Evolution of pigmentation in anatomically modern humans of Europe: a new paradigm?

The colours of human skin, eyes and hair in living people across the world are determined by variants of genes (alleles) found at the same place on a chromosome. Since chromosomes are inherited from both mother and father, an individual may have the same two alleles (homozygous), or one of each (heterozygous). A dominant allele is always expressed, even if a single copy is present. A recessive allele is only expressed if the individual inherits two copies of it. Most characteristics of individuals result from the interaction of multiple genes, rather than a single gene. A commonly cited example is the coloration of eyes. If we had a single gene for eye colour – that of the iris – that had alleles just for blue (recessive or ‘b’) and one for brown (dominant or ‘B) pigmentation, brown-eyed individuals would have one or two ‘B’ alleles (bB or BB), whereas those with blue eyes would have to have two ‘blue’ alleles (bb). But inheritance is more complicated than that: there are people with green, hazel or grey eyes and even left- and right eyes of different colour. Such examples suggest that there are more than two genes affecting human eye colour, and each must have evolved as a result of mutations. Much the same goes for hair and skin coloration.

A group of scientists from the University of Ferrara in Italy have analysed highly detailed ancient DNA in anatomically modern human remains from Russia (Palaeolithic), Sweden (Mesolithic) and Croatia (Neolithic) to tease out the complexities of pigmentation inheritance. Then they applied a statistical approach learned from that study to predict the likely skin-, eye- and hair pigmentation in 348 less detailed genomes of ancient individuals whose remains date back to 45 Ma ( Silvia Perretti et al, 2025. Inference of human pigmentation from ancient DNA by genotype likelihood. Proceedings of the National Academy of Science, v. 122, article e2502158122; DOI: 10.1073/pnas.2502158122).

An artist’s impression of a Mesolithic woman from southern Denmark (credit: Tom Bjorklund)

All the hunter-gatherer Palaeolithic individuals (12 samples between 45 and 13 ka old) bar one, showed clear signs of dark pigmentation in skin, eyes and hair – the outlier from Russia was probably lighter. Those from the Mesolithic (14 to 4 ka) showed that 11 out of 35 had a light eye colour (Northern Europe, France, and Serbia), but most retained the dark skin and hair expected in descendants of migrants from Africa. Only one 12 ka hunter-gatherer from Sweden had inferred blue eyes, blonde hair, and light skin.  The retention of dark pigmentation by European hunter-gatherers who migrated there from Africa has been noted before, using DNA from Mesolithic human remains and in one case from birch resin chewed by a Mesolithic woman. This called into question the hypothesis that high levels of melatonin in skin, which protects indigenous people in Africa from cancers, would result in their producing insufficient vitamin D for good health. That notion supposed that out-of-Africa migrants would quickly evolve paler skin coloration at higher latitudes. It is now known that diets rich in meat, nuts and fungi – staple for hunter-gatherers – provide sufficient vitamin-D for health at high latitudes. A more recent hypothesis is that pale skins may have evolved only after the widespread Neolithic adoption of farming when people came to rely on a diet dominated by cereals that are a poor source of vitamin-D.

However, 132 Neolithic farmers (10 to 4 ka ago) individuals studied by Perretti et al. showed increased diversity in pigmentation, with more frequent light skin tones, yet dark individuals persisted, particularly in southern and eastern Europe. Hair and eye colour showed considerable variability, the earliest sign of red hair showing up in Turkey. Even Copper- and Bronze Age samples ( 113 from 7 to 3 ka) and those from Iron Age Europeans (25 from 3 to 1.7 ka ago) still indicate common retention of dark skin, eyes and hair, although the proportion of lighter pigmentation increased in some regions of Europe. Other analyses of ancient DNA have shown that the Palaeo- and Mesolithic populations of Europe were quickly outnumbered by influx of early farmers, probably from the Anatolian region of modern Turkey, during the Neolithic. The farming lifestyle seems likely to have allowed the numbers of those who practised it to rise beyond the natural environment’s ‘carrying capacity’ for hunter-gatherers. The former inhabitants of Europe may simply have been genetically absorbed within the growing population of farmers. Much the same absorption of earlier groups seems to have happened with the westward migration from the Ukrainian and Russia steppes of the Yamnaya people and culture, culminating in the start of the European Bronze Age that reached western Europe around 2.1 ka, The Yamnaya introduced metal culture, horse-drawn wheeled vehicles and possibly Indo-European language.

