Friday, January 21, 2011

DNA, Game Theory and Risk in partner selection....

This is quite thought provoking.  There are a slew of confounds and different directions to take the research... but that's not what interests me initially.

I was interested in the two types of graph patterns that were being discussed. Not if they were correct, just the thoughts that I had trying to explain them.

Firstly, the two profiles are essentially the "Normally Attractive" and the "Split Hot or Hate" shapes. It got me thinking about DNA and partner selection along with some game theory.

The first point is how to explain the "Split Hot or Hate" graph.

If we assume that the "Normally Attractive" pattern represents a female partner who has effective enough genes to be successful in the current environment. This means that her DNA has been selected for and reinforced across a significant part of the population enough to be considered the "normal" look. (This also assumes that appearance and whatever else was being overtly or covertly evaluated by the fairly simple measure is tied directly to DNA or social DNA... anyway)
So people who are outside this "normal" are aberrant in some way. This may be because they express non-normal characteristics.  Now if the environment is static, then the conservative strategy for picking a mate would be to always pick a "normal" mate and work on the assumption that others have taken all the risks and normal is good enough to survive.  The higher risk strategy is to look for someone who exceeds normal in some fashion and try to breed with an exceptional partner.

However in the event that the environment is not stable, picking a "normal" is no longer the risk free or conservative strategy. Because "normals" are adapted for the environment that was previously stable and may not be so tomorrow. (The question is if our DNA is smart enough to express that kind of strategy via testosterone or just uses blind selection to deal with this scenario.... which is simpler do you think?)

So how does this explain the "Split hot or hate" pattern?  I would suggest that risk taking in mate selection is essential for a healthy population and the ability to explore different mutations. But its probably only valuable if a small-ish part of the population engages in these risky ventures. The rest of the population should be steered toward only breeding with "normal" partners and avoiding anyone "abnormal". This way the population should have a large central pool of "normal" stock with a smaller pool of mutants ready to take advantage of any useful mutations or environment changes. So these graphs represent the difference between "normals" and "abnormals". While the "normals" get a response pattern that suggests they are acceptable to conservative and risk taking partners, the "abnormals" are either highly attractive to risk taking partners or highly repulsive to conservative partners.

This study is possibly more interesting because it was done on the male response to female potential mates.  The dis-equality between the male and female illustrates just how wildly different mate selection is on the two sides of the fence.
The cost to a male of breeding is relatively tiny if there is no husbandry involved. While the cost to a female is potentially a year or so of her life or ~ 1/15 - ~1/20th of her possible breeding events(Assuming starting breeding about 15 and being fertile until mid to late 30s).   So for Males to breed with a female outside the "normal" pool is fairly low cost/low risk. While for females its a much higher cost, but with the same risk.

Once you involve husbandry and the social conventions of mating, it gets much more complex but the underlying biology is the same.

I would predict that a similar study from the female point of view would show a similar pattern for the "normal" pattern males but a much smaller percentage of "hot" ( high risk but worth it) types and a much larger percentage of clear "hate" group.

This reflects the percentage of "conservative" choices being higher for women due to the cost and risk of breeding with an "abnormal" being higher.

It would be interesting to break the scoring given to each partner down into a set of finer grained plus or minus scores. IE.

Like their profile information  (score 1-5)
Like their picture (Score 1-5)
Overall like ( Score 1-5)


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