There are many, many more things that nobody knows...!

Why do we have five fingers? Do animals have a sense of humour? Did the universe have a beginning? What causes deja vu? Why do cats purr? How fast did dinosaurs move?

In Even More Things That Nobody Knows, William Hartston once again explores the limits of human knowledge, revealing 501 further mysteries in subjects as diverse as cosmology, mathematics, animal behaviour, medical science, music, art, language and literature.

From the trivial to the profound, this is an enthralling and enlightening investigation into the things we just don't know, and which lurk tantalizingly beyond the bounds of our understanding.