httksacuto h ogtr itr frf yaisadpoie eosrcin of research reconstructions scale. new provides appropriate and for an dynamics at need rift landscape of the physical evolutionary history emphasise the long-term human the and of the primates, account with takes other that associated from features divergence better and anatomical a trajectory specific tree- provides solely from topography the transition complex based for evolutionary how hypotheses explanation show the of bipedalism, for limitations ground-dwelling accounting to the in dwelling change highlight active vegetational We and or factor. rifting climate driving of on typical key forms a land complex as the tectonics particularly and landscape physical the u h rgnlsvna yohsssiludrismn icsin fhmnorigins human of discussions many underpins still hypothesis (Cerling savannah 2007), Elton original & (O’Higgins the acceptance gained but has characteristics human some producing in ef .Bailey N. Geoff vial ohmnn.Teohrfcsso pcfi eeaintpsta ih have might that types to vegetation species niches these specific for the opportunities on ecological in (Blumenschine unique exploit changes generating focuses climatic by corresponding traits in other hominin of changes for The selected drivers or hominins. as 1972) to Morgan 1998b) available Potts 1925; 1987; (Dart (Foley shifts the climate, emphasises variability climatic characterise One simple groups. to two either sets into fall positing data They palaeoenvironmental hominisation. driving and regimes selective theories drawing each evolutionary 2007), 1998, different (Potts environments on hominin about hypotheses many are There Introduction valleys rift landscape, grasping, enduring, sprinting, agile, Keywords: that today. became know doing we so that in of athlete and dale two-legged kind down jumping terrain—the and rugged pursued hill man” “Scrambler up steep remains. prey hominin by are his early presented produced savannah has incentives or that forest physical landscape varied to of tectonically adaptations favour on in based models here Previous challenged upright? walk humans did Why Winder C. Isabelle link missing the evolution: human and topography Complex 2 1 * ANTIQUITY  C niut ulctosLtd. Publications Antiquity nti ae,w ou nteaaoia etrsascae ihlcmto,proposing locomotion, with associated features anatomical the on focus we paper, this In igig.r [email protected]) [email protected]; ntttd hsqed lb ePrs obnePrsCit Paris Sorbonne Paris, de Globe du Physique (Email: de UK Institut 7EP, YO1 York Manor, King’s [email protected]) York, [email protected]; of University Archaeology, of Department correspondence for Author tal et 7(02:11 http://antiquity.ac.uk/ant/087/ant0870001.htm 1–17 (2012): 87 fia ey,SuhArc,hmnn,bpdls,tretilsto,tectonic terrestrialisation, bipedalism, hominins, Africa, South Kenya, Africa, 01 ebl2011). Feibel 2011; . 1 tal et 1 , ∗ 97 Thorpe 1987; . efryCP King C.P. Geoffrey , tal et 1 07.I eetyasterl fwoodlands of role the years recent In 2007). . ´ ,Ui ai ieo,CR,Prs rne(Email: France Paris, CNRS, Diderot, Paris Univ e, 1 , 2 ,MaudDev es ` 2 &

Research Complex topography and human evolution

Here we propose that conceptualising hominin environments as ‘landscapes’ of complex topography brings into focus a variable that has been missing from evaluations of anatomical evolution, and one that helps to explain the inconsistencies in existing theories. This ‘complex topography hypothesis’ supplements and complements vegetational and climatic alternatives rather than completely replacing them. It entails predictions about the hominin evolutionary trajectory which can be tested against those produced by alternative hypotheses, and opens up a new research agenda of field investigation.

