One point Temple Grandin made in this book had to do with opioids. As she described it, it appears that "normal" people are born with different levels of endogenous opioids than autistic persons are. The opioids in question tend to keep people's moods high. A person with naturally-occuring high levels is going to be less likely to seek out companionship with other people. Social contact, and touching especially, raises levels of opiods.
Here's where it get sticky for me. I believe that these substances are manufactured by the body and a person will not have a set amount at any one time. So perhaps what she means is that an autistic person may tend to manufacture more of them on a regular basis.
I read somewhere - don't remember what or when - that people "need" to connect with other people at least seven times in a day. These connections can be very short. A "hi" or a comment at a checkout counter, for example. If I am at home all day I tend to feel the urge to go out to be among people. I don't need to seek out a close personal relationship. I don't need a friend. I have noticed, though, that Paul rarely goes out. He'll go out for beer or cigarettes or groceries now and then. Not every day. So I have wondered why he does not feel the need to get out. Could it be that he is manufacturing more of these opiods than most of the rest of us do? For that matter, is this why I may not need to be social? Because I really am okay on my own?
I looked up "opioids" and then "endogenous opioids" on the web and most of what I got was about pain-relieving drugs. I was looking for more about this social connection. I suspect it's there but it's harder to find.