A xenobiologist decided to study the mating behaviors of many other races from the the weakest havenworlders to the strongest deathworlders. However, when it came to ... ah... HUMAN mating behaviors, well, things just got weird! -- DaniAndShali
It was the study of centuries, greatly aided by just hanging out in various public zones of crossroads stations and people-watching. Of course, the more invasive aspects of the study were a matter for each species individual fictions and documentaries. This study was about the social aspect of things, not the physical act of mating.
If two cogniscents were trying to attract each other, the reasoning went, it was wise to know how all species preferred to do so. One being's flirting, after all, was someone else's deadly insult. A little cultural understanding between various peoples was always a good thing.
As far as sociological studies went, it was doing very well. Havenworlders were generally straightforward with each other, and most species had stopped messing about with various manipulation games by the time they got to space.