Wednesday, July 04, 2007

ERVs are functional.

Index to Common Creationist Claims about ERVs

As a defense against the argument that 'junk DNA', including nonfunctional ERVs, is evidence against their choice* of 'Designer', Creationists insist that ERVs are functional.

There is a very big difference between a functional ERV, and a functional component of an ERV. Creationists do not understand this (specific example here)

Yes, we have found a retroviral env that has been co-opted by mammals. Yes, somewhere around 100 human proteins might have evolved from co-opted gag proteins. Yes, we can find retroviral transcripts floating about cells, sometimes. But these are not examples of ERV functionality. They examples of evolution in action-- the host organism salvaging ERV parts for its own use.

Complete ERVs are recombined, mutated, and methylated into junk. When they regain some semblance of functionality, they cause disease! Which is no surprise, as exogenous retroviruses like HIV and HTLV cause AIDS, leukaemia, lymphomas, and various other autoimmune diseases.

ERVs specific to humans, called HERVs, have been tied to multiple cancers, including germ-cell tumors, breast cancer, seminomas, melanoma, ovarian cancer... And autoimmune diseases like multiple sclerosis, rheumatoid arthritis, psoriasis, and lupus (please see this source for more information).

These are just the human-specific ERVs. We have lots more.

DISCLAIMER-- Currently, ERV->disease research is very new, as are the methods we use for studying why they become active (epigenetics). 'Functional' ERVs might be the cause of disease, the effect of disease, or both (the effect, but perpetuates the disease, what I think is going on with ERVs and cancer).

But one thing is certain thus far-- You do not want ERVs to be functional.

* This argument is inappropriate when discussing 'design' with polytheists, deists, or those who believe in a malicious deity. I believe it is also incompatible with theistic evolution. This stance only applies to Creationists.

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