Part 1: the (biological) antiquity of man, 1911–1921

Late nineteenth- and early twentieth-century accounts of human fossils had tended to be grounded in race: in particular, in efforts to find in fossil bones the ancestors of modern population groups.Footnote ¹⁵ But the discovery of Eugène Dubois's Java man in 1895, and even more importantly the flurry of further Neanderthal excavations in the first decade of the twentieth century, provided a range of remains which showed consistent and systematic differences from modern populations.Footnote ¹⁶ Triangulating these ever more pithecoid (ape-like) fossils in chronological time and genealogical space seemed increasingly to demand an explanation of human biological evolution.Footnote ¹⁷ Arthur Keith, in 1908 appointed conservator at the Museum of the Royal College of Surgeons, was well placed to provide such an account, as was Grafton Elliot Smith, who returned from the Cairo School of Medicine to a chair in anatomy in Manchester in 1909.Footnote ¹⁸

In 1911, books by both Keith (Ancient Types of Man) and Smith (Ancient Egyptians and the Origins of Civilisation) appeared in Harper's Library of Living Thought.Footnote ¹⁹ Both sought ‘to stimulate public interest in the remote history of mankind’, but while Keith focused on the origin of modern (neanthropic) man and the relationships of the extant fossils, Smith developed his theory of the dissemination of civilization from its Egyptian origins to other Mediterranean and Western European shores by an anatomically distinctive (‘Egyptian’) race.Footnote ²⁰ A few months later, Smith's presidential address to the anthropology section of the British Association tied his account of the origins of civilization to the earliest origin of all – the primitive mammal ancestral to all primates – through an account of fossil man that ended with the invention of agriculture.Footnote ²¹ In little over a year, when looked at in combination, the two anatomists had separately contributed to the development of a public narrative which identified and accounted for the evolutionary origins of the hominid line, of the species Homo sapiens and of civilization itself – the three key points around which lay accounts of prehistory were to coalesce.

While both men, unlike their predecessors, organized their accounts around evolutionary, rather than racial, conceptions, their work did show structural similarities with that of their forerunners. Scholars like Sir John Lubbock and Sir William Boyd Dawkins had structured their narratives of prehistory around a series of steps backwards through time. Keith adopted this technique, beginning his 1911 account with the youngest fossils and leading his audience back from the almost familiar to the strikingly strange. In his case, however, this chronological passage was conceptualized as a physical expedition, making it possible for his audience to bear virtual witness to the sites of key fossil finds through his situation of each discovery within a detailed geographical context.Footnote ²² His account of Tilbury man, for example, required the reader to leave the east coast of Essex and travel with him to the valley of the Thames. His use of the present tense and focus on the details of geographic location provided his reader with a sense of physical immediacy, a sense accentuated by his comparison of Tilbury man with the bones of the infamous ‘Thief-Taker General’, Jonathan Wild, available for inspection in the Hunterian Museum. This both gave his audience a familiar reference point with which to visualize the ‘man’ and began to lay the groundwork for the controversial ‘presapiens’ notion that the modern human form was extremely ancient.Footnote ²³ The comparison with Wild made it abundantly clear that Tilbury man, despite his great age, was of the modern type. This point was hammered home throughout the short book: 200,000 years ago, man was ‘so modern in build that we might meet him on the streets of London today and pass him by unnoted’.Footnote ²⁴

