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I saw some documents which were trying to say that they can prove via sweat smell selected by women that humans are developed to find a partner with similar genes. At the first glance, I refused it as absurd for many examples of organisms behaving in reverse but then I realized that I don't know any satisfying evolutionary explanation for this (and more: I could even explain the contrary: If less developed and more developed human had a baby, the better genes could be maybe annulled by the worse genes, on the contrary two very developed partners would have not only a lot of descendants, but their descendants would have also lot of descendants and so on.)

And more thing: if genetic diversity is truly evolutionary practical, could for example even people with genetically transmitted disease help our gene pool?

Thanks a lot.

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  • $\begingroup$ You should add a link to that document. $\endgroup$ – WYSIWYG Apr 25 '15 at 14:24
  • $\begingroup$ @WYSIWYG Sorry, I've seen it in TV and I can't find it anymore (apart from the fact that the document was in czech :-) $\endgroup$ – Probably Apr 25 '15 at 16:39
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    $\begingroup$ Identification of potential partners by body odors is actually selecting for different genes, not similar ones - see this article on "genetic matchmaking" for some additional details. $\endgroup$ – MattDMo Apr 25 '15 at 17:56
  • $\begingroup$ @MattDMo Yeah, that's what I though, in that document was definitely the contrary. $\endgroup$ – Probably Apr 25 '15 at 19:29
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Genetic diversity is indeed very important for many reasons, most notably resistance to diseases.

The Gros Michel banana used to be the most cultivated banana, until it was almost completely wiped out by a fungal disease due to lack of resistance in the genetically homogenous cultivars grown in plantations. As a result, it had to be replaced by the Cavendish banana across most of its former range by banana growers.

Furthermore, the answer is a definite "yes" to people with genetically transmitted diseases helping the gene pool.

For example, the case of sickle cell anemia clearly shows why even people with genetic diseases can help the gene pool by providing useful alleles. Heterozygotes for the sickle cell allele are resistant to malaria. This has led to the allele having a high propensity in subsaharan Africa, where malaria is endemic.

The first example of genetically controlled innate resistance to human malaria was the demonstration in 1954 that sickle-cell heterozygotes have less severe Plasmodium falciparum infections than do children with normal adult hemoglobin. This observation has been repeatedly confirmed, most recently by independent studies of genome-wide associations in severe falciparum malaria, which have identified the HBB locus as the major signal of association.

Additional examples are the cystic fibrosis gene, which confers resistance to cholera, and thalassemia, which confers resistance to heart attacks.

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