chemical love

I recently came across an article (thanks Jason) linking levels of a certain neurotrophin, nerve growth factor (NFG), to being in romantic love. granted, I'm neither a neurophysiologist, nor a brain expert, nor a statistician, but their conclusions seem a little too strong. if you take a look at their scatter plot, it looks to me like just a bunch of random noise through which they have drawn a regression line. besides that, people have been shown to score highest on the PLS (passionate love scale) during the first 6 months of a new relationship. I mean, I guess that's the point of regression, to do mathematically what we can't see with just our naked eye in a plot of the data. but their results just seem to strong.

the authors do go into some of the problems with the study in the results section. they sort of touch on one of my main problems, but they don't go into it in any detail. basically, love of any sort, be it romantic, long term, whatever, is an incredibly complex and multifaceted experience. I find it hard to believe that a score on a psychological test such as PLS could be linked to the level of some neurotrophin. I mean, part of the premise of human behavior (as I understand it) is that the mind is an emergent process from the brain, because we can't see the direct correlation between low level functions and high level observable behaviors. maybe this is evidence against that viewpoint, but I still remain unconvinced. anyone out there want to persuade me?