Using skulls and skeletons as stepping stones, extrapolating from one to the other in relation to both age and relatedness and using the river Thames as an external clock-like check, laying down strata in steady sequence, Keith took his audience back in time. Travelling from Tilbury through Dartford and Galley Hill, he brought his audience face to face with the ‘men’ of Brunn, Combe Capelle and Grimaldi. But as he dealt with ever-older fossils, his emphasis also moved from the claim that he was tracing the same kind of man back through the years and came, again controversially, to challenge a set of assumptions about the regular progression of human evolution. The commonly held expectations that man would become ‘more primitive in mind and body as his history was traced into the past’ were not being met, he argued: the Cro-Magnon discoveries demonstrated that ‘the evolution of human types was not an orderly one’.Footnote ²⁵ More archaic types appeared in the fossil record after, not before, the emergence of anatomically modern man – and individual fossils could show a surprising combination of modern and archaic characters, as the anatomies of Neanderthal and Java man showed. Keith's central message for his first essay in popular prehistory was clear and potentially provocative – the evidence from anatomy demonstrated that human evolution was not linear, but surprisingly uneven, and that modern man was in fact exceedingly ancient.Footnote ²⁶

Grafton Elliot Smith's account mapped human origins – if not Homo sapiens itself – even further back into the far geological past. Like Keith, he did so specifically in relation to his own speciality – the structure and function of the brain.Footnote ²⁷ His 1912 address represented an account of human cultural and biological evolution that audaciously tied the origins of civilization together with those of the hominid line, locating both in key changes in brain structure and physical locomotion. His argument was clear: the previous generation of anthropologists and biologists had unjustly neglected the role of brain anatomy in understanding evolution, ‘due to the discredit cast upon this branch of knowledge by the singularly futile pretensions of some of the foremost anatomists who opposed Darwin's views in the discussions which took place … more than forty years ago’.Footnote ²⁸ Smith's work in comparative neuroanatomy, however, enabled him to trace the ‘broad lines of man's pedigree right back to the most primitive mammals’, a phylogenetic mirror of Keith's reverse-chronological ordering of the extant fossils, to pinpoint the beginnings of human distinctiveness in the earliest of tree shrew-like mammals.Footnote ²⁹ The development of cortical structures such as the neopallium and changes in the temporal–parietal areas and the visual cortex enabled him, he argued, to identify the likely pattern of human ancestry in extant species, and to reconstruct the environment that had, through the mediation of hand–eye coordination, encouraged their production.Footnote ³⁰ On this neuroanatomical foundation, Smith began to build his account of a human (‘Egyptian’) civilization oriented towards the pursuit of individual immortality through the accumulation of cultural and economic resources.

Smith and Keith treated neuroanatomy as both the critical site for the identification of evolutionary trends and the fundamental element in the art of fossil interpretation, since judgements about brain size and structure – which both men considered essential to the assessment of a putative human fossil – derived directly from the knowledge and experience necessary to accurately reconstruct and interpret skull and jaw fragments. It is no surprise, then, that Keith began his 1915 account of the Antiquity of Man by emphasizing the importance of anatomical training at the expense of geology, archaeology and palaeontology. Consciously positioning himself in the tradition of Dawkins, Geikie and (lately) Sollas, he was clear that his anatomical expertise outranked their specialities. Anatomy, he stressed, was the only discipline that ‘gives ancient man the centre of the stage’: ‘the geologist and the archaeologist provide him with the scenery and the stage accessories’.Footnote ³¹ But he immediately deployed these backstage disciplines to facilitate his adoption of the same strategies of virtual witness and emotional identification that he had used to such effect in his earlier account. As his account opens, he is walking with his reader down ‘the road from London to Maidstone’ on the way to the ‘great stone monument at Coldrum’ (a long barrow in Kent), using the present tense and focusing on the immediate sensory environment:

Similar vignettes introduce each new fossil, their importance emphasized by his insistence that, wherever possible, they were based on his personal examination of the site of fossil discovery.Footnote ³³ This personal witness, demonstrated through mastery of geological and archaeological detail, is deployed alongside his anatomical expertise to underpin Keith's two controversial claims about human prehistory: that the course of human evolution was not linear, but distinctly uneven, and that the modern human form was decidedly ancient.Footnote ³⁴ Neither claim was solidly supported by anatomical evidence, particularly given his conclusion that the extant fossil record, in combination with stone tools (which he treated as cultural fossils of particular biological groups), represented cousins, not ancestors, of Homo sapiens.Footnote ³⁵