Limitations of existing hypotheses The original savannah hypothesis proposed that aridification thinned out the forests and forced hominins out of the trees onto savannah plains via an intermediate stage involving the use of the remaining trees for security (Dart 1925). Terrestrialisation was identified as the driver of the hominin-panin split, responsible for the appearance of most characteristic hominin features including upright bipedalism. However, the theory ultimately lost support precisely because no savannah niche exploitable by semi-terrestrial and relatively defenceless apes was identified. Newer ‘woodland’ hypotheses (Blumenschine et al. 1987; Potts 2007; Thorpe et al. 2007) have proposed that upright posture or even bipedal gait evolved in the ancestral hominids within a closed, forested environment, and that this served as a pre-adaptation that later facilitated the transition from arboreality to terrestriality as the forests disappeared (O’Higgins & Elton 2007). In these newer theories, the relative timing of evolutionary changes is different, but climatically driven vegetational change remains the key driver promoting evolutionary diversification within the hominin lineage (Figure 1). However, an upright climbing adaptation, evolved within the context of tree-dwelling, would not produce all the features required for effective rapid, long-distance terrestrial bipedalism. Explaining how our ancestors survived a locomotor transition in a relatively dangerous semi-open habitat remains a critical challenge to these hypotheses. Palaeoenvironmental evidence is insufficient to distinguish between these alternative vegetational hypotheses because preservational biases, time-averaging and the post- depositional transport of remains make it impossible to obtain precise dates for the evolutionary and climatic events that constitute their key predictions. The transition from closed to semi-open habitats proposed by most theories (see Figure 1) for example, cannot be identified in the fossil record without ambiguity. The earliest hominin sites are located in woodlands (Pickford & Senut 2001; White et al. 2009) and mixed habitats (Vignaud et al. 2002) with later ones across the full habitat spectrum (Winder 2012). There are, however, elements of environment that have been missed. Recent research has demonstrated that hominin site distributions are strongly linked to topographic patterns (King & Bailey 2006; Bailey et al. 2011; Reynolds et al. 2011). In particular, hominin sites are found in topographically complex regions where active tectonics and other geomorphological processes produce and maintain vegetational mosaics, accessible water sources, and rough topography providing tactical advantage in avoiding predators and accessing mobile prey. C Antiquity Publications Ltd.

2 COLOUR sue oivleasic rmacmlx3 niomn oarltvl a one flat relatively a to implicitly is environment ground 3D the complex to a trees the from from switch structural transition 1). a the specific (Figure model involve a this than to although of rather perspective, assumed stages topographic forest, a later is of this the implications habitat because important in However, the identify to humans. that anatomy fails and fact the it chimpanzees landscape, to the of linked on (LCA) closely focuses ancestor as hypothesis seen common is last branches the of of configuration structural implicitly; complex topography recognise the already bipedalism terrestrial to pre-adaptation a as ancestor promote where simply instances landscapes (Bailey clear patterns by observed these of 2011). challenged explanation complete that been a provide has cannot pattern, factors 2007), taphonomic (Kullmer this discovery of and fossilisation interpretation traditional The topography the complex between the timings and relative environments in evolutionary differences hominin and of pattern theories broad vegetation-based in hypothesis. several similarities by substantial proposed the histories showing Schematic 1. Figure hoislk Thorpe like Theories Forest e s t Last common Last common a ancestor nces tal et Approximate posture ofupright origin A

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Research Complex topography and human evolution

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Figure 2. For legend see next page

C Antiquity Publications Ltd.

