Evolution Question: Shared Ancestry / 'Family Tree' Evidence in the DNA

The evidence showing 'shared ancestry' between apes and humans seems to be one of the strongest arguments for evolution.

As mentioned in other threads, I kind of considered this to be the 'nail in the coffin' for 'instant' Creation of any kind. After leaving YEC recently, I was leaning toward Day-Age Creationism until I looked at the evidence for evolution. And the evidence for shared ancestry in the DNA basically shut me up.

In researching this topic, I couldn't find many sites dealing with the issue, perhaps because the DNA research is fairly new.

I was wondering if there are any scientists or others who have researched the topic, and have an opinion one way or the other.

Recently, I e-mailed Christian apologist, Dr. Norman Geisler, and his view on this issue seemed less than enlightened:

"In regards to common DNA between apes and humans… this may be evidence of common design for existence in the same biosphere, rather than evidence of a common ancestor. For example, just because the tea spoon, skillet, pot, and cauldron have similar design, does not mean that the cauldron descended from the spoon. (See Frank Turek’s and my book, I Don’t Have Enough Faith to be an Atheist.)

In regards to Christians and Theistic Evolution… theistic evolution (though, not necessarily Old Earth Creationism) is contrary to conservative Christian doctrine. First, because it fails to take Genesis literally. Second, it disregards the doctrine of original sin (Rom. 5). And third, it violates Jesus’ affirmation in a literal Adam and Eve (Matt. 19:4-6). I hope this helps you in studies."

That probably represents a typical Christian view of this issue, but it's far from a scientific argument, once you have even a basic understanding of the DNA evidence, which I got from watching Dr. Francis Collins' online video at www.asa3.org, and then from reading Coming to Peace with Science by Darrel Falk.

Here's one article from Talk Origins that addresses the issue of 'copied errors' in the DNA - showing shared ancestry:

"Plagiarized Errors and Molecular Genetics"
http://www.talkorigins.org/faqs/molgen/

And here's a Creationist argument against shared ancestry from a Christian perspective:

"Shared Errors in the DNA of Humans and Apes"
http://www.cs.unc.edu/~plaisted/ce/junk.html


I thought I'd post this topic, in hopes that others might know of other research or comment on it. I guess I'm wondering if the jury's really still out on this or not...

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Also, Taoist (Jesse) posted this in another thread. I found it very convincing, even though I don't really understand it all :)

Originally posted by taoist

Greetings once again, mpb1,

I've been following with interest your thread in Protology, not least because many of the feelings you express find an echo in my own experiences. But once one has been bitten by a fact that cannot be denied, as you have been in your understanding that light falling now on earth from stars billions of light-years from us rings the death knell for a young earth worldview, you open yourself to similar facts that speak directly to the crux of the objections against the theory of evolution.

It is not evolution of other species that disturbs us, it is the evolution of the human species. We are not overly concerned with four footed creatures on land evolving from four finned creatures of the sea. It is our own history that concerns us. And a view of that history that shows us as something less than the special creations of a concerned intelligent being is a blow to our feelings of self-worth. I've been there, so I know how hard this is to accept. The idea that we have come into being through nothing more than the impersonal and uncaring forces of nature is anathema to us. But it does seem to be supported by the evidence. And summoning up the humility we learned as a virtue in our christian upbringings, it is a bridge we can indeed find the strength to cross.

Take courage in hand, and follow the evidence in front of you. Do not let yourself be deceived by what you wish to be true.

__________

Each human is a bit changed from the parents who preceded it. Literally.

At the molecular level, the level of the DNA that shapes us, we are not merely a bit of this and a bit of that from our parents. Each of us includes about a hundred of these "random" point mutations we've spoken of, and are referenced in the Time article on your table in addition to the larger scale mutations. But let's just consider the point mutations, which actually do make up the majority of genetic change over the generations. Consider the consequences of such changes over a specific period of time, say the last 6-8 million years, call it a half-million generations.

In the course of a journey half a million generations into the past, these hundred point mutations per generation turn into 50 million differences. Now let this ancestral group split into two groups, one that stayed in the forests and one that took to the plains, no longer interbreeding, and roll the clock forward again to the present day. These two groups, now separate species, will differ by about 100 million nucleotides, 50 million per group from the common ancestor, just due to point mutations alone.

