In this masterwork, Russell H. Tuttle synthesizes a vast research literature in primate evolution and behaviour to explain how apes and humans evolved in relation to one another, and why humans became a bipedal, tool-making, culture-inventing species distinct from other hominoids. Along the way, he refutes the influential theory that men are essentially killer apes – sophisticated but instinctively aggressive and destructive beings.
Situating humans in a broad context, Tuttle musters convincing evidence from morphology and recent fossil discoveries to reveal what early primates ate, where they slept, how they learned to walk upright, how brain and hand anatomy evolved simultaneously, and what else happened evolutionarily to cause humans to diverge from their closest relatives. Despite our genomic similarities with bonobos, chimpanzees, and gorillas, humans are unique among primates in occupying a symbolic niche of values and beliefs based on symbolically mediated cognitive processes. Although apes exhibit behaviours that strongly suggest they can think, salient elements of human culture – speech, mating proscriptions, kinship structures, and moral codes – are symbolic systems that are not manifest in ape niches.
This encyclopedic volume is both a milestone in primatological research and a critique of what is known and yet to be discovered about human and ape potential.
1. Mongrel Models and Seductive Scenarios of Human Evolution
Theories of human evolution have been biased by folk beliefs about the meaning of individual, sexual, and group differences in appearance and customs, and by world events, like warfare, and personal experiences of theorists. As apes became subjects of detailed study their behavior served variously to reinforce or refute notions of close similarity between them and us.
Part I: Terminology, Morphology, Genes, and Lots of Fossils
2. Apes in Space
Although the old argument about which nonhuman primates are closer to humans has settled on the apes, many puzzles remain regarding the extent to which we can draw on them as models for specific aspects of our variable genomes, morphology, and behaviour. This chapter contains the vocabulary and features that are essential to explore our phylogenic position vis-à-vis living apes.
3. Apes in Time
Rare major and many minor fossil discoveries underpin phylogenic models of primate evolution over a ~65–Ma span of geologic time. A variety of refined geochemical and excavation methods allow ever more precise placement of specimens in time; however, small samples of fragmentary specimens and very patchy spatiotemporal representation usually limit their informational value.
4. Taproot and Branches of Our Family Tree
The past century of field research has produced a trove of fossil specimens indicating that our Linnaean family, the Hominidae, contained a notable number and variety of species that is difficult to organize into phylogenic lineages, only one of which terminated in modern Homo sapiens.
Part II: Positional and Subsistence Behaviors
5. Apes in Motion
Apes display highly diverse repertoires of locomotive behaviours that inspire models on the evolution of human anatomy. Chimpanzees, bonobos, and most gorillas engage in vertical climbing to move from ground to canopy, and orangutans and gibbons frequently climb up and down trunks and vines. Gorillas, chimpanzees, and bonobos knuckle-walk on the ground and on large horizontal branches. Gibbons, orangutans, and less frequently, chimpanzees and bonobos arm-swing (brachiate) beneath branches.
6. Several Ways to Achieve Erection
Modellers of the evolution of human obligate erect bipedal posture employed living apes to exemplify precedent behaviour and anatomy upon which various selective forces acted to produce the human form, viz., brachiators and knuckle-walkers, closely resembling chimpanzees. Instead, a small-bodied vertical climbing, bipedal branch-running ape is a more likely model because similar lower limb mechanics are involved in vertical climbing and human bipedal walking.
7. Hungry and Sleepy Apes
The daily food quest and need for secure lodge trees affect the ranging patterns of all ape species. They prefer fruits; however, during fruit shortages, they are remarkably versatile in accommodating a wide variety of vegetal and animal foods. Great apes build arboreal nests at night. Gorillas, chimpanzees, and bonobos sometimes also rest in ground nests during the day. Like Old World monkeys, gibbons roost in trees on ischial callosities (sitting pads).
8. Hunting Apes and Mutualism
All apes ingest invertebrates inadvertently or via active searches. Chimpanzees and, to a lesser extent, bonobos are notable for capturing small and medium-sized mammals. Chimpanzees also engage in infanticidal cannibalism. The extent to which chimpanzee hunting is cooperative is arguable, as is the relation between food sharing and mating behaviour in chimpanzees and bonobos.
Part III: Hands, Tools, Brains, and Cognition
9. Handy Apes
Unlike human hands, which are free of obligate locomotive functions, ape hands are evolutionary compromises serving various locomotive activities, grasping, and fine manipulation, including tool making and use. Their hands are highly sensitive, which allows them to feel fruits for ripeness and to engage in social grooming. Fossil hominid hands before 1.5 Ma retain features that would facilitate arboreal climbing.
10. Mental Apes
Scientists employ a diverse array of approaches and devices to explore the structure and functions of outsized human brains in comparison with those of apes. There is general consensus that apes possess self-awareness and think about situations and actions, albeit not comparable to or necessarily on the same basis as those underpinning human cognitive abilities.
Part IV: Sociality and Communication
11. Social, Antisocial, and Sexual Apes
Apes are a rich resource for theorists who model emergent hominid and early human social structures. Gibbons are attractive to those who believe that human monogamy is deeply rooted in the past. Orangutans are usually ignored because adults do not form stable groups. Gorillas and especially chimpanzees are favourites of persons who emphasize male dominance and aggression, while bonobos are preferred by modellers who view our apish ancestors living in quasi-egalitarian societies with notable female agency.
12. Communicative Apes
Laboratory studies revealed that great apes can learn to communicate with humans and one another via sign language and non-iconic symbols. Their natural vocalizations offer fewer clues to a system of communication that might have been used by early hominids. There is notable disagreement about when fully human language emerged and the sequence of events that culminated in it.
Part V: What Makes Us Human?
13. Language, Culture, Ideology, Spirituality, and Morality
Humans live in a symbolic niche: virtually everything we say, do, create, and make is consciously or unconsciously dependent upon symbols. Although many other animals probably think about proximate situations, humans have beliefs about phenomena and relationships. Humans have social and moral codes, while apes are probably amoral. Their survival and perhaps that of our species ultimately depends upon us.
Russell H. Tuttle is Professor of Anthropology on the Committee on Evolutionary Biology, at the Morris Fishbein Center for the History of Science and Medicine, and in the College at the University of Chicago.
"Witty, readable, compendious, learned, and judicious, Russell Tuttle's big new book offers every reader a thorough survey of the biology and evolution of apes, including humans and their ancestors. For scientists, it will be an invaluable resource and a treasury of unfamiliar facts and challenging ideas."
– Matt Cartmill, Professor of Anthropology, Boston University
"In this masterly overview, Tuttle interprets human evolution through detailed comparisons with our closest zoological relatives, the apes. This is a truly monumental treatise, not only in scope but particularly because of the depth of scholarship that has been brought to bear. Drawing on a lifetime of study focusing on anatomy but also including behavior and ecology, this is destined to become a classic reference work."
– Robert D. Martin, A. Watson Armour III Curator of Biological Anthropology, The Field Museum, Chicago
"A rare accomplishment. Apes and Human Evolution is an unusually fine contribution to the field and will foster great interest in any reader."
– Duane Rumbaugh, Emeritus Professor of Psychology, Language Research Center, Georgia State University
"Tuttle provides both a synthesis and a history of the evolution of one of the most interesting species of all: ourselves. An impressive achievement, written by an authority on the topic."
– Karen B. Strier, Vilas Professor and Irven DeVore Professor of Anthropology, Department of Anthropology, University of Wisconsin–Madison