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Does natural selection in humans work out in "best outcomes" or do subjective biases affect it? That is, how much is natural selection "guided by nature" and "guided by humans"?

E.g. given "fully rational" reproducers, then would the gene pool get increasingly better and produce better and better humans over time? Or is this somehow "independent" of "reasoning"? Such as that the natural selection does not follow all kinds of rationalizations.

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  • $\begingroup$ What do you mean by "bad traits" ? $\endgroup$ – Shred Jun 18 '18 at 11:19
  • $\begingroup$ @Shred Low-worth to community, low-skill and learn-ability, low physical fitness, unattractive physical features, sicknesses. $\endgroup$ – mavavilj Jun 18 '18 at 11:31
  • $\begingroup$ What do you mean by "better"? And how did you come to the conclusion that evolution produces "the best"? Evolution only produces that which is able to survive, reproduce, escape the predators (sufficiently enough) - and all of this better then those competing within the same niche (en.wikipedia.org/wiki/Ecological_niche). If the evolution "optimizes" something, it optimizes only those traits for which there is pressure of natural or sexual selection.I recommend you to read The Blind Watchmaker by Richard Dawkins. The book is popular, but gives the understanding of the basic principles. $\endgroup$ – Honza Zidek Jun 18 '18 at 13:43
  • $\begingroup$ @HonzaZidek I think that one could hold as an abstract ideal that evolution could be altered to lead to better, improved humans. If it doesn't do it on its own. And the reason is that better humans would be even more successful? Isn't science pretty much about improving humans? But there's the difference as to up to how much can humans affect evolution, and how much of it is beyond control by humans? $\endgroup$ – mavavilj Jan 22 at 9:03
  • $\begingroup$ I completely do not understand the term "better improved humans". All this "better" and "improved" is based only on anyone's biased view. Evolution does not operates with these terms. Evolutionary good = able to pass the genes forward. Evolutionary better = able to pass the genes forward for more generations, able to reproduce in larger scale (and still survive). Evolution-wise, our euro-american (= science-based) civilisation is not very "good", taking into account the decreasing fertility rate (worldpopulationreview.com/countries/total-fertility-rate). $\endgroup$ – Honza Zidek Jan 22 at 10:10
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That is, given "fully rational" reproducers, the gene pool would get increasingly better and produce better and better humans over time.

Environmental conditions change over time. What may once have been an advantageous trait in a human population may become deleterious in some form at a later time or different environment (i.e. by spatial migration).

Case in point: Central Africa is plagued with malaria, a disease caused by a parasite of the Plasmodium genus which infects red-blood cells (RBC). Sickle cell anemia (SCA) is a hereditary disease which can be deadly, unrelated in its cause and prognosis to the Plasmodium infection, BUT, it confers a resistance to Plasmodium infections due to the RBC of SCA-patients having an aberration in the shape of their RBC's. Here is a selective pressure caused by malaria that "promotes" the profileration of SCA in the local population. As a result, what you have is a large section of Central Africans that are Sickle Cell Anemics, whom have better survival rates than non-anemics in that environment. But if you take these anemics to northern Europe or North America, where malaria is virtually non-existent (spatial, environmental change), the anemics have a higher mortality rate than the rest of the local population.

You get what I'm saying?

Natural selection doesn't produce better and better humans over time - it produces humans that are better able to survive in that era, in that place.

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