[LMB] Gene cleaning in real life

Marc Wilson marc.wilson at gmx.co.uk
Tue Nov 14 13:58:14 GMT 2017

On Mon, 13 Nov 2017 18:15:01 -0500, Matthew George <matt.msg at gmail.com>

>Although needing eyeglasses is, like almost any trait we can imagine,
>linked to genes, it's surprisingly not-controlled by them.  The best
>explanation I've heard is that our physiologies "expect" us to spend a
>great deal of time in relatively bright light, and the growth of our eyes
>is actually dependent upon that condition.  Spending lots of time indoors,
>where 'bright light' is much dimmer than conditions outdoors, seems to be
>highly correlated with the malformations of the eyes responsible for
>nearsightedness and farsightedness.

The other issue about being indoors a lot is that you spend much less
time focused on "infinity" (which for all practical purposes is a couple
of hundred feet), unless you live in a massive mansion, of course.

Farsightedness comes in two flavours, too: you can have it from a very
early age, due to a misshaped eyeball- or there's the sort that
inevitably creeps up on you with age, as the eyeball loses some of its
elasticity and thus its ability to accommodate to different focal
lengths.  This is also a process with variable speed, but it will get us
all in the end if we live long enough.  A treatment to slow that down
would be fabulous.
>It might be possible to select for alleles that screw up that developmental
>process.  Much the same way we might select for mutations which interfere
>with the careful feedback our muscles and bones use to remain strong enough
>to meet ordinary needs while not expending vital resources, so that we
>wouldn't be affected by low gravity and wouldn't need to exercise to
>maintain muscle tone.
>Whether those changes would be truly adaptive in the long term is an open,
>and very difficult to answer, question.

The problem with creating "lazy" genes like that is that there is little
evolutionary pressure to keep them, except under difficult
circumstances.  If we engineer for "no-exercise" muscles and
simultaneously engineer our society to eliminate most of the exercise,
these genes can be lost without real consequence. 
A train stops at a train station, a bus stops at a bus station.
On my desk is a workstation ...

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