The New Humanities

where, when, and why our ancestors first stood up

(Princeton University Press: 2003)

“Speciation, especially multiple speciation, has to take place in geographic or ecological compartments.... All animals have finite distributions that are loaded with many detailed implications for their ecological adaptations, evolutionary origins, and ability to spread or disperse. Both contemporary and ancient Africa can be understood as a pattern of ecological islands.... Discussion of the geography of human evolution has often been so threadbare, abstract, and generalized that our many and different ancestors have no perceptible existence in time and space. There needs to be a fuller acknowledgement and awareness that our forebears were embedded in the same ecological matrices that other animals are and have been, all with specific and finite distributions.”

(Kingdon, p.10)

This, to put it bluntly, has been the major weakness in previous hypotheses regarding the early evolution of hominids. “And then they went out onto the savanna & stood up” is, implicitly or explicitly, the basic story in dozens of books, and literally thousands of scientific papers. The one thing that virtually no-one seemed really prepared to do was to treat our common ancestor as just another big mammal - which, by definition, it was - and apply the full range of biogeographical information to the problem of its origin. Similarly, standing upright requires a whole host of anatomical shifts, which must have occurred as an ongoing adaptive process that was viable throughout...otherwise, no descendants.

Putting these two rich sources of information together is the key innovation in Jonathan Kingdon’s Lowly Origin, a work which has clearly set a new benchmark for approaches to human evolution. Quite simply, it outclasses all previous attempts at answering this question, making them appear simplistic & naive in their failure to address the biogeographical context, or the genuine complexity of the anatomical rearrangement that was required.

Kingdon is amply qualified for this work. A leading expert of African mammalian ecology and anatomy, he is also a very good writer & a subtle thinker who is at ease with multicausal explanations - which he constantly ends up with, despite his efforts to distinguish between diffferent adaptations, in an attempt to make the processes involved clearer to the reader:

“One difference between this account and many that have preceded it is that I try not to amalgamate adaptions.... A second peculiarity of my own understanding of human evolution can be contrasted with the pictures that are painted in innumerable books, articles, and dioramas representing hominins and other extinct mammals in picturesque ‘National Park-like’ fire-climax savannas...[which] became common only 1 to 2 mya [million years ago].... Another primary difference between my approach and those of my predecessors is that I envisage standing as a relatively inefficient response to an exceptionally benign but very localized environment, This is the exact converse of previous explanations, which attempt to understand bipedalism in terms of increased efficiency under very widespread ‘savanna’ conditions that were more difficult and trying than those in the forests or woodlands that preceded this supposed ‘ordeal’.... [As well] there have been various suggestions for the isolation of vaguely eastern or southern ape populations, but none has identified a habitat both ecologically distinct enough to elicit an entirely new form of locomation, nor geographically separate enough to impose the necessary isolation. My own outline addresses both shortcomings.”

(Kingdon, pp.14-18)

As is made evident here, not only is the typical “savanna” model likely to be incorrect, it is literally impossible - as such landscapes only became common enough to be a major evolutionary factor much more recently...and, quite possibly emerged - as we shall see - only in the wake of “firestick farming”.

“For the most part, I have used the often random and accidental provenances of fossils as mere guides to the larger ecological and geographic contexts for human evolution, seeking clues in those details of African biogeography and ecology that we can still retrieve and reconstruct today. I have also sought to put the likely anatomical and behavioral responses of early hominins to a succession of environmental challenges into a sequential and spacial order that is consistent with the fossil record.... The first tie-up between time, place, ecology, and behavior is located on the east African coast, the second and third involve movement into the interior (each involving subtly different but highly significant divergences). The hominin trail leads on into the Highveldt and other interior uplands and thence, very much later, to the Atlas Mountains (or Arabia).... Finally, as a specialist in the evolution of mammals, the perspective that I have sustained the longest (and reinforced most decisively in this book) is that of the emergence of humans as the evolution of yet another mammal - a very peculiar and special one, true, but in essence just one more African mammal.”

(Kingdon, pp.5-6)

“As for mechanism, I have not sought global drought crises, nor even fewer trees. Rather, I see an ape population adapting to a different, more deciduous kind of forest and...different, perhaps richer, menu. I have postulated a switch to more terrestrial feeding, but instead of actively pursuing fleet prey, east coast ground apes would have found a rich supplement of small, sessile animals and plant matter from the forest floor to augment crops of fruit; the latter being predictably less diverse and growing nearer the ground than in the high forests further west.... The argument hinges on changes in the spine, pelvis, and head-neck junction (perhaps also the heel) being necessary precursors to standing and balancing on two legs.... In common with my colleague, Clifford Jolly, I hold that it was foraging, mainly on the ground, in a squatting position that demanded these necessary modifications.”

(Kingdon, p.19)

By this stage, readers should be under no illusions. This is not the usual tale of human evolution they are used to. In parallel with Merlin Donald’s Origins of the Modern Mind (1991) - which redefines cognitive evolution - I would argue that Kingdon’s work ought to decisively reorient human evolutionary approaches towards much more detailed and coherent models, which fully think through the implications of our ancestors as real, functioning animals, who evolved in specific ecosystems that are hardly likely to be well represented in the modern world.

