Freethought & Rationalism Archive

scigirl · 03-11-2002, 06:04 PM

Ok, hopefully the randman has scampered off and the E/C can return back to normal. I.E. actually talk about science!

The Feb 15th 2002 episode of Science had a big article on Human evolution. Some excerpts:

Quote:

As paleoanthropologists begin to peer back beyond 4 million years ago, they are also filling in the details of the characters that followed, revealing stunning new fossils of hominids that lived 3 million to 4 million years ago. . . The first surprise is that more than one type of hominid may have been living between 6 million and 5 million years ago and that these very early hominids show diversity in their teeth and anatomy. That suggests a period of hominid evolution even earlier than most researchers have believed. . . Another surprise is that the oldest hominids were walking upright yet living in woodlands, dealing a lethal blow to the hypothesis that bipedalism emerged when hominids first stood up and stretched their legs on the savanna. "These fossils are causing a paradigm shift," says paleontologist Martin Pickford of the College De France in Paris. "A lot of old ideas will be put into the wastebasket."

Into the trash, in fact, may go the very definition of what it menas to be a hominid. . . "Preconceptions of a large-toothed, fully bipedal, naked ape standing in the Serengeti 6 million years a go are X-files paleontology," says White. "What we're learning is we hae to approach this fossil record stripped of our preconceptions of what it is to be a hominid."

I quoted this passage to illustrate to the likes of Randman that scientists do periodically make "paradigm shifts" when the evidence requires them to. In fact, it happens quite frequently that a scientist will have to re-think his or her theories.

The article then goes on to explain in detail several hominid fossils. The conclusions:

Quote:

Single line or bushy tree?
Given all this diversity, it is "quite obvious that australopithecines lived all over Africa," says Walker. But he thinks that all these ew fossils may represent diversity within single species that unfolded into each other in a linear procession. Although the number of new species has doubled in the past decade, Walker cautions that they are spread over millions of years. "I think there's no strong evidence that there's anything more than one evolving hominid from 6 million years to 2.5 million years," he says. White and his collaborators share this linear view, even connecting the dots between species, saying that Ardipithecus ramidus gave rise to A. anamensis, then A. afarensis on down to Homo, with some diversity at about the time Homo emerges.

But the field is deeply divided over this issue. When researchers such as Leaky, Wood, Tattersall, Pickford, and Senut look at the new fossils, instead of a parade of homonids, they see a bushy tree with different hominids hanging off different branches at the same time, making it difficult to draw a lear line of descent. "We're seeing a radiation," says Wood. "If you look at other mammals, what's so unusual about that?" Indeed, says Tattersall, "the big lesson from each of these new finds is that diversity [in anatomy and species] was present from the start."

Defining what is special about the human lineage gets harder as the fossils gt older and older. "I just told my students, 'I'm sorry, but I don't know how to distinguish the earliest hominid from the earliest chimp ancestor anymore,' " says Wood. Others say there are a few signs of hominid status - at least for now. "Right now the two key traits are bepedality and anine reductions and shape modification," says Arizona State's Kimbel. "As we go back further in time, it will be fascinating to see if one of these fades away, leaving the other as the seminal hominid modification."

Even the current favorite trait, bipedalism, may not be enough to qualify as a hominid if other ancient apes were bipedal too. In the late Miocene, "there was a whole proliferation of these apes, sometimes running around on two legs, sometimes not. Why do they have to be ancestral to us?" wonders paleoanthropoligiest Peter Andrews of the Natural History Museum in London.

For casual visitors to that museum of human evolution, all the early figures may look similar - and very much like other apes. But in one ape-man's smile or stance, researchers hope to find the hint of things to come.

One thing I took away from this article was the difficulties of classifying fossils as ape or human. Which, if you do believe in evolution, should not be surprising. If creationism is correct, why is it so difficult to classify these fossils, hmmm?

scigirl

Jesus Tap-Dancin' Christ · 03-11-2002, 08:59 PM

Thanks scigirl for the ver interesting read. Finally, something that has not the taint of the fundie by the time I get to it.

Bane · 03-11-2002, 09:16 PM

With randman's ego he probably thinks the scientists just set that up for him to make him look like a moron.

Jesus Tap-Dancin' Christ · 03-11-2002, 09:26 PM

I MANAGED TO POST BEFORE HE WAS BROUGHT INTO IT! (other than the title and the blurb about him scampering off)! I GOT IN BEFORE THE NEGATIVITY STARTED!!

Oh to scigirl:
<img src="graemlins/notworthy.gif" border="0" alt="[Not Worthy]" /> You are my idol.

Oolon Colluphid · 03-12-2002, 03:21 AM

Wonderful, Scigirl! Many thanks!

I also note that the article was written by A Gibbons. Another example of <a href="http://www.science-frontiers.com/sf108/sf108p14.htm" target="_blank">nominative determinism</a>, methinks. (See also <a href="http://www.accesscable.net/~chapmand/aptonyms/en/weather.html" target="_blank">here</a> for many more.)

Did you copy that out yourself, or do you have full online access? I'd very much like to see the whole thing... is it just a journalisty round-up of the current situation, or does it have enough detail to justify $5 to view it, beyond what you've already told us?

Cheers, Oolon

[ March 12, 2002: Message edited by: Oolon Colluphid ]</p>

Oolon Colluphid · 03-13-2002, 03:10 AM

Not really worth starting a new thread for, but here's a couple of items from the current Nature that may be of interest...

(Creationists please note: Science and Nature are weekly publications, and there's nearly always something of major evolutionary significance in them. And every biology-related article takes evolution as a fact which underpins the reported findings. And these are not even journals specifically devoted to evolution!)

