John Gribbin & Jeremy Cherfas. The First Chimpanzee (2001)

    John Gribbin & Jeremy Cherfas. The First Chimpanzee (2001) An extended (and unnecessarily long IMO) argument that humans, chimps, and gorillas shared a common hominid ancestor some 3 to 4 M years ago. In other words, the chimp-gorilla line did not split from the human line before the evolution of hominids, but afterwards. That would make chimps and gorillas hominids. This hypothesis was developed by Sarich and Wilson in the late 1960s, when the molecular clock was first calibrated.
     The argument rests on molecular biology, and the development of the molecular clock. It’s been shown that DNA/RNA and hence proteins evolve at surprisingly steady rates. This enables the calculation not of dates but of ratios of time spans, and hence of the relative positions of divergence points in the evolutionary trees of related species. Fossil evidence has calibrated the molecular clock pretty accurately for non-human genera, and for vertebrates and chordates generally, so that its application to the primate group should be a no-brainer. However, it seems that paleontologists don’t like to have their speculations checked by objective evidence from a different discipline. Even amongst themselves, they get rather testy when a colleague finds a fossil that requires “re-evaluation” of existing guesses.
     Along the way, Gribbin and Cherfas provide reams of interesting data, the most important of which is that the sum total of all humanoid fossils could be laid out on a dining room table. Most of them are teeth.
     Insofar as I can judge the evidence, I go with Gribbin and Cherfas. Well written but somewhat whingey in the final chapters, where they discuss the reception of the Sarich-Wilson hypothesis **½ (2007)