What is this thing we call "consciousness"? It feels like a non-physical thing that somehow exists as a separate entity to our physical body. We might think of it as being located up in our brain where our internal chatter is generated, but the 'mind' still somehow feels separate to the 'brain'.

Then along comes an octopus to complicate the matter. Octopuses clearly have consciousness and high intelligence. But the last common ancestor between us and them is a flatworm that trawled the sea floor about 750 million years ago, so it's not surprising that their brains have evolved to be very different to ours. In fact, some people say they have nine brains. This is due to a complex neural network that runs throughout their body, meaning they have the ability to make different decisions from all eight arms without having to send messages back up to the central brain.

So how can the mind of an octopus be seperate to its body? And does this mean that our mind and body are also one and the same?

Featuring writer Sy Montgomery, author of 'The Soul of an Octopus', and philosopher Julian Baggini, author of 'How the World Thinks'.