There's so many feathers now turning up in fossils that I’ve lost track if this is new or not, but here it is anyway:

Quote:

Nature 416, 36 – 37, 7 March 2002

Palaeontology: 'Modern' feathers on a non-avian dinosaur

Mark Norell, Qiang Ji, Keqin Gao, Chongxi Yuan, Yibin Zhao & Lixia Wang

Discoveries of integumentary coverings on non-avian theropod dinosaurs are becoming commonplace. But the only definitive evidence so far that any of these animals had feathers as we know them today has come from the oviraptorosaur Caudipteryx and the enigmatic coleurosaur Protarchaeopteryx, both of which are considered by some to be secondarily flightless birds. Here we describe the occurrence of pinnate feathers, which clearly feature a rachis and barbs, on a small, non-avian dromaeosaur from northern China. This finding indicates that feathers of modern aspect evolved in dinosaurs before the emergence of birds and flight.

And there’s this long and fascinating-looking article by Templeton:

Quote:

Nature 416, 45 – 51, 7 March 2002

Out of Africa again and again

Alan Templeton

The publication of a haplotype tree of human mitochondrial DNA variation in 1987 provoked a controversy about the details of recent human evolution that continues to this day. Now many haplotype trees are available, and new analytical techniques exist for testing hypotheses about recent evolutionary history using haplotype trees. Here I present formal statistical analysis of human haplotype trees for mitochondrial DNA, Y-chromosomal DNA, two X-linked regions and six autosomal regions. A coherent picture of recent human evolution emerges with two major themes. First is the dominant role that Africa has played in shaping the modern human gene pool through at least two—not one—major expansions after the original range extension of Homo erectus out of Africa. Second is the ubiquity of genetic interchange between human populations, both in terms of recurrent gene flow constrained by geographical distance and of major population expansion events resulting in interbreeding, not replacement.

Cheers, Oolon

Oolon Colluphid · 03-13-2002, 03:17 AM

And while I'm at it, it also seems that onchocerciasis (river blindness) isn't actually caused by filarial worms, but by endosymbiotic bacteria in them. See <a href="http://www.nature.com/nsu/020304/020304-9.html" target="_blank">Bacteria Cause River Blindness</a>.

Either way, however, a rather nasty bit of creation by a loving god.

Oolon

scombrid · 03-13-2002, 05:06 AM

Quote:

Tattersall:
..."the big lesson from each of these new finds is that diversity [in anatomy and species] was present from the start."

Why do I have this sinking feeling that some cretinist will skim the article, pull this quote, and forget the rest of the article. Then they'll come here and start howling: "See, all kinds were prezent frum the start!!! Tattersall, an evilutionist, even sez it!!!"

Great article BTW. I know little about homonid phylogeny and need to learn more. However, given the changing state of the science I guess I'm not alone.

Oh, on the subject of onchocerciasis. How much would you like to wager that their are folks in Africa that have mutated so that the molecular receptor in the eye is no longer sensitive to Wolbachia? These people wouldn't be susceptible to river blindness. It wouldn't take much of a mutation to alter a molecular receptor, just change a couple of proteins and you're there. It might even render them more succeptible to other eye problems but be advantageous where the filarial parasites carry heavy burdens of Wolbachia.

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03-11-2002, 08:59 PM	#2
Jesus Tap-Dancin' Christ Veteran Member Join Date: Apr 2001 Location: Heaven Posts: 6,980	Thanks scigirl for the ver interesting read. Finally, something that has not the taint of the fundie by the time I get to it.

03-11-2002, 09:16 PM	#3
Bane Regular Member Join Date: Jan 2002 Location: Canada Posts: 180	With randman's ego he probably thinks the scientists just set that up for him to make him look like a moron.

03-11-2002, 09:26 PM	#4
Jesus Tap-Dancin' Christ Veteran Member Join Date: Apr 2001 Location: Heaven Posts: 6,980	I MANAGED TO POST BEFORE HE WAS BROUGHT INTO IT! (other than the title and the blurb about him scampering off)! I GOT IN BEFORE THE NEGATIVITY STARTED!! Oh to scigirl: <img src="graemlins/notworthy.gif" border="0" alt="[Not Worthy]" /> You are my idol.

03-12-2002, 03:21 AM	#5
Oolon Colluphid Contributor Join Date: Sep 2000 Location: Alibi: ego ipse hinc extermino Posts: 12,591	Wonderful, Scigirl! Many thanks! I also note that the article was written by A Gibbons. Another example of <a href="http://www.science-frontiers.com/sf108/sf108p14.htm" target="_blank">nominative determinism</a>, methinks. (See also <a href="http://www.accesscable.net/~chapmand/aptonyms/en/weather.html" target="_blank">here</a> for many more.) Did you copy that out yourself, or do you have full online access? I'd very much like to see the whole thing... is it just a journalisty round-up of the current situation, or does it have enough detail to justify $5 to view it, beyond what you've already told us? Cheers, Oolon [ March 12, 2002: Message edited by: Oolon Colluphid ]</p>

03-13-2002, 03:17 AM	#7
Oolon Colluphid Contributor Join Date: Sep 2000 Location: Alibi: ego ipse hinc extermino Posts: 12,591	And while I'm at it, it also seems that onchocerciasis (river blindness) isn't actually caused by filarial worms, but by endosymbiotic bacteria in them. See <a href="http://www.nature.com/nsu/020304/020304-9.html" target="_blank">Bacteria Cause River Blindness</a>. Either way, however, a rather nasty bit of creation by a loving god. Oolon

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