So, as Smith was doing with respect to the increasingly global wanderings of his ‘Egyptian’ race, in order to provide a basis for his speculations concerning this ancestor, Keith consciously moved outside his own specialization to draw on a range of different evidential sources. Stepping out from anatomy to anthropology, he argued that it was possible to extrapolate backward from the distribution of the modern races to estimate the latest point by which modern man must have come into existence – from his calculations, the end of the Pliocene. With that as the base point, archaeological evidence – material culture as encapsulated in the eoliths (possible flint tools) of Reid Moir – suggested that the ‘period at which the brain of man had reached a human level or standard’ could have occurred as early as the beginning of that era.Footnote ³⁶ If that were the case, then given the enormous variety in extant hominid fossils, which must themselves have had time to evolve, humans in their modern form must at a minimum have existed for over a million years. In the absence of any fossils for anatomical study, and despite his earlier relegation of the other disciplines to a secondary role, his belief in the extreme antiquity of the human form was justified to his audience by reference to a combination of geological, archaeological and anthropological evidence.

This willingness to widen their intellectual casts and to deploy evidence and knowledge drawn from different disciplinary sources became increasingly characteristic of both Smith and Keith in the interwar period. To return to Keith's metaphor, their pre-war writings had given centre stage to their anatomical work, using other specialisms as scenery and props. But after the wartime hiatus, both became increasingly concerned with the wider intellectual and political implications of their interpretations of the anatomy of prehistory. The conclusions that they had drawn from their anatomical investigations could not be fully supported by anatomical evidence. As a result, their accounts began to depend ever more explicitly on the resources (conceptual and methodological) of other disciplines.

Part two: tracing culture through contour, 1921–1931

In those years immediately following the Great War, new fossil discoveries jostled for scholarly attention with work at established sites, familiar fossils were estranged by novel material, and the various iterations of the human family tree became so numerous that Keith devoted an entire volume of the Forum series to an investigation of their different histories.Footnote ³⁷ In 1921, the Broken Hill skull was found in a Rhodesian mine: sent to London for evaluation, Arthur Smith Woodward classified it as Homo rhodesiensis, and it was placed between Piltdown and Neanderthal in terms of its affiliation with modern humanity.Footnote ³⁸ In the same year, J. Gunnar Anderssen, then adviser to the Chinese Geological Survey, moved his palaeontological survey to the quarry at Chou Kou Tien, where the first traces of Peking man were found.Footnote ³⁹ In 1922, Henry Fairfield Osborn proclaimed the (short) existence of Nebraska man.Footnote ⁴⁰ A particularly fertile year for such discoveries was 1925: the Taung fossil was reported from South Africa, Francis Turville-Petre and Dorothy Garrod discovered both anatomically modern and Neanderthal specimens in Palestine, and the London skull was found in the old East India House site.Footnote ⁴¹ The new edition of Keith's Antiquity of Man, first published only ten years previously, now ran to two volumes.Footnote ⁴²

Other excavations – specifically the work of Carter and Caernarvon in Egypt – fired public interest in Egyptology, causing Smith to remark that the two men had ‘accomplished in one winter what we have been striving in vain to do at the British Association’ for years.Footnote ⁴³ Smith's Ancient Egyptians, in which he explained his theory of cultural diffusion, was also by now in its second edition. Inspired by the racial resemblances he had noted in skulls collected by explorers from the Mediterranean to the Pacific, and drawing heavily on ethnographic material, the new edition argued that the highly individual ‘Egyptian’ cultural complex, previously associated with specifically Eurasian mummification and megaliths, was actually global in distribution. With William Perry's help, he was also able to explain this wanderlust: these ‘men of old were doing precisely what their modern successors are doing in California, Klondyke, Johannesburg … searching for … materials which had some definite economic or magical value’.Footnote ⁴⁴ Egyptian explorers ventured around the world in pursuit of resources that would assure them better lives, in this world and the next.

