By Belinda Smith - Via CosmosMagazine The intelligence of these brainiest of birds has been compared to that of a seven-year-old human. Belinda Smith delves into the behavioural neuroscience behind crow cognition. They can recognise faces, use tools – even drop nuts on a road for cars to crack (then pick them up with the safety of pedestrian lights). Birds in the corvid family – most famously, crows – are known for their intelligence. Even ancient Greek storyteller Aesop wove their problem-solving nouse into his famed fables. But why are they so smart? Well, first up: not all crows are super smart. There are around 40 species of crows and ravens from a family of more than 120 corvids. "There's a fair bit of disparity between crow species," says Matt Brown, a PhD student in crow cognition at Griffith University in Queensland, Australia. The New Caledonian crow is, so far, the most intelligent of its crow brethren, Brown says: "They're to crows what we are to the rest of the primates."