This is an engaging book that addresses questions such as:

• How does love begin?
• What drives mothers to care for their babies?
• What accounts for the gender of the people at whom we aim our affection?
• What does it mean to say one is male or female?

The book is based on rigorous research using data from both animal and human subjects. It has been written to be accessible to a non-scientific reader. In order to build and develop the theoretical arguments to address the above questions, Young and Alexander describe and explain the significance of the experiments carried out—some readers may find this aspect of the book disturbing.

Young and Alexander manage to convey complex theory in a clear and concise manner. Effective use is made of wry humour to lighten what could be quite dense material. Diagrams are occasionally used to help clarify particular issues, though on a personal note I have to admit that I did occasionally skip over some of the more technical terms.