Consciousness is the most fascinating but tantalizingly difficult topic in biology. Although many people now believe that mammals, birds, and possibly all vertebrates are conscious, there are also claims that many other animals such as crabs and insects may be conscious too. Such claims, if true, would have major implications for what we eat, how we control pests, and for our relationship with the animal world. Now, more than ever, it is important to question the evidence and ask: what do we really know about animal consciousness? Who is Conscious? is an adventure into animal minds. It is a guide into the conscious experiences of animals with no words to tell us what they might be thinking or feeling. It proposes some simple questions to help us decide which evidence to believe. It looks at recent evidence for consciousness in various animal species and asks how well it stands up to being challenged. It describes research on human consciousness and asks whether we should conclude that