Published by: Thames & Hudson
Human Evolution: A Pelican introduction by Robin Dunbar
Published by: Pelican Books
Did a focus on local life leave Neanderthals perilously isolated? (Image: Elisabeth Daynes/SPL)
The idea of human as networker is fast replacing the idea of human as toolmaker in the story of the human brain, claim two new books on our evolution
“HELL is other people,” goes Jean-Paul Sartre’s famous line. It is a hell that may have created us and our culture, judging by two new books. They show that the idea that we are defined by our struggles to deal with our fellow humans is shaking up archaeology and how we think about the key force driving human evolution.
The first book is Thinking Big by archaeologists Clive Gamble and John Gowlett and evolutionary psychologist Robin Dunbar. It is the story of a seven-year project – From Lucy to Language – that confronted archaeologists with the social brain hypothesis of human evolution.
The result is a dramatic demolition of the “stones and bones” approach to archaeology, which keeps researchers firmly fixed only on the physical evidence they dig up, and a move towards a grand look at the evolving human mind. There is “more to humanity than the bits of chipped bone”, write the authors as they seek a framework for all human psychological traits, from kinship and laughter to language and ceremony. Old dogma is derided as never moving beyond “WYSWTW” (What You See is What There Was).
The second book is a solo effort by Dunbar, the key thinker behind the social brain hypothesis. In Human Evolution, he lays out the big ideas that the archaeologists later took up. At its heart is the observation that as brains grew bigger, so did the groups we live in: bigger brains were built for and by social life. Modern humans have a cognitive limit of about 150 friends and family (the well-known “Dunbar’s number”). Within that circle are an average of five “intimates”, 15 best friends and 50 good friends. Chimps have an average community size of 55.
Studies of living, non-human primates show why you might need bigger brains to live in bigger groups. The more others are around, the more likely you are to be bullied out of a juicy food patch or a safe sleeping site. Such stress can be hell, especially for low-ranking females, who can be driven into infertility. To cope, primates create cliques of allies which they sustain through the pleasurable endorphin rush induced by regular mutual grooming. This solution fails if groups grow bigger, for there is not enough time for one-on-one attention. Bigger brains are key to developing smarter ways of dealing with others, the theory goes.
For Dunbar, these included laughter and singing, both great endorphin-releasers within groups. There was also fire, which gave light so evenings could be used for cooking and more “social grooming”. Then came language, together with a growing ability to read others’ intentions, which ultimately made it possible to tell stories, maintain far-flung relationships and usereligion to bind communities.
The Thinking Big archaeologists take from Dunbar the grand hypothesis that social life drives human change, switching from a view of “man the toolmaker” to “man the networker”. Alongside that, the proven relationship between brain size, group size and mental skills makes it possible to estimate the size of groups our ancestors lived in and their capacity to interact with others.
A fresh look at the Neanderthals is telling. They dominated Europe for 250,000 years, much longer than modern humans. They were skilled hunters, toolmakers and had mastered fire. Their brain size suggests they lived in groups of about 110 and had the cognitive skills to understand the feelings of others. That fits well with archaeological evidence that older and disabled Neanderthals were cared for: they perhaps knew compassion.
So why did they vanish so fast during a time of changing climate, when modern humans prospered? It may be that their mental skills were not quite adequate to maintain relationships beyond immediate group members, something we can do easily. That may have been crucial to our success: in hard times, bigger networks can mean gaining help from distant friends who are still doing well, and who you’ll help in turn. Without that “social storage” of resources, local extinction may loom. Archaeological evidence again tallies with the social brain theory: one study shows that 70 per cent of the raw materials of Neanderthal tools travelled less than 25 kilometres, while 60 per cent of those of contemporaneous humans had travelled more than 25 kilometres.
The two books fit well together but are very different. Thinking Big inspires, but much wonderful research is passed over too briefly amid general argument. An exception is a story from Beeches Pit, a 400,000-year-old site in the east of England. Archaeologists there painstakingly reassembled the flint flakes struck from a rock in the process of making a hand axe. Two flakes were found burnt bright red; they had fallen into a fire just in front of the axe-maker. We can almost see our ancestors working around what must have been a communal fire, for no one person could have gathered enough wood to keep it burning.
Dunbar’s solo work, Human Evolution, however, is a must-read. It has the great strength of showing you the inner workings of an imaginative mind, while allowing you the freedom to think, and even to disagree about whether that hellish social pressure really has given us our distinct cognitive design, along with science and the arts.
This article appeared in print under the headline “Beyond bones and stones”
Alun Anderson is a consultant for New Scientist