This 2014 video says about itself:
How to speak monkey: The language of cotton-top tamarins – Anne Savage
The cotton-top tamarin is a very vocal monkey — the species communicates using a sophisticated language of 38 distinct and grammatically structured calls! Anne Savage teaches a few of these chirps and whistles, taking us through a day in the life of Shakira the tamarin (using sounds pulled from the wild) as Shakira signals to her family, talks to her food and warns against potential predators.
Lesson by Anne Savage, animation by Avi Ofer.
By Bruce Bower, June 26, 2020, at 2:00 pm:
Monkeys may share a key grammar-related skill with humans
A capacity for recursion evolved early in primate evolution, a contested study suggests
An aptitude for mentally stringing together related items, often cited as a hallmark of human language, may have deep roots in primate evolution, a new study suggests.
In lab experiments, monkeys demonstrated an ability akin to embedding phrases within other phrases, scientists report June 26 in Science Advances. Many linguists regard this skill, known as recursion, as fundamental to grammar (SN: 12/4/05) and thus peculiar to people.
But “this work shows that the capacity to represent recursive sequences is present in an animal that will never learn language,” says Stephen Ferrigno, a Harvard University psychologist.
Ferrigno and colleagues tested recursion in both monkeys and humans. Ten U.S. adults recognized recursive symbol sequences on a nonverbal task and quickly applied that knowledge to novel sequences of items. To a lesser but still substantial extent, so did 50 U.S. preschoolers and 37 adult Tsimane’ villagers from Bolivia, who had no schooling in math or reading.
Those results imply that an ability to grasp recursion must emerge early in life and doesn’t require formal education.
Three rhesus monkeys lacked humans’ ease on the task. But after receiving extra training, two of those monkeys displayed recursive learning, Ferrigno’s group says. One of the two animals ended up, on average, more likely to form novel recursive sequences than about three-quarters of the preschoolers and roughly half of the Bolivian villagers.