We can only speculate about situations from even earlier times. What were the people of GBY doing 780 thousand years ago (Chapter 6)? Or indeed those early people with their Oldowan toolkits by the lakesides at Ain Hanech, Baza, or Ubeidiya? In all probability they were not moving around more than they needed to. The common denominator, along with predictable resources, in all these sites is the presence of a substantial and fairly permanent water supply. Predictable water argued in favour of a sedentary life but its distribution, I will now argue, restricted the spread of this way of life.
Take the case of the Murray-Darling Basin. People adopted a sedentary life and the population grew to a significant size, but it was contained. It did not spread beyond the boundaries of the river system because the desert lay beyond and, even if people colonized such areas of instability, they would have again been limited to low densities. In other cases, the barrier was imposed by time and changing climatic conditions. The Natufians seem to have been able to domesticate rye but the instability brought by a period of cold and arid conditions around 12.8 thousand years ago6 ended the experiment. A permanent source of water and stable conditions of resource diversity or abundance were therefore needed for population growth and settlement and it happened on a number of occasions in different parts of the world. Geographical expansions needed something else: a physical continuity of the conditions long enough to permit the spread. That also happened repeatedly, probably on more occasions than we realize and, as we have seen, followed two major avenues: water bodies and high ground, also associated with reliable water supply. Some readers may be surprised that I have not added the coast as an avenue. It is because I do not consider the coast to have provided the conditions suitable for prolonged geographical expansion. At best the coast was a particular example of an avenue that followed water bodies and quite often, as in southern Africa and south-western Iberia, it was a refuge and cul-de-sac, but rarely a launchpad.
These geographical expansions started with the very origin of Homo sapiens, 1.8 million years ago. On a number of occasions they conquered significant tracts of geography. The expansions probably did not always involve nomadic people. My guess is that they most often involved sedentary or semi-sedentary people. These would have been the ones that were able to settle in areas of stability and generate population growth spurts which translated into dispersal. The nomadic people would have always been at low density so their rate of expansion would have been slower; when it happened, it would have got people across arid and semiarid regions.7 Global expansions probably involved a mix of sedentary and nomadic lifestyles, depending on where the growing populations were situated and what the ecological conditions were like.
The 6-million-year-long story of our evolution is in contrast with the much younger story which started after 10 thousand years ago. This younger story was to lead to the eventual encounter of western colonists and native peoples across Australia and the Americas in particular. Can we see anything in this more recent story that we could relate to the patterns that we have established in this book? I think that we can. If we take a broad survey of regions in which agriculture originated or had an early success,8 we find that they have features in common. For starters they all occurred in the time frame after 10 thousand years ago, which is when the world reached a level of stability in the context of a warm interglacial, the Holocene. Many of these areas of origin or early spread are associated with significant water bodies, usually large rivers in warm, often arid, areas of Middle Earth and beyond: Tigris and Euphrates Rivers; Jordan River; Yangtze and Yellow Rivers; Indus River; Nile River; Mississippi and Ohio Rivers; and possibly the Niger River in the African Sahel. A second group is associated with hills and mountains in tropical areas, which as we saw provided alternative conditions as refuges and launchpads in earlier times: the Andes; Meso-American Highlands; New Guinea Highlands; and the Ethiopian Highlands. One region in which agriculture did not originate but to which it spread rapidly was western Europe, particularly around the warm Mediterranean. We have already seen how parts of the oceanic west of the Eurasian continent had been favoured by the Neanderthals on account of the generous rainfall there. That rainfall provided the predictable and stable conditions that equated to the large rivers or the tropical highlands.
We have seen in this book how the favoured human habitat combined trees, open spaces, and water. The farmers developing agriculture in some areas, such as the New Guinean Highlands or western Europe, hit areas of dense forest. They resolved the problem by opening these up by cutting down or burning trees, later by allowing grazing animals like goats to maintain a patchwork of open spaces and trees in places with abundant water. The active land management that started in Niah Cave and in Australia was now taken to a new level. Where the ideal human habitat was not available, we created it—provided there was water at hand. This powerful combination of increasing the environment’s carrying capacity by growing and farming our favourite foods, linked to intense land management, created an unprecedented population explosion. Now we were no longer hemmed in. Provided there was water, and we found systems of harnessing those waters for irrigation, we could spread across the world in an unprecedented manner, and we did.