Our genome is 3 billion nucleotides long, that's 3000 million nucleotides. 100 million of them represents a difference of 1 in 30, or about 3 percent or ... and here's the important part ... about the same difference we see in the genomes of humans and chimpanzees. These figures alone lead me to the inescapable conclusion that Homo sapiens and Pan troglodytes are near cousins on the tree of life.

__________

But that is by no means the only pillar in what has become an immense fortification shoring up our belief that our species evolved from a common ancestor with the the other great apes, and most specifically the chimpanzee.

Not all of our genome is filled with genes. In the "non-coding" regions, we find smudges and smears, places where viral invaders have hijacked our genome and inserted inert pieces of their own genetic code that are nonetheless copied from generation to generation in the normal process of human reproduction. Freeloaders, just there for the ride. These are the "endogenous retroviral insertions" or ERVs, you hear about. They are like the accessories your wife or girlfriend can't leave the house without, despite all your protests that the movie's going to start in fifteen minutes.

They do not occur often, but when they do, they're there for good. We know of 14 specific ERVs that occur in equivalent chromosomes among the primates, thoughtfully charted at talkorgins here to show the nested hierarchy. Remember, these bits of the genome don't do anything but sit there and look pretty. Except that we can use them to direct us along the branches of the tree of life. There are ...

• 2 ERVs shared among all New World Monkeys, Old World Monkeys, gibbons, orangutans, gorillas, chimps and humans ... evidence for their common ancestry
• 2 more ERVs not shared by New World Monkeys — but shared by Old World Monkeys, gibbons, orangutans, gorillas, chimps and humans ... evidence for the early split-off of New World monkeys at the time of the breakup of Pangaea
• 3 more ERVs not shared by New World Monkeys or Old World monkeys — but shared by gibbons, orangutans, gorillas, chimps and humans ... evidence for the later split-off of Old World monkeys
• 2 more ERVs not shared by New World Monkeys, Old World Monkeys, or gibbons — but shared by orangutans, gorillas, chimps and humans ... evidence for the still later split off of gibbons
• 2 more ERVs not shared by New World Monkeys, Old World Monkeys, gibbons, or orangutans — but shared by gorillas, chimps and humans ... evidence for the yet later split off of orangutans
• 3 more ERVs not shared by New World Monkeys, Old World Monkeys, gibbons, orangutans, gorillas or chimps — but shared by humans ... evidence for the yet later still split off of gorillas and chimps

These inferences agree with both cladistic analysis of anatomic similarities and molecular analysis of the relative sizes of DNA differences. Three independent sources saying the same thing is powerful evidence. We know our ancestors and cousins on the tree of life, and how we are related. No, it's not proof, but any other hypothesis has to account for these facts.

_________

Then there's the interesting case of our second chromosome. It is the longest chromosome in our genome and has a rather unusual feature. The middle of a chromosome is called the centromere and the ends are called telomeres. Oddly enough, our second chromosome seems to have a degraded copy of a second centromere, and what appear to be two telomeres butting head to foot in the middle of the chromosome rather than on the ends where they belong. In other words, where we should see telomere / centromere / telomere, we instead see telomere / centromere / telomere / telomere / centromere / telomere, as if two chromosomes had been fused together.

Humans have 23 chromosome pairs where chimps, gorillas and orangutans have 24. At this point, no doubt you've anticipated what I'm about to say. Yes, two of these chromosomes, in each of these groups, seem to match up quite well with our second chromosome when placed end to end.

__________

There are many other evidences available, but I'll stop here for now. Suffice it to say that I am convinced, and as Genesis, where not actually contradicted by the evidence, does not even address these relationships, it's not reasonable to fill in additional chapters to cover these gaps we have ourselves filled through painstaking observation and long, hard work.

__________

Originally posted by mpb1

I thought I'd post this topic, in hopes that others might know of other research or comment on it. I guess I'm wondering if the jury's really still out on this or not...

That will depend which jury; of course. It's completely uncontroversial in the scientific community.

