Funny enough, despite the deep sense of resentment in the original comment, it's actually kind of accurate.
Lower social standing is often associated with changes in cytokine expression mediated by cortisol signalling, and changes in cytokine expression and cortisol signalling are closely linked to depression (it looks more and more like at least some cases of depression are immunological in nature). There's a possible evolutionary advantage to inhibiting cortisol downregulation through glucocorticoid resistance (this is linked to depression) in situations where individuals would be in "defeated social positions." However, the theory goes that those situations and the related glucocorticoid resistance are not meant to be long term systemic changes, merely short term ones, and long term use of this feedback mechanism results in depression. I am hungover and running purely on modafinil at the moment, so I am unable to eloquently explain and I'll link a paper.
So, to the extent that anti-depressant drugs are based on observed changes to molecular signals in the brain (that's how SSRIs came about), and that those changes in the molecular signals are due to essentially a miswired social cue, the original comment is correct.
Here are some papers:
glucocorticoid resistance, depression, cytokines (this is a great paper): http://www.europeanneuropsychopharmacology.com/article/S0924...
evolutionary perspective on cytokines and depression: http://www.sciencedirect.com/science/article/pii/S1471490605...