Much later, in Renaissance Italy, or in the Age of Enlightenment, or in Victorian England, painters chose to portray the ideal and idyllic human landscape in their works of art. Almost without exception these wonderful works of art featured certain elements that will by now be familiar to us: trees, open spaces, and water. Many also included grazing herbivorous animals—cows, horses, sheep—which were domesticated equivalents of the kinds of wild animals that we grew up with during the course of our evolution. They also included rocky places or their modern equivalents, buildings.9 In the high-density, urban, post-Industrial Revolution world of the west, we created parks inside cities. They too always combine trees, open spaces, and water. The improbable primate, long-distance runner and walker par excellence, now chooses to jog across these parks that recreate the ancestral habitat. We may have taken huge cultural and technological strides in the last 10 thousand years but our biology, put together slowly over millions of years, still shines through no matter how hard we try to pretend otherwise.
ENDNOTES
PREFACE
1. E. Mayr, ‘Taxonomic Categories of Fossil Hominids’, Cold Spring Harbor Symposia on Quantitative Biology 15 (1950): 109–18.
2. J. R. Stewart and C. B. Stringer, ‘Human Evolution Out of Africa: The Role of Refugia and Climate Change’, Science 335 (2012): 1317–21.
3. E. Mayr, Animal Species and Evolution (Cambridge, Mass.: Harvard University Press, 1963).
4. E. Aguirre, ‘Homo erectus and Homo sapiens: One or More Species?’, Courier Forschungs-Institut Senckenberg 171 (1994): 333–9; M. H. Wolpoff, ‘The Systematics of Homo’, Science 284 (1999): 1773c.
5. G. G. Simpson, ‘The Species Concept’, Evolution 5 (1951): 285–98. Palaeontological species are all fossil species that intergrade to form a chronological series. They are defined by arbitrary morphological limits in the time series. They are, in effect, lineages. Whether two lineages represent distinct biological species, i.e. they could not have interbred, or not is impossible to determine on morphological grounds alone. Recent advances in genetics, including fossil DNA, are resolving some of these issues. See also, A. J. Cain, Animal Species and Their Evolution (London: Hutchinson, 1954).
6. C. Finlayson, The Humans Who Went Extinct: Why Neanderthals Died Out and We Survived (Oxford: Oxford University Press, 2009).
7. C. Finlayson, Neanderthals and Modern Humans: An Ecological and Evolutionary Prespective (Cambridge: Cambridge University Press, 2004).
8. F. L. Mendez et al., ‘An African American Paternal Lineage Adds an Extremely Ancient Root to the Human Y Chromosome Phylogenetic Tree’, American Journal of Human Genetics 92 (2013): 454–9.
9. D. Lordkipanidze et al., ‘A Complete Skull from Dmanisi, Georgia, and the Evolutionary Biology of Early Homo’, Science 3
42 (2013): 326–31.
CHAPTER 1
1. Finlayson, The Humans Who Went Extinct.
2. K. Milton, ‘Diet and Primate Evolution’, Scientific American (Aug. 1993): 86–94.
3. Milton studied the highly active fruit-eating black-handed spider monkeys Ateles geoffroyi on Barro Colorado Island in Panama. There, she compared them with the less-active mantled howler monkeys Alouatta palliata which took a greater proportion of leaves and flowers and fewer fruit than the spider monkeys. Her study was the basis for future work on the relationship between diet and behaviour in primates. K. Milton, ‘Food Choice and Digestive Strategies of Two Sympatric Primate Species’, American Naturalist 117 (1981): 496–505.
4. Among the most intensely-studied primates and our closest living relatives. For range of foods consumed see R. Wrangham, ‘Feeding Behaviour of Chimpanzees in Gombe National Park, Tanzania’, in T. H. Clutton-Brock(ed.), Primate Ecology (London: Academic Press, 1977).
5. See K. B. Strier, Primate Behavioral Ecology (Boston: Allyn and Bacon, 2000) for a useful summary.
6. J. L. Gittleman (ed.), Carnivore Behavior, Ecology, and Evolution (Ithaca, NY: Cornell University Press, 1989), vol. i.
