I remember reading Prozac Nation years ago and being profoundly moved by Wurztel's accounts of chemical depression, and how medication just wasn't cutting it for her. I think we have to take science as a: best guess discipline, much in the same way that religion requires a little faith. We all have massively different levels of serotonin and it is used to explain away a variety of behaviours and maladies. I like the old introvert/extrovert one. That theory goes that introverts have too much serotonin flowing and extroverts have too little. Essentially introverts are constantly alert and thinking and are highly stimulated by the world around them. Any form of extra information, like noise or social groupings causes the introvert brain to shut down because it can't handle any more serotonin. The extrovert by contrast is therefore a bit of a dullard who doesn't have very much serotonin and needs to seek out thrilling experiences to make life seem to have any sort of stimulating point to it. Introvert: overbalance. Extrovert: underbalance. Sounds like a load of old nonsense, right? Well, scientifically it is highly observable. As is the old chemical imbalance theory in depressive people. It doesn't mean it is true. It doesn't mean it is false. I am starting to read more Ben Goldacre, and more about scientific statistical proof, as I feel this is where the future path of scientific truth lies.
My experiences of modern science are that we are applying new techniques and new words to achieve the same aims as medicine was try to achieve before. We don't blood let to reduce/remove pressure, we use pharmacology. We don't believe in phrenology, but use MRi to achieve the same/similar belief that functioning is localised. I hold my head in my hands as my professor bangs on about Broca's area in one sentence, then talks about connectionist modelling with the next. WHICH IS IT TO BE? We still really cling to the same biological and physiological beliefs, we just use new technologies, new words, and new treatments to describe what is going on. New wallpaper on top of old wallpaper.
So I say again, science is the stuff of best guessing. Whilst we may only have a hammer and everything may only look like a nail, people still want some sort of solution thrust at them for what is going on with their body and science is trying to be the best hammer it possibly can be when people arrive with nails sticking out, wanting them banged back in.
Side note: I read yesterday that before we had street lighting we hairless humans used to sleep in two shifts during the 24 cycle. Once the world became lit 24 hours a day we switched to this 8 hours sleep pattern that we have now. This was accompanied by the notion that lying about in bed is a massive waste of your time. This may be unnatural and could explain why we seem more stressed and uptight as a species now. Not enough quality rest, and not enough time to introspect between each sleep period.