How big does a brain need to be to for an animal to be intelligent?

Bumblebees show that size does not matter.

In a new study, scientists taught buff-tailed bumblebees to push a ball into a goal for sweet rewards.

This complex exercise turned out to be simple for the insects, whose brains are a size of a sesame seed. They solved the puzzle (in the video above) just by observing a demonstration, and some even innovated their own ways to perform the task. This behaviour explains how pollinators memorise objects and fly miles to collect nectar.

The experiment was conducted by Clint Perry, a cognitive biologist at Queen Mary University of London, who initially wanted to make a vending machine for bumblebees.

Such mental flexibility could also help bumblebees in the wild who are currently facing a huge decline in their numbers.