The interesting question in the scientific community concerns the degrees of relationship between humans, chimpanzees, and gorillas.

Consider a human, an orangutan, and a fish. The human and the orangutan are the most closely related in this trio. All three are vertebrates; but the human and the orangutan are primates.

What about a human, a chimpanzee and an orangutan? A hundred years ago we'd have probably said that the chimpanzee and the orangutan were the most closely related pair; but the evidence of genetics shows that the orangutan is actually the odd one out. The chimp and human are much closer to each other than either is to the orangutan.

What about chimpanzee, gorilla, and human. This one is interesting; because it's a fairly close call. Initial work in the 1960s, by Sarich and Wilson, established the close relationship of the trio, but was not able to resolve it further. In the 1980s, Sibley and Ahlquist reported experiments on DNA hybridization, which suggested that chimpanzee and humans are closer to each other than either one is to the gorilla. Subsequent work has tended to confirm this result; though it is a close call. Basically, it would mean that we have a common ancestor with chimpanzees about 5 to 6 million years ago; and then with gorillas a bit further back.

Note that there is a lot more to a species than simply how closely related they are to each other. Things have happened in the human lineage that are unprecedented in the animal kingdom; and humans are a very unusual kind of animal indeed. But any creature – even ourselves – has relatives. In our case, our most closely related living species is the chimpanzee.

Cheers – Sylas

Hi Mark,

Over on IIDB, there are a number of professional, published biological researchers who take an interest in this topic. Many are also involved with talkorigins. I put out a call on your behalf.

A recently reformed YEC is looking for answers / IIDB

I'd imagine some of them will show up eventually, or you could head over there. My own academic background is in mathematics, not biology, so I'm in much the same layman position as yourself.

As ever, Jesse

Thanks for the info. Sylas, and thanks for posting that question Jesse. I'll keep an eye on that board...

For Christians reading this, I guess I find it odd that ministries like 'God and Science' and 'Reasons to Believe' aren't yet convinced by the DNA evidence. I e-mailed both ministries today, asking about this. But I'm assuming they consider the DNA evidence (at least somewhat) inconclusive...

Originally posted by Geisler

[b]

In regards to Christians and Theistic Evolution… theistic evolution (though, not necessarily Old Earth Creationism) is contrary to conservative Christian doctrine. First, because it fails to take Genesis literally. Second, it disregards the doctrine of original sin (Rom. 5). And third, it violates Jesus’ affirmation in a literal Adam and Eve (Matt. 19:4-6). I hope this helps you in studies."

This is so wrong. It is true that most TEs do not take the scripture literally, but I do, and I am TE.

quite frankly there is only one sensible conclusion when you examine the DNA evidence - common ancestry

Originally posted by mpb1

Evolution Question: Shared Ancestry / 'Family Tree' Evidence in the DNA

The evidence showing 'shared ancestry' between apes and humans seems to be one of the strongest arguments for evolution.

As mentioned in other threads, I kind of considered this to be the 'nail in the coffin' for 'instant' Creation of any kind. After leaving YEC recently, I was leaning toward Day-Age Creationism until I looked at the evidence for evolution. And the evidence for shared ancestry in the DNA basically shut me up.

In researching this topic, I couldn't find many sites dealing with the issue, perhaps because the DNA research is fairly new.

I was wondering if there are any scientists or others who have researched the topic, and have an opinion one way or the other.

Recently, I e-mailed Christian apologist, Dr. Norman Geisler, and his view on this issue seemed less than enlightened:

"In regards to common DNA between apes and humans… this may be evidence of common design for existence in the same biosphere, rather than evidence of a common ancestor. For example, just because the tea spoon, skillet, pot, and cauldron have similar design, does not mean that the cauldron descended from the spoon. (See Frank Turek’s and my book, I Don’t Have Enough Faith to be an Atheist.)

In regards to Christians and Theistic Evolution… theistic evolution (though, not necessarily Old Earth Creationism) is contrary to conservative Christian doctrine. First, because it fails to take Genesis literally. Second, it disregards the doctrine of original sin (Rom. 5). And third, it violates Jesus’ affirmation in a literal Adam and Eve (Matt. 19:4-6). I hope this helps you in studies."

