Whether we realize it or not, we carry in our mouths the legacy of our evolution. Our teeth are like living fossils that can be studied and compared to those of our ancestors to teach us how we became human. In Evolution's Bite, noted paleoanthropologist Peter Ungar brings together for the first time cutting-edge advances in understanding human evolution and climate change with new approaches to uncovering dietary clues from fossil teeth to present a remarkable investigation into the ways that teeth – their shape, chemistry, and wear – reveal how we came to be.
Ungar describes how a tooth's "foodprints" – distinctive patterns of microscopic wear and tear – provide telltale details about what an animal actually ate in the past. These clues, combined with groundbreaking research in paleoclimatology, demonstrate how a changing climate altered the food options available to our ancestors, what Ungar calls the biospheric buffet. When diets change, species change, and Ungar traces how diet and an unpredictable climate determined who among our ancestors was winnowed out and who survived, as well as why we transitioned from the role of forager to farmer. By sifting through the evidence – and the scars on our teeth – Ungar makes the important case for what might or might not be the most natural diet for humans.
Traveling the four corners of the globe and combining scientific breakthroughs with vivid narrative, Evolution's Bite presents a unique dental perspective on our astonishing human development.
"In Evolution's Bite, palaeoanthropologist Peter Ungar offers a compelling account of how the interaction of teeth, diet and environment has shaped human evolution."
– Louise Humphrey, Nature
"[A] fascinating exploration of the world of teeth and what they have to teach us about the evolution of modern humans and the environments that shaped that process [...] Ungar's book is about as close to a tour de force as a science book is likely to get. The writing is accessible, often witty, and the balance between discussion of what the empirical data has to show us and the history of the field of paleoarchaeology itself creates a narrative of the lives of both the discovered and the discoverers that is hard to put down [...] I recommend this book with my highest praise."
– David Brock, NSTA Recommends
"Ungar has spent his career studying the evolution of teeth. [Evolution's Bite] blends the results of his work with new research from many other disciplines [...] An excellent book for those with a serious interest in anthropology."
– Library Journal
"The story of how we became human is recorded in our teeth. With wit and expertise, Peter Ungar shows us how scientists use clues in ancient teeth to reveal what our ancestors ate, how they looked, and how they adapted to climate change, hunting, cooking, and lousy paleodiets. Anyone who wants to know where we came from and how we ended up with such messed up teeth and jaws should read Evolution's Bite."
– Ann Gibbons, author of The First Human: The Race to Discover Our Earliest Ancestors
"With grace and clarity, Peter Ungar leads us through the complex world of discovering fossil and modern teeth and the clues they reveal to our evolutionary history. In the process, he teaches us much about the mechanisms of evolution itself. I highly recommend this book not only to those in the field but also to those who want to understand how we know what we know."
– Pat Shipman, author of The Invaders: How Humans and Their Dogs Drove Neanderthals to Extinction
"A compelling tale, Evolution's Bite highlights the ways our teeth work and the clues they preserve about our evolutionary origin. Serving as an eloquent guide to fossil teeth, past environments, and archeological finds, Peter Ungar shows how the union of scientific fields shapes the profound story of food, diet, and evolution."
– Rick Potts, director of the Human Origins Program, Smithsonian Institution
"This impressive book serves as a window into human history through the lens of teeth and diet. Ungar's seamless narrative brings bits of bone and teeth to life, and does so against a vivid backdrop in which paleoanthropologists arrive at their conclusions about why, how, and what we eat. This book is a pleasure to read – Ungar has that rare gift of engaging us through personal insight while simultaneously explaining complex scientific principles."
– Joanna E. Lambert, University of Colorado, Boulder
"Evolution's Bite is not simply about teeth – it brings together evidence from geology, paleontology, biology, climatology, and even materials science in order show how our dynamic relationship with the environment shaped who we are today. An enjoyable read."
– Shara Bailey, New York University
1 How Teeth Work 5
2 How Teeth Are Used 34
3 Out of the Garden 60
4 Our Changing World 87
5 Foodprints 110
6 What Made Us Human 140
7 The Neolithic Revolution 169
8 Victims of Our Own Success 198
"Show me your teeth and I will tell you who you are" Cuvier is reported to have said. That, in short, is the brief of this book. Drawing on a range of disciplines – such as archaeology, palaeoclimatology, materials science, primatology, anthropology and evolutionary biology – this book weaves a compelling narrative of what our teeth, and those of our ancestors, can tell us about our past diets, and how we came to be the species we are today. Why teeth? Because, as Ungar contends, teeth are special.
Peter Ungar is an American paleoanthropologist and evolutionary biologist who has researched teeth and human evolution and written extensively about it. The reason teeth are so interesting is that, due to their high mineral content, they are pretty much ready-made fossils and are the most commonly preserved parts of the digestive system. The narrative of human evolution used to be simple: we left the trees and ventured out in the African savannah and beyond, overcoming new challenges and developing new skills in the process. In Evolution's Bite, Ungar draws together findings from many different disciplines to show that the story actually is a lot more complex than that.
