Deep Thinkers

S1, E2: Focusing on the intelligence of whales and dolphins. Like humans, they have large brains, are quick to learn new behaviours and use a wide range of sounds to communicate with others. However, how similar are their minds to ours? In the Bahamas, Professor Denise Herzing believes she is close to an answer, theorising that she will be able to hold a conversation with wild dolphins in their own language within five years.