That probably represents a typical Christian view of this issue, but it's far from a scientific argument, once you have even a basic understanding of the DNA evidence, which I got from watching Dr. Francis Collins' online video at www.asa3.org, and then from reading Coming to Peace with Science by Darrel Falk.

Here's one article from Talk Origins that addresses the issue of 'copied errors' in the DNA - showing shared ancestry:

"Plagiarized Errors and Molecular Genetics"
http://www.talkorigins.org/faqs/molgen/

And here's a Creationist argument against shared ancestry from a Christian perspective:

"Shared Errors in the DNA of Humans and Apes"
http://www.cs.unc.edu/~plaisted/ce/junk.html


I thought I'd post this topic, in hopes that others might know of other research or comment on it. I guess I'm wondering if the jury's really still out on this or not...

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Hi mbp. I cant find your other thread about your worries with the PBS series so thought I'd post this.

SEATTLE--In an ironic greeting to the seven-part public television series "Evolution" that begins tonight, 100 scientists have declared that they "are skeptical of claims for the ability of random mutation and natural selection to account for the complexity of life." The signers say, "Careful examination of the evidence for Darwinian theory should be encouraged."

Discovery Institute, a Seattle-based public policy center, compiled the list of statement signers (attached). Among other things, the long list may help to answer the contention of designated spokespeople for the series "Evolution" that "virtually all reputable scientists in the world" support Darwin's theory. Institute officials charge that officials of WGBH/Clear Blue Sky Productions have used that contention to keep any scientific criticism of Darwinism from being acknowledged or examined in the eight-hour series. "They want people to think that the only criticism of Darwin's theory today is from religious fundamentalists," said Discovery president Bruce Chapman. "They routinely try to stigmatize scientists who question Darwin as 'creationists'."

Chemist and five time Nobel nominee, Henry "Fritz" Schaefer of the University of Georgia, commented on the need to encourage debate on Darwin's theory of evolution. "Some defenders of Darwinism," says Schaefer, "embrace standards of evidence for evolution that as scientists they would never accept in other circumstances." Schaefer was on the roster of signers of the statement, termed "A Scientific Dissent on Darwinism."

Meanwhile, a Zogby Poll released today shows overwhelming public support--81 percent--for the position that "When public broadcasting networks discuss Darwin's theory of evolution, they should present the scientific evidence for it, but also the scientific evidence against it." Only 10 percent support presenting "only the scientific evidence that supports" Darwin's theory. (Less than 10 percent said "Neither" or "Not sure.")

"Public television producers are clearly at odds with overwhelming public sentiment in favor of hearing all scientific sides of the debate," said Chapman, a former Director of the US Census Bureau. "The huge majorities in the poll cross every demographic, regional and political line in America." The national sample of 1,202 adults was conducted by Zogby International from August 25-29. The margin of error is +/-3.0%.

Discovery Institute commissioned the Zogby poll, though the survey itself was designed by the Zogby organization. It also included questions on education and "intelligent design," a theory that some scientific critics of Darwin support. (That theory makes no religious claims, but says that the best natural evidence for life's origins points to design rather than a process of random mutation and natural selection.) Discovery Institute last week also opened a special website (www.reviewevolution.org) to critique the WGBH/Clear Blue Sky series in a scholarly "Viewer's Guide." Discovery officials say that the website analyzes all program segments in the series and has uncovered numerous scientific and historical errors, exaggerations and omissions. Full results of the Zogby poll also are available on the website.

"The numbers of scientists who question Darwinism is a minority, but it is growing fast," said Stephen Meyer, a Cambridge-educated philosopher of science who directs the Center for the Renewal of Science and Culture at Discovery Institute. "This is happening in the face of fierce attempts to intimidate and suppress legitimate dissent. Young scientists are threatened with deprivation of tenure. Others have seen a consistent pattern of answering scientific arguments with ad hominem attacks. In particular, the series' attempt to stigmatize all critics--including scientists--as religious 'creationists' is an excellent example of viewpoint discrimination."