Ungar starts off explaining how teeth are used to fracture food. So, you can use tooth shape to infer diet. But, as thousands of hours of observations of living primates has shown, what teeth can do and how they are actually used are two different things. Ungar introduces the concept of the "biospheric buffet": the total of food items that animals can pick and choose from wherever they live. And this buffet is far from constant. Seasonality, competition with the neighbours, longer-term changes in the climate – food choice fluctuates on a monthly, weekly and even daily basis. Chapter 3 gives a crash course on the key players in palaeoanthropology, both the fossils and their discoverers. Over the decades, evidence has been accumulating that environmental change influenced our evolution. This is where Ungar weaves another strand into his story and walks the reader through key palaeoclimatological findings, showing how hominin habitats have flipped back and forth between warm and wet vs. cool and dry, sometimes gradually, sometimes abruptly.
Another telltale sign of what animals actually ate in the past are, what Ungar calls, "foodprints", the microscopic patterns of wear and tear on teeth revealed via scanning electron microscopy. Since teeth wear down continuously, studying these patterns only tells you about the animal's diet shortly before it died. This is where isotope analysis comes in (isotopes are the different variants of a chemical element, differing in number of neutrons). Different food sources differ in the ratios of carbon isotopes. These atoms are passed along the food chain and incorporated in the body when building bones and teeth. These add yet more pieces to the puzzle of what our ancestors actually ate.
Ungar then continues how palaeoanthropologists have answered the question of how we came to be different from our primate relatives. He dives into the archaeological record to show what we have learned about tool use and traces of our hunting and gathering past, but also looks at anthropological studies on the last few remaining hunter-gatherer tribes such as the Aché people in Paraguay, or the Hadza people of Tanzania. He then briskly walks us through the Neolithic revolution and the shift from humans as roaming hunters and gatherers to sedentary farmers. There's plenty of archaeological evidence for this transition. But why did it happen? The answer might very well lie in a changing climate.
Ice cores retrieved from the Greenland ice sheet have allowed us to reconstruct a detailed picture of the climate over the last 100 millenia or so. This, too, has left its traces in the fossil record. The discipline of palaeopathology is introduced here: signs in fossils pointing to malnutrition, disease and other conditions. And these seem to have increased as we switched to farming. There was the back-breaking labour involved in farming, but also the switch to fewer, easier-to-grow food items that were less nutritional. Processed food (we're not talking about what the health-food crowds typically think of when you use these words), that is, the simple acts of milling grain and cooking food, has had another drawback: softer diets. The lack of work-out has resulted in our jaws shrinking with time, bringing with it a host of dental problems (overbites, crowded front teeth, problems with wisdom teeth etc.).
The book concludes with a short chapter looking at the perennial question of what our natural human diet is, and the popularity of the Palaeolithic Diet. Ungar makes an excellent point here that this diet, like most of these dietary fads, is utter rubbish. Without even having to resort to nutritional considerations, the question "what is our natural diet?" is a logical non sequitur. This question has no sensible answer because it's not a sensible question to begin with. As Evolution's Bite convincingly shows, our diet has been in constant flux throughout our history, both in time and in space. You just cannot point to a particular moment in time and say "here is when we were eating as we were meant to". It's the same fallacy that affects a lot of thinking in wildlife conservation: there's no pristine state of nature to which we can return as our environment has always been in flux.
This is not to say that we cannot benefit by looking at the relationship between diet and health through an evolutionary lens. Other than shrinking jaws, highlighted above, Ungar points to the problems caused by table sugar, which only became widely available during the Industrial Revolution. We simply haven't had enough time yet to evolve a proper response to our increased sugar intake.
With Evolution's Bite, Ungar gives a sweeping overview of what we currently know about teeth and human evolution. Drawing on findings from many discplines, he makes a convincing case that a changing climate drove human evolution, largely by influencing the food options available to us on our biospheric buffet. For once, the word "interdisciplinary", often a buzzword, is entirely appropriate. The earlier chapters sometimes get quite technical when Ungar gets down and dirty with the details, but the book is neatly structured, and by equally focusing on the people behind the findings, he writes a compelling narrative. He also does an excellent job ending each chapter by rounding up the findings before moving on to the next relevant topic. Once the groundwork has been done, and you have been sufficiently briefed on what you need to know, he gathers pace in the last three chapters and brings the book to a convincing and satisfying conclusion. An excellent read!
Peter S. Ungar is Distinguished Professor and director of the Environmental Dynamics Program at the University of Arkansas. He is the author of Teeth: A Very Short Introduction and Mammal Teeth: Origin, Evolution, and Diversity and the editor of Evolution of the Human Diet: The Known, the Unknown, and the Unknowable. He lives in Fayetteville, Arkansas.