"Junk DNA" Defines Differences Between Humans and Chimps

[Jim__]

From Alaska Native News (originated in Georgia Institute of Technology):

GEORGIA — For years, scientists believed the vast phenotypic differences between humans and chimpanzees would be easily explained – the two species must have significantly different genetic makeups. However, when their genomes were later sequenced, researchers were surprised to learn that the DNA sequences of human and chimpanzee genes are nearly identical. What then is responsible for the many morphological and behavioral differences between the two species? Researchers at the Georgia Institute of Technology have now determined that the insertion and deletion of large pieces of DNA near genes are highly variable between humans and chimpanzees and may account for major differences between the two species.

The research team lead by Georgia Tech Professor of Biology John McDonald has verified that while the DNA sequence of genes between humans and chimpanzees is nearly identical, there are large genomic “gaps” in areas adjacent to genes that can affect the extent to which genes are “turned on” and “turned off.” The research shows that these genomic “gaps” between the two species are predominantly due to the insertion or deletion (INDEL) of viral-like sequences called retrotransposons that are known to comprise about half of the genomes of both species. The findings are reported in the most recent issue of the online, open-access journal Mobile DNA.

“These genetic gaps have primarily been caused by the activity of retroviral-like transposable element sequences,” said McDonald. “Transposable elements were once considered ‘junk DNA’ with little or no function. Now it appears that they may be one of the major reasons why we are so different from chimpanzees.”

...

“Our findings are generally consistent with the notion that the morphological and behavioral differences between humans and chimpanzees are predominately due to differences in the regulation of genes rather than to differences in the sequence of the genes themselves,” said McDonald.

a little bit more ...

[RaleighNCDUer]

1. IOW, junk DNA is NOT junk DNA.

I've always had problems with scientific myopia - if they can't explain why something exists they simply say it is unimportant - white noise.

Like they used to say 'we only use 10% of our brain' because they couldn't figure out the use of the other 90%, until brain scans were developed that showed that 90% being used.

[KT2000]

2. +1 n/t

[valerief]

3. Not in teabaggers, I'm afraid. nt

[laconicsax]

4. This "myopia" you describe wasn't scientific.

The 10% myth was never grounded in science, but in popularization and reporting.

The term "junk DNA" also came of popularization of genomic study since the "junk DNA" was non-coding. It wasn't that it was considered junk, but was seen as non-coding (still true) and probably didn't contribute to the overall genome as a result (now known to be false).

It would have been quite a leap to assume that a non-functional bit of DNA is likely to be a major factor in tue delineation of species.

[hunter]

6. The popularization of DNA as "blueprints" is where it went wrong.

Blueprints are static until revised by an intelligent designer.

Evolution is not intelligent design. DNA is a messy kit of tools, instruction snippets, odd spare parts, things of indeterminate use, all acted upon within a chunky soup of self-assembling machines.

The particular soup of self assembling machines the DNA ends up within matters too. Many patterns of inheritance are non-Mendelian.

Overall and most importantly, there's no fixed plan to living cells whatsoever; all these mechanisms are churning away without any intrinsic purpose until they don't. Some of these patterns are so resilient they've been conserved for millions or billions of years. Others patterns are much less stable and transitory as individuals die, and the fuzzy groupings of individuals we call species become extinct.

[FiveGoodMen]

8. Thank you. I've always hated it when people used that term.

A blueprint describes certain desired aspects of the finished product and leaves it to intelligent builders to make it happen.

DNA is more like an algorithm -- a long list of 'do this, then that, followed by...' -- except that, as you point out, the whole thing runs on chance.

[bananas]

5. A lot of junk DNA is transmitted through genetic engineering.

They usually don't splice out just the gene they want, they splice out a section containing it.
Then they insert that into another cell.

[FiveGoodMen]

9. Sort of a frightening thought

We may accidentally change a whole lot more stuff than we intended to.

[Nihil]

10. "Law of unintended consequences" anyone? (n/t)

:shrug:

[Javaman]

7. One persons trash is another persons treasure. ;) nt