4 iia adcpsi h at ihatpgahccmlxt eetdyrjvntdby rejuvenated repeatedly complexity topographic a with processes. past, tectonic these the in landscapes similar Bailey 1996; (Burke southern systems of river whole Reynolds the the of affecting adjustments and uplift corresponding fossils regional and from human Africa, active In resulting with early-dated features associated 3). closely of and (Figure are East features finds sites tectonics tectonic In too, important here Valley topography. Nevertheless, with Valley. Rift Rift flat sites no to and but many archaeology, related complex are directly there both relatively Africa, is are across Transvaal South topography found and complex Serengeti is the this type of Africa habitat plains’ ‘great every the and fact, small In 2). (Figure true hold epydsetdb rso vrtels –M Drse l 00.Wti h ai h eino h aaasa site Makapansgat the of region with the associated basin 2011). the therefore al. Within et is 2010). (Bailey tectonics boundary al. active et This local been (Dirks has with 1996). Dome 2–3Ma associated of Johannesburg also (Burke last erosion The is the points. headward Africa circle) nick over by (white of southern erosion catchment migration upstream by their of the dissected extending with whole been deeply associated the valleys have sided tributaries of boundary steep its and catchment uplift downcutting and the river of from Part This topography. resulting shown. and 2a) rivers is environments; local in River is of as Limpopo Serengeti impression (classified the The misleading black vegetation a grassland). of The showing provides Valley not Africa, consequently Rift is South and most the smooth, region, Transvaal and (though around the grassland vegetation and ‘savannah’ both within is indicate topography it colours because Yellow complex unusual sites. of fossil prevalence hominin the are showing circles Africa East in topography and iue2. Figure oee,ti qaino ersra eioe roe aiaswt a rudde not does ground flat with habitats open or semi-open terrestrial of equation this However, a) otnna a fArcnvgtto ueipsdo a ftpgah rmST3 data: SRTM30 from topography of map a on superimposed vegetation African of map continental A tal et 01 iue ) ec,bt ein fArc ol aehosted have would Africa of regions both Hence, 5). & 4 Figures 2011; . sbleC Winder C. Isabelle 5  C niut ulctosLtd. Publications Antiquity tal et b) vegetation 2011; . c)

Research Complex topography and human evolution

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Figure 3. Images of complex landscapes in East Africa, including (a) the Ethiopian rift from Addis Ababa, with old eroded volcanoes visible; (b) ‘baboon country’ near the Gemeri Lake, showing an active scarp locatable on Google Earth; (c) Google Earth map of the same region near the Gemeri Lake; (d) the region near Lake Victoria showing the edge of the granite exposure and mosaic habitats near the forest edge.

Testing the alternatives Early bipedalism Any convincing hypothesis of hominin evolution must explain the appearance of key human adaptations like upright ‘striding’ bipedalism, endurance running, large brains and bodies, manual dexterity, advanced tool use and changes to life history, which together form an adaptive suite of interlinked characteristics. Manual dexterity and tool use, for instance, are interlinked and may follow naturally from upright posture as arms lose their locomotor function. Successful hypotheses thus do not need to provide separate explanations for each adaptation. Instead, many focus primarily on explaining bipedal locomotion as this is both the first ‘human’ characteristic to appear in the fossil record and one that permitted or drove subsequent changes. Figure 6 contrasts the predictions for hominin locomotor evolution made by the ‘traditional’ hypotheses (left) and the complex topography hypothesis (right). The first important difference relates to the major outstanding question of what our bipedal locomotion evolved from (Harcourt-Smith 2007). Our closest living relatives, the African apes, are knuckle-walkers. Therefore, either the LCA of Pan and Gorilla (and thus Homo)was C Antiquity Publications Ltd.

