Carl Zimmer in The New York Times:
In 2015, while working as an undergraduate researcher at the North Carolina Zoo, Laura Lewis became friends with a male chimpanzee named Kendall. Whenever she visited the chimps, Kendall would gently take her hands and inspect her fingernails.
Then she disappeared for the summer to study baboons in Africa. When she returned to North Carolina, she wondered if Kendall would still remember her face. Sure enough, as soon as she stepped into his enclosure, Kendall raced up and gestured to look at her hands. “The feeling I got was that he clearly remembered me after four months away,” said Dr. Lewis, now a comparative psychologist at the University of California, Berkeley. “But I didn’t have the data to prove it.” Now she believes that she does. In a study published on Monday, Dr. Lewis and her colleagues have demonstrated that chimpanzees and bonobos can recall faces of other apes that they have not seen for years. One bonobo recognized a face after 26 years — a record for facial memory beyond our species.
More here.