An ERV is an endogenous retrovirus, meaning "virus of the past inside the genes." More specifically, it is a "fingerprint" left on a cell's genome after a virus invades the nucleus of a cell and scars the DNA. If the host of the ERV is a sex cell (e.g. sperm or egg) that is used in the host organism's fertilization and reproduction, then every cell in the organism's offspring will have the same ERV in every cell of the body, and the ERV will be passed down consistently from generation to generation.
Two organisms who share the same ERV in identical gene locations must also share the same ancestry. They must be, for example, father and son, brother and sister, uncle and nephew, grandfather and grandson, cousins, second cousins, third cousins, or etc.
Now look at the following diagram published by genetic scientists.
Source: Lebedev et al. via Douglas Theobald.
Each arrow represents an ERV insertion in identical gene locations of various primates. There are three ERVs shared exclusively among humans. There are two ERVs shared exclusively among humans, chimps, and gorillas. There are two ERVs among humans, chimps, gorillas, and orangutans. Three among all said primates and gibbons. Two ERVs among all primates originating in the continents among Asia. And lastly, two ERVs are shared exclusively among all primates of the world.
The ERVs weave a family tree connecting humans and apes that is identical to the family tree long-declared by evolutionary scientists.
What do young-earth creationists have to say about this?
Young-earth creationists say:
quote:...it is an unprovable theological assertion that God would not place the same nonfunctional sequences at the same locus in separate species. He may have a purpose for doing so that is beyond our present understanding [...], not all ERVs are nonfunctional. Some are transcriptionally active, and studies have revealed ERV protein expression in humans. We simply do not know all that ERVs (or other transposons) may be doing in an organism or what roles they may have played in the past.
ERVs probably do not serve any function useful to an intelligent designer, but it doesn't matter if they do. It wouldn't explain why ERVs are shared in a pattern that matches evolutionary predictions exactly. More importantly, ERVs, by definition, are the marks left by viruses. If instead God put the marks in the genes, then it is strange that he would make them resemble ERVs so closely.
Young-earth creationists say:
quote:There are [too] many times that a retrovirus should be found in common species and it is not. For example, the RAV-O is found in Red Junglefowl and they expected to find it in Green Junglefowl and they did not find it there. study cited]
A few studies of shared ERVs among organisms (like the Junglefowl study) are rare examples of "horizontal transfer" of gene lines. It happens when a piece of DNA latches on to a virus, the virus travels to another organism, and the foreign DNA incorporates itself into the new genes. So why does this phenomenon not destroy my argument? Because horizontal transfers do not explain identical locations of gene lines. When an ERV horizontally transfers from one genome to another, it does not usually land in the same location as before. But the ERVs described in diagram A are in "identical chromosomal locations" (as cited by Douglas Theobald).
Young-earth creationists say:
quote:...some ERVs (and other transposons) also exhibit an insertion bias. Perhaps this is another remnant of a more finely tuned system. Sverdlov writes: "...There were identified ‘hot spots’ containing integration sites used up to 280 times more frequently than predicted mathematically..."
This argument has slight relevance only if we assume horizontal transfer (described above), because insertion biases would explain only identical locations, not identical ERV sequences. But the amount of insertion bias described in the study by Sverdlov isn't nearly enough to accomodate the idea of special creation. If we assume special creation and the insertion bias is as cited in the study, then we would still not expect each arrow in diagram A to represent "identical chromosomal locations." And even if the insertion biases were 100% predictable, we would not see a family-tree structure in diagram A. We would instead see lines connecting organisms merely by geography.
CONCLUSION: Your mind may deny it, but the DNA of your entire body contains a smoking gun. Monkeys are closer cousins than you may realize or have the courage to admit.
There are more examples of recent activity in ERVs with phylogenetic implications for example polymorphic HERVs in humans
quote:Turner G, Barbulescu M, Su M, Jensen-Seaman MI, Kidd KK, Lenz J. Insertional polymorphisms of full-length endogenous retroviruses in humans.Curr Biol. 2001 Oct 2;11(19):1531-5.
