As humans, we often think of ourselves as uniquely rational, complex creatures, yet emotions actually stem from an evolutionarily older part of our brain found in other animals. Emotions determine how we perceive the world, what we remember or forget, and the decisions we make. Integrating the latest insights from biology, primatology and psychology, Kret unveils a world of largely subconscious bodily processes that evolved to enhance social bonding, and so offer greater chances of individual survival. Some of these, like a baby’s cry, are innate, while others, like a smile, are learned through social feedback. While common ancestors certainly play a role in similarities between species, a common environment can equally shape the ways different animals express their emotions, such as monkey calls and birdsongs in the jungle. What’s more, scientists are discovering just how much animals like us communicate to one another beyond facial expressions, through posture, pupil dilation, temperature and chemical signals. Between a smile and a grimace lies a lot: complex body language and social context.

Kret dives into the many experiments she and her colleagues have been conducting, while also addressing emotion’s measurement and the fiery debates in the field. She also addresses the limits of empathy and human emotions in social media, robots and AI. Ultimately there remains a stubborn gap as to what emotions humans can identify in animals vastly different from ourselves. And yet, as much as we might like to consider the unfamiliar as simple or unintelligent, Kret believes ‘The challenge for humans lies in recognising and taking into account the emotions and well-being of fellow humans and other animals.’

Informative and accessible, this book reveals the world of emotions as one of beauty. Kret sketches, with enthusiasm and wit, an exciting area of research – though time is running out as our chances to study our closest relatives in the wild are shrinking. For readers of Frans de Waal.