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== Rise in mutations ==
Some evidence suggests that there are more people with deleterious mutations in the human population due to a number of factors, including but not limited to: milder ecological conditions, modern medicine, tall, athletic, high IQ, and or masculine women not contributing to the gene pool by reproducing, leading to a smaller pool of genetically masculine men in modern societyas well as a smaller number of fertile females, smaller family sizes<ref>https://www.ncbi.nlm.nih.gov/pubmed/9371795/</ref>, advanced paternal age<ref>https://www.spectrumnews.org/news/parental-age-different-impact-autism-schizophrenia/</ref> and especially due to much lower infant mortality.<ref>https://doi.org10.1007/s40806-017-0084-x</ref>
Given the complex nature and function of the human brain, one would expect it to be particularly vulnerable to deleterious mutations,<ref>https://www.ncbi.nlm.nih.gov/pubmed/23153596/</ref> which may be reflected in the apparent rise in the prevalence of Autism Spectrum Disorders, as it has been argued that up to 30% of cases of this condition in simplex families (where only one member has the condition) could be attributed to ''de novo'' mutations.<ref>https://www.ncbi.nlm.nih.gov/pubmed/26401017/</ref>
Extrapolate of the rate of deleterious mutational load in mice and other organisms has led to a rough estimate of a 1% decline in the baseline physical and mental performance attributes of populations in conditions of extreme relaxed selection pressures (both natural and sexual) per generation. This estimate may be overly conservative, however, particularly in regards to brain function.<ref>https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4788123/#bib64</ref> Some researchers have also argued factors that decrease deleterious mutational load in populations, such as reductions in the rate of [[inbreeding depression|inbreeding]] and pre-natal therapeutic fetus selection (the abortion of offspring with severe abnormalities revealed through pre-birth screening) may serve to counteract these effects somewhat.<ref>https://www.researchgate.net/publication/323320480_Relaxed_selection_and_mutation_accumulation_are_best_studied_empirically_Reply_to_Woodley_of_Menie_et_al</ref>

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