Remnants of Ancient Life: The New Science of Old Fossils

Greenwalt, resident research associate at the Smithsonian National Museum of Natural History, guides readers through the relatively new science of paleobiochemistry, which uses the chemical traces left behind by long-dead species to provide new insights into evolution and the biology of ancient life. While most fossils are composed of rock that has replaced once-living tissues or the impressions left by plants and animals in soft mud that has hardened, sometimes actual, physical molecules of the original organisms remain. The range of biomolecules recovered—from pigments that recast the past into vibrant color, to proteins and biopolymers that provide the literal building blocks of connective tissues, horns, feathers, and wood—is astonishing. Especially exciting, though controversial, are claims of finding readable ancient DNA, the blueprint for life. Time, pressure, and heat degrade all of these molecules, so finding samples that can be analyzed with any certainty is a matter of luck, location, and improved methods of detection and analysis. Particularly intriguing is the final chapter that looks toward present-day applications, such as using extinct enzymes to make wood a better source of fuel.