6 COLOUR acysm-pnhbtt) eyltl rtcini fee yabraiy vnapredator a even arboreality; and by from offered forests is risk riparian protection the (including little increases canopy very cover discontinuous habitats), forest a semi-open reduced with patchy that areas is In difficulty predators. The terrestrial cover. forest reduced of of all—species not 2004). Aiello some—though & Harcourt-Smith (indeed forms in ancestral discussed bipedalism these terrestrial how of is Neither for Australopithecus another. remains suited that to question mode perfectly key locomotor is the one entirely), from else shifted something hominins indeed (or climber bodied osi cdt u emgtepc ofidarchaeology. find to expect might we past; but the acidity in soil existed to vegetation; have savannah would beneath features hidden similar usually but evolved has landscape vlto.Bt aebe doae ntercn ieaue(..Ditn&Mco1999; Macho Richmond & 2001; Dainton Kelly (e.g. literature 2000; convergent recent Strait from the & result in Richmond adaptations advocated gorilla been have and Both chimpanzee evolution. many or too, knuckle-walker a visitors; by missed including often Africa, topography South complex in the landscapes showing Complex 4. Figure htvrteacsrlfr a,taiinlmdl niinti hnea h result the as change this envision models traditional was, form ancestral the Whatever upright- an or knuckle-walker a was form ancestral the whether of regardless However, ih o aebe htefiin tti omo oooinete,as either, locomotion of form this at efficient that been have not might (d) ope oorpya aaibr,weeteeaen oii osl due fossils hominin no are there where Magalisberg, at topography complex sbleC Winder C. Isabelle (b) (a) 7 alycoet h utaoihcssdb nso.The findspot. sediba Australopithecus the to close valley a iwtwrsSekoti rmteajcn adrock hard adjacent the from Sterkfontein towards view a tal et 01 Crompton 2001; . (c) adcp ipaigsalsaeroughness small-scale displaying landscape a  C niut ulctosLtd. Publications Antiquity tal et 2008). .

Research Complex topography and human evolution

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Figure 5. The Johannesburg dome is associated with an ancient granitic intrusion (∼3000Ma) that has upwarped overlying rocks to produce an ‘eye’ shaped structure. Downcutting of rocks of widely varying strength has produced complex and varied topography. Rates of ∼50m per Ma have been documented (Dirks et al. 2010). Red star = the Sterkfontein site; white star = the approximate location of the Australopithecus sediba site; small white circles = other fossil sites.

that cannot climb trees can simply lie in wait for an ape trapped in the small habitat of one or a few trees. For the complex topography hypothesis, this is not a problem. Whatever body form the LCA had, a transition from climbing in a complex 3D arboreal environment to scrambling across a complex 3D terrestrial landscape is easier to envision than the corresponding ‘traditional’ 3D–2D transition. Complex topography affords access to terrestrial food resources and protection from predators that cannot scramble or climb. This includes most large African carnivores, with the key exception of leopards, which can climb both trees and rocky faces and would have preyed on hominins under either scenario. Evidence from living primates also suggests that the provision of supporting rocky structures might make the acquisition of bipedal locomotion easier even if the ancestral hominin was not pre-adapted for it. Chimpanzees engage in postural or supported C Antiquity Publications Ltd.

8 COLOUR tne hreigo h pe ib n,i h oe ib,acmrms between compromise a limbs, lower the during leverage in and rigidity entailing and, those and limbs ability grasping upper and flexibility the upright for more adaptations it of a as incorporate shortening presumably niche a would development terrestrial which stance, the adaptation a to scrambling lead finding generalist, would a in This of forms, and experimentation. 2011) and body King transitions & of (Bailey locomotor trees range facilitates isolated than wide predators many a from protection of better monkey- provides or any ape-like an with support creature, would topography like complex Using 6). Figure (see LCA our of (Stanford fluently habitats move arboreal complex can in and postures 2006). walking bipedal independent and tripedal in quadrupedal, than between often more (tripedalism) bipedalism explain to bottom. of abilities the (left) models’ ancestor at hypothesis two common sapiens savannah last these Homo the predicted in between the by culminate differences with predicted and the begin as illustrating sequences capabilities and Both locomotor history. (right) hominin our hypothesis of topography evolution complex the the showing and cartoon A 6. Figure nfc,tecmlxtpgah yohssrqie oasmtosaottelocomotion the about assumptions no requires hypothesis topography complex the fact, In sbleC Winder C. Isabelle 9 Pan and Homo  C niut ulctosLtd. Publications Antiquity taot6atwrstetop the towards 6Ma about at

Research Complex topography and human evolution terrestrial locomotion on uneven surfaces. Under this model, the australopith anatomical mosaics of terrestrial and putatively ‘arboreal’ traits (Harcourt-Smith & Aiello 2004) could be identified as adaptations to scrambling as easily as to semi-arboreal locomotion, and a range of different mosaics would be expected as the hominins radiate to fill different ecological niches on complex landscapes. These anatomical complexes would constitute an effective morphology for scrambling, rather than one riddled with relic features or caught uncomfortably between two niches. The shift from one refugium (trees) to another (complex topography) by a group near the LCA might also explain our lineage’s divergence from the panins, as such shifts are likely to have been important right up to our own species’ evolution (Stewart & Stringer 2012).

