Sophie Scott's investigation of silent messages begins with the smells that animals and even plants produce to communicate with each other or to send information, from plant pheromones to a snake's forked tongue and how dogs use their sensitive noses to explore the word.
It's not all about smells, some species have harnessed bacteria to generate light and light messages are used by some insects and deep-sea fish for a range of reasons including attracting prey.
Exploring how body language communicates huge amounts about us and other species, Professor Scott shows why a dog's wagging tail does not always mean it is happy and how humans can tell a lot about someone's state of mind from their posture alone. She reveals why yawns and smiles are contagious and how this can play a key role in social bonding and cohesion.
In a glimpse of how we might send messages silently in the future, Sophie also explores the possibility of direct brain-to-brain communication. Could the science fiction idea of telepathy ever become reality?