Year old article explaining Lenski's research

Fun read, and sure seems to run counter to Behe’s thesis. For the lay readers among us.
https://www.sciencealert.com/one-of-longest-evolution-experiments-overthrowing-previous-assumptions

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I especially found the part about “hyper-mutaters” interesting:

“Six of the 12 initial populations have become hypermutators. They picked up early mutations in genes controlling DNA repair, which then enabled them to accrue more mutations in the rest of their genomes. These bacteria undergo bouts of molecular evolution that yield jumps in their degree of genetic diversity.”

This illustrates really well what I had been trying to ask about in regards the possibility of some ancient human populations having similar hypermutation tendencies.

Do some humans or human populations exhibit similar mutations in genes that inhibit repair?

Yup, also this is not plausible in human populations and has never been observed. For good reason. That mutation just kills a human. It causes an error catastrophe, because negative selection does not have time to work.

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Not plausible, or not possible? :slight_smile:

Never been observed, but the human equivalent in Lenski would have been 1M years ago where the hypermutaters were strongest it seemed, yes? And it also seemed Lenski showed the overall mutation rate across all populations declined over time as well, yes?

And again, by “observed” does that mean in the mostly modern samples we have prior to 15k years ago? If there were a few small populations of hypermutators (with high mutation rate, but low enough not to trigger error catastrophe), isn’t it possible they would have escaped direct detection thus far?

Have we seen examples of humans with errors in the DNA repair genes (similar to those in Lenski), but who are otherwise healthy?

  1. We observe that high mutation rates like this cause death.
  2. We observe that lower mutations rates then this cause disease.
  3. We see no evidence of sustained increases of mutation like this, and expect we should see this evidence. So we have good reason to reject it.

I won’t say not possible. I would say strongly ruled out by evidence.

No we do not. This leads to childhood cancers, and severe impairment.

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I pretty sure I saw articles with evidence that human mutation rates may have been higher in the past and that chimps have a 50% higher rate than humans but I can go back and find these.

But the question remains to me as to how high would be too high?

Unless we have more data going back further in time, still not convinced we can rule this out, but maybe I can be.

50% higher for some populations (not all) for periods of time (not indefinitely) is entirely consistent with the evidence.

The hyper mutators in Lenski’s experiment were several times faster than normal (perhaps 500% higher?). To have a very recent single couple, it would require more than even this.

You mentioned a small group of people, say 100. That could be consistent with the evidence, possibly.

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