metabolism for ALife

Played around a bit with Artificial Life software some time ago. Animals grazing fields and ants developing their sight.

The essence of it being like this:
A gene codes for the 'eye', with a parameter coding the distance the ant can see. The genetic algorithm creates new ants of which some can better survive than others, because they have the right 'sensitivity' to the (simulated) environment.

A few questions about this:
- What is sensitivity. It seems to require the 'physics' of the environment to be the same as that of the sense organ.
- No new senses can develop in this way, they are not encoded in the gene.
- Somehow this relates to 'embodiment'. Senses develop in a body because the body itself is sensitive to its environment that has the same physics as the body. The distinction between a body per sé and a specialized sense organ is a relative one.
- How is it that the body has the same physics and thus sensitivity? Because it is made out of the environment by a process called metabolism.

So, basically ALifers should attend more to eating and shitting.