An interesting HERV-K (one of the more active groups i.e. the Class II HERVs) that groups chimps and gorillas more closely than chimp to human.
quote:Barbulescu M, Turner G, Su M, Kim R, Jensen-Seaman MI, Deinard AS, Kidd KK, Lenz J. A HERV-K provirus in chimpanzees, bonobos and gorillas, but not humans. Curr Biol. 2001 May 15;11(10):779-83.
And human unique HERVs (again HERV-K)
quote:Barbulescu M, Turner G, Seaman MI, Deinard AS, Kidd KK, Lenz J. Many human endogenous retrovirus K (HERV-K) proviruses are unique to humans.Curr Biol. 1999 Aug 26;9(16):861-8.
Keep your eyes peeled in Virology over the next few months...a certain EvC poster has a paper in press on the evolution of all ERV classes in anthropoid primates :) Wait a bit longer and the comparative expression in different non-human primate tissues will be published as well.....
A paper on the expression of HERVs in different human tissues just came out in January.
quote:Seifarth W, Frank O, Zeilfelder U, Spiess B, Greenwood AD, Hehlmann R, Leib-Mosch C. Comprehensive analysis of human endogenous retrovirus transcriptional activity in human tissues with a retrovirus-specific microarray.J Virol. 2005 Jan;79(1):341-52.
For functional uses of ERVs, I have often brought up syncytin..of great interest to me, an example of convergent evolution for Syncyctin has been found in mouse where an unrelated element i.e. not a HERV-W or HERV-FRD related element is responsible for placenta formation in mice, just like in humans
quote:Dupressoir A, Marceau G, Vernochet C, Benit L, Kanellopoulos C, Sapin V, Heidmann T. Syncytin-A and syncytin-B, two fusogenic placenta-specific murine envelope genes of retroviral origin conserved in Muridae. Proc Natl Acad Sci U S A. 2005 Jan 18;102(3):725-30. Epub 2005 Jan 11.
Finally, a very important paper just came out in Nature demonstrating one way the genome controls HERVs so that they don't retrotranspose out of control and destroy the genome.
quote:Esnault C, Heidmann O, Delebecque F, Dewannieux M, Ribet D, Hance AJ, Heidmann T, Schwartz O. APOBEC3G cytidine deaminase inhibits retrotransposition of endogenous retroviruses. Nature. 2005 Jan 27;433(7024):430-3.
Junk DNA seems to be pretty busy these days...with lots of nice data supporting evolution...tough luck for Charlton Heston and the rest of the creationists :)
Again, can someone in this thread please explain how apes and humans can exchange genes with each other whe there is a natural sperm barrier keeping them from interbreeding?
Given the level of your posts around the site so far I think we need to ask: how old are you?
The reason is that you appear to be completely ignorant in the area of biology - so the question is it because you simply haven't received the education yet or is there some other reason?
If it is simple lack of education there are people here who are knowledgable enough to point you in the right direction to at least be able to ask sensible questions. If it is some other reason - well I don't think you'll last long.
In case you are wondering, the reason your quoted question isn't sensible is because nobody except for misguided (or misguiding) creationists think that the Theory of Evolution requires that humans and apes can exchange genes.
P.S. Since I asked the question I'll answer for myself - I just turned 47.
Edit: I see Yaro has begun engaging you in the Evolution for Christians and Dummies Thread, so you don't need to reply here.
This message has been edited by MangyTiger, 12-07-2005 02:36 PM
And Elvis lives! Sorry but posting a picture of "godzilla" and Charelton Heston who dressed up as an ape here is not smoking gun evidence that we descended from apes. But this is what scientists do to dupe the people who can be easily fooled. And how many mutations had to have occurred to in the same family of offspring to produce all the changes that led to a human being? And how do evolutionists know how fast or slow these mutations occurred? Just a guess?
This message has been edited by Carico, 12-09-2005 09:23 AM