In a paper published in the journal Nature in 1993, Dr. Insel’s group reported that vasopressin is “both necessary and sufficient for selective aggression and partner preference formation, two critical features of pair bonding in the monogamous prairie vole.”

The paper was widely reported, and again put the mental health institute in the vanguard of a new area of research. But the agency was changing emphasis, phasing out its research into social behaviors. Dr. Michael Brownstein, the scientific director at the time, politely instructed his young research star to find another project — or another job. (The two are now good friends.)

He chose Door No. 2, and it took all of three months. Emory University was looking to replace the director of the Yerkes primate center, who was about to retire, and Dr. Insel was at the top of their list. He had already run a lab, as chief of the neurobiology division of the mental health institute, and his work with voles would diversify Yerkes’s portfolio, which then was focused on studying H.I.V. in primates.

He packed up his family and his voles, and moved south. “Acclaimed Researcher to Head Yerkes Center,” read the headline in The Atlanta Journal-Constitution on Aug. 20, 1994, the day the hiring was announced. “All I know is I had to go out and buy my first tie,” is how Dr. Insel tells it.

He quickly expanded rodent research at the center and also deepened his own work on the biology of attachment, with the help of an Emory postdoctoral student, Larry Young, who has since extended the research on his own. The work with voles effectively scotched the assumption that a complex behavior could not be reduced to brain biology. Oxytocin and vasopressin are now a focus of intense interest as possible modulators of social behaviors in other species, though the effects of such proteins are still a matter of debate.

His necktie came in handy at Yerkes. Between the march on his home in Decatur and other crises, the “psychiatrist who became a bench scientist,” as he has described himself, took on yet another role: He became a public official.

He was comfortable in front of audiences, relaxed with the news media, and willing to see at-home protests as part of the job, nothing to lose sleep over. The precociousness was long gone. By 2000, he had some well-tailored suits to go with his ties, a commanding view over his field, and some strong beliefs about how to improve its infrastructure.