“Hodi!” The old man called out the Swahili greeting.
“Karibu.” I put aside a letter home and welcomed him to my tent. “How are you, Oketch?”
“My head is very bad.”
The ibuprofen I’d brought to the chimpanzee preserve had become popular. I gave him two tablets.
“In our culture,” Oketch said, “we believe if we thank someone fo…