Subject to natural selection

2012/05/17 Carton Virto, Eider - Elhuyar Zientzia

• Eboluzioa

Is modern man still subject to natural selection? Or has it escaped through culture and technology? It is a repetitive question that, from time to time, takes effect when some evidence is presented in favor of one or another hypothesis. This is due to a work published in PNAS magazine earlier this month. This paper analyzed the experiences of 5,923 people born in Finland between 1760 and 1849, in order to check whether the evolution of these human groups coincides with the characteristics of populations subjected to natural selection. And the quick answer is yes.

Specifically, the main screens of natural and sexual selection have been crossed with the data collected in the registries: survival, procreation, reproductive success and fertility (number of reproductive descendants) until the fertile age. For tax reasons, the then Finnish church collected in detail all births, deaths and marriages, and researchers have been able to fully monitor the genealogy. Being monogamous populations, who seriously thought not to act like this, researchers have been able to take weddings as an indicator of procreation.

The results of the crossing show that the variability measured in the four parameters coincides with the usual of populations suffering from natural selection. And despite the monogamous populations, the predictions of the theory of sexual selection were fulfilled: the most severe sex (in this case, men) presented a greater variability in success and reproductive success, and a greater link between the two previous parameters.

According to the researchers, the measurement of this type of results in monogamous populations living from agriculture and fishing is wrong if it is considered that the influence of natural selection had long been eliminated. “Successive monogamy and agriculture would limit selection options, but analysis shows that it still has enough space to act,” they said.

In fact, agriculture has been considered man's first blow to natural selection. The passage of hunting and collecting what nature gave to social systems that could sow and grow, triggered the existing ecological balance. The strongest and most definitive blow has been technological and medical development since the industrial revolution. According to this hypothesis, the capacity for technological, medical and cultural adaptation has rendered meaningless the system of selection guided by the differential survival of the most suitable that arose according to the laws of nature.

For example. Suppose a good vision influences our survival and reproductive success; without glasses or laser intervention, the genetic agents of poor vision would tend to disappear from the human gene group. However, technology removes the selection pressure from the equation to eliminate these genes, thus disappearing the advantage of individuals with good vision and the raw material of natural selection.

If this simple example extends to all the complex aspects of the way of life surrounded by culture and technology, it seems almost inevitable to conclude that we do not depend on natural selection. In addition, the equation of natural selection to the law of the strongest and the social misinterpretations that have been made of the laws of natural selection also make it desirable before many.

Beyond the West of visual metaphor, critics of elimination do not believe that modern life has eliminated classic selection pressures. They say they are softer, but still there, and they insist that modern life would generate others that are not yet measurable through changes in the environment, the effect of obesity on fertility... The question is that being outside the question makes it difficult to find an answer.

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