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

[Ben Zaiboc]

On 24/03/2020 21:32, billw wrote:
> Someone asks me if nature or nurture mostly affects height and I say ...

You say "Sorry, you're asking the wrong question". Then point out why. 
Hopefully they'll realise that it's actually an invalid question because 
it assumes something false about the way biology works.

It would probably help to be armed with some examples of how environment 
modifies the genetic material, which can also modify the environment, 
etc., and how one gene can code for a product that's used in different 
ways in different places and times (haemoglobin might be a very simple 
example).

It's not even a case of imperfect execution of instructions, as several 
people here have said. Sure, that happens, but that's not the point. The 
point is deep and constant interaction between genetic material and 
metabolism, plus several different aspects of the environment, at 
different levels.

We might label a particular sequence 'the gene for height', but what 
does that mean when we discover* that actually it has a lot more to do 
with someone's ability to taste mint as having a cool sensation, as well 
as being intimately connected with nephron development in the kidneys 
and the propensity for developing tinnitus in later life? And almost 
certainly dozens of other things as well. One gene-product expressed in 
one tissue often has completely different interactions and effects to 
the same gene-product in a different tissue. Or the same one, at 
different stages of life.

Much more than facebook relationship statuses, biology actually does 
deserve the label "It's complicated". Simple answers rarely work, and 
simple questions are rarely applicable.

To go back to the original question, though, and what might be a 
reasonable answer, how about "Both. It's always both, never** just one 
or the other (or even 'mostly' one or the other)"? That would be a good 
start.
Asking if 'Nature' is more important than 'Nurture' is like asking "Is 
Warp more important than Weft?".


* I'm making these examples up, to illustrate the point. They aren't at 
all far-fetched, though, and we're finding out more all the time about 
just how damned complicated all this is.

** and of course, that's probably a simplification, as well!

-- 
Ben Zaiboc