In 1970, Hugh Drummond stepped on a plane for a voyage that would change his life. Twenty-four years old, he had recently finished his studies to become a solicitor in the British courts and seemed destined to lead a quiet existence of offices, paperwork, and perhaps a neatly trimmed garden. But before he settled in, he wanted to see the world. He set out for Mexico and, after that, Thailand, and then wherever the winds of fortune took him.

In the end, he never made it past Mexico. He immediately fell in love with its rugged beauty and vibrant culture. Raised in a bleak post-war Britain, he was dazzled by the country’s wild jungles, mountains, rivers, and especially its wildlife. He abandoned his plans for Asia or ever returning to Britain, thus beginning a lifelong love affair with his adopted country.

Forty-five years later, Drummond is one of Mexico’s most respected scientists and among the world’s top animal ecologists studying behavior. His life’s work with a bizarre seabird called the blue-footed booby on a tiny island off the Pacific coast has created an unparalleled behavioral database. His specialty is the terrible things they do to each other, especially the cruel, often downright homicidal behavior between siblings.

Thirty-five years of unbroken observations of fighting, cheating, and murder has shown him that animal behavior is tied to a complex tapestry of factors like weather, food availability, and each creature’s particular strategy for survival. And as he came to understand the motivations of squabbling birds on a lonely Pacific island, he gleaned hints about our own behavior and what it means to be human.