WHO says scientists don't have a sense of humour? Over drinks the other night with an egghead from the Smithsonian Institute in Washington DC, we listened with interest as he recounted his research into the love life of elephants. Our biologist friend was on his way back to the US after an exhaustive - and, by all accounts, exhausting - study of Sri Lanka's elephant breeding programme. ''It was a remarkable assignment,'' our contact said, shaking his head at the memory. ''I enjoyed it thoroughly, even though it has given me an incurable inferiority complex.''