It is strange, when you think about it, that the leading metropolises in one of the world’s most technologically advanced countries should have been fashioned out of humanity’s oldest building material. But we rarely think about it. Wood has a way of slipping from view. We characterize historical epochs by their most advanced materials and energy sources: the Stone, Copper, Bronze, and Iron Ages of prehistory and the recent fossil-fuel–powered Anthropocene. Yet, as the biologist Roland Ennos argues, if you looked at people’s actual lives, you’d conclude that nearly the whole of human history deserves a different title: the Age of Wood.
“Who can tell of every use that wood has?” the theologian Martin Luther once asked. To chronicle them all, as Ennos aims to do, is to write a history of the world, because once you look for wood, you see it everywhere. It has been not only a ubiquitous presence but also a driving force, helping to explain the European colonization of the Americas or the rapid expansion of the United States. More to the point, in emphasizing how resolutely wooden the past has been, Ennos shows the deep continuities that connected Luther’s day to prehistoric times—and just how abrupt our recent ejection from the wooden age has been.
Ennos specializes in biomechanics and writes with an appreciative eye for wood’s physical qualities. Two stand out in his view, and both appear to be evolutionary accidents, in that they confer no obvious advantage on trees. First, when you break wood off a living tree and let it dry, it stiffens without losing strength or toughness. Very few materials share this property—bone, horn, and fingernail all weaken as they desiccate. The second “fortuitous” property of dead wood is that it’s flammable. These twin serendipities account for wood’s two great uses: You can build with it, and you can burn it.
A sense of just how useful wood is can be gleaned from the human form. We are, in profound ways, shaped by wood. Binocular vision, hands rather than paws, and differentiated front and hind limbs, Ennos notes, are not human features so much as they are animals-living-in-trees features. We share them with our primate cousins; they allowed our ancestors to navigate arboreal canopies. It may also be that great apes’ large and energy-intensive brains evolved by favoring individuals who could make complex calculations about the mechanics of branches—crucial for heavy tree-dwellers. Certainly, great apes have a feel for wood. All of them can build sophisticated nests in trees, and all can craft wooden tools. The savanna chimpanzees of Senegal strip branches and sharpen them with their teeth to fashion spears and hunt other primates.