Signers of the statement questioning Darwinism came from throughout the US and from several other countries, representing biology, physics, chemistry, mathematics, geology, anthropology and other scientific fields. Professors and researchers at such universities as Princeton, MIT, U Penn, and Yale, as well as smaller colleges and the National Laboratories at Livermore, CA and Los Alamos, N.M., are included. A number of the signers have authored or contributed to books on issues related to evolution, or have books underway.

Despite repeated requests, the series' producers refused to cover scientific objections to Darwinism. Instead, the producers offered only to let scientific dissenters go on camera to tell their "personal faith stories" in the last program of the series, "What About God?" According to Discovery's Chapman, "This was almost an insult to serious scientists. Some of these dissenting scientists are not even religious. When you watch that last program, you realize they were wise to refuse to take part in it."

Jed Macosko, a young research molecular biologist at the University of California, Berkeley, and a statement signer, said, "It is time for defenders of Darwin to engage in serious dialogue and debate with their scientific critics. Science can't grow where institutional gatekeepers try to prevent new challengers from being heard."

Red Wine,

Here are the threads where I went round and round on the issue, before concluding that theistic evolution seems to make the most sense (to me at least), although I would much prefer Day-Age Creation to be true... The DNA evidence is what appears to eliminate that possibility.


Former 'Young Earth Creationist' - Now Confused 'Old Earth Creationist'...
http://www.theologyweb.com/campus/sh...ad.php?t=84762


What About the Mathematical Impossibilities of Evolution?
http://www.theologyweb.com/campus/sh...ad.php?t=85013


What Happens When You Take the Blinders Off?
http://www.theologyweb.com/campus/sh...ad.php?t=85758

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In his book, Coming to Peace with Science, Falk describes one the most compelling DNA evidences being the 'copied errors' - a string of gibbrish that appears in the DNA - that was copied generation after generation. The same gibbrish appears in human and ape DNA, and the only way that appently could have happened is if they were in the same line of evolution.

The only other explanation is that God copied 'DNA errors' (or junk) from one species (ape) into another species (humans) - in special acts of Creation - and this seems absolutely ridiculous to believe. Like I said though, I'm still hoping it's not this 'cut and dry,' 'cause I'd really rather not believe it, if I can possibly help it :)

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there is an ever increasing body of good genetic evidence for common ancestry.
from the human chromosome 2 being a union event of chimp 2p + 2q with the predicted 2nd centrosome and interior telomeres. To the HERV's creating a 3rd (after taxonomy and protein sequences) parallel clade. To things like HERV-W and syncytin, a placental attachment protein from a co-opted viral insertation. There is simply such an overwhelming genetic evidence for common descent that it meets the legal requirement for beyond reasonable doubt.

Hi RMW (and anyone else),

I've been a little puzzled by something... It seems that certain scientists or authors focus on the things you mentioned (RMW), and others focus on the 'duplication of errors' in both the ape and human DNA.

Being far from a scientist or geneticist, when I've seen the information presented, I thought that maybe 'instant Creation' could somehow account for the things you mentioned (possibly).

But the copied errors - the SAME gibbrish - in the human and ape DNA code seemed the most compelling evidence for evolution, to me at least. Otherwise, God would have been intentionally copying junk from ape DNA into human DNA, which seems absurd.

It's all pretty confusing. I'm hoping there will be some more online videos or presentations of some kind to explain all this in detail. Then I'd love to get some 'perspective' from the spokesmen for Day-Age Creation, to see what they make of it...

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NOTE: Taoist's request for info. from another board ended up being referred to this active thread: http://www.iidb.org/vbb/showthread.php?t=184329 by that board's admin., in case anyone wants to take a look at it...

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MORE LINKS - I'm just posting these as I find them. I don't understand much of the info. I'm just posting so the links are here for those who understand this stuff, and have the inclination to interpret or explain any of it here, OR for Creationists who want to look into it...


