Tiergarten Nürnberg

They are clever...

In proportion to their total weight, squirrel monkeys have the largest brain of all primates. It makes up 1/17 of their total weight. In humans, the brain weighs only 1/35 of our body weight. That does not mean that squirrel monkeys are smarter than other monkeys; but they can move quickly and are even able to catch small birds when they’re flying.

... but need reading glasses!

Squirrel monkeys are naturally farsighted. Before eating, they hold their food as far away as possible, with outstretched arms and examine it closely.