Top positive review
Our many complex natures
on January 3, 2001
According to Jared Diamond, "The one book to read on human evolution." Human Natures is clear, quite readable, and concise thus bringing a difficult subject into focus. Ehrlich disabused me of several notions that I had built up over many years of reading about evolution in various publications. No longer will I blame "genes" for everything that goes right and wrong in my life or the lives of those around me. Certainly, genes will still hold a prominent position in my understanding of human natures (plural, for there are many), but our environment will be moved up as at least an equal partner. Here is an example of his excellent style; Ehrlich writes (page 119 & 120): "Despite the uncertainties, several general points with particular evolutionary relevance about the mechanisms of the human brain seem quite will established. In summary, they key points are as follows: 1. The brain is an organ that, like other organs, has evolved a structure that serves its various functions. 2. The brain can compensate for partial damage and, often, keep thinking. 3. The brain has many "programs"--connected sets of neurons--that have been built in over hundreds of millions of years by natural selection. 4. More recently evolved programs in the brain enable us to solve problems of relationships and causation that are difficult or impossible for other animals to solve. 5. Although selection has led to these capabilities by creation of appropriate genotypes, appropriate environments (both internal and external) are essential to produce the behavioral characteristics we observe. 6. Natural selection has designed the brain's programs to bias certain perceptions and behaviors. 7. Nonetheless, the genetic code does not build specific instructions into the brain's structure for dealing with every conceivable behavioral situation or even large numbers of them. 8. Natural selection has trouble doing just one thing at a time with respect to the brain, just as with other organs. It is unlikely, for example, that selection could produce a brain program that predisposes females to desire males with curly hair without changing other programs of the brain or, perhaps, other aspects of the human phenotype."
Ehrlich then goes on to explain all these concepts in detail with easily understood supporting evidence, arguments, and theories. From genes, to religion, to cultures, our complex human natures are unraveled and put before us to see and recognize as the wonder they are. Evolution of the human species is explained in the timeframe and the manner supported by the best scientific evidence of the day. Yet, the wonder and mystery of sentient beings is not in any way denigrated. This is definitely a book to read, and perhaps the only one those of us not in the sciences needs to read for some time to come.