Analyze each of the following investigations, or arguments, and indicate which of the methods of causal reasoning—Mill’s methods—are being used in each of them:

The sequence of DNA units in the genome of humans and in that of chimpanzees is 98.8 percent identical; humans and chimps shared a joint ancestor as recently as five million years ago. Relatively few genes, therefore, must define the essence of humanity, and biologists have long supposed that if they could identify genes that have changed in the evolutionary advance leading from that joint ancestor, they would better understand the genetic basis of how people differ from chimpanzees, and hence what makes humans human.
This project received a significant boost in 2001 when a large London family with barely intelligible speech was found to have mutations in a gene called FOXP2.
Chimpanzees also have an FOXP2 gene, but theirs is significantly different from ours.
The human version shows signs of accelerated evolutionary change in the last 100,000 years, which suggests that the gene acquired a new function that helped to make human speech possible.
—Reported by Dr. Michelle Cargill of Celera Diagnostics, Alameda, CA, and Dr. Andrew Clark, of Cornell, in Science, 11 December 2003