Friendship is like water. We need it to survive, we crave it when it's scarce, it runs through our veins and yet we forget its value simply because it's always available. The basic compulsion to make friends is in our DNA; we've evolved, chimp-like, to seek out connection with other human beings. We move through life in packs and friendship circles and yet we are stuck in the greatest loneliness epidemic of our time. It's killing us, making us miserable and causing a public health crisis. But what if friendship is the solution, not the distraction?

Journalist Kate Leaver believes that friendship is the essential cure for the modern malaise of solitude, ignorance, ill health and angst. If we only treated camaraderie as a social priority, it could affect everything from our physical health and emotional well-being to our capacity to find a home, keep a job, get married, stay married, succeed, feed and understand ourselves.

In this witty, smart book - an appealing blend of science, pop culture and memoir - she meets scientists, speaks to old friends, finds extraordinary stories and uncovers research to look at what friendship is, how it feels, where it can survive, why we need it and what we can do to get the most from it - and how we might change the world if we value it properly.