I remember in archeology class that we have a fairly good idea how our species developed up to about 5 million+ years ago, but what about prior to that? Are there any good links describing our possible lineage in the more distant past, what species might be our direct ancestors?
Claiming that we have a fairly good idea how our species developed up to 5 million years ago is being very generous to say the least.
Realistically we have a fair idea how our species developed form about 80, 000 years. That was the point when we became indisputably Homo sapiens. And I say fair because it’s by no means complete or uncontroversial even that recently.
Anything prior to that is mostly speculation. We don’t even know precisely when or where H. sapiens evolved. Most palaeontologists believe that our species evolved in Central/Southern Africa around 170, 000 years ago and migrated out through Asia. However another school believes that the species resulted from a mixing of H. rudolfensis/Archaic H. sapiens with various local variants such as H. erectus and H. neanderthalensis and that this species evolved in Central or even SE Asia as recently as 80, 00 years ago and swept back into Africa, displacing it’s ancestors. Still a third, though dwindling, school believes that our species evolved multiple times in SE Asia, Europe/the near east and Africa.
So as you can see we can’t even go back 100, 00 years with any fairly good ideas. We actually have so few specimens and such small fragments of those specimens that we can’t even decide for sure what species were our ancestors. Most sources will say it was H. erectus but there are those who say that erectus was only one of many, and those who postulate heidelbergensis as a separate species that was our ancestor. Still others have postulated still undiscovered Asian species as the ancestors, a claim that gained some additional credibility after the recent discovery of a species of hominid surviving in SE Asia at least as recently as 20, 000 years ago, and possibly much later. That means this species and Neanderthalensis at least were in contact with both sapiens and erectus for much of their history.
And the further back we go he murkier it gets. We have no real idea at all what the ancestor of erectus was. It may have been H. habilis, but we can’t even agree on whether habilis was in the genus Homo or was an abberant Australopithecine. And it may not have been habilis at all, we may well have evolved directly form a much more primitive Australopithecine.
By the time we get to the Australopithecines it’s pure SWAG time. Australopithecines have some of the characteristics that we might expect from out ancestors but none of them discovered so far (and we aren’t in any way sure how many that may be) are particularly good candidates for ancestors of the Homo genus. Everyone who finds specimens in that age range seems to claim they have found the definitive ancestor, which means at last count that we have at leats 7 distinct ancestors. And the debates are noted in the scientific community for the inflexibility of the disputants, and the vitriolic nature of the debate.
Prior to that we have simply no idea. And this isn’t going back 5 million years. The earliest Australopithecines appear about 4 million years ago. Prior to that we have nothing. Genetic evidence suggests the hominids split form the chimps about 5.5 million years ago. That’s all we have to go on, and even that is open to a lot of dispute because of the assumptions it requires. We have at least 5 different ape species from the period 10-20 million years ago that have been put forward as the common ancestor of chimps and hominids, and the situation is much like the first hominid ancestor: everyone has found one. Unfortunately not even one is very convincing. Those with the right dentition have completely the wrong types of skeletal articulation, or are clearly arboreal. Those that have the right habitat or skeleton have the wrong teeth entirely. And even if one of these contenders was in the line, it still leaves a gap of at 5-15 million years with nothing at all to full it.
OMO 1 and OMO 2 are modern humans that were recently dated to approximately 200,000 years old. this supports the “out of africa” theory.
the transition to bipedal movement occured approximately 4.5 to 5 million years ago.
I’ve frequently thought that one of the most interesting things I’d like to see is magically accurate animation showing the first single cell life form evolving into the human form.
Do you have a few billion years to kill? 
I’d take it back a stage - always a good practice in scientific enquiry - and be absolutely fascinated to watch a reconstruction of the genesis of the first single cell life form.
It’s the Missing Link. If you knew what it was it wouldn’t be missing would it?
not quite what you’re looking for but it’ll help you pass the time waiting
REVERSE EVOLUTION
Heh. I suppose it might be advantageous to have it going a bit faster that real-time…
Carl Sagan did that on an episode of Cosmos.
