[mannigfaltig]

I think, the main effect of sexual reproduction is that, much like GANs and competitive self-play, it creates species-internal competition: Both sexes need to impress, which makes cheating an obvious strategy (makeup, steroids, Shakespeare quotes, LISP etc., but many such examples can be found in the animal world), and hence both sexes also need to be able to detect cheating. Some species are rather asymmetric in that regard. For example, in humans it is mainly women who attract (they masquerade as fruits [make up is likely a cross-cultural phenomenon; and, well, breasts] tapping into male food gathering circuitry); men compete in hierarchies trying to impress and women select men from the top of the hierarchy. Complex dynamics emerging from this likely lead to the immense growth of the human cortex.

Sexual reproduction basically outsources some of the selection effort to the cognitive apparatus of the species itself, thereby introducing a massive amount of additional selection signals (mainly by the much increased necessity to model other minds, namely minds of the opposite sex). Many of these signals promote traits that are useful for survival (mainly intelligence and health).

[mfrye0]

I was thinking the same thing. I think it would be interesting to explore this area more and try to model it computationally.

Your point about physical features made me think of how physical attractiveness plays into human development as well.

Research has shown that beauty in humans is defined as physical symmetry. So "novelty" in our case might be defined as someone who is really ugly - the elephant man.

So in this case, beauty wouldn't really fit into the robot walking example as it's neither fitness (moving the foot forward) or novelty. More a different type of fitness that increases the odds of reproduction.

[mannigfaltig]

My guess would be that symmetry is a simple heuristic measure of physical fitness. Visual attraction is basically a strong regularizer that restricts the search space to phenotypes with particular traits. Asymmetry means that the joints wear out more quickly and muscles might not coordinate optimally leading to less strength and a reduced ability to hunt and to fight predators. AFAIK it is also a quite robust predictor of all kinds of diseases because it often means that the growth signalling is out of tune throughout the system. Visual selection basically performs environmental selection more immediately and more effectively: an asymmetric person might still survive, but its offspring has a lower overall chance to survive. The teaching signals of that are much weaker.

[mfrye0]

Good points. Never thought of it that way.