What are the origins of life? How did things go from non-living to living? From something that could not reproduce to something that could? Earth is estimated to be about 4.5 billion years old, and for much of that history it has been home to life in one form or another. Our planet is teaming with life, from the highest mountain to the deepest ocean; life is everywhere. But what was the firing pistol that started the evolutionary race? How did material go from non-living to alive? It's one of the most fundamental and difficult questions that has challenged us since the beginning of time.
Did you know that bananas are berries, but strawberries aren’t? A lot of thought goes into classifying fruits and vegetables, and it all has to do with anatomy.
The last episode in the series examines how humans perceive and experience time, investigating the internal body clock which tells people when to eat, drink, sleep and relax. The importance of accurately measuring time is explored in relation to human evolution, and there's a debate about whether mankind will ever be able to travel between past, present and future.
Comedian Jimmy Carr takes over Horizon for this one-off special programme, produced as part of BBC2's sitcom season. Jimmy turns venerable documentary strand Horizon into a chat show, with eminent laughter scientists as guests and a studio audience to use as guinea pigs. Jimmy and his guests try to get to the bottom of what laughter is, why we enjoy it so much and what, if anything, it has to do with comedy. Between them, and with the help of contributions from other scientists on film, Jimmy and guests discover that laughter is much older than our species, and may well have contributed to making us human. With professors Sophie Scott, Robin Dunbar and Peter McGraw.