Natural Selection and Mating

Imagine if you will two Dingdongs: Dingdong A and Dingdong B. What species of animal a Dingdong is is irrelevant (mostly because I just pulled it out of thin air). Dingdong A and Dingdong B are completely identical in all ways except for one: Dingdong A is feisty when it comes to partnering and mating, whereas Dingdong B is indifferent. Both Dingdong A and Dingdong B have the same machinery for producing offspring; however, Dingdong A has a drive to find a mate, while Dingdong B will do it only if the opportunity arises.

Assume that the children of both Dingdong A and Dingdong B have an equal probability of growing to sexual maturity - who do you think will produce more children?

I would venture to say Dingdong A. Dingdong A will "beat out Dingdong B to potential mates. So while Dingdong B sits around and takes a mate when he/she can, Dingdong A is out and about actively seeking a mate.

So now let's say that we start with a population of 50% Dingdong A and 50% Dingdong B. What will happen to this population? Over generations, it will slowly shift to become Dingdong A heavy and Dingdong B light. Who knows, maybe Dingdong B will disappear. It isn't that Nature "desired" one over the other, or one was intrinsically better than the other. Random chance has given us two characteristics: feisty and non-feisty. Over time, one characteristic is better able at producing descendants than another. More descendants, more evolutionary success, more of your genes out in the gene pool.

This hypothetical example shows that an animal with a drive to attain a mate is going to be selected for over against an animal without a drive to attain a mate.

What's the point?

Well, twofold. First, it shows how evolution could work in simple, observable terms. Second, it shows a possible reason why we humans actually desire a partner and a mate. It just may be a parting gift from one of our ancestors.