[7] After completing his PhD at Caltech and a postdoctoral fellowship at Harvard University working with Jim Watson, Davis joined the faculty of Stanford's department of biochemistry in 1972.

[14] Davis, with David Botstein, Mark Skolnick, and Ray White developed the method[15] for constructing a genetic linkage map using restriction fragment length polymorphisms that enabled and led to the Human Genome Project.

Dr. Davis is the director of the Scientific Advisory Board at the Open Medicine Foundation, a non-profit organization, whose goal is to fund and initiate research into chronic complex diseases.

“The small device that Davis and his colleagues created was originally developed to detect changes in electrical signals when cancer cells were exposed to different treatments.”, as described in Stat News.

People with this disease are described as not using energy well and taking a long time to recover from energy expenditure; “the researchers decided to mimic this by stressing cells from 20 healthy controls and 20 ME/CFS patients by exposing them to increased levels of salt.”[19] Rahim Esfandyarpour, lead author of the paper, said “When they [cells from ME/CFS patients] face this new environment, their reaction is different than the reaction of healthy cells.”[19] Davis's research became more urgent and important after Dr. Anthony Fauci warned that some COVID-19 survivors showed symptoms in line with those of ME/CFS.

According to Fauci, "a considerable number" of COVID-19 survivors struggle with extreme exhaustion, memory lapses, and cognitive difficulties many months after they have been officially cleared as recovered.

Davis is part of a high-level interagency work and research group with the Centers for Disease Control and Prevention (CDC), National Institutes of Health, the Veterans Administration, and the Department of Defense looking at the long-term consequences of COVID-19 and Long COVID.

Dafoe's need for treatment is the motivation for Davis to direct his medical and scientific research efforts toward this disease; he dropped all other projects in hand before his son became so ill.[17][8]