Joining John and Bridget are psychotherapist Philippa Perry, wildlife cameraman Doug Allan, and architect Carlo Ratti.

Philippa Perry, a psychotherapist who has written a graphic novel about her world, presenter of documentaries Being BiPolar and The Truth About Children Who Lie, and author of The Book You Wish Your Parents Had Read (and Your Children Will be Glad That You Did), donates a swarm of fruit flies, because they can be used in both psychological and social experiments.

Carlo Ratti, an Italian architect, inventor, professor at MIT, and a specialist at looking at how cities will evolve in the future, provides a bionic arm. Ratti has experimented on them, and has come across bionic arms that can build Ikea furniture.

Doug Allan, a cameraman who specialises in underwater wildlife, who has contributed to Blue Planet, Frozen Planet and Planet Earth, offers up the feeling you get when a wild animal trusts you, on the grounds that if more people had this feeling that the world would be a better place.