Sweet! I wonder if they’d have to put a disclaimer on that commercial if they aired it in Kansas…
I’m fan of Sagan, but I doubt he was magically accurate…
Maybe you couldn’t, though. Isn’t that one of the theoretical features of chaotic dynamical systems, that you can’t predict their outcomes faster than they actually happen?
No telling how accurate he was, but it was plausible. He presented a case for each organism and how it ‘branched off’. Then he ‘sped up’ the animation to condense it all into like 45 seconds.
Accurate? Maybe, maybe not. ‘Magically accurate’? Probably not. (Hey, the guy was an astronomer; not a biologist or archaeologist.) But plausible, and it got the point across.
i just moved (prior to the storms) from new orleans to tulsa. so, i’m just a bit too close to kansas to think that’s funny.
been doing alot of reading on id.
here’s a good bit: ID?
Events don’t have to occur in real time.
What Blake said. In spades, doubled and redoubled.
My wife took her degree, not quite a decade ago, in human evolution. So I’ve been exposed to a lot of the material on this.
The basic summary is that we have a fair sampling of human skeletal remains, with artifacts through much of the period, from not quite 4.4 million years ago to the present. But an enormous superstructure of theorizing has been constructed from these remains, and in point of fact where one draws the line for Homo sapiens, for genus Homo, etc., is more the educated opinion of the individual paleoanthropologist than anything cast in concrete by the evidence. For example, some “lumpers” put the evidence grouped as “Heidelberg Man” (the type specimen, finds at Swanscombe, in Andalucia, and elsewhere) as a subspecies of Homo sapiens; splitters consider it a separate species. Whether Neanderthal Man was a separate species or not is hotly disputed. Lumpers put all of genus Homo in three species: H. sapiens, H. erectus, and H. habilis; splitters recognize up to ten species (H. neandertalensis, H. heidelbergensis, H. antecessor, H. rudolfensis, etc.). There is not even any consensus on how many genera preceded Homo.
In particular, the informed speculation about which forms gave rise to which other forms, and why, to trace what was our direct evolutionary ancestry and what were extinct side branches, looks more like a mystery novel missing the last chapter that gives the solution than it does a clearcut analysis like the descent of the Equidae (horses and ancestors).
In summary, we have evidence that points to the actual line of human descent. But not enough to confirm any one lineage, and well-reasoned speculation is rife among the paleoanthropological community.
As for forms tying Ardipithecus ramidus (if it was in fact our oldest living hominid ancestor) back into the main primate line, that is so scanty that quite literally, you’re welcome to read the evidence and come up with your own hypothesis. There’s plenty enough to speculate with, but nowhere near enough to show anything definite.
It depends on your definition of “fairly good”. As **Blake **said, there are important gaps in our knowledge as to which fossil species were actually our direct ancestors. If you can live with that, then maybe you’re right, although I wouldn’t go too far past 3M years, since the number and quality of fossils isn’t that great further back in time.
By the time you get to 5M years, it gets really murky. Really, really, REALLY murky. This cite is pretty good, but I’m not sure when the last time it was updated-- it might be a few years out of date.
It’s not completely correct to say that prior to Australopithecus, we have nothing; there are a number of finds in the range of 4-6m y.a. which are potential ancestors, and some thought to be very close to the chimpanzee-human split, but the exact line of descent isn’t clear.
One problem is that our hominin forbears are believed to have taken to a ground-dwelling, erect walking lifestyle around 5 m y.a. and before that to have mainly lived in forests. Ardepithicus, of which the famed ‘Lucy’ is one, still had somewhat elongated fingers suggesting a fair amount of time spent in trees. If before that, human ancestors were spending even more time in forests, we’re not likely to find many fossils of them. Forests tend to be moist, humid places that are among the worst environments for the preservation of fossils.
Did anyone say that?
No. “Lucy” is a member of Australopithicus afarensis.