Later in 1923, Smith elaborated on this theme during an evening lecture to the British Association in Liverpool. He used it to frame both his account of human origins and his reiterated call for the development of a ‘science of the humane’, more scientific than the humanities and more human than the sciences – and which would ultimately provide the resources for the wise government of empire.Footnote ⁴⁵ He proposed that a merger of physical and cultural anthropology would provide the vital empirical and methodological linkages (between brain architecture and behaviour) upon which such a science could be based. Only from such a science, he argued, could the wise and humane administration of empire derive: an ironic aspiration, given his quasi-imperial conscription of other disciplines in the service of that claim. In support, his accounts immediately deployed comparative anatomy, embryology and palaeontology.

These disciplines linked together into a narrative of primate ancestry that now focused tightly on the specific changes in the brain that had made humanity unique, and which could be visibly traced on the skulls of prehistoric ‘man’, through a series of key changes to cranial structure and brain anatomy. Crucially, Smith emphasized that these changes were driven by context: it was the interaction between hand, eye and brain within a particular environmental setting that produced an animal capable of making fine visual, tactile and (finally) auditory discriminations. This last made the accumulation and intra-generational transmission of knowledge possible, thus enabling Smith to link cultural with biological evolution, the ability both to manipulate the natural world and to pass on the knowledge of how to do it. In this, Smith was trying to give his audience a clear empirical demonstration of the extraordinary explanatory and intellectual power that would be harnessed through fusing the natural and the human sciences, which he believed was essential both to an understanding of the human past and to the hope for humanity's future.Footnote ⁴⁶ Culture could be accounted for by brain contour if disciplines and scholars would cooperate, and would result in a new level of understanding of human behaviour that could revolutionize the political administration of empire.Footnote ⁴⁷

The imperial theme was maintained through Smith's later work, as for example in his Conway Lecture of 1927, where he argued that civilization and private property had disrupted the innately peaceful and gentle nature of man, and that the only hope for future harmony was that found in paternalistic empire.Footnote ⁴⁸ These rallying calls for interdisciplinary cooperation in pursuit of the Pax Britannica were, however, slightly dulled by his confrontational approach to his intellectual (and particularly his anthropological) opponents. Comparing them to flat-earthers and Darwin-deniers, he claimed that they had fundamentally misunderstood the nature of evolution by denying cultural diffusion, preferring to speculate instead about parallel evolution/independent invention.Footnote ⁴⁹ His ire was not confined to one group: even those who, like Keith, agreed with the need to amalgamate the human and natural sciences – but who suggested different strategies – were castigated.Footnote ⁵⁰ Smith wanted to create a ‘science of the humane’, but this seems to have been a science in which the methodological practices of other disciplines (anthropology in particular) were to run on a neuroanatomical leading rein.

During the same period, Keith had been beating a cautious and reluctant retreat from his belief in the deep antiquity of the modern human form, while remaining utterly committed to the notions of the uneven progression of human evolution and the coexistence of biologically distinct hominid groups in prehistory.Footnote ⁵¹ But while Smith focused on phylogenetic adaptations, Keith's accounts concentrated on proximate mechanisms. Here, the anatomist found his answer in another emergent speciality – endocrinology. The RCS Museum held the skeletal remains of a number of individuals who had been affected by growth disorders and Keith had realized as far back as 1911 that the anatomical structures affected by these hormonal disorders were those thought particularly characteristic of Neanderthal or other ‘primitive’ remains. From this, he theorized that it was hormonal activity that produced the physical differences between human races – and, eventually, human species. This was one of the reasons he had initially believed Neanderthals to be human ancestors: inhibit glandular action and Neanderthal would be indistinguishable from modern man. While he had long abandoned this particular position, he saw no problem in reworking it in the context of his increasing fascination with the role that race played in human evolution. Fundamentally, he believed that racial difference was the physical manifestation of a species-wide tendency to cultural isolationism based on in-group cooperation and out-group hostility. Cultural differences would encourage individuals to mate with familiars, and, as a result, between-group physical distinctiveness would increase, creating something like the modern pattern of racial distribution.

