I have been persuaded for about 30 years by the idea that a strong light can be shed on modern human economic behavior by considering its biological basis. I wanted to otherwise stick to the usual theoretical methodology in carrying out this program. Research on this topic definitely wasn't short-run career optimizing, but it has been, and still is, tremendous fun to do something new.  Recently this research interest has been expressed as work on neuroeconomics. This field has the added attraction of being in close contact with direct observation.