[FRIAM] bilateria

[Santafe]

> On Jul 15, 2025, at 2:41, glen <gepropella at gmail.com> wrote:
> 
> Now, I'm sensitive to the argument that all this falls under parallax, even radially symmetric body types and the 9 octopus ganglia. And bi- vision, hearing, etc. is a simple form of parallax: triangulation. 

When I was a kid, there was some article (maybe Sci. Am.?) that I found wonderful.

It had to do with owl ear asymmetries, which are produced by tufts of stiff feathers at unequal positions in front of whatever feather-hood (or something) channels sound to the ear canals.

Upshot of the articles was that owls need resolution in the vertical as well as the horizontal, from phase, intensity, and packet-arrival-time differences (including what acousticians term the “head-shaped transfer function”, as I learned some decades later working among the acousticians for a few years).

Article claimed (I have no way to check without a dive to see what has been done since) that owls and people have about the same acuity in lateral position of a sound’s origin, if the sound has enough shape (so, not a clarinet) to cue from.  But people have terrible vertical acuity.  For owls, the vertical acuity is ballpark-comparable to the lateral.

Eric