This focus on the individual body was reflected in Keith's broader interpretation of evolutionary theory and its application to human social and physical development. His perspective was becoming increasingly dependent on a series of socio-somatic metaphors through which he developed his account of the specific relationship between capitalism and evolution. In a 1927 essay, for example, he drew parallels between the womb and placenta on the one hand and the Carnegie Trust and the Royal Institution on the other: the first capitalists were, he suggested, the female reproductive cells. His later work – particularly in the later 1930s and the post-war years – dealt more concretely with the manner in which human evolution could be understood as a process of transforming these thrifty reproductive cells into full-blown industrial capitalism.Footnote ⁵² Importantly, for him, this turned on the role of race, particularly inter-group competition, as the driving factor in social, economic and technical development. Race was treated as an effect and cause of both cultural and biological evolution. But, notably, race was also a key factor – as Keith himself acknowledged – in his own interpretation of the fossil record. Calling on all prehistorians to reflect on the influence their own assumptions had over their interpretations, he was absolutely clear that his own racial prejudices had affected his accounts. Fundamentally, he did not believe that Africans had the capacity to innovate.Footnote ⁵³

Part three: African prehistory in public, 1927–1935

By the early 1930s, Africa was increasingly becoming the focus of prehistoric discovery and speculation. Keith's New Discoveries Relating to the Antiquity of Man (1931) was dominated by the new African work, and in particular by his analysis of Raymond Dart's Taung skull. As before, he opened with the now tried-and-tested technique of virtual witness, although rather than walking with the reader down the valley of the Thames, he now rode the railway from Kimberly to Bulawayo with them. Stopping at Vryburg, ‘in order that we may examine … the scene of the discovery of the Taung skull’, the location and history of the infant skull are described in detail before assessing the likely adult brain shape and size – and thus its location on the human family tree.Footnote ⁵⁴ Anatomically speaking, he concluded, ‘of all the fossil apes yet discovered Australopithecus comes nearer to our expectations of what our fossil ancestor should be like than any which has come to light so far’.Footnote ⁵⁵ Geology, not anatomy, denies the Taung skull human status: it was found, Keith declared, in strata that were much too recent to have contained human ancestors. Other African discoveries caused him greater concern, especially in relation to neuroanatomy: Boskop and Fish Hoek man appeared to have unexpectedly large brains. On the one hand, this confirmed Keith's belief in the uneven and non-linear nature of human evolution: the cranially well-developed Boskop race had apparently ‘degenerated into its modern representative, the modern Bushman’. This implied that brain evolution was contingent rather than progressive.Footnote ⁵⁶

But on the other hand, as Keith was well aware, his own prejudices and presumptions regarding the relationship between biology and cultural innovation underpinned this model of neuro-degeneration. A few pages later he made them explicit in his assessment of Louis Leakey's claim to have discovered at Kanam the biological, cultural and social origins of humanity.Footnote ⁵⁷ Keith was deeply sceptical of Leakey's interpretation of the material culture he had discovered, but also wary of his own position. As he argued,

Keith's scepticism about Leakey's claims rested on his firm belief that biological heritage limited the capacity for cultural innovation. But in contrast to his relative weighting of anatomy and geology in the case of the Taung skull, here his commitment to the anatomical significance of brain size meant that the archaeological evidence, present or absent, was relegated to secondary importance.