Obligate bipedalism For the earliest stages of hominin evolution, then, the complex topography hypothesis performs better than other hypotheses as an explanatory framework for terrestrialisation. But what of the appearance of obligate (i.e. permanent and necessary) ‘striding’ bipedalism and endurance running later in our history? This is an area where the implicit 2D ‘plains’ assumption of older hypotheses comes into its own, and is an important challenge for our hypothesis. The two major adaptive changes to the human foot—the aligned hallux (big toe) and the foot arches—seem well fitted to striding and running, as their key function is to make the foot act as a rigid lever during locomotion. This is clearly advantageous on flat terrain, but would also serve an important function on complex topography: it would enable the release of stored energy to lever the body upwards even if only a small part of the foot was in contact with the substrate. This more efficient means of transmitting gait forces and driving locomotion on rough substrates would mean there was less need for scramblers to use their arms to assist locomotion once these features had appeared, thus facilitating further changes to the upper limbs and body proportions and matching the observed trajectory of adaptations in the fossil record. This initial adaptation for efficient scrambling or climbing would open up a broad spectrum of niches, both in complex terrain and elsewhere, that would be unavailable to a more specialised knuckle-walker or arboreal climber. For example, it is easy to see how a hominin with adaptations that include relatively shorter arms, some form of foot arch and some spinal, pelvic and lower limb adaptations for upright posture, could begin to move out of complex terrain to exploit savannah animals. Species tied to particular regions for security (as early hominins likely were to areas of complex topography) are often under strong selective pressures to expand their dietary repertoire, either by eating a wider range of foods or by extending their foraging range. The ability to exploit large savannah animals, perhaps by driving them back onto rough terrain or by making short excursions away from secure areas, would be a major advantage permitting both encephalisation and population growth (Aiello & Wheeler 1994). This would set off a ratchet effect, whereby the initial adoption of a more savannah-oriented niche by an early hominin would isolate that lineage and lock it into a rapid adaptive change that would drive the elaboration of existing anatomical, cognitive, social and technological capacities to better exploit the new niche. By this account, explanations of human adaptations for running/striding remain the same but are based on C Antiquity Publications Ltd.

