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Underground > Laboratory >

There was no 'Missing Link'

09:47 / 11.07.02

According to the BBC's news site: an astonishing skull found in Africa undermines the theory that there was a single 'missing link' between ancient hominids and modern humans. The skull is thought to be around seven million years old and evidences a radical mixture of ape-like and human-like features that suggests that the change between then and now might have been a gradual development between the species over the years...

10:19 / 11.07.02

this seems to be far more realistic than a 'jump', with the missing link as the bridge, yes? if of course, the find is for real. i don't know why, but part of me thinks it's a hoax.

Fengs for the Memory

10:33 / 11.07.02

Sfd - A hoax,Why? Is it the Darwinist camp making a another claim to bolster an under attack theory. Why is it so important?

10:52 / 11.07.02

Because otherwise God wins. And it means that Jehovah's Witnesses have something else to be smug about.

I must admit the missing link idea has always confused me. Are we talking about an actual mid-species (which some people seem to think should still be in existence today) or are we talking about a link more in terms of a gradual evolutionary process and finding evidence of the developments?

I always thought the latter was the case anyway. Is it just that there isn't much in the way of artifacts? Maybe they had crumbly bones.

11:24 / 11.07.02

Wasn't there a BBC documentary about this idea a little while ago? IIRC, it was saying that Man has no special evolutionary place and there isn't a single lineage back to an ape-like ancestor through a missing link. I'll try to dig it up.

The Natural Way

12:43 / 11.07.02

Yep, I saw that too.

13:40 / 11.07.02

It was a BBC Horizon and you can find out about it here. From the site,

[There is] proof that there were two different bipedal human ancestors living at the same time, more than three million years ago. And it's the first sign of the adaptive radiation that the theory of evolution says should have followed the planet of the apes.

As I understand it, "The Planet of the apes" is a period of history when ape species proliferated. Adaptive radiation describes the shape of an evolutionary tree. From the transcript,

NARRATOR: This is how evolutionary family trees develop. Two species split to form separate branches. These branches can split again and then again and so a whole host of related species will develop.

ROBERT FOLEY: So what is happening is that each time you're getting proliferation of branches, you're getting divergence taking place and with that divergence comes what we think of as an adaptive radiation.

NARRATOR: Adaptive radiation is one of the fundamental truths of evolution. There are signs of it in virtually every type of animal that has ever lived, like the cat family.

13:56 / 11.07.02

I know what you mean about the hoax element. One assumes that there are ways in which you can check this stuff, but it doesn't really look like a skull that was just found. It very much looks reassembled. That's not to say it's not real of course, just that from my position of relative inexpertise, I don't know how they'd prove it...

14:07 / 11.07.02

The idea of a missing link, a half-man half-ape, is quite dated. These days people only really trot it out as a strawman. Fossil and genetic evidence has established that the decent of homo sapiens from earlier hominids is bushy, not linear. In other words, we’ve found not one “missing link”, but scores.

I guess the search for our most recent common ancestor with the bonobo/pongo species is roughly analogous to the old search for a missing link, except that “missing” seems to imply that its absence is a flaw, but evolutionary theory requires that this common ancestor be extinct for speciation to have occurred.

The cool thing about this skull find is that it’s so old, and yet so human. It suggests that our species’ roots date back longer than we had previously believed.

14:52 / 11.07.02

It really doesn't sound like a hoax - the French discoverer circulated plaster casts of the skull to major names in archaeology before publishing his findings. Johansen, the fellow who discovered Lucy, he looked it over, and expressed no doubt as to its authenticity (he was interviewed on NPR yesterday).
There's more in Nature.

from one of the links along the side:

This short new face of the past contains an odd mixture of primitive and advanced features. Toumaï's braincase is very ape-like, but his or her canines are small, more like those of a human. Toumaï has prominent brow ridges of the kind seen only in our own genus, Homo.

The exciting thing is that this rather human-faced hominid predates our more ape-like ancient ancestors by at least a couple million years. Which means they might not have been our ancestors at all. (Unless, of course, DEVO was right....)