By the early 1930s, Leakey was (not quite literally) leaving no stone unturned in his efforts to bring East Africa and the achievements of its prehistoric inhabitants to the centre of British prehistory, both popular and professional – even as he himself continued to insist that these vanished inhabitants were not, in fact, anatomically ‘negroes’. In 1926 he had organized and led the first East African Archaeological Expedition, which discovered an entire fossil skeleton at Elmenteita, as well as evidence that – he felt – justified the creation of a relative dating scheme for both Kenyan and European finds. This meant that developments on one continent could be directly compared to contemporaneous discoveries on the other.Footnote ⁵⁹ For Leakey, this was crucially important, since by summer 1928 he was passionately defending Kenya's claims to be the ‘cradle of modern man’ in the London Times, arguing that Homo sapiens in Africa had been both contemporary with the Neanderthal occupation of Europe and in possession of a sophisticated stone tool culture.Footnote ⁶⁰ Further discoveries were confidently expected, Leakey asserted, as the second expedition set sail in August of that year.Footnote ⁶¹ By 1931 Leakey had publicly identified Kenya as the earliest known point of origin for human biological and cultural beginnings, and was eagerly organizing his third expedition, which was to link the Kenyan excavations with the work done by Hans Reck in Oldoway Gorge, Tanzania, before the Great War.Footnote ⁶²

As The Times announced, Leakey, accompanied by Reck and Arthur Hopwood, a mammal palaeontologist, left England in June 1931.Footnote ⁶³ By December, The Times was reporting that under ‘unpleasant and difficult’ conditions, the expedition had established that ‘homo sapiens [sic] goes back in East Africa to an age in the evolution of modern man far more remote than the evidence found anywhere in the world suggests’.Footnote ⁶⁴ Indeed, the arduous and difficult nature of the fieldwork – including being ‘charged by a rhinoceros’ – was a recurring theme in the accounts of Leakey's activities.Footnote ⁶⁵ His discoveries were received with both scepticism and support.Footnote ⁶⁶ Leakey's own belief in his fossil was such that in March 1932 he ghoulishly told The Times that the evidence of fire found in association with hominid bones at Chou Kou Tien suggested that the bones of Peking man were merely ‘the relics of [Oldoway man's] meat feasts’.Footnote ⁶⁷ This expedition's discovery of the Kanam jaw raised the stakes further, since this fossil – as Nature drily noted – ‘carries back Homo sapiens to Pre-Chellean, a stage further removed than Oldoway man’.Footnote ⁶⁸ Later that summer, Leakey proudly told The Times that he had now excavated a complete sequence of Paleaolithic Stone Age cultures, correlated them with the Tanganyikan beds, and linked them to the bones of the men of Kanam, Kanjera and Oldoway.Footnote ⁶⁹ Bones and stones, in Leakey's hands, were finally being made to march in step: the geologists, anatomists and archaeologists who gathered at Cambridge in 1933 to investigate his claims could find no reason to dispute them.Footnote ⁷⁰ Later that year, Elliot Smith was a supportive chair of the Royal Anthropological Institute meeting where the formal announcement of the oldest man, Homo kanamensis, was made, identified both as the source of pebble-tool culture and as the ancestor of Kanjera (modern) man. Kanjera man was identified with the Aurignacian culture, and as the prehistoric victor over the ‘beetle browed rivals’ exemplified by Peking and Neanderthal man.Footnote ⁷¹ Notably, Leakey continued to insist that despite their geographical origin, neither Kenyan specimen showed ‘negroid’ anatomical characters.

In the following year, Adam's Ancestors tied these claims for Kenyan primacy in human evolution into an account of fossil discoveries that emphasized again and again the practical and methodological aspects of the study of human prehistory. As Keith and Smith had done many times, Leakey described for his readers what had been found, where and when, and how these finds had been interpreted. Like Keith and Smith, he found himself faced with the problem of distinguishing – or not – between biological categories (species/race) and cultural ones (tools), as well as with the problem of determining age (relative and absolute) of fossils and artefacts. But what made his book different was the emphasis he laid on methodology, on the process and problems of excavation and on his personal experiences. He was less interested in explaining why humans had evolved as they did, and far more intent on demonstrating the correct relationships between and within fossil remains, both biological and cultural. In order to do that, he argued, close attention to the process of scientific excavation was essential: the disaster of the Broken Hill skull showed the consequences of ignoring these principles.Footnote ⁷² In contrast, his own discovery of Kanam man had begun, he claimed, with careful identification of the areas in which fossils were likely to occur, followed with detailed, exemplary, professional excavations. Leakey's authority lay not in the laboratory or within disciplinary specialization: it was grounded in his ability to read and navigate the African field.

