Pilbeam begins with an account of "Human Evolution". This includes a lucid explanation of the different ways of approaching evolution and of some of the pitfalls that lurk in the particular case of Homo sapiens. A great deal of space is devoted to primate anatomy and evolution, perhaps more than is really warranted in a general introduction to palaeoanthropology (this probably reflects the author's special interests), but I found this interesting in its own right. None of the really controversial ideas about human evolution are discussed in detail, and Pilbeam seems to be trying to "stick to the facts" and to avoid speculative theorising.
At almost two hundred pages, Harrison's "Human Genetics and Variation" is the longest of the four sections. It contains a good general introduction to genetics (assuming little or no prior knowledge) but some of the material covered is pretty technical: blood groups, haptoglobin types, melanin concentrations and electrophoretic protein polymorphisms are discussed in some detail.
Tanner's "Human Growth and Constitution" is a readable account of human development and variation in shape and physique. He leans a bit further to the nature end of the nature-nurture debate than I am comfortable with, as he doesn't seem to make full allowance for the complexities of interactions between genetics and environment during development. I'm also not sure how much of his fascination with Sheldon somatyping (classification of variation in physique into endomorphic, mesomorphic and ectomorphic components) is justified; it seems to me that it could be another one of those delusions brought on by too much factor analysis. But those uncertainties aside, there was a lot of interesting material in this section that was completely new to me.
In "Human Adaptability" Baker looks at human adaptation — physiological, genetic and cultural — to different environments. There are chapters on a number of themes: responses to extremes of temperature and altitude (a subject which is clearly the author's particular special interest); nutritional stress; human energetic and dietary requirements and diet differences between populations; the variation of weight and shape with latitude; and infectious diseases, particularly human-parasite coevolution, the effects of demographic changes and migration, and variation in susceptibility between populations. The final chapter looks at recent changes in population demographics, nutrition and diseases in response to modernisation.
Human Biology is a book with a lot of really interesting stuff in it, but one which is perhaps a little bit of a misfit. It is a little too detailed to be suitable as a general introduction for the novice to the subjects it covers, but not systematic enough to be a good reference (the lack of bibliography and references hurts here, though there are suggestions for further reading at the end of each section). Its target audience is probably students of anthropology or the social sciences who want some biological background to their discipline, and medical students who want a broader perspective on theirs.