Re: [dinosaur] Theropod and bird lifestyles from ungual bone curvatures (free pdf)

["David Marjanovic" <david.marjanovic@gmx.at>]

Gesendet:ÂDonnerstag, 06. Februar 2020 um 22:53 Uhr
Von:Â"Dann Pigdon" <dannj@alphalink.com.au>

> On Fri, Feb 7th, 2020 at 3:11 AM, David Marjanovic <david.marjanovic@gmx.at> 
> wrote:
>
> > On the other hand, if the differences between left and right sides of the
> > same individual are real, they're telling us claw curvature simply isn't 
> > 100%
> > genetically determined. What's not genetically determined isn't heritable 
> > and
> > isn't accessible to natural selection.
>
> That final sentence isn't strictly the case. Epigenetic studies have muddied 
> the waters of heritability in
> recent decades.

Yes, but to a smaller extent than what every single media report made it sound 
like. Histone modification is indeed heritable and not genetically determined, 
but it's also modifiable again, so it doesn't generally last beyond one or two 
generations.

> Learned behaviour (i.e. 'culture') can also be passed down to offspring, or 
> indeed to any group member
> regardless of genetic affinities.

Yes, but that's not likely to affect claw curvature (except by wear, which 
should be visible even in 2D fossils that are well enough preserved to retain 
the keratin in the first place).

> Also, a genetic predisposition towards phenotypic plasticity might be 
> positively selected for in complex or
> highly changeable environments.

It is, absolutely.