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Icons of Evolution

Gene2memE

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Stephen W. Schaeffer (Professor Emeritus of Biology) claims that the theory of common descent has proven useful in identifying so-called conserved sequences in human DNA (if "conserved", such sequences are understood to serve a functional purpose ... as opposed to so-called junk DNA, which is generally understood to serve no functional purpose).

My understanding is that process involves comparing human and chimps DNA, then finding similar DNA sequences, which are alleged (according to the theory of common descent) to have been "conserved" by natural selection from a common ancestor.

But it seems debatable to me if identifying conserved sequences has actually proven fruitful in curing or improving the treatment of any disease.

Conserved sequences aren't just compared with chimpanzees and other primates, we see them in comparisons throughout the rest of life. Here's a paper comparing the genomes of humans and pufferfish, which found "nearly 1,400 highly conserved non-coding sequences".


What's really cool is that despite last sharing a common ancestor about 450 million years ago, the comparison found that: "Without exception, all reported examples of non-coding conservation between these two species have been associated with genes that play critical roles in development." Which suggests that purifying negative selection is at play here (and has been for a very, very long time).

Here's another paper that shows humans have around 500 'ultraconserved' elements in common with the rat and mouse genomes. Ultraconserved meaning regions of at least 200 contiguous nucleotides that are perfectly conserved between the genomes.


What's fascinating is that there are still lots of unanswered questions about these 'ultraconserved' regions. We know that a majority of these regions play critical roles in regulating gene expression that is responsible for the development/growth of an organism - yet, when deleted half of them don't actually seem to have no impact on an organism's "viability, fertility, or fecundity". Why?
 
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Buzzard3

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Conserved sequences aren't just compared with chimpanzees and other primates, we see them in comparisons throughout the rest of life. Here's a paper comparing the genomes of humans and pufferfish, which found "nearly 1,400 highly conserved non-coding sequences".


What's really cool is that despite last sharing a common ancestor about 450 million years ago, the comparison found that: "Without exception, all reported examples of non-coding conservation between these two species have been associated with genes that play critical roles in development." Which suggests that purifying negative selection is at play here (and has been for a very, very long time).

Here's another paper that shows humans have around 500 'ultraconserved' elements in common with the rat and mouse genomes. Ultraconserved meaning regions of at least 200 contiguous nucleotides that are perfectly conserved between the genomes.


What's fascinating is that there are still lots of unanswered questions about these 'ultraconserved' regions. We know that a majority of these regions play critical roles in regulating gene expression that is responsible for the development/growth of an organism - yet, when deleted half of them don't actually seem to have no impact on an organism's "viability, fertility, or fecundity". Why?
Interesting indeed.

My knowledge of genetics is very (very) limited, but it seems to me that the concept of conserved sequences is predicated on the assumption that some DNA is considered functionally useless - aka "junk" DNA.

It also seems to me that if a function cannot be ascertained for some DNA sequences, it is regarded as non-functional. If so, surely the possibility exists that at some later date, when knowledge of genetics has advanced, it could be discovered that "junk" DNA is in fact functional, thus throwing the concept of conserved sequences into serious doubt.
 
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Warden_of_the_Storm

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If no one is aware of any use for the theory of common descent in medical or biological research, it's a fair guess that none exist.

You just saying that no-one is aware of any use for the theory of common descent in medical or biological research does not mean that no-one is aware.

You keep doing this: just saying that something is wrong and doing nothing to show that something is wrong, especially with regards to common descent since, oh surprise surprise, WE HAVE EVIDENCE.
 
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AV1611VET

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You just saying that no-one is aware of any use for the theory of common descent in medical or biological research does not mean that no-one is aware.

If we're so closely related to Magilla Gorilla, then why can't we receive organ transplants from them?

We can't even receive organ transplants from each other without requiring anti-rejection medication for the rest of our lives.
 
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Warden_of_the_Storm

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If we're so closely related to Magilla Gorilla, then why can't we receive organ transplants from them?

We can't even receive organ transplants from each other without requiring anti-rejection medication for the rest of our lives.

Yeah, I'm not asking you AV. So sling your hook.
 
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