Kingdon also wants to reconceive the debate surrounding the freeing-up of our hands through upright posture, by exploring the long different nature of fore- and rear-limbs...something that was obscured when vertebrates first took to the land:

“From the very beginning, tail-end limbs have had quite different origins and functions from forelimbs. The latter first evolved in close association with the head - indeed, so close that pectoral fins were actually tethered to the head of early fishes.... Likewise, the anterior sources of forelimb nerve networks testify to the very separate limb origins. Subordinate to the brain, forelimbs still serve many vertebrates to alter and adjust their sense-driven decisions about the direction and pace of forward movements... Even in species with well-matched limbs and great similarities in hand and foot structure, a clear separation of functions between fore- and hindlimbs is evident. All four extremities function as clamps, but there is a premium on both strength and ankle flexibility in the rear clamps whereas ‘exploratory skill’ and deft, multiple use distinguish the fore clamps.”

(Kingdon, pp.26, 50)

“A reasonable working hypothesis is that primates arose from the already aboreal and nocturnal [mammalian] stock as a peculiar lineage of tiny visually oriented insect eaters, foraging at night, singly, and probably rather slowly, through the fine foliage of tropical rainforests.... Realignment of the eyes seems to have been an intrinsic part of the muzzle’s shrinkage, an expansion of the brain, and a downward bending of the skull and shortening of the face.... In an evolutionary perspective, [primate visual] improvements essentially redifferentiated and regained properties of vision that were never lost by birds, reptiles, even some fish!”

(Kingdon, pp.45-6)

“I think that what took place was less a case of bipedalism initiating new behaviors, than the removal of frustrating constraints on many existing talents. These could be said to have been warped or at least hampered by the anatomy of a weight-bearing wrist and hand. Before becoming bipedal, the potential for more effective manual manipulation of foods or fellows must have been curtailed by the persistent intrusion of weight-bearing duties.”

(Kingdon, p.126)

By setting the scene in this way, Kingdon frames the problem afresh. Rather than intensified selection pressures on locomotion leading the way, these were relaxed whilst the underused potential of the hands were mobilized afresh. Given the sheer complexity of the redesign of the spine, pelvis and shoulder involved, this appears a considerably less “miraculous” adaptive process, and one well-fitted to the now almost lost ecosystem Kingdon identifies as our ancestral home...

“It was squat-feeding, not bipedalism, that induced changes in the upper body, backbone, and pelvis of ground apes. The special legacy of squat-feeding was to disengage a heavy, cantilevered upper body from an equally oblique pelvis, and to rebalance a more lightly built head and thorax vertically over a compact basinlike pelvis. That these changes could improve balance on two legs would have been an almost accidental bonus, an anatomical by-product.”

(Kingdon, p. 153)

“If the bifurcation within a common chimp-hominin ancestral population took place in eastern Africa, it is essential to explore how habitats in central Africa might have related to those in the east at the same time. In the Horn, recurrent cycles of drier climate have repeatedly interpolated an ecological barrier between east-central Africa and the humid coast.... [It was] climatic change operating through this Somali arid zone, rather than the Rift valley, that premitted protohominins to become a new, highly distinctive and aberrant primate.”

(Kingdon, pp. 106-7)

“Kiwengoma, in the Matumbi Hills on southern Tanzania’s Indian Ocean littoral, is a last vestige of the forests that one capped hilltops and filled valleys all along the east African coastline. The distinctness of this habitat has only begun to be documented and appreciated in very recent times...as a ‘Center of Endemism’ quite distinct from the main forests of central and western Africa. That distinctness lies not only in the different climates, soils, and species. For the animals and plants that live there, the narrowness of the coastal strip implies both diminished population sizes and much greater susceptibility to fragmentation.... [As well] the distribution of many plants and animals testifies to the east coast being the core area for forest and thicket regimes that spread far inland, mostly along broad valley systems and up the moister slopes of inland hills and mountains.”

(Kingdon, pp.116-18)

And the innovative ideas (and the evidence to support them) just keep coming. Kingdon makes no bones about the fact that the fossil record is very likely to provide only a sample of the plethora of early hominin species, based upon the species radiation patterns we observe in other large mammals. He also makes a strong case connecting this with the environmental context he describes:

“If my suggestion is correct that the hominin radiation began with a coastal stock of ground-living apes...a discontinuous distribution over some 4000 km may well have given rise to genetic differences [even] in a purely coastal species. As soon as that parental population began to expand inland from its coastal base, the possibilities for genetic differentiation would have multiplied.”

(Kingdon, pp. 157-8)

“’Last ape’ to ‘first hominin’ is only a conceptual transition (and a largely semantic one at that), but there could be a convenient geographic dimension whereby the former remained ‘squatters’ that lived in moist, warm, nutritionally rich coastal lowlands, whereas the latter were (probably rather slow) ‘walkers’ that took to a somewhat more exposed way of life beside rivers in the drier, cooler, and higher uplands.... During later periods of global cooling, these upland populations may well have been forced to descend from the heights, but an acquired tolerance of cold and drought should have put south African and Ethiopian populations or groups at an advantage.”

