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Prehistoric proteins: Raising the Dead

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posted on Jan, 1 2013 @ 10:57 PM
Although the thread title suggests a home in Origins & Creationism, I have chosen to post it in Science & Technology because, to me at least, the interest in the long linked article is in the scientific work it describes. The religio-political angle, though potent, is secondary. If the staff feels the subject is better suited to O&C, move it there by all means.

Prehistoric proteins: Raising the dead

To dissect evolution, Joe Thornton resurrects proteins that have been extinct for many millions of years. His findings rebut creationists and challenge polluters.

The article is about a scientist who rebuilds extinct proteins.

One deep-frozen vial holds the more-than-600-million-year-old ancestor of the receptors for oestrogen, cortisol and other hormones, which Thornton brought to life nine years ago. Other tubes house proteins more than 400 million years old, which Thornton resurrected a few years later to show how an ancient receptor had changed its preferences — and how the march of evolution cannot be reversed. In another corner of the freezer rest the ancient protein components of a sophisticated cellular machine that acquired a more complex form through random mutations rather than selection for superior function...

Thornton reverse-engineers these ancient proteins from those found in nature today.

Starting with the genes for steroid hormone receptors from a slew of living organisms, he clambered backwards through the evolutionary tree to deduce the most likely sequence of the common ancestor of all such receptors, which existed some 600 million to 800 million years ago – in the common ancestor of 'you and a snail', as he puts it. Instead of stopping there, as most evolutionary biologists would have done, he then built the gene and inserted it into cells that could manufacture the ancient protein.

It wasn't till Thornton started studying steroid hormone receptors, though, that he fell foul of the creationists:

He chose to explore a pair of steroid hormone receptors: the mineralocorticoid receptor (MR), which binds the hormone aldosterone and regulates salt and water balance; and the closely related glucocorticoid receptor (GR), which binds cortisol and controls stress response. A gene duplication more than 450 million years ago produced the two receptors — but aldosterone didn't arise until many millions of years later. The timing seemed to make the MR a textbook example of irreducible complexity: how could selection drive the evolution of a lock (the MR) to fit a key (aldosterone) that didn't yet exist?

You'll find the answer to that question, along with a lot of other fascinating stuff about the winding, often tangled paths that natural selection has followed to produce the incredibly complex organisms we see around us today (and that we ourselves are) in this Nature News article. It's long, though not as long as a single ATS page is, but fully worth reading whatever you know (or don't know) about evolution.

If anyone has any comments to make afterwards, I should be interested to read them.

posted on Jan, 1 2013 @ 11:46 PM
Interesting article and information. I think many people do not appreciate the facts of the process of evolution. There seems to be this prevailing thought that I see over and over again, although it is not true, which basically states that organisms develop some specific trait in response to their environment. Or that specific traits are developed because they would be useful to the organism in the environment in which it dwells.

But in reality every single mutation that occurs and is subsequently passed on to the newer generations of offspring arises from a completely random mutation. And it is important to remember that a very large percentage of all random mutations negatively affect the organism in which the change occurs. After that, the next most common effect of a random mutation is that it does not really affect the organism's survival. And then a very small percentage of the time that random mutation allows an organism to gain some measure of an advantage over the other organisms competing for the same resources.

Thus this mutation, when passed on to the organism's offspring, also gives those offspring that same advantage in survival. After generations of this, the organisms without the mutation will likely die in a larger percentage than those with the beneficial mutation, until eventually the mutation exists across the entire population. But more often, as I mentioned earlier, the mutation has a negative affect on the organism. In this case, the organism will likely not even live long enough to pass this negative mutation on to its offspring, thus preventing that negative mutation from spreading through more of the population. If the organism does live long enough to pass on offspring, those offspring who inherit this disadvantage will likely not be able to compete with the other organisms for food.

This also works with things like colors and other traits in certain animals. For instance, females of a species may have the desire to mate only with the males who portray a certain characteristic, and any males without this trait are unlikely to pass on their genes since no females will mate with him. This is a part of the process that occurred to give the peacock such a beautifully feathered tail. And it is so beautiful that the peacock has a harem of multiple females, lol.

I wanted to mention all of this, even though it is only slightly relevant to the thread, because I feel that people need to understand these basic facts if they wish to truly understand articles such as the one in the opening post. I know that you shied away from the religious aspect of the article, and rightly so in my opinion, but I will go ahead an make a short comment on that idea. Personally I see absolutely no problem between the existence of evolution and creationism.

I think some creationists interpret the Bible too literally, and they fail to learn what God is attempting to teach them through the advancement of science via brilliant minds. If God chose to create life, He would have done so in any way he saw fit. So who is anyone to say that evolution is evil or wrong, when it very well may have been chosen by God as a mechanism for life. So many aspects of our universe involve randomness, and evolution is not any different.

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