10 leigstsbtsedterdy nteEhoinpan (Gr plains Ethiopian ( the on geladas days are their only spend slopes but the rocky sites unique: sleeping use been have to would primates hominins other topographies, complex occupying In models. to fitted are adaptations unlikely. hominin that is savannah environments. idea survival these to the savannah in that survival solutions suggests aid however, alternative to above, serve discussion genuine would The either overlap)— are of adoption of adaptations the that areas lineages’ and challenges, in two competition the minimise that to assumes diverge and (where a baboons adaptations displacement such character alternative—that species’ undergo be to The co-occurring as cannot thought. competition plains close previously sufficiently to as in were adaptation history hominins or our plains, on savannah influence ‘savannah’ to so-called major the adaptations that essential fact not the is are challenge key a stages), throughout later baboons— (whether the component in key hominins only a why or as explain evolution savannahs to identifying ability hypotheses its For is unique. hypothesis are palaeoanthropological any of test final The primates ground-dwelling other from Divergence strategic for topographies complex of use pre-adapted (King active the humans The modern of locomotion use. in freeing of tool seen consequent form advantage, like with tasks this developed, explains dextrous foot on also for the reliance hand of climbing in decreasing adaptations found while by lever capabilities the grip facilitated extreme as be to The would hands dexterity. humans manual the modern increasing Using regular and on Crompton weights. adaptations reliance & heavy a grasping through (Wang fairly explained bipedalism be of to striding has carrying this of hypotheses, pull considerations traditional to Under energetic shorter 2004). them are arms by enable humans’ modern to predicted why explain shorten can than this initially fact, In would climbing. limbs when up upper themselves Hominins’ 7). (Figure specialised. their simple more predators. be became adaptations to from their cease and escape might act to and but continued lineages, prey ratchet these the of as to niche pursuit accessible when primary be only the still plains aided would the topography which onto Complex traits venture possessed to already hominins allowed they which features scrambling earlier ol lofcltt h perneo h oenhmnlf itr,wt extended models. hypothesis with previous history, topography than better complex life evolution hominin the human of Overall, events modern key intervals. the the interbirth explains of shorter of appearance and development the childhood the facilitate and environments also areas complex topographically open would by offered flat security relative into positive The a adaptations. excursions running initiating drove thus enabling ultimately (meat), topographies’ food which these quality of feedback high effects obtain to the hominins through defenceless bodies relatively and brains larger towards trends lista hycmeewt te pce.Ohrta anann h blt oclimb to ability the the on maintaining is than it Other as species. pressure, selective other the with means of compete grasslands majority they flat vast that of the plains occupation exerts daytime environment their latter but the that night, by topography rough exploit eeaantecmlxtpgah yohssprom etrta h vegetational the than better performs hypothesis topography complex the again Here fairly is anatomies human uniquely other explain to trajectory evolutionary this Expanding Papio p.psesnn fteaattoso h oiis ihrteefeatures these Either hominins. the of adaptations the of none spp.—possess sbleC Winder C. Isabelle tal et 11 94 ruh20) a vnepanthe explain even can 2004), Crouch 1994; . hrpteu gelada Theropithecus n20) hs populations These 2008). on ¨  C niut ulctosLtd. Publications Antiquity ,wihuecif as cliffs use which ),

Research Complex topography and human evolution

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Figure 7. Schematic summarising the ways the traditional hypotheses (left) and complex topography hypothesis (right) explain modern human anatomical features. Explanations are classified: those labelled (A) are based on active selection for the trait, (F) indicates a feedback loop based on selection for another trait, and (P) is passive selection or drift. The silhouette is coloured accordingly: red indicates adaptations only indirectly explained by the hypothesis, orange those explicable by a single direct selective pressure, and green those subject to more than one direct selective pressure.

short distances, geladas would not be expected to be directly adapted to complex topography but rather to plains survival. If hominins are indeed adapted to using complex topography as their primary habitat rather than as a refuge, we would not expect them to share many adaptations with either savannah baboons or the gelada. According to the complex topography hypothesis, hominins C Antiquity Publications Ltd.