The "missing link" thing is a bit of a different issue, actually - that label has always been more of a way of framing the idea of a half-man, half-ape creature, which many of the hominids fit in different ways. The debate over finding a "missing link" is mostly just quibbling over fossil details - how "human-like" is human enough to definitively prove this creature or that isn't just an extinct monkey....

16:58 / 11.07.02

Uh, what he said while I was looking at monkey pictures.

21:50 / 11.07.02

i don't really know what the hoax thing is about. just a wierd feeling - sorry, not very scientific but for a mad moment i was convinced the skull was made of plastic! i agree that it's an exciting find.

14:09 / 12.07.02

This is off-topic I know, but can anyone explain to me how a skull can remain intact for over 7 million years while antlers & horns rot after only a fraction of that time?

14:22 / 12.07.02

In short, Margin Walker, it can't. Fossils are NOT bones, they are sedimentary deposits that have seeped into the creche of where a bone has fallen, in effect, taking the place of the bone itself. Over time and through geologic pressure, these sediments become lithified (ha, ha). Thus, fossils. That's why you can't find, in the words of the 'creation scientists' a half-a-fossil, or one that's not thoroughly lithified- by breaking the creche to early, it merely dissolves. Why don't we have fossils of antler and horn? They, being proteins grown from an organic follicle (sp?) decompose too quickly for that aeons long sedimentation replacement project.

The very concept of a missing link is pretty silly- you can only trace back the family tree of species to a common ancestor.

14:32 / 12.07.02

Some of what we call horns and antlers are made of keratin, and some are made of calcium. The calcium ones are essentially bone and can fossilize like other bones.

Also, some fossils have preserved imprints of keratin horns and antlers, as well as scales, feathers, etc. It’s a different fossilization process than the one that substitutes minerals in bone.

19:24 / 03.09.02

On the other hand....

ScienceDaily:
According to the journal Nature, the fossil bones predate the oldest previously discovered human ancestor by more than a million years. The teeth and bone fragments apparently are from a hominid that emerged sometime after the split. The hominid is part of a newly named subspecies of early man called Ardipithecus. The discoverers state that Ardipithecus ramidus kadabba is a "Missing Link" -- the yet-undiscovered creature that lived at the cusp of the evolutionary division between man and chimp -- but researcher Haile-Selassie said the hominid certainly is very close to the branching point.

The world's media trumpeted the news of this anthropological find. Time magazine dedicated a cover story to the discovery; a staff writer, referred to the special toe bone stating "This (AME-VP-1/71) proves the creature walked on two legs. . . . How apes became human. Ardipithecus ramidus kadabba. What a new discovery tells scientists about how our oldest ancestors stood on two legs and made an evolutionary leap."

but the American Physiological Society concludes:
The research results suggest that the famous AME-VP-1/71 bone had scant similarity to human bone, was dissimilar to baboon bone and was most dissimilar to chimpanzee bone. The baboon bone was similar to the chimpanzee and dissimilar to human bone. The chimpanzee was most dissimilar to humans. Human bone had no similarity to monkey or ape bone. Accordingly, the objective ancestry analyses for fossil bones assert that the conclusions of Haile-Salassie and Robinson were farfetched speculations.

There's a lot of wiggle room way back in the ancient past....

21:19 / 03.09.02

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I'd like to know what's the basis for the last statement.
As they can't possibly have a gene reading - the thing's a fossil, no more organic stuff in it, sorry - using only the cranium morphology of a single individual to say that the poor critter was "very close to the branching point" has more to do with media coverage and fund-rising than scientific research.
What if the thing was just a deformed individual, suffering from some congenital problem?

As a a palaeontologist, I'd like to get a full skeleton.
Or two.
Then I'd place the critter in the human genealogy tree, like, realy cautiously, and still wait for peer reviews.

Problem is, institutions are cutting funds for mere palaeontological research, which is perceived as "not economically rewarding".
So if you find a fossil bone, it better be the Missing Link (an outdated concept, as others have pointed out) or the Lock Ness Monster, or something equally media-friendly.
Which leads certain researchers to be less than cautious when presenting their finds.

And yet, it's still another little piece of the puzzle.