Kyle.

One particularly interesting question regarding this issue would by: why does Autism Spectrum Disorder (ASD) still exist? One in 68 children is diagnosed with ASD in the US. This should not be described as "rare". Theoretically, since individuals with ASD have social difficulties (which is what "autism" means; auto=self, -ism= condition or state,) they should have gone extinct. One explanation would be that the mutation that causes the condition is a point mutation, that is, a mutation of a single gene, but this is not applicable to ASD. Actually, ASD, as is the case with many other conditions affecting cognition and processing of the brain, is thought to be caused by abnormalities (or mutations) of many genes. According to Psychologytoday, there are similarities between the genes implicated in autism and genes thought to be related to high intelligence. Higher intelligence (within limits) could make the individual more favorable for reproduction, therefore passing on the genes that are related to intelligence and autism. This could explain why autism still exists. Another explanation would be that natural selection selects certain genes that favor survival and reproduction, and those same genes are either susceptible to mutations that can lead to ASD, or that they are themselves implicated in autism (like the genes that are related to high intelligence and ASD). Although the main goal for natural selection is to increase the frequency of traits favoring reproduction, some selected genes may actually lead to unintended consequences. That's why I wrote that almost all motivations and instincts could have been naturally selected for their reproductive advantage. It can go wrong sometimes. Natural selection chooses the relative best, not the absolute best traits for reproduction.

That’s correct. The example of the individual I explained above was only for clarification.

Not directly, but, indirectly, survival must be related to reproduction. If an individual has traits that contribute to his/her survival but is unable to reproduce, he/she won’t be able to pass on their traits. An individual could be born with an inborn disease that only gives him 2 years to live. This can happen because the incidence of mutations is not 0%. His trait won’t be as frequent as another fertile individual living for 80 years. Natural selection chooses the most effective traits (compared to other traits that existed) to be the most frequent in a group. Diabetes and other conditions that strike late in life shorten life (or survival) by about 8-10 years (in type 2 diabetes). Type 2 diabetes has a genetic factor, so it is subject to natural selection. This condition clearly affects survival, but, in average, it starts between 40-50 years of age. This means that an individual with traits that increase the likelihood of developing diabetes II can reproduce up until 40 years of age and pass on their traits (assuming that diabetes will affect their fertility, which does not happen in all individuals with diabetes).

I agree. But this was not the idea I was trying to present. The point is that when such traits exist, they could be related to reproduction somehow. I read in a book, and checked women’s responses on Quora about whether they found muscular men more attractive, and found that most of them do. Yes, not 100% of them, but most of them did. I tried to relate that to fertility. I think that most men, too, care about curvature and and other secondary sexual characteristics that are suggestive of female fertility. An interesting thing here is that some traits may become less common in the future because, for example, women no longer need a man to protect them. We have rules, bodyguards, self-defence weapons or tools, and police. I believe that this preference is more common in women living in less developed countries. However, I expect that it will never disappear because it is actually related to male fertility. I should exclude those extremely muscular men who likely use anabolic steroids because they actually decrease fertility. I think that the "sweet spot" for women is something in between because exercise improves fertility. (Although, I should admit that this last point was an assumption I made. I will look for researches and studies about this particular point.) On the other hand, money and a sensitive and considerate partner may be more important to some other people than strength. Both are related to reproduction. Another way of explaining individual differences: We inherently prefer partners that have similar personalities as ours. To relate this to reproduction, I assume it is because we understand others with similar personalities to ours more than others with different personalities, so it is more likely that the communication would be more effective and successful because, simply, she knows what he wants, and, therefore, an individual attracted to others with similar personalities would likely have a more successful approach and relationship (and reproduction) than another person attracted to others with different personalities than his. So, it could be that a man not being attracted to a very attractive female, that is, a female with more desirable sexual characteristics and more fertility is because he thinks that she is "out of his league."

Natural selection determines what genes are going to be more frequent. Preferred genes are the ones that help in reproduction because, simply, if a human being can not reproduce, he/she is not going to be able to pass their genes on to next generations. Therefore, the ultimate result of natural selection is genes (or combination of genes) that are the most suitable or potent for reproduction. This explains why most people that exist today are able to reproduce; they are prepared physically (have functioning sexual organs). Similarly, we are prepared psychologically. After all these years of natural selection of our genes (or combination of genes,) one should assume that the main purpose or goal of our motivations, whether we consciously know it or not, is reproduction. Natural selection must have chosen the combination of genes that was relatively best for reproduction as the most frequent one in our species. Behaviors and motivations must have been naturally selected. For example, the majority of people are social. We just like hanging out with others. We compete with each other, and, mostly, we compete against others of the same sex. Males inherently prefer females that have "more prominent" signs of fertility, such as lateral curvature, more feminine voice (which, by the way, is a sign of less testosterone levels, which is a hormone that negatively affects ovulation,) the feminine distribution of fats (in thighs and buttocks,) etc. Likewise, females inherently prefer stronger males, which could be a sign of more testosterone levels (and hence, better fertility,) men with deeper voices, etc. Those choices, behaviors or motivations are obvious and are directly related to reproduction. Could it be that other motivations and behaviors are less directly and less obviously related to reproduction? Could it be that all (or, at least, most) of our motivations have one main and ultimate purpose, reproduction? I am going to take some random examples and try to relate them to reproduction somehow. Eating, drinking, sleeping or basically any behavior contributing to our well-being and health: it leads to our survival; therefore, the chances of reproducing are higher than in people who are not inherently driven to eat, for example, who are either rare or do not exist. Being nice to and helping others: we have an inherent motivation to help other people who are suffering. It creates bonds with them and increases the likelihood of reproduction when compared to another group of people who are indifferent about other people's emotions. Work: Money --> Food --> Survival --> Reproduction Or Money --> Shelter or House --> Privacy --> Reproduction Or Money --> Better reputation and social status --> Attraction --> Reproduction Helping same-sex people: It could be because males and females express the same facial expressions when having the same emotions. However, one has to note that consoling the opposite sex, I think, has the priority. Also, it may increase the chances of survival of the suffering person. Thoughts?