PDF version
X-ray sequence of a human skeleton running
Our bones have evolved over millions of years.Credit: Nick Veasey
Skeleton Keys: The Secret Life of Bone Brian Switek Riverhead (2019)

The bony scaffolding beneath our skin can move us emotionally as well as physically. In enabling our lives, yet enduring beyond them, our skeletons challenge our understanding of ourselves. This premise underpins Brian Switek’s Skeleton Keys, a thoughtful, engaging meditation on the origins of the human skeleton, how it functions (or malfunctions) and how we come to terms with our essential but unsettling osseous framework.

Bone’s potential for physical immortality reminds us all too vividly of our personal mortality. Switek conveys the Grand Guignol aspects of this with suitably horrified fascination — contemplating, say, the bones of England’s King Richard III, hacked and broken in his final hour on the battlefield. Dinosaur bones, however awe-inspiring, cannot chill the spine in quite the same way as the fleshless frames of our own kind.

A ênfase é assim muito no "nosso". Switek há muito entusiasmou e escreveu elegantemente sobre os ossos de nossos parentes distantes, não menos os dinossauros. E alguns, como o monstruoso Supersaurus, são abordados neste livro. A história ainda mais antiga dos vertebrados é bem delineada desde o início, suas origens no período Cambriano, exemplificado pelo Pikaia, um organismo marinho extinto parecido com uma enguia que não tinha esqueleto, mas provavelmente possuía uma notocorda, a precursora da coluna vertebral. O Pikaia foi encontrado nos cerca de 508 milhões de anos de idade Burgess Shale, um rico tesouro descoberto no Canadá em 1909 pelo temível paleontólogo Charles Doolittle Walcott.

As outras criaturas da cornucópia Burgess - e os muitos esqueletos sofisticados, principalmente externos, então sendo conjurados por grupos de invertebrados, como os artrópodes - são mencionados apenas brevemente. Esta é uma narrativa de osso, não de carapaça, e os primeiros organismos revestidos de carapaça são significativos aqui principalmente para efetivamente empurrar os vertebrados para os lados por mais de 100 milhões de anos. O esqueleto dos vertebrados finalmente prosperou, e Switek descreve alguns passos importantes ao longo do caminho, como a forma como passou de externa para interna entre os primeiros peixes.

Further towards our particular twig of life’s tree, dinosaurs make a guest appearance, with legendary nineteenth-century US bone hunters and sworn enemies Edward Drinker Cope and Othniel Charles Marsh in the spotlight. Obsessively driven, and each burning their way through a family fortune, they unearthed many iconic dinosaurs, such as Triceratops and Diplodocus. There is nothing on their UK counterpart Mary Anning, although she performed comparable palaeontological miracles in extracting ichthyosaurs and plesiosaurs from dangerous Dorset cliffs. This nascent scientific field had formidable female protagonists, too, working against tremendous odds.

Close to the bone

Os próximos 100 milhões de anos, nos quais os mamíferos floresceram, são cobertos rapidamente, para chegar à bonança óssea do Pleistoceno dos depósitos de alcatrão de La Brea, em Los Angeles, Califórnia. Descrevendo-os como o mais importante sítio fóssil do planeta (que é a luta entre os paleontólogos), Switek concentra-se no conjunto de ossos humanos encontrados entre os mamutes e leões e gatos com dentes de sabre. Chamada de La Brea Woman, seus restos de 10 mil anos permitem que Switek explique as complexidades físicas e químicas do osso em geral e dos ossos humanos em particular. E é uma coisa extraordinária, permitindo resiliência e força, e contínua remodelação interna. Os esqueletos dos vertebrados, ao contrário dos dos artrópodes, não precisam ser sucessivamente mudados à medida que o animal cresce, e assim podem alcançar vastas dimensões - como na baleia azul.

This narrative is neatly done, but the fascination exerted by human bone on human minds lies at the book’s heart. With Switek, we visit Neolithic tombs and medieval ossuaries, consider skull cults and muse on the bony personification of Death. The book makes extended explorations of how nineteenth-century anthropologists such as Samuel Morton in Philadelphia, Pennsylvania, used skull measurements to claim the existence of racial differences, a malign legacy that, although long discredited in science, lingers today in apologias for racism. Switek also describes the protracted tug-of-war between scientists and the Native American community around the Columbia River in Washington state over who owns the 9,000-year-old skeleton of the Ancient One, also known as Kennewick Man (D. H. Thomas Nature 531, 302–303; 2016). This is terrain most palaeontologists never navigate; Switek picks through it well.

In the book’s coda, the narrative gets up close and personal. Switek considers his own skeleton, and how it might follow those of the dinosaurs into geological immortality. Switek’s deep-time focus comes through a little too strongly, I think, in his assertion that it is mainly our skeletons that will be left to tell of our passing. Of the detritus that each of us casually scatters — thousands of ballpoint pens, polyester socks, aluminium cans and so on — much is a good deal more decay-resistant than the average cranium or femur. Our bones might be only a small part of our ultimate legacy.

Nevertheless, as this book shows, the skeletal side of life grips us now, and might enthral whoever excavates our remains in the far future. As Switek ponders the sediments in which his own bones might be fossilized, he needs to think of larger geological processes. The sea floor off the shore of New Orleans, Louisiana, might provide a good start: there are stagnant muds, and local tectonic subsidence will allow the fossil to be securely entombed. In the meantime, we should enjoy Switek’s talent for spinning compelling tales of old bones.

Nature 566, 452-453 (2019)

doi: 10.1038/d41586-019-00679-9