They checked the offspring's DNA to see how the frequency of different versions of their genes shifted compared with those frequencies in the parents. (sciencemag.org)
To try to determine how those changes influenced the gene's function, that group put the human version of the gene in mice. (sciencemag.org)
Then they slipped a human version of each gene into yeast cells whose own copy of the gene had been turned down, turned off, or removed. (sciencemag.org)