Book ReviewAlejandra Manjarrez
Daniel E. Lieberman:
The Evolution of the Human Head.
Hardcover: 768 pages
Publisher: Belknap Press of Harvard University Press; 1 edition (January 3, 2011)
Price: 30.00 EUR
They look straight, but watch out! They’re not human. Photo: Paramount Pictures
Grafted onto a slim neck, we carry around an energy-wasting appendage that torments us with headache, hair-loss and protruding ears. However, we can’t get by without it. Daniel Lieberman, Professor of human evolutionary biology, explains in a heady volume, how our most important body part evolved.
What makes us human, apart from hubris, hypertension and the ability to produce a wide variety of sugar-free chewing gums? If we look at our closest cousins, the chimpanzees, the answer is obvious: it’s the skill to discuss absurdities on TV chat shows.
However, in historical – evolutionary – terms, the answer is not that simple. What were the things that made us diverge from the rest of the apes? Even though the list of contributing factors is long, we cannot deny that most of these differences are related to what lies above the neck. So if we want to know more, we should start by asking “why is the human head the way it is?” This is a question that Daniel Lieberman brings up at the beginning of his book The Evolution of the Human Head.
As a professor of human evolutionary biology at Harvard University in Cambridge, Massachusetts, Lieberman is well placed to tell the story of how he and other scientists have tackled this problem. His research has mainly focused on studying the unique features of human heads and the evolutionary transitions behind them. In this book, he reviews and discusses the main ideas and arguments that this subject has to offer, resulting in a comprehensive and up-to-date volume.
An outstanding feature of The Evolution of the Human Head is the inclusion of almost all scientific disciplines that have contributed to the picture: palaeontology, molecular and developmental biology, anatomy, biomechanics and others. All of them make sense in the light of evolution, quoting Dobzhansky. Unfortunately, however, Lieberman incorporates all of these views into three defined sections that divide the book.
He starts by writing about the developmental processes that lead to the formation of our head during the embryonic, foetal and postnatal periods, followed by a section which is centred on function. Here he discusses, for example, how we eat and smell, how we perceive images and sounds (the prerequisites for speech) and why our brains are so big. Lieberman also tells us some important truths about cookery. Cookery? Well, preparing food with fire had immense effects on many of our skills and abilities, thus playing an important role in human evolution, some anthropologists believe. We don’t need to spend half our time chewing food like the chimpanzees and Lieberman argues that cooking food not only made everything easier to chew but also improved nutrient accessibility, thus contributing to skull growth.
The book’s final section restates developmental, anatomical and functional knowledge from an evolutionary perspective. One of Lieberman’s major themes is that many of the changes that took place during the evolution of our heads occurred thanks to the process known as “tinkering”, where natural selection takes advantage of preexisting variation in ancestors in order to develop new traits. His arguments in this sense are strong, though not new, and as the title of the first chapter suggests, we can easily call ourselves “tinkered apes”.
Moreover, he argues that the earlier transformations that led to the hominin lineage, next to the divergence from Australopithecus to Homo, were the most intense transitions, while the changes that gave origin to Homo sapiens were modest by comparison. Even the basic craniofacial layout does not differ significantly in ape, hominin and human heads. This fact does not ignore how distinctive we are from other genera or species, but instead emphasises how small changes can result in huge divergence.
A book that discusses fossils, genes and molecular pathways at the same level of detail to explain the evolution of the human head has probably never been written before. It is therefore a valuable reference work that tackles some of the debates behind the evolution of one of the most distinctive parts of our bodies.
So, should you run out and buy Lieberman’s opus at your nearest book store? Hold on. The Evolution of the Human Head is a very academic work and perhaps too detailed for a first encounter with the subject. It’s more the kind of book that one reads for study or for autodidactic learning. Any biologist or archaeologist, from bachelor to professor level, will get a complete picture of human head evolution. In addition, the book can also play the role of an encyclopedia of information about heads, as every chapter will answer a particular question without having to read the whole section.
Definitely, it was a clever head who wrote this book. That’s something chimpanzees can’t manage.
Letzte Änderungen: 29.07.2013