The irony is, that for so many years we have been lead to believe that the Caucasian is at the top of the evolutionary ladder; now we learn that they are the ones mucking-up the gene pool:
"Amerindians showed the lowest diversity in CGG repeats and DXS548/FRAXAC1 haplotypes. Some rare alleles, for example, the 148-bp (FRAXAC1) or 200-bp (DXS548) variants, which seem to be almost absent in Europe, occurred in higher frequencies among African Brazilians. This suggests a general trend for higher genetic diversity among Africans; these rarer alleles could be African in origin and would have been lost or possibly were not present in the groups that gave rise to the Europeans." Copyright 2002 Wiley-Liss, Inc.
"Daughters who receive the fragile X may appear normal or they may be intellectually disabled, usually to a lesser degree than boys with the syndrome. The transmission of fragile X often increases with each passing generation. This seemingly anomalous pattern of inheritance is referred to as the Sherman paradox." Wikipedia
"From their 40s onward, males with FXS begin developing progressively more severe problems in performing tasks that require the central executive of working memory. Working memory involves the temporary storage of information 'in mind', while processing the same or other information. Phonological memory (or verbal working memory) deteriorates with age in males, while visual-spatial memory is not found to be directly related to age. Males often experience an impairment in the functioning of the phonological loop. The CGG length is significantly correlated with central executive and the visual–spatial memory through regression analysis. However, in a premutation individual, CGG length is only significantly correlated with the central executive, not with either phonological memory or visual–spatial memory." Wikipedia
What if the same is true for the female. Trisome 21 is more likely to occur in infants born to 40+ mothers. Why is it so hard to imagine the "stronger X" getting weaker in 40+ women?
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