The Age of Mammals Nature, Development, & Paleontology in the Long Nineteenth Century

In modern palaeontology, dinosaurs always hog the limelight. However, as science historian Chris Manias shows in The Age of Mammals, for a long time this was not the case. This scholarly book shows how palaeontology, from its inception in the 1700s until the 1910s, revolved around mammals. In a wide-ranging book that examines historical episodes around the world, Manias convincingly shows that you cannot understand the history of palaeontology without considering mammals.

Rather than a book about fossil mammals or mammal evolution, this is about the history of palaeontology as a scientific discipline, showing how central the study of fossil mammals has been to its development. One thing to note is that this is not popular science and it took me a few chapters to get into the groove of Manias's academic writing style. Nothing here is impenetrable, but this is a serious intellectual history. The depth of scholarship is evident from the reference list as Manias has mined the peer-reviewed literature, archives of correspondence, and numerous newspapers and magazines. He has also dug up some remarkable period illustrations and photos that recreate the flavour of this bygone era. I noticed three major themes running through this book.

First, fossil mammals were instrumental in revising our understanding of life's history and evolutionary patterns. We have long clung to the idea of a scala naturae that orders life from lowest to highest. Mammals were considered superior to all other animals with humans (of course) placed at the summit. Insights from mammal palaeontology started upending this idea in various ways. Fossil mammals revealed just how diverse life had been, making it increasingly hard to arrange them in any meaningful order. The discovery of Permian fossils of the mammal ancestor Dicynodon cast doubts on the idea that mammals evolved from reptiles. Maybe that was a too-literal reading of the scala naturae and both groups evolved from amphibians instead? (That starts sounding more modern, but is still not quite right; Beasts Before Us and The Rise and Reign of the Mammals explain our current understanding.) It became increasingly clear that "the history of life therefore was not an easy ladder of progress (even if some aspects could be made to fit this narrative)" (p. 207).

Closely related to this was the idea that geological history was one of progress and improvement, an idea that has been almost impossible to shake. However, the discovery of Pleistocene ice ages upset the notion of a steady story of progress and scholars argued whether there had been one or many. "Linear and cyclical visions of development jostled and persisted" (p. 188). And then there were the poster children of linear evolution: horses. The images that show them progressively evolving into larger horses with longer legs and higher-crowned teeth are iconic. The actual story is more complicated and already in 1907 James W. Gidley and Henry Fairfield Osborn of the American Museum of Natural History (AMNH) wrote a taxonomic revision that concluded as much. Most groups in this sequence had become specialized and left no descendants, showing instead that "evolution had a disjunctive rather than a continuous pattern" (p. 261), though these insights did not necessarily filter through to museum displays.

Two further ideas in biology influenced by fossil mammals were extinction and biogeography. It was by studying fossil elephant remains that Cuvier conceived of the idea of extinction. The later realisation that so many large mammals had gone extinct in the Pleistocene raised questions about the role of humans. Were we the baddies, or did it involve many factors? That debate rumbles on even today. Meanwhile, the distribution of fossil mammals was used to divide the world into six biogeographic zones. Manias flags up a nice bit of subversion here: the realisation that the elephant, that most noble animal, had evolved in Africa suddenly made that continent appear less backward. "Biogeography could be an imperial science, but in doing so could also center modern colonized regions" (p. 333).

The second major theme of The Age of Mammals is a healthy dose of museology. Manias describes the history of major institutes such as the MNHN, AMNH, NHM London, all of whom relied on fossil mammal exhibits for some of their fame. He delves into the new museum movement of the 19th century for which the AMNH was a poster child. These large, professionally organized and bureaucratic museums, sponsored by the state and philanthropists, contrasted with the lurid penny museums and travelling exhibits, aiming instead to educate and elevate their public. A well-stocked palaeontological display containing a "canon of fossil mammals" (p. 225) became mandatory. But these museums were not the only game in town. University-based institutions could hold their own by offering educational opportunities. Outside of Europe and North America, some countries successfully drew on their unique fossil mammal fauna. But even in the Western United States, small museums set themselves apart not by showcasing the whole history of life, but by building collections of local fossils.

The third major theme is that Manias is finely attuned to all the cultural and historical baggage. Palaeontology virtually always followed in the wake of colonial expansion, piggybacking on economic activities. It inspired and was inspired by economic and political narratives of improvement, e.g. the idea that under enlightened colonial rule, certain areas could again be made as fruitful as fossil mammals suggested they had once been. Key scholars had horrible views by today's standards: Edward Drinker Cope was a racist while Osborn supported eugenics. The input of women was marginalized and only a few succeeded in building a professional career. And the contribution of local people and fieldworkers was often belittled or completely erased. However, some clever rereading of history by Manias shows they were not always without agency or power. He leaves no opportunity unused to highlight all of the above disturbing history, and the amount of ideological assumptions foisted on both animals and humans that he unearths is staggering. In my opinion, he is neither judgemental nor moralizing, instead striking the right tone by putting people and events in context.

The Age of Mammals is a comprehensive and revelatory history that is full of fascinating stories from around the world. It is also an incredibly welcome addition to the literature as most books on the history of palaeontology all focus on a certain group of extinct reptiles. Thus, I warmly recommend this to readers interested in the history of palaeontology and, more generally, science history and museology.