7. Based on cranial shape analysis. B. Figueirido, F. J. Serrano-Alarcón, G. J. Slater, and P. Palmqvist, ‘Shape at the Cross-roads: Homoplasy and History in the Evolution of the Carnivoran Skull towards Herbivor/, J. Evolutionary Biol. 23 (2010): 2579–94; B. Figueirido, P. Palmqvist, J. A. Pérez-Claros, and W. Dong, ‘Cranial Shape Transformation in the Evolution of the Giant Panda (Ailuropoda melanoleuca)’, Naturwissenschaften 98 (2011): 107–16.
CHAPTER 2
1. A feature—the ability to eat a wide range of foods—that allowed primates to occupy many different ecological opportunities. I. Crowe, The Quest for Food: Its Role in Human Evolution and Migration (Stroud: Tempus, 2000).
2. Whiten et al. summarized information from seven long-term chimpanzee Pan troglodytes study sites and found that 39 different behaviour patterns, including tool use, courtship, and grooming, were present in some communities and not in others. They discounted ecological explanations for the differences which they attributed to cultural variations. A. Whiten et al., ‘Cultures in Chimpanzees’, Nature 399 (1999): 682–5.
3. The time when the earliest fossils of our potential ancestors are thought to have lived. These have been ascribed to Sahelanthropus tchadensis. M. Brunet et al., ‘A New Hominid from the Upper Miocene of Chad, Central Africa’, Nature 418 (2002): 145–51. I discuss these fossils’ relevance to our ancestry in The Humans Who Went Extinct.
4. The evidence for these dramatic changes in the environment is described in The Humans Who Went Extinct so I will not elaborate further. Since Humans, Cerling has provided a useful analysis of environmental conditions in eastern Africa over the past 6 million years (hereafter myr), supporting the view that grasslands became dominant during this time. This was indeed a new world of grasslands and the world changed for ever. T. E. Cerling et al., ‘Woody Cover and Hominin Environments in the Past 6 Million Years’, Nature 476 (2011): 51–6.
5. The recent discussion has revolved around the habitat of Ardipithecus ramidus which is the best known of these early ancestors and lived in Ethiopia around 4.51–4.32 myr: T. D. White et al., ‘Macrovertebrate Paleontology and the Pliocene Habitat of Ardipithecus ramidus’, Science 326 (2009): 67, 87–93; T. E. Cerling et al., ‘Comment on the Paleoenvironment of Ardipithecus ramidus’, Science 328 (2010): 1105d; T. D. White et al., ‘Response to Comment on the Paleoenvironment of Ardipithecus ramidus’, Science 328 (2010): 1105e.
6. See reasoning behind lack of credence of the Aquatic Ape Theory in John Hawks’s weblog, ‘Why anthropologists don’t accept the Aquatic Ape Theory’, at
7. A. Hardy, ‘Was Man More Aquatic in the Past?’, New Scientist, 17 March 1960.
8. See, for example, E. Morgan, The Aquatic Ape: A Theory of Human Evolution (New York: Stein and Day, 1982); E. Morgan, The Aquatic Ape Hypothesis (Bury St Edmunds: Souvenir Press, 1997).
9. Toumaï and Ramidus were vernacular names which I used in The Humans Who Went Extinct.
10. P. Vignaud et al., ‘Geology and Palaeontology of the Upper Miocene Toros-Menalla Hominid Locality, Chad’, Nature 418 (2002): 152–5.
11. Anancus kenyensis and Sivatherium spp., Vignaud et al., ‘Geology and Palaeontology’.
12. Isotopes are chemical variants of an element, sharing the same number of protons but differing in the number of neutrons. The ratio of different isotopes in teeth can give a good indication of diet. Carbon isotopes are taken into the teeth through the diet during the course of an animal’s life. We can infer, for example, if the diet of a herbivorous animal consisted largely of grazing grasses (C4 plants) or browsing leaves (C3 plants). In the case of Ramidus, the carbon isotope signal of its teeth resembled that of the small arboreal baboon Pliopapio and the leaf-browser Tragelaphus (see also nn. 14 and 15) suggesting little intake of grasses. See also The Humans Who Went Extinct, 76–7.
