My Take on the Law of Accelerating Returns (myLAR) - Part I - Runaway Sexual Selection

by phil on Friday Sep 19, 2003 12:19 PM
Law of Accelerating Returns, evolution_old

My conversion from Catholicism to Agnosticism coincided with my first exposure to Darwinian natural selection in the 9th grade. In Natural Selection I saw the beginnings of what seemed like a better sketch than Christian genesis. However, I had my doubts about Natural Selection; Darwin's theories still made it seem like it would take forever to bore out only average or gray species. How was this simple thing supposed to ever spontaneously produce life, or create something as complex as the eye?

These questions remained unaswered for me until I read Kurzweil's Age of Spiritual Machines, wherein I first learned about hidden mechanisms and algorithms laced within the structure of order and time that showed how rapidly increasing complexity was the rule.

This begins the first of a long-series--hopefully daily--of metaphors and vignettes that will make you feel more confident about the power and truth of the law of accelerating returns.

The first one that's simple is runaway sexul selection. Sexual selection is a subset of natural selection. This is a process where features are selected for during the mating process, such as having big muscles or colorful plumage.

Here is an excerpt from Introduction to Evolutionary Biology

Evolution can get stuck in a positive feedback loop. Another model to explain secondary sexual characteristics is called the runaway sexual selection model. R. A. Fisher proposed that females may have an innate preference for some male trait before it appears in a population. Females would then mate with male carriers when the trait appears. The offspring of these matings have the genes for both the trait and the preference for the trait. As a result, the process snowballs until natural selection brings it into check. Suppose that female birds prefer males with longer than average tail feathers. Mutant males with longer than average feathers will produce more offspring than the short feathered males. In the next generation, average tail length will increase. As the generations progress, feather length will increase because females do not prefer a specific length tail, but a longer than average tail. Eventually tail length will increase to the point were the liability to survival is matched by the sexual attractiveness of the trait and an equilibrium will be established. Note that in many exotic birds male plumage is often very showy and many species do in fact have males with greatly elongated feathers. In some cases these feathers are shed after the breeding season.

In this model, features can explode out of nowhere. For example, among human populations, there could be various subpopulations with different preferences for male height. In one particular subpopulation for example, the women could favor men who were at least one standard deviation above the mean. Over time, this would pressure the mean height to rise. If this increase were successful for this subpopulation in its survival rate, then this preference for height would propagate to other human subpopulations.

This illustrates a sexual selection based on intraspecies relativity, and not just feature-existence. By women having a preference for the best of a group, a consistent pressure for quality-increases emerges. Eventually, the utility of the quality-increases could surpass its use for survival. Well, having a knack for speedy quality-increases could be what gives a certain species a competitive edge over other species.

This also makes it obvious how intelligent homo sapiens could have evolved from not so intelligent ape-like ancestors. If subpopulations of women (or men) continuously favored the handful of smart members of their group, then the overall mean intelligence would drift up.

To further accelerate this process, throw in the growing ease of communication among humans throughout history (dark ages excluded). The more connected we became, the faster trophy mates would become norm, giving rise to a higher standard for trophy mates. Even today, celebrities probably get laid the most for (previously) good evolutionary reason. A phenotype that is celebrated the most by a species should have its genotype spread proportionally as well in order to improve the overall quality of the species.

The impact of increased connectivity on evolution would be an example of a network effect. More on this later.