12 onu ogs ocnccns aafils aktligaogfutbudre n rift and boundaries fault along scarps, back-tilting rift fields, forms: land lava of cones, complexity volcanic resulting and gorges, features downcut tectonic of diversity and range and deposits. interim separated widely the between in correlation belief changes stratigraphic recently, geological the of of in Until complexities because avoided resulting sites. difficult been the too hominin generally are have reconstructions early that territory such of impression geographical that mistaken wider characteristic the a characterised defining for of typically the accounts reconstructions preserved are doubt is deposited, no locations topography been fact such smooth have this of and to topography, surroundings likely immediate smooth most their immediate by and is The margins, material exposed. river where and and is lake this at because typically environs, deposits, sedimentary ancient expose of highly to to likely focus perspective. of spatial most narrowing restricted consequent are a a and that with conditions fossils, locations geological human localised for of discoveries searching early on and ancient new the emphasis to the conditions present-day African and from East topography, extrapolating the of on as unreliability such occurred perceived regions has volcanic the the that and Rift, tectonic change is actively geological in hypotheses of scales time above complexity Plio-Pleistocene some and the face degree reconstructions testing the such obstacles: However, in landscapes. formidable requirements physical ancient important reconstruct most to ability the of one Clearly, landscapes physical past reconstructing directions: above. hominins Future described Once as predictably been. differed have have would would they australopiths areas the flat access than them to survival 1)—make began Table plains (see at adulthood of efficient than onset more (rather early sociality, rapid abilities, defences, running adaptations—group endurance) Baboon trajectory. evolutionary separate while it, for preference strong a shown have Papio would and terrain rough to adapting actively were etrt o ih?Yes Yes Yes Yes ? Yes Yes ? ? No High Endurance Large Low Slow Sprint No Yes Small Technological Rapid Dexterity Running Biped Development Quadruped Social size Brain strategy Defence Locomotion ( species they primate other movements while of first, sequence feet the that moving reversing fact up, exactly the climb almost to is by use explicable, faces adaptively cliffs/rock not down perhaps climb although humans noting, worth ( Also baboons them. ‘savannah’ explain between differences ecological major the and of Summary 1. Table onot. do oee,n iio oteArcnRf a alt eipesdb h extraordinary the by impressed be to fail can Rift African the to visitor no However, edges eroding on focus to tended have sites archaeological and fossil of studies Existing oosapiens Homo aon iigo oeoe,sote adcpswudhv endie ln a along driven been have would landscapes smoother open, more on living baboons n h blte ftesvna n ope oorpyhptee to hypotheses topography complex and savannah the of abilities the and , aonHmnTaiinlhptee ope topography Complex hypotheses Traditional Human Baboon sbleC Winder C. Isabelle 13 Theropithecus xlie by: Explained  C niut ulctosLtd. Publications Antiquity and Papio Papio included) spp.)

Research Complex topography and human evolution

scarps with basins that trap sediment and water, large fault-bounded lake basins on the rift floor, smaller volcanic crater lakes, and a complex staircase-effect of faulting, rift scarps, volcanic features and localised basins rising on either side of the main rift axis. Some of these features have come into existence within the Pleistocene, long after the occupation of the earliest hominin sites, others have been erased or modified, and yet others have remained relatively unchanged, subject only to climatically imposed variations in vegetation and water supply, and this is to be expected in a dynamic landscape that has been continuously remoulded over at least the past five million years. Geological and stratigraphic studies of these landscapes reinforce the impression of extreme and variable complexity (Brown & McDougall 2011; Feibel 2011b). It is axiomatic that sites such as the famous hippo butchery site of FxJj3 on Lake Turkana occur near a lake margin in a locality that was originally characterised by flat terrain in the immediate vicinity, COLOUR and many other early sites are on lake or river margins (Isaac & Isaac 1997). But it remains unclear to what extent such sites are representative of all the locations and activities undertaken by early hominins, or whether they represent more than fleeting visitations and a tiny fraction of the full range of places of significance in the daily lives and lifetimes of their creators, who are likely to have ranged over a larger territory. In the Kenyan Rift, a more complex topography of faulting and other tectonic features is rarely far away from these lake and river margin sites, whether around Lake Turkana in the north, at Olorgesailie in the Figure 8. A map of the Kenyan Gregory Rift region, highlighting the locations of Olorgesailie, Kariandusi and south, or in the Naivasha-Baringo corridor the Suguta Valley. Red dots = australopith findspots; pink in between (Figure 8). Investigation of dots = Homo findspots. Graphic constructed using modified this hinterland topography is essential in ETM and SRTM data. understanding the wider context of existing early hominin sites, and may prove rewarding in the discovery of new ones. C Antiquity Publications Ltd.

