It’s a familiar problem with any shared household - there’s always someone who doesn’t do their fair share. Studies have shown that when people with different thresholds live together, the person with the lower tolerance for mess cleans up more, quickly leading to resentment and conflict. So why do some people clean up more than others? What needs to happen for everyone to pull their weight? Evolutionary science has some answers. Ella Al-Shamahi speaks to Dr Nichola Raihani, Professor of Evolution and Behaviour from University College London, to find out about free riders, cheaters and public goods, and how evolutionary scientists view cooperation challenges. Great British Bake Off star Michael Chakraverty shares his own anecdotes of untidy flatmates and failed attempts to enhance cooperation.