A revised edition of a book which emphasizes aspects of biology relating to medicine, as well as the social aspect of health science in a worldwide context. In this edition as in the first Dr. Grant is an effective propagandist for the World Health Organization (WHO) and the Food and Agriculture Organization (FAO). The revisions are significant. There is an updating of the work of WHO with particular emphasis on the increased control over tuberculosis and malaria. Two chapters have been added: ""The Battle Against Polio -- A Success Story"" and ""Can the war against hunger be won?"" The major new biological context is that related to the Watson-Crick model; this information is then used at other points, such as in explanation of how polio vaccines work. There are omissions. This is especially evident anent praise of DDT for its contribution to malaria control without indication that it may harm health as well. In the new chapter on hunger more extensive consideration of population control would be appropriate. The book remains a readable one, however, and the revisions warrant adding this edition to one's holdings.