Once they discovered that the holes in the termite mount contained mustard, most of the chimpanzees at the Regenstein Center for African Apes were intrigued. But Hank couldn’t be bothered.

While adult females like Nana quickly learned to retrieve the tasty yellow goop using nothing more than twigs and chimpanzee intuition, the dominant male was sunbathing. And after a few days, when even youngsters like Chuckie and Optimus had gotten the hang of it, Hank was snoozing.

His indifference juxtaposed the excitement of his exhibit mates, who gleefully climbed atop the mound when it was first loaded in 2004, tested out a variety of twigs and attempted retrieving the goodies with tongues and fingers that proved too short to reach into the tubes holding the mustard, a chimpanzee treat. You can’t go fishing without a stick.

Elizabeth Lonsdorf, Ph.D., wasn’t surprised. “Hank’s behavior is what I would expect, given what we know about chimpanzees in the wild,” says the director of the Lester E. Fisher Center for the Study and Conservation of Apes, who published a  groundbreaking study about chimpanzee termite fishing. “Females tend to termite-fish much more often than males, and young females learn to termite-fish more quickly than young males. In the wild, adult males are typically the last to acquire a new cultural behavior, if they do at all.”

The chimpanzees, who had never been exposed to termite mounds before, were quick studies. After they mastered the basics, the tubes inside the mound were lengthened and curved to maintain the challenge for the apes.

And Hank, their leader, has mastered indifference. After nearly three years of exposure to the termite mound, he is still choosing to work on his napping technique, with the hint of yellow mustard in the air.