(Kingdon, p.164-5)

By making substantial use of the observational work of primatologists, Kingdon also develops a useful - and likely - approach which sets the stage for proto-culture firmly within the capacities of a band of upright apes. And, at every stage of his argument, the clear evidence from a variety of sources - supporting overdetermined shifts in highly likely directions - sets, yet again, a new standard for such work.

“In spite of a menu of behavioral options and some potential for learning refinements, the displays of most species (including ‘bluffing’ or ‘mobbing’ routines) are stereotyped and genetically fixed. Apes, instead, can elaborate or adapt both individual and group actions...[which] can justifiably be described as cultural, learned behaviors.... Scavenging, in the popular sense, could have been the late manifestation (after Homo had become a full member of the open country fauna) of a much larger trait in our lineage. This trait has less to do with a taste for meat from dead animals than with particularly acute sensitivities to other animals as guides to hidden or potential food sources. This sensitivity could have been to the animals themselves, as prey, but progressively tended, more and more, toward appropriating some or all of the other animals’ own subsistence...displacing or discouraging any other species from food sources they might otherwise be able to use. Scavenging, as commonly understood, is typical of open country species. I contend that its beginnings, in forest-based members of the Homo lineage, could have provided a major mechanism not only for expansion out tof the forest, but for a diversification of diet that led away from species-specific diets and, even more significantly, a rapid elaboration of flexible technologies for obtaining food.... Combining the predator’s alertness to other species’ behavior with a periodic intolerance of actual and potential competitors (as food choices increased), this unprecedented foraging technique might better be termed ‘niche-stealing’ than scavenging.”

(Kingdon, pp.214-19)

If Jonathan Kingdon is right, and I strongly suspect that he is, our complete picture of early human evolution will have to be totally redrawn. Even so, his book does not address all the issues - concentrating on material rather than psychological processes - making it particularly strong on the period up to the emergence of Homo ergaster/erectus. As I noted early in this review, perhaps the best counterpart to Lowly Origin is Merlin Donald’s Origins of the Modern Mind. For there is very little overlap between the two, whilst they complement each other marvellously.

However, despite the major contrast in focus, and their almost entirely different disciplinary backgrounds, there is one main feature which unites the two, and which is sadly lacking in most treatments of human evolution. This is the insistence, by both authors, that we need to develop models that envisage our ancestors as fully functional & integrated beings, not just some half-way house between apes and humans. And, although this principle attracts a great deal of lip service, it is rarely treated as the difficult task that it is...particularly at the level of Homo ergaster/erectus. Equidistant from us and our closest cousins - the two chimpanzees - erects colonized Eurasia, mastered fire, and developed the first highly-worked technology. Yet their anatomy strongly suggests that they could not speak, despite their substantially enlarged brains, and the evidence is clear that their culture was basically static compared to ours.

“It will be clear enough now that my piecemeal approach to hominin evolution includes the possibility of a ‘slow start’ for the Homo lineage (relative to the Praeanthropus /Paranthropus group, which I regard as belonging to a more precocious sibling lineage).... Further, I am suggesting that the most radical transformation could be be ascribed to an outlying population suffering a relatively late but lengthy isolation in a distant, dry, open habitat.... The association of ergaster with fire is of exceptional interest, because scholars have long ascribed the reduced size of human teeth to cooking and food processing, and it is the small cheek teeth that most immediately distinguish H. ergaster.... [And] if the Atlas region was this species’ region of origin, it can be remarked that (in common with some other Mediterranean environments) fires triggered by lightning are an annual hazard....[Moreover] the link between H. ergaster may be much more extensive than has been appreciated. What are commonly called ‘secondary grasslands’ are in fact made by two principal agencies: one is grazing, browsing, and trampling by large or numerous herbivores; the other is fire.... Thus, the spread of fire-climax grasslands may not have preceded the burgeoning population of highly successful hominins, but could have followed hard on their pyromaniac heels.”

(Kingdon, pp.271-7)

Lowly Origin reconfigures the entire frame for debating human origins, by immeasurably enriching our understanding of the context in which it occurred - and the exact nature of the anatomical changes involved. There is simply no substitute for this book...and until other researchers come near to matching its sophisticated grasp of these issues, it will be difficult to say whether other evolutionary scenarios can match it. Kingdon’s book is that most rare thing - genuinely original, and the best in its class. Read it...

“As yet, there is no direct evidence for the detailed population structure or demography within groups of prehistoric foraging humans.... Up to a third could have been less than fully adult (in spite of high mortality or low birth rates), which would have given this class some sort of proportional role in determining the day-to-day functioning of the group. It would be wrong to see nonadults as mere hangers-on...they must have been active participants in the overall foraging.... A high proportion of nonadults defines what might have been special about human evolution. It also hints at where the power of natural selection is targeted and is most influential. In thinking that selection favors smart kids and loving mothers, I depart from most other students of human evolution, who have concentrated on sexual selection and mate choice in their search for primary selection mechanisms.”

(Kingdon, p.294)