Excellent exploration of the current state of human / chimpanzee / bonobo understanding and research.

The book is divided into three sections: Blood, Brains, and Bodies. The Blood section explores the primate family tree, including where modern and fossil humans are, in relation to modern chimpanzees and bonobos (humans are approximately equidistant from each). But there is also a more detailed discussion of how hybrids "work" in the larger evolutionary framework. The discussion starts with ligers, the hybrid of a lion father and tiger mother. And they are not just a product of zoos and private breeders - they occur more frequently in the wild than one might think. From here, the author discusses how genetic flow (as the author comments, "scientists' way of saying doing the nasty") from one species to another influences the genes of the offspring and their adaptability to new ecological niches. And that hybridization in the distant past explains some of the puzzling similarities and differences between humans and our closest primate cousins.

The section then goes on for several chapters about similarities and differences between humans and these apes with respect to diseases. This is the part of the book that makes one uneasy, because it describes how animals are used in this part of research, and it is not pretty. But much has helped provide basic research into what may or may not be useful in treating hepatitis and AIDS, for instance.

Part 2, Brains, is about the cognitive similarities and differences between humans and chimps and bonobos. The author gives an overview of the various attempts to teach these apes human language, whether audible, signed, or via symbol manipulation. Parts worked, parts didn't. And what did not work tells us as much about what is unique about humans as about how a chimp "thinks." There is some fairly detailed discussion of FOXP2 genes, and how they appear to cause particular effects in the humans that have defective versions, and how this gene is expressed in many animals, including chimps. It has to do with how humans recognize and use language. The chapters are fairly technical, and I skimmed through the "hard parts". Physical brain architecture is the subject of one entire chapter - parts of the brain, brain size, amount of folding, the kinds of cells within the brain, the connections between parts, and timing of brain growth. Some of these relates to Alzheimer's research, among other things.

But it also had a couple sentences that resonated with a recent Senate race. It noted an experiment done with mouse brains related to the study of human brains.

Part 3 - Bodies - has a chapter devoted to the human upright stance. This pulled in some more of the research that I had read about in "Born to Run" about how human gait differs from chimp gait, and what it might mean, including the human's loss of body hair, sweat glands, and even skin color. There is also a telling graphic about the size of a baby's head, for orang, chimp, gorilla, and human vs. the size of the birth canal. "Chimp birth is very fast, and it doesn't look tramatic at all" wrote one researcher. And the apes do not appear to miscarry with near the frequency of humans.

The author concludes with the state of chimp populations world wide, both wild and captive. Many recent laws have outlawed or strongly hampered medical use of captive chimps, which has had the result of fewer chimps being bred.

I found the book to be a fascinating peek at these apes, and what they show us about what it means to be human, as well as what it means to be ape. ( )