Dr. Michael Lewis of Cardiff University had people evaluate more than 1,200 photographs of white, black and mixed-race faces on attractiveness.
"A random sample of black, white, and mixed-race faces was collected and rated for their perceived attractiveness," Lewis said in a statement. "There was a small but highly significant effect, with mixed-race faces, on average, being perceived as more attractive."
British naturalist Charles Darwin said in 1876 that heterosis is a biological phenomenon that cross-breeding leads to offspring genetically fitter than their parents and this may apply to humans as well, Lewis suggested.
"There is evidence, albeit anecdotal, that the impact of heterosis goes beyond just attractiveness," Lewis said.
"This comes from the observation that, although mixed-race people make up a small proportion of the population, they are over represented at the top level of a number of meritocratic professions like acting with Halle Berry, Formula 1 racing with Lewis Hamilton; and, of course, politics with Barack Obama."
Lewis presented his findings to the British Psychological Society's annual meeting in Stratford-upon-Avon, England.