29+ Evidences for Macroevolution - Part 4:
The Molecular Sequence Evidence
http://www.talkorigins.org/faqs/comdesc/section4.html


Evidences for Evolution
http://en.wikipedia.org/wiki/Evolution


Different Species With The Same "Junk DNA"
http://www.don-lindsay-archive.org/c...dna_virus.html


Evidences of Macroevolution
http://www.life.uiuc.edu/bio100/lect...8evidence.html


Transitional Hominids - Diagrams & Info.
http://hometown.aol.com/darwinpage/hominid.htm


Molecular Evidence 2: DNA Functional Redundancy
http://evolution-101.blogspot.com/20...unctional.html


Comparison of the Human and Great Ape Chromosomes as Evidence for Common Ancestry
http://www.gate.net/~rwms/hum_ape_chrom.html
http://www.gate.net/~rwms/EvoContents.html#hum_ape_ca


Macroevolution Evidences - including molecular / DNA info.
http://www.life.uiuc.edu/bio100/lect...-evidence.html


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Here is yet another piece of genetic evidence for shared ancestry, something I wrote up for another forum.

Sylas is right: this is simply not an issue among geneticists who have anything to do with this kind of work. Common ancestry is the framework that makes sense of the entire field.

To muddy the waters a little more...

Material on shared ancestry from Day-Age Creationists


Descent of Mankind Theory: Disproved by Molecular Biology
http://www.godandscience.org/evolution/descent.html


A Scientific and Biblical Response to "Up from the Apes. Remarkable New Evidence Is Filling in the Story of How We Became Human"
http://www.godandscience.org/evoluti...eresponse.html


New DNA Evidence Supports Multiregional Evolutionary Model?
http://www.godandscience.org/evoluti...iregional.html


The Origin of Man and the Races (PowerPoint presentation)
http://www.godandscience.org/ppt/originofman.ppt

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Article from Apologetics Press:

Do Human and Chimpanzee DNA Indicate an Evolutionary Relationship?
by Brad Harrub, Ph.D. and Bert Thompson, Ph.D.
http://www.apologeticspress.org/articles/2070


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Genome info. & Links:


National Human Genome Research Institute
http://genome.gov/


"International Human Genome Sequencing Consortium
Describes Finished Human Genome Sequence"
http://www.genome.gov/12513430


Analysis of the Human Genome (in light of other mysteries)
http://www.world-mysteries.com/sci_1.htm


NPR Radio Show: "DNA Shows Human-Ape Links, Differences"
http://www.npr.org/templates/story/s...toryId=4826786


Simple explanation of DNA
http://en.wikipedia.org/wiki/Dna
http://www.cubagenweb.org/dna.htm


What are Pseudogenes?
http://en.wikipedia.org/wiki/Pseudogene


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NPR Radio Show webcast:
Human Origins Update - Talk of the Nation, March 19, 2004. A study out this week bolsters the theory that Neanderthals didn't breed with early humans. Another recent study suggests a new branch on the family tree.
http://www.npr.org/templates/story/s...toryId=1778709

Sorry to be the spoiler here, and I really hate to find myself in a position where I have to defend those nasty cursed retroviruses -- considering all the misery they cause, .......but if HERVs have a useful function, you really don't have a slam-dunk here vis-a-vis shared ancestry.

You see, if there is a useful function, then the HERVs are located where they're supposed to be located, the same as other loci in the genome. And why wouldn't it be a similar location in the closest matching genome of the chimpanzee.

And it turns out HERVs so seem to have useful functions:
http://www.amazon.com/Dancing-Matrix...439801-7676069

Dancing Matrix: How Science Confronts Emerging Viruses Robin Marantz Henig Page 80 ISBN 0679730834

Endogenous retroviruses may serve several functions that actually serve the host organism. One might be to make the host resistant to other viral infections. “Consider for example, what happens when domestic cats are exposed to the baboon endogenous virus,” writes Russell Doolittle of the University of California at San Francisco. “If the cat is carrying the closely related feline leukemia virus in its germline as a consequence of previous ancestral exposure, the cat is not afflicted. Cats not carrying the virus in their germline are smitten.” (citing Nature June 1st, 1987 News and Views Section)

Another function of endogenous retroviruses might be in aiding in the routine operations of the cell itself. Before he started working full-time on AIDS research, Martin (Malcolm Martin, chief of microbiology at the National Institute of Allergy and Infections Diseases) discovered a particular viral genome in the human placenta that might play a role in fusing cells between the lining of the uterus and the placenta (citing “Viruses Revisited” New York Times Magazine November 13th, 1988)

