
A mutational timer is built into the chemistry of DNA - dnetesn
https://phys.org/news/2018-01-mutational-timer-built-chemistry-dna.html
======
ucaetano
> "An interesting question is: What determines the mutation rate in a living
> organism," Al-Hashimi said. "From there, we can begin to understand the
> specific conditions or environmental stressors that can elevate errors."

Which leads to an interesting point: higher mutation ratios lead to more
diversity and faster evolution/adaptation, but also lead to a higher % of
cells/embryos failing due to destructive mutations (such as cancer).

Similarly, lower mutation rates increase stability and decrease cell/embryo
mortality rates, but at the cost of adaptability and evolution.

With that in mind, you'd expect that fast-changing environments would select
for genes that increase mutation rates, leading to faster evolution but with
higher mortality rates, and stable environments would select genes that
decrease mutation rates, resulting in larger populations and lower mortality
rates.

It is amazing to think that even the rate of mutations is probably an
evolutionary response to the environment.

~~~
jon_richards
>With that in mind, you'd expect that fast-changing environments would select
for genes that increase mutation rates

I've seen the opposite in a bioreactor (about the most stable environment you
can have). Variants slowly emerged and outcompeted each other until a variant
emerged with a DNA repair pathway deleted. The spawns of that variant quickly
out-competed the old ones and from then on there were ~10 dominant variants at
any given time instead of the previous 1-3.

Because the environment was so stable, the genes did not need to "remember"
previous states of the environment and were free to optimize for the current
state. The way to do this is to increase the mutation rate, as you potentially
delete old genes that are no longer necessary and create new genes that are
right for the moment.

Edit: I suppose this points out a difference between "fast-changing" in a
single direction and "fast-changing" that repeats states, such as seasonal
changes.

------
mcqueenjordan
> certain C/C++ variables can shape-shift for a thousandth of a second,
> transiently morphing into alternative states that can allow the program to
> crash or produce an incorrect result

I knew it!!!

~~~
tzahola
No surprise:
[https://en.wikipedia.org/wiki/Single_event_upset](https://en.wikipedia.org/wiki/Single_event_upset)

~~~
mcqueenjordan
Nice reply, was secretly hoping someone would mention this. Funnily enough,
we've encountered this at work before.

------
eggie
> certain DNA bases can shape-shift for a thousandth of a second, transiently
> morphing into alternative states that can allow the replication machinery to
> incorporate the wrong base pairs into its double helix

I find this fascinating. I had always assumed that it was the shapeshifting of
the polymerase that caused replication errors. Clearly that's not the whole
story!

~~~
ABCLAW
We already know the polymerase error rate is the dominant factor - Comparison
between various different polymerase error rates shows differences in error
rates span across a 6-7 orders of magnitude.

[http://www.jbc.org/content/279/17/16895.full](http://www.jbc.org/content/279/17/16895.full)

------
lkrubner
As I understand it, its already been mathematically proven that the efficiency
of a utility function declines with the search space, and there can be no
global optimum when the search space is infinite. When there is no global
optimum it becomes more and more important to have a novelty function that can
at least maximize the number of future possible local equilibriums, from the
current equilibrium.

The search space of "Every possible life form over 4.5 billion years" is very
large, so you would expect there to be a large reward for the right novelty
function. And this appears to offer proof of such a mechanism.

------
danesparza
Wow! This seems to be connected (in my mind, anyway) to another story on
Hacker News this morning: [https://www.nytimes.com/2018/01/29/health/heart-
disease-muta...](https://www.nytimes.com/2018/01/29/health/heart-disease-
mutations-stem-cells.html)

Couldn't the mutations in stem cells be linked to this 'mutational timer' in
DNA?

------
agumonkey
fascinating, disease/death or evolution/survival, two sides of the same coin

~~~
sitkack
If the old don't get out of the way of the young, how are the young to thrive?
Can't innovate if there is no space.

Waste, creates niches for organisms operate in, creating an ecosystem. 100%
efficiency makes it really hard for an ecosystem to bootstrap itself.

~~~
agumonkey
Interesting considering humanity strives for 100% and is nearing an all time
high in technological capabilities.

------
woliveirajr
> Such mismatches, though rare, could serve as the basis of genetic changes
> that drive evolution and diseases, including cancer.

The evolution part caught my attention. So we are generating some random
changes that can lead to evolution (not that all evolution is good or bad,
it's just different from the previous version).

And chemical processes are reprodutible, i.e., given the same conditions, you
get the same the result... but in a broader sense, DNA has some unstable,
changing configuration, where the molecules are constantly reshaping and can
generate different combinations.

Seems that it's not easy to recreate life from chemicals elements alone.

~~~
fabian2k
This is just another chemical process, tautomers of nucleic acid bases are
well known. Other chemical processes are just as random, but you almost always
look at an ensemble of molecules where everything is averaged already.

------
excalibur
I'm not saying this is going to lead to X-Men. But if you were going to
engineer some X-Men, this would be a good place to start.