14 n adtercmeios nml,amdr nlg o h odtosi hc we which in rift early conditions the in the predators other for with analogy compete to modern landscape. had cattle populations their a hominin protect early animals, to that region welcome competitors’ believe the not of do their and topography military, raid complex are and of the surprisingly, police and use deterrent state not they the added day, of who, this the sight To tribes, of also outsiders. Turkana out is activities and is their There Pokot access keep foot. to rival and keen on region, between treks this raiding into lengthy cattle access or chronic road helicopter no by almost possible advantageous is supporting particularly only there been of However, have to today hominins. believe extreme we early capable of that for areas, landscape range of wide fertile type the a 100km with and with herds, a interspersed 8), cattle Valley, (Figure features Turkana Suguta volcanic Lake the of and is south tectonic pursue Rift example to Kenyan necessary extreme the are of An that investigations section hypothesis. field of typography types complex the topographic to the deterrent of added an prospect is this realistic and a techniques offer new dating, and and dynamics evolution. mapping human rift reconstruction. field characteristic of of imagery, defining span understanding satellite time a and of the been theories throughout has the improved and complexity of Moreover, range topographic discerned geographical combination of be overall this the Kenyan condition can throughout that sure the and enough be of can Africa, features we parts But South Rift, of Large extremes. these in confidence. (Bailey the between with somewhere possible as of lie reconstructions may is spectrum, Rift sector make time analogy the Ethiopian to by in of topography the approach point end original as an any other only such at the that existed change At changed it dramatic has as of much area regions so large In a elusive. over prove topography surface original the lmn nftr eerhaedsi eaeflyt nesadterl fenvironmental, essential of an role the be evolution. understand will human to and in fully possibility, changes are realistic climatic we and a if ecological now agendas archaeological research is and future setting fossil in landscape of element wider investigation detailed their more in diet. through sites protein-rich ideas a a these obtaining as of and later testing populations arose Field increasing strategically then ranges, plains and home flat expanding dynamic onto of highly Excursions means topography. but complex stable of relatively areas rich, advantageous expect occupying would we initially what are creatures sociality extent) of based other an and (to evidence, and climate humans palaeoenvironmental biology between human current differences Modern or better. ecological primates with the than vegetation well like convincingly patterning as additional more traditional least explains evolution and at to hominin fits in alternative hypotheses, processes traditional key viable the the all and explains new It hypotheses. a locomotor offers and anatomical hominin change of trajectory the for hypothesis topography complex Our Conclusion ehp o upiigy oenra cestnst vi ra fcmlxtopography, complex of areas avoid to tends access road modern surprisingly, not Perhaps of details the all confidence with reconstructing however, landscapes, dynamic such In sbleC Winder C. Isabelle 15  C niut ulctosLtd. Publications Antiquity tal et 2011). .

Research Complex topography and human evolution

Acknowledgements We acknowledge funding support from the European Research Council (ERC Project 269586 DISPERSE). ICW also acknowledges additional support from the Holbeck Charitable Trust, the Leathersellers’ Company Charitable Fund, the Department of Archaeology (University of York) research fund and a Charles A. Lockwood Memorial Grant administered by the Primate Society of Great Britain. We thank the National Museums of Kenya and the British Institute in Eastern Africa, and in particular Purity Kiura (NMK) and Matt Davies (BIEA), for facilitating a reconnaissance trip in the Kenya Rift on which the field observations and the map of Figure 8 are based. We particularly thank Karega Munene for helpful advice, and for assistance and hospitality in Nairobi. We also acknowledge fruitful conversations with Dan Olago and Tina Atieno, Department of Geology, Nairobi University. GK would like to thank Paul Dirks for field excursions and discussions in South Africa and Zimbabwe. Finally, we thank Sarah Elton, Robyn Inglis, Inmaculada Lopez-Bonilla, Terry O’Connor, Paul O’Higgins, Penny Spikins and two reviewers for helpful comments. This paper is DISPERSE contribution no. 0001 and IPGP contribution no. 3315.

Note Since this paper went into production, we have become aware of Romano’s (2006) hypothesis of uphill clambering carrying moderately heavy weights as a selective pressure on the development of hominin bipedality, which also focuses on topography as a key variable.

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