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© source where applicable

http://www.pubmedcentral.nih.gov/art...i?artid=138943

News/Article: PubMed CentralL June 5 2001 Endogenous retroviruses in the human genome sequence

The best example of a HERV with a known function is HERV-W. The envelope proteins of this HERV are thought to mediate fusion of trophoblasts, an essential step during formation of the placenta [9]. A role in membrane fusion is not surprising since this is the role of the viral Env protein during retroviral infection following binding to a cell surface receptor. Interestingly, trophoblast fusion by HERV-W Env appears to be independent of a specific receptor molecule. A different HERV (ERV-3) had previously been suggested to provide the trophoblast fusion function but was later ruled out by the discovery of individuals who are homozygous for an inactivating mutation [10]. Sequence comparisons in different individuals may yet reveal such polymorphisms for HERV-W.
Another function proposed for HERVs is in determining resistance to viral infection. In mice, resistance to infection by MLV is controlled by a Gag-like protein encoded by Fv1, an otherwise defective endogenous retrovirus related to human HERV-L [11]. The molecular basis of this restriction is not yet known, but it has been suggested that the Fv1 protein interacts with the incoming core of the MLV viral particle in a dominant-negative manner, thereby inhibiting infection. Cell lines from other species, including humans, also have an intracellular restriction to MLV infection [12], but the mouse and human restrictions occur at different stages of viral entry. Although the inhibitory factor in humans has yet to be cloned, it is possible that endogenous retroviral Gag proteins may provide a general mechanism for controlling retroviral infection in mammals.

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© source where applicable

What happens is that HERV-W produces syncytin, is a highly fusogenic membrane glycoprotein.
http://www.pubmedcentral.nih.gov/art...i?artid=164757

News/Article: PubMed Central May 23 2003

We recently demonstrated that the product of the HERV-W env gene, a retroviral envelope protein also dubbed syncytin, is a highly fusogenic membrane glycoprotein inducing the formation of syncytia on interaction with the type D mammalian retrovirus receptor. In addition, the detection of HERV-W Env protein (Env-W) expression in placental tissue sections led us to propose a role for this fusogenic glycoprotein in placenta formation. To evaluate this hypothesis, we analyzed the involvement of Env-W in the differentiation of primary cultures of human villous cytotrophoblasts that spontaneously differentiate by cell fusion into syncytiotrophoblasts in vitro. First, we observed that HERV-W env mRNA and glycoprotein expression are colinear with primary cytotrophoblast differentiation and with expression of human chorionic gonadotropin (hCG), a marker of syncytiotrophoblast formation. Second, we observed that in vitro stimulation of trophoblast cell fusion and differentiation by cyclic AMP is also associated with a concomitant increase in HERV-W env and hCG mRNA and protein expression. Finally, by using specific antisense oligonucleotides, we demonstrated that inhibition of Env-W protein expression leads to a decrease of trophoblast fusion and differentiation, with the secretion of hCG in culture medium of antisense oligonucleotide-treated cells being decreased by fivefold. Taken together, these results strongly support a direct role for Env-W in human trophoblast cell fusion and differentiation. Evidence has recently accumulated suggesting that endogenous retroviral gene expression may be involved in mediating the cell fusion observed in the placenta. Indeed, high expression of retroviruses is one of the characteristics of the human syncytiotrophoblast (21, 23). The observation of retroviral particles in the placenta, along with the presence of fused placental cells morphologically reminiscent of virally induced syncytia, led to the proposal that an ancient retroviral infection may have been a pivotal event in mammalian evolution (21). In connection with this, we previously characterized the HERV-W family by screening a placental cDNA library (5). Surprisingly, this multicopy family contains a unique locus, termed ERVWE1, coding for a full-length envelope (43). The presence of inactivating mutations in the other viral genes borne by the ERVWE1 provirus led us to propose that Env function has been selectively preserved (5). We recently demonstrated that the product of the HERV-W env gene (Env-W) is a highly fusogenic membrane glycoprotein that induces the formation of syncytia on interaction with the type D mammalian retrovirus receptor (7).