The scientific excavator, Leakey explained, needed imaginative flair and the capacity to identify emotionally with prehistoric man. Leakey urged on his readers the importance of envisaging how a hunter might have used a landscape, not just in order to predict where his tools and fossils might be found, but in order to help reconstruct the circumstances surrounding his death and to work out how to use the tools he left behind. Such creative excursions should then, he argued, be tested by immediate practical experiment, in a manner that directly recalled the work of John Evans in the previous century.Footnote ⁷³ But unlike Evans, Leakey gloried in his reconstructions, describing his past efforts at translating fantasy into reality:

Bubbling with enthusiasm, he outlined his future plans to his readers: ‘I am not aware that the experiments were ever carried so far as to test the killing power of a hand-axe so hafted. I hope to carry out such an experiment myself when I am next in Africa.’Footnote ⁷⁵ He urged his audience to emulate his example, using his book as a text through which to interpret the British landscape. He firmly believed that there were many fossils still to be found, many critically endangered by road and brickwork building. ‘Any reader of this book’, he claimed, with the time ‘to visit such commercial undertakings might have the honour of finding one of the many links that are missing in the chain of evidence concerning the evolution of man’.Footnote ⁷⁶ Even more intriguingly, he tried to encourage them to use his book as an interactive tool through which to produce visual aids that would improve their understanding of prehistoric cultures:

This exhortation to immediate physical imitation was undoubtedly a step beyond Keith's efforts at virtual witness when it came to inspiring and enlisting the public imagination in support of prehistoric studies. Again, however, it grounds authority in physical and practical skill, rather than in disciplinary specialization – within the context of discussion of the capacity of the amateur to contribute to the emerging profession of palaeoanthropology.

Unfortunately, Leakey's claims to have identified the earliest-known human biological and cultural remains, based on his methodological and practical proficiency, were about to be very publicly obliterated. According to Nature, despite the ‘close and expert scrutiny’ to which Leakey's ‘evidence for the early occurrence of man in Kenya has been subjected’, it was still ‘eminently desirable that no means of verifying and substantiating the data should be neglected’.Footnote ⁷⁸ Despite the positive conclusions of the interdisciplinary Cambridge conference, Nature at least still clearly regarded the fossils with a dubious eye. Thus the geologist Professor Boswell was to accompany Leakey on the fourth East African Archaeological Expedition. His expertise at assessing the ages of and relationships between the different geological strata at the key sites would provide ‘final and decisive verdicts’ on the chronological status of Leakey's discoveries. Unfortunately for Leakey, in his absence local people had removed the iron pegs that he had set in concrete to mark the location of the Kanam jaw's discovery.Footnote ⁷⁹ Further problems exacerbated the situation: the jaw had originally been found by a local assistant, not by a credentialled excavator, and Boswell was not inclined to accept the local's unsupported word. Finally, heavy rain had eroded the local landscape, making it hard for the returning Westerners to orient themselves in the area. Boswell's letter to Nature, reprinted in the Times, was brutal:

In his judgement, the Kanam bone beds were so geologically complex that only ‘careful investigation of the deposits by an experienced geologist at the time of discovery’ could have reliably dated the human remains. Since no geologist had been included in the earlier expeditions, Boswell concluded that their age was now ‘uncertain’, and that the evidence brought before the Cambridge conference for both the stones and the bones of Kenya had been ‘unintentionally misleading’.Footnote ⁸¹ Leakey's claims to have identified the biological and cultural origins of humanity were in shreds. His claimed possession of exemplary methodological and practical skills had been spectacularly blown out of the water: what was left of his ship shattered fatally against his lack of geological expertise.