Hi EricC

I will drop out of this soon because of time conflicts.  But an edit or two 
below:

> On Mar 31, 2026, at 15:47, Eric Charles <[email protected]> 
> wrote:
> 
> I'll also note that "function" can't do the work on its own to explain 
> evolution. We still need to know why some functions are favored by selection 
> and others are not. EricS seemed to indicate that we assess "fit" by 
> determining if animals are "happy"….

In this case, no.  Exactly not that.  The long tedious first post from me was 
an objection to vague gestures at what “fit” means, using “happy” as an example 
of vagueness.  The aim in the passage was to explain the role of Fisher’s 
supplying specific constructions of summary statistics defined on instances of 
population processes.  

Not to say that we have to do things Fisher’s way; I had other comments on that 
question.  Rather, to say that one doesn’t generate a tautology by first 
providing a definition of what quantity you are pulling from data, to which you 
are trying to fit a regression model.

> but the metaphor of "fit" is like a key in a lock. To explain evolution you 
> need the matching of form-and-function-to-a-particular-environment.  That 
> matching *sometimes* increases reproductive success, and *sometimes* the 
> traits in question are hereditary. 

All the sometimeses and hedges are certainly right.  I didn’t belabor them.  
But for sure, if one writes regression models, it is because there is supposed 
to be data scatter that the model isn’t trying to account for.  Also the other 
comments here and there in the threads about all the things that one or another 
regression model will leave out; where they go in a Price equation 
decomposition, and the question of whether your regression model falls apart 
when some formerly-unconsidered dummy variables are added.


I didn’t end up saying as much about flavor text in these threads as I guess 
the main thread would have motivated.  I guess that is because I got 
sidetracked on trying to provide language for an account of what geneticists 
and others are doing, behind the various human-language terms, since it wasn’t 
clear to me that all that was familiar.

> Population genetics combined with field research can be very powerful along 
> those lines, but the math of population genetics on its own, floating out in 
> the ether, can't do it at all. 

Again, yes.  Both of the last two replies to Nick today were meant to say 
something specific about those limitations.

There is _much_ more that can be said.  A regression model at all is, only in a 
_very_ generous widening of the notion of “causation”, a “causal model”.  But I 
have comments littered here and there in the messy posts about how other 
domains in functional biology go after those other forms of descriptions.

Anyway, I agree with you; time for me to stop.  I will hope that in there, 
there was some commentary on extant practice that Nick will at some point find 
useful.

Eric


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