[ExI] Evolution - Nature versus Nurture, but random noise as well

[BillK]

Nature Versus Nurture? Add ‘Noise’ to the Debate.

We give our genes and our environment all the credit for making us who
we are. But random noise during development might be a deciding
factor, too.
March 23, 2020

<https://www.quantamagazine.org/nature-versus-nurture-add-noise-to-the-debate-20200323/>

Quotes:
Nine-banded armadillos always have litters of identical quadruplets.
Researchers are now taking advantage of that system to study
nongenetic sources of variation among individuals.

Everything not chalked up to genetic control tends to get attributed
to diverse environmental factors, ranging from nutrition to stress to
idiosyncratic social interactions. It’s a line of thought that
“suggests that it must be something outside the organism,” said Kevin
Mitchell, a geneticist and neuroscientist at Trinity College Dublin.

But proof abounds that this is not entirely true. Identical human
twins who share both a genome and a home don’t look or act exactly the
same. A mutation that causes a disorder in one might not in the other.
Twins even have different fingerprints.

Research is making it ever clearer that these differences can’t all be
written off as unexplained environmental effects.

Which leaves noise — the random tremors and fluctuations that
characterize any biological process. “Noise is inevitable,” said
Andreas Wagner, an evolutionary biologist at the University of Zurich,
“an inevitable byproduct of life.”

“The genome is not a blueprint,” Mitchell said. “It doesn’t encode
some specific outcome. It only encodes some biochemical rules, some
cellular algorithms by which the developing embryo will
self-organize.” Molecules bounce around and interact in a cell,
binding and pulling apart and diffusing at random. The processes that
make proteins and turn genes on and off are subject to this “molecular
jitter in the system,” as Mitchell calls it — which leads to some
degree of randomness in how many protein molecules are made, how they
assemble and fold, and how they fulfill their function and help cells
make decisions.
etc.
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Long article, but worth a read.

BillK