Tuesday, November 27, 2007

Evolution for Creationists Part Three

This is the third installment in my series "Evolution for Creationists". I appreciate any and all comments and criticisms that you may have about this.

Evidence #5
Endogenous Retroviruses

I will begin this essay by quoting the intelligent design blog Uncommon Descent:

"Endogenous retroviruses are molecular remnants of a past parasitic viral infection. Occasionally, copies of a retrovirus genome are found in its host’s genome, and these retroviral gene copies are called endogenous retroviral sequences. Retroviruses (like the AIDS virus or HTLV1, which causes a form of leukemia) make a DNA copy of their own viral genome and insert it into their host’s genome. If this happens to a germ
line cell (i.e. the sperm or egg cells) the retroviral DNA will be inherited by descendants of the host. Again, this process is rare and fairly random, so
finding retrogenes in identical chromosomal positions of two different species indicates common ancestry."

So let's review: On a rare occasion a virus will insert itself into it's host's genome at random, and the host's descendants will inherit this and have the
virus in their genome. Our genome is 3 billion base pairs, so it is extremely unlikely that any creature would share the exact same virus in the exact same
place in the genome. But yet humans and primates do have the same viruses in the same places in their genome. This is because they were inherited from a common ancestor.

The above article was written by Douglas Theobald, the assistant professor of biochemistry at Brandis University.

In order to prove this truly is evidence of evolution, let me consider the following questions:

1. Is the viral insertion really random?
Yes. Here are two papers creationists use in support
of the nonrandom viral insertion hypothesis:

The first paper simply states that some retroviruses like to insert in genes, some like to insert near promoters of genes, and some like to insert in the middle of no where. The specific insertion sites, what base pairs on on the left, which ones are on the right, is random. Thats exactly what they looked for in that papers methods.

In the second paper the researchers found two independent Viral insertions in deer mice. They could tell the insertions apart because the virus had infected two different places, because this event happened twice.

So Retroviral insertion is indeed random.

2. Do the Viruses serve any good purpose?
No. When ERV's do become functional, they cause

In closing, you can google "endogenous retrovirus" and pull up plenty of medical, scientific, and educational websites. If you email the website, they will tell you
the exact same thing I am. You could also visit a university and contact a geneticist who will provide you with the same information.

Some of this material was referred by Abbie Smith in her series "Common Creationist Claims About ERV's"

Evidence #6

What is an atavism? It's an evolutionary throwback. It's when an ancestral gene that has been "switched off" gets "switched on" again. It's the most bizarre evidence for evolution you've ever seen. One of the tamer examples would be the horses who are born with three toes, just like their ancestors. Even more bizarre are the humans born with true tails. Stranger still is the whale found with legs, feet, and toes. Here is the story of human tails, and how we know that these are atavisms:

"Less than one third of the well-documented cases are what are medically known as "pseudo-tails" (Dao and Netsky 1984; Dubrow et al. 1988). Pseudo-tails are not true tails; they are simply lesions of various types coincidentally found in the caudal region of newborns, often associated with the spinal column, coccyx, and various malformations.

In contrast, the true atavistic tail of humans results from incomplete regression of the most distal end of the normal embryonic tail found in the developing human fetus The true human tail is characterized by a complex arrangement of adipose and connective tissue, central bundles of longitudinally arranged striated muscle in the core, blood vessels, nerve fibres, nerve ganglion cells, and specialized pressure sensing nerve organs. It is covered by normal skin, replete with hair follicles, sweat glands, and sebaceous glands. True human tails range in length from about one inch to over 5 inches long (on a newborn baby), and they can move via voluntary striped muscle contractions in response to various emotional states."

Talk Origins

The whale with legs
Whales and Dolphins with Legs

Live Science reports that,
"There are many cases where whales have been found with rudimentary hind limbs in the wild, and have been found in baleen whales, humpback whales, and in many specimens of sperm whales. Most of these examples are of whales that had only leg bones, but there were some that included feet with complete digits."

This fits in perfectly with the fossil evidence that whales descended from walking land mammals.

Recently a dolphin was captured which appeared to have hind limbs.

The Bird With Teeth

"Working late in the developmental biology lab one night, Matthew Harris of the University of Wisconsin noticed that the beak of a mutant chicken embryo he was examining had fallen off. Upon closer examination of the snubbed beak, he found tiny bumps and protuberances along its edge that looked like teeth--alligator teeth to be specific. The accidental discovery revealed that chickens retain the ability to grow teeth, even though birds lost this feature long ago."

From a Scientific American Article.

This of course compliments the fossil evidence that birds are descended from reptiles: Archaeopteryx had teeth as well.

In the next part of this series, I intend to answer common and important questions about evolution. I hope you have enjoyed reading this, and if you want more, check out Talk Origins' 29+ Evidences for MacroEvolution.


Aaron said...

The first time I heard about cetacean (whale) evolution, it was from Terry Mortensen, a lecturer from AiG. (We were crashing their party to editorialize)

To be quite honest, I admit that I was skeptical. The idea was "cetaceans evolved from Pakicetus, which was a tapir-like animal." This seemed really far-fetched. I figured maybe Terry didn't fully understand it, so I went and read online about it myself.

The evidence is pretty compelling, and I admit that after reading several different documents and seeing pictures and photos of the fossils, it just MADE SENSE.

Things like jaw bone, the direction they flap their fins (vertically) which is different than fish (laterally), and then of course the fact that they are AQUATIC MAMMALS.

AIGBusted said...

Indeed, the evidence from whales alone makes a huge case for evolution. We have several transitional fossils, whales develop hair as embryos, and finally we have proof positive of atavisms in whales (legs).

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Anonymous said...

About the apparition of new information in the genome...

It is a common mistake that Creationists make to assume that new information must be added to the individual - it is the species that evolves, not the individual, and therefore there isn't a need for a mechanism that would add information to an individual's genome.

An exemple: Let's say that you've written up the whole genome of species A. Let's also say that every individual of species A has brown eyes; then one day an individual of that species is born with blue eyes (because of a mutation). What happens? You have to reopen your book where you've noted down the whole genetic makeup of species A and add the genetic information that causes an individual from that species to have blue eyes.

That's as simple as that. You can count on Creationists to create false problems.