Comment by alsaaro | Hacker News Reader

Comment by alsaaro | Hacker News Reader

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The article states that mutations arise randomly (de novo mutations), but the rate of of these mutations differ based on populations experiencing differing environmental pressures.

The naïve hypothesis would be to expect that de novo mutations, being random, should arise in differing populations -- even in different environments -- at the same rate; apparently this isn't the case.

The article doesn't explain the underlying mechanism, so I assume this is just premilitary observational science? The authors say this challenges neo-Darwinism, how?

One explanation is that environmentally selected genes (meta genes?) that promote mutation of de novo genes in regions of the genome under environmental pressure. These meta genes dispersed in a population would prime that population for the synthesis of new adaptations.

The underlying paper lists 3 different hypotheses that could explain the results.

1. Unrelated fragility of this particular sequence in Africans

2. Modifier theory

3. Having mutations makes future generations more susceptible to nearby mutations. This what the authors are suggesting.

There's a sort of soft-assumption in modern biology that mutations are approximately random, which underlies things like the molecular clock. It's well-known to be wrong, but at scale the experimental evidence suggests that it still holds in many useful situations.

Combine a paper pointing out a limitation of that assumption with popsci press and you get the breathless headline above.

> One explanation is that environmentally selected genes (meta genes?) that promote mutation of de novo genes in regions of the genome under environmental pressure.

This has been studied. They’re DNA repair pathways. Put a bunch of E. coli in a bioreactor and trace the lineages. As soon as one lineage loses a DNA repair pathway, new mutations explode and out-compete the old lineages (and each other).

Besides cancer and viability concerns, highly stable DNA is mainly beneficial in cyclical conditions (as adaptive memory). In the stable—but highly competitive—environment of a bioreactor, sacrificing DNA stability for adaptive pace is a very beneficial mutation.

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