13. The relevant papers in the Science volume are referred to in n. 5. See also: T. White et al., ‘Ardipithecus ramidus and the Paleobiology of Early Hominids’, Science 326 (2009): 64; G. Woldegabriel et al., ‘The Geological, Isotopic, Invertebrate, and Lower Vertebrate Surroundings of Ardipithecus ramidus’, Science 326 (2009): 65; A. Louchart et al., ‘Taphonomic, Avian, and Small-Vertebrate Indicators of Ardipithecus ramidus Habitat’, Science 326 (2009): 66.
14. Kuseracolobus aramsi which was a leaf-eater with a strong preference for trees. The carbon isotope signature of its teeth indicated that it was feeding in dense to open forest. The third primate was a small baboon, Pliopapio alemui.
15. A kudu, Tragelaphus species, whose present-day counterparts are associated with wooded habitats.
16. Dukiers, Cephalophus species, are small antelopes that are common in the dense African forests.
17. Arguing for a tree or bush savannah with 25 per cent or less woody canopy cover. The environment ranged from riparian forest to grassland with C4 grasses making up between 40 and 60 per cent of the biomass. Cerling et al., ‘Comment on the Paleoenvironment of Ardipithecus ramidus’.
18. Of 275 fish specimens, catfish Clarias dominated (175 specimens) followed by barbs Barbus (20) and cichlids Cichlidae (21). These are species of poorly oxygenated, shallow waters. The crocodiles were indistinguishable from present-day Nile crocodiles. Freshwater turtles were the African mud turtle Pelusios and a flapshell softshell turtle Pelomedusa. Woldegabriel et al., ‘The Geological, Isotopic, Invertebrate, and Lower Vertebrate Surroundings’.
19. The scavenging habits of wild boar in southern Spain have been the subject of a recent study: E. Bernáldez Sánchez, ‘Biostratinomy Applied to the Interpretation of Scavenger Activity in Paleoecosystems’, Quaternary International 243 (2011): 161–70.
20. Whittaker gives a list of the productivity of world biomes (in grams of organic matter per square metre per year). Tropical rainforest is second after algal beds and reefs with 2,200 g/m2 and it is followed by swamp and marsh (2,000) and tropical seasonal forest (1,600). Savannah is eighth at 900 g/m2. R. H. Whittaker, Communities and Ecosystems (New York: Macmillan, 1975).
21. This paragraph, taken from Cerling et al.’s paper (‘Comment on the Paleoenvironment of Ardipithecus ramidus’), shows how predefined habitat categories can easily get us tied down in a level of detail that the initial observations simply cannot answer and in debates that cannot be resolved: ‘We adopt the United Nations Scientific and Cultural Organization (UNESCO) definitions for classification of African vegetation used by White et al. [‘Macrovertebrate Paleontology’] in which “forests have continuous stands of trees with overlapping crowns, forming a closed, often multistory canopy 10 to 50 m high; the sparse ground layer usually lacks grasses; closed woodl
ands have less continuous canopies and poorly developed grass layers; woodlands have trees with canopy heights of 8 to 20 m; their crowns cover at least 40 per cent of the land surface but do not overlap extensively. Woodland ground layer always includes heliophilous (sun-loving, C4) grasses, herbs/forbs, and incomplete small tree and shrub understories; scrub woodland has a canopy height less than 8 m, intermediate between woodland and bushland. As proportions of bushes, shrub, and grasses increase, woodlands grade into bushland/thickets or wooded grasslands. Wooded grassland is land covered with grasses and other herbs, with woody plants covering between 10 and 40 per cent of the ground. Grassland is land covered with grasses or other herbs, either without woody plants or the latter not covering more than 10 per cent of the ground.” The UNESCO classification does not include a definition of savanna because of its ambiguous use, but common usage of the term would include wooded grasslands and grasslands of the UNESCO terminology.’
22. Facultative bipedal means that it could walk on the two hind limbs but that its anatomy did not make it exclusively (obligate) bipedal. Since it was partly arboreal we should conclude that Ramidus walked on two hind legs for part of the time and on all fours at other times, perhaps when on the branches of trees. We have little to inform us on Toumaï’s level of bipedality.
The Improbable Primate Page 15