June 24, 2005


Did humans evolve in fits and starts? (Gaia Vince, 6/17/05, NewScientist.com)

Humans may have evolved during a few rapid bursts of genetic change, according to a new study of the human genome, which challenges the popular theory that evolution is a gradual process.

Researchers studying human chromosome 2 have discovered that the bulk of its DNA changes occurred in a relatively short period of time and, since then, only minor alterations have occurred.

This backs a theory called “punctuated equilibrium” which suggests that evolution actually occurred as a series of jumps with long static periods between them.

Evolutionary stages are marked by changes to the DNA sequences on chromosomes. One of the ways in which chromosomes are altered is through the duplications of sections of the chromosomes. These DNA fragments may be duplicated and inserted back into the chromosome, resulting in two copies of the section.

Evan Eichler, associate professor of genomic sciences at the University of Washington in Seattle, US, and colleagues looked at duplicated DNA sequences on a specific section of chromosome 2, to compare them with ape genomes and Old World monkey genomes. They expected to find that duplications had occurred gradually over the last few million years.

Instead, they found that the big duplications had occurred in a short period of time, relatively speaking, after which only smaller rearrangements occurred.

You can't expect them to just keep tinkering.

Posted by Orrin Judd at June 24, 2005 12:00 AM

Rapid evolution, eh? Oxy, meet Moron.

Posted by: ghostcat at June 24, 2005 1:56 AM

So Stephen Jay Gould may have been right after absolutely everybody in the "serious" scientific community told us he was nuts?

Posted by: Matt Murphy at June 24, 2005 3:05 AM

Heh. This supports my theory of punctuated interventionism: God instigates a series of changes at a fundamental (very early embryonic) level, then lets things play out before intervening again.

Posted by: Ptah at June 24, 2005 5:13 AM

This represents the emergent molecular biological assault on the Neo-Darwinian Theory of Evolution and a shift in the entire paradigm. Note what this article implies:
1) That evolution is not a matter of continuous small accumulated changes (like this conventional tree representation), but rather of discontinuous jumps (like this line graph). Hence, the conventional reconstructions of the origins of species are now questionable.
2) That proteins, once produced, are extremely stable, and not subject to much mutation. Mutation is not a matter of "point" random mutations, but rather the splicing of bits of genetic code into other sequences of genetic code. This should have been obvious from all the fruit fly experiments which failed to produce a new species but instead produced only freaks.
3) This "splicing" cannot occur in existing genes, which are necessary and highly stable, and hence it must occur in the "junk" DNA.
4) But this "junk" DNA is not subject to natural selection, since it is not expressed until it is converted by the "splicing" mutation. This eliminates any argument appealing to recursion (hello Jeff and Mr. Dawkins).
Thus, this result undermines the entire Neo-Darwinian Paradigm, i.e., continuous incremental change, random point mutation, and natural selection. The required level of evidence has changed from morphological classification to recovering the DNA of organisms that lived hundreds of millions of years ago.

Posted by: jd watson at June 24, 2005 5:49 AM

"Humans may have evolved during a few rapid bursts of genetic change, according to a new study of the human genome, which challenges the popular theory that evolution is a gradual process."

If you read the actual article, it turns out that the "rapid burst" they are talking about occurred over a period of approx. 10 million years. So the story is not that this was not a gradual process, but that the rate of change is not constant - which in itself is not remarkable, and entirely compatible with the current theory of evolution.

Posted by: creeper at June 30, 2005 1:20 AM

Ah, when you need it to be geological time should be brief?

Posted by: oj at June 30, 2005 8:25 AM

When you need it to, geological time should be precluded from being able to contain both relatively short and relatively long times?

Would you call 10 million years historical time?

Posted by: creeper at June 30, 2005 3:45 PM

No, history is the written period.

Posted by: oj at June 30, 2005 4:44 PM

Thank you.

Posted by: creeper at June 30, 2005 7:14 PM