Chewing the Qat in Yemen

Winston Churchill once illustrated the comparatives, bad, worse, worst, with a parallel, 'lies, damned lies and statistics.' I was reminded of this recently while wandering in the rocky hills of Yemen where, at first glance, you'd suspect that some dietary deficiency afflicted the locals with physical disfigurement. You can accept that no well-dressed tribesmen would be seen dead without a phallic rhino-horn handled knife in his belt and an AK47 on his shoulder, but why did they all have one