Why do we have living fossils?

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Offline thedoc

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Why do we have living fossils?
« on: 05/08/2015 06:50:01 »
Liam Krut asked the Naked Scientists:
   
If mutations occur at a constant rate, why do we have living fossils? I would expect the accumulation of new genetic material to make things like ginkos and horse shoe crabs unrecognizable from their fossilized ancestors.

What do you think?
« Last Edit: 05/08/2015 06:50:01 by _system »

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Offline RD

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Re: Why do we have living fossils?
« Reply #1 on: 05/08/2015 08:53:06 »
If mutations occur at a constant rate, why do we have living fossils?

The mutants would only succeed if the mutation provided a benefit , otherwise they are an evolutionary cul-de-sac.
If the environment is constant, natural-selection will keep the design constant , once an optimum design has come about.

[ Note: Even though the body-plans of so-called "living fossils", have changed little over hundreds of millions of years, there will have been inconspicuous evolutionary changes,  e.g. evolution of their immune-systems , as that milieu is not constant ]. 

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Offline alancalverd

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Re: Why do we have living fossils?
« Reply #2 on: 05/08/2015 16:03:20 »
Quote
If mutations occur at a constant rate

Quite obviously, they don't, otherwise we wouldn't have long-lived species like ginko and horsehoe crabs. And people would evolve as quickly as cold viruses.
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Offline Pecos_Bill

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Re: Why do we have living fossils?
« Reply #3 on: 05/08/2015 18:55:51 »
Another reason that we have living fossils is that women continue to breed with obvious throwbacks like the current crop of GOP  presidential candidates.

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Offline alancalverd

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Re: Why do we have living fossils?
« Reply #4 on: 05/08/2015 20:01:35 »
I say, steady on, old chap. Are you suggesting that Jeb Bush, the brother of a towering genius, isn't in the running for a Nobel Prize and sainthood? Or that the intellectual quality of candidates has gone downhill since Ronald McDonald Reagan? Has that charming lady killed all the bears in Alaska and learned to read yet?

Democracy: government of the people (demos) by the worst (krassos). Where better than in America?
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