From The NewYorker:
Such images, according to AverageExplorer’s creator, Alexei Efros, a philosophically inclined professor of electrical engineering and computer science at the University of California, Berkeley, have a long cultural history. They were pioneered by Sir Francis Galton, a cousin of Charles Darwin, who is perhaps best known today for being the father of eugenics. In an attempt to characterize the facial characteristics typical of criminals, he created what he called “composite portraits” by “throwing faint images of the several portraits, in succession, upon the same sensitised photographic plate.” He published his methodology in the journal Nature in 1877, noting, It will be observed that the features of the composites are much better looking than those of the components. The special villainous irregularities in the latter have disappeared and the common humanity that underlies them has prevailed.