemed to have been genetically isolated for long timespans. And still, we only interbred with one line of Neanderthals? And several times over thousands of years but only with one lot? It is hard to credit. (Also, the scarcity of evidence for human introgression into Neanderthals is interesting).
On a divergent population in west Africa, and multiple instances of hybridizing with other archaic populations, some cases startling late, if not record-holders for late outcrosses: “Recovering signals of ghost archaic admixture in the genomes of present-day Africans” Still in preprint.
That was pretty much to be expected though. We evolved in Africa, so a more gradual cline with a number of separations of shorter duration was to be expected.
Thanks for the references, they are fascinating to me. However, I’m not equipped to decipher everything and there seems to be some assumption of common knowledge among researchers that’s not common to me. So, a couple more questions.
- I’m going to simplify this to ask the question and maybe I’m oversimplifying but here goes:
Human nose hair gene: ATCG. Known Neanderthal nose hair gene: ATCC. Not a match.
Human ear hair: GCTA. Known Neanderthal: GCTA. Aha! We share genes!
Human back hair: GGGA. Known Neanderthal: GGGT. Inference: This gene is from a “ghost population” of Neanderthals. How can we make that leap?
- The first article mentioned using for comparison the DNA of an archaic human who was not a direct ancestor of present day humans. Is it possible that modern humans are simply descendants of one group who bred with one particular group on Neanderthals, and that other archaic humans DID interbreed more with other groups of Neanderthals? Or is that question answered by the article and I just didn’t realize it?
I have trouble imagining wood knives or hand axes - or whatever they would be - being useful to cut up relatively fresh raw meat. One can imagine the first one to cut his /her hand on a sharp stone thought - Hey, this will divide up the ham hindquarters nicely. After all, we generally didn’t have the teeth to pull kills apart barehanded.
Any thoughts as to when clothing/covering or constructed shelters first happened? There’s the presumption that caves pre-dated constructed shelter, but I would imagine by the age of Neanderthals that a cave was just a convenient time-saver.
I didn’t mean to say that wood tools were used for cutting meat. Just that wood tool making almost certainly preceded stone tool making. The wood tools would have been used for other purposes.
There is conjecture based on the evolutionary history of lice that supports clothing at around 60k years ago. But it’s hard to imagine Neanderthals without some sort of clothing, and unless their ancestors were covered with fur, they would have needed it, too. Neanderthals, as a species, are about as old as we are (about 300k years ago), and their predecessors in Europe go back much further than that.
Right. You get an idea of how this is like when you find someone has already picked the wild blackberries you have been harvesting year after year. Either you give up blackberry jam, find a new berry patch, or kill the intruders.
My thought is that it’s one thing to find a freshly killed carcass abandoned by the lions, and chase away the hyenas with pointy sticks (wood tools). It’s another to have an intact gazelle with a few pointy stick wounds or a bashed in skull and then figure out how to translate intact skin into dressed meat ready to cook; not to mention disassembly to make the meal take-away.
Presumably one tack is to burn off the skin - build a fire around the thing and wait until you can pick or scrape off the outer bits and chew on the interior… but that’s out in the open, there better be firewood nearby. I don’t imagine them backing off and letting the hyenas get things started, but that’s a strategy. More likely, they learned to scrape the last bits off found carcasses with stones found with a sharp-ish edge, then refined that skill when they began taking out their own game.