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© source where applicable

What is syncytin?
http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Abstract

News/Article: PubMed citing Nature

Syncytin is a captive retroviral envelope protein involved in human placental morphogenesis.
Many mammalian viruses have acquired genes from their hosts during their evolution. The rationale for these acquisitions is usually quite clear: the captured genes are subverted to provide a selective advantage to the virus. Here we describe the opposite situation, where a viral gene has been sequestered to serve an important function in the physiology of a mammalian host. This gene, encoding a protein that we have called syncytin, is the envelope gene of a recently identified human endogenous defective retrovirus, HERV-W. We find that the major sites of syncytin expression are placental syncytiotrophoblasts, multinucleated cells that originate from fetal trophoblasts. We show that expression of recombinant syncytin in a wide variety of cell types induces the formation of giant syncytia, and that fusion of a human trophoblastic cell line expressing endogenous syncytin can be inhibited by an anti-syncytin antiserum. Our data indicate that syncytin may mediate placental cytotrophoblast fusion in vivo, and thus may be important in human placental morphogenesis.

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© source where applicable

(I'll attach a picture with the syncytiotrophoblast from my Langman's so people will know what we're talking about)

In mice ERVs have been found to have apathogenic properties, (thats a good thing -- as in better than pathogenic)
http://www.ncbi.nlm.nih.gov/books/bv....section.44958

News/Article: LANDES BIOSCIENCE

The disease in mice from Lake Casitas in California is another example. These wild mice consist of two populations. 15 One population gets a degenerative neurological disease, a myelitis. It is caused by a pathogenic variant of MLV. After infection early after birth, the infection becomes chronic, with viremia for several months. The other mouse population is resistant against the disease. The resistant mice have a genetic property (FV4), which is a defective endogenous MLV sequence. This apathogenic ERV produces an envelope glycoprotein which protects against the exogenous virus by binding to and blocking the same cell surface receptor that is used by the pathogenic exogenous MLV. The example shows i. that infection just after birth followed by a chronic viremia eventually can lead to disease, and ii. that an endogenous retroviral sequence can protect against an exogenous retrovirus. In this case ERV expression is negatively correlated with disease. The epidemiology of the disease is determined both by heredity and infection after contact between individuals (environment).

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© source where applicable

Neocon_Voter

Well, what do you know. I'd never have believed we could have a meaningful post from the neocon voter. It's fundamentally wrong, of course, but it's still far more meaningful than I'd have given him credit for being able to create. There's nothing like making lowered expectations do your work for you.

Greetings, neocon,

but if HERVs have a useful function, you really don't have a slam-dunk here vis-a-vis shared ancestry.

The case for shared ancestry lies in the visibly hierarchical nature of the ERVs we find in the primate line. Here's a useful diagram to consider.

[attachment=1]

Source: TalkOrigins

The presence and absence of HERVs is responsible for the structure of this tree. If instead, say, there was an HERV shared between new world monkeys and humans, but not chimps, the tree structure would fall apart. This is not the case. There are no HERVs that break the tree.

You see, if there is a useful function, then the HERVs are located where they're supposed to be located, the same as other loci in the genome. And why wouldn't it be a similar location in the closest matching genome of the chimpanzee.

The real question is why they fall into a tree structure at all, not whether they are useful. It is the tree structure that leads us to the conclusion that there have been splits along the evolutionary corridors, and that is what makes the case for shared ancestry.

And it turns out HERVs so seem to have useful functions:

This is rather overstated, don't you think? Three slices of celery do not a stew make. And we can be fairly sure the celery is not thanking us for cutting it down in its prime for our needs.

At best, you make the case that some HERVs have been retasked. In fact, HERVs make up nearly 10 percent of our genome.

[attachment=2]

Source: Institute of Molecular Virology: Human Endogenous Retroviruses

Given the evidence that new functions for DNA are often co-opted through normal evolutionary processes and that HERVs are so common in our genome, it would be unusual to find no HERVs had found another job. But it's useful to keep in mind that these HERVs no longer perform their original function. If, for example, a portion of an ERV now performs an apathogenic function in a cat, we can be sure that was not its purpose before it was incorporated into the cat's germ line.

In fact, your examples are no more than what we expect, and simply do not make a case against shared ancestry.

As ever, Jesse