So the novel probabilistic approach to ancient DNA by Perretti et al. also casts doubt on the diet-based evolution of light pigmentation at high latitudes. Instead, pulses of large population movements and thus changes in European population genetics probably account for the persistence of abundant evidence for dark pigmentation throughout Europe until historic times. The ‘lightening’ of Europeans’ physiognomy seems to have been vastly more complex than previously believed. Early Europe seems to have been almost bewilderingly diverse, which make a complete mockery of modern chauvinism and racism. The present European genetic ‘melting pot’ is surprisingly similar to that of Europe’s ancient past.

A new timeline for modern humans’ colonisation of Europe

Aurignacian sculptures: ‘Lion-Man’ and ‘Venus’ from the Hohlenstein-Stadel and Hohle Fels caves in Germany.

The earliest culture (or techno-complex) that can be related to anatomically modern humans (AMH) in Europe is called the Aurignacian. It includes works of art as well as tools made from stone, bone and antler. Perhaps the most famous are the ivory sculptures of ‘Lion-Man’ and Venus of the Hohlenstein-Stadel  and Hohle Fels caves in Germany,  and also the stunning cave art, of Chauvet Cave in France. Aurignacian artefacts that are dated at 43 to 26 ka occur at sites throughout Europe south of about 52°N. It was this group of people who interacted with the original Neanderthal population of Europe and finally replaced them completely. There is a long standing discussion over who ‘invented’ the stone tools, both human groups apparently having used similar styles of manufacture (Châtelperronian). Likewise, as regards the subsistence methods deployed by each; in one approach Neanderthals may have largely restricted their activities to roughly fixed ranges, whereas the incomers were generally seasonal nomads. As yet it has not been possible to show if the interbreeding between the two, which ancient and modern genetic data show, preceded the Aurignacian influx or continued when the met in Europe. Whatever, Neanderthals as a distinct human group had disappeared from the geological record by 40 ka. (Note that the three thousand years of coexistence is as long as the time between now and the end of the Bronze Age, about 150 generations at least.) But that aspect of European human development is not the only bone of contention about the spread into Europe. How did the Aurignacian people fare during and after their entry into Europe?

Despite continuing discovery of AMH sites in Europe, and reappraisal of long-known ones, there are limits to how much locations, dates, bones and artifacts can tell us. The actual Aurignacian dispersal of people across Europe is confounded by the limited number of proven occupation sites. These were people who, like most hunter gatherers, must have moved continually in response to variations in the supply of resources that depend on changing climatic conditions. They probably travelled ‘light’, occupied many temporary camp sites but few places to which they returned generation after generation. Temporary ‘stopping places’ are difficult to find, showing little more than evidence of fire and a ‘litter’ of shards from retouched stone tools (debitage), together with discarded bones that show marks left by butchery. A group of archaeologists and climate specialists from the University of Cologne, Germany have tried to shed some light on the completely ‘invisible’ aspects of Aurignacian dispersal and subsistence using what they have called – perhaps a tribute to Frank Sinatra! – the ‘Our Way Model’ (Shao, Y. et al. 2024. Reconstruction of human dispersal during Aurignacian on pan-European scale. Nature Communications, v. 15, Article 7406; DOI: 10.1038/s41467-024-51349-y. Click link to download a PDF).

The reality of hunter-gatherer life during a period of repeated rapid change in climate would clearly have been complex and sometimes precarious. To grasp it also needs to take account of human population dynamics as well as climatic and ecological drivers. The team’s basic strategy was to combine climate and archaeological data to model the degree to which human numbers may have fluctuated and the extent and direction of their migration. Three broad factors would have driven both: environmental change; culture – social change, curiosity, technology; and human biology. Really, environmental change is the only one that can be addressed with any degree of precision through records of climate change, such as Greenland ice cores. Archaeological data from known sites should provide some evidence for technological change, but only for two definite phases in Aurignacian culture (43-38 ka and 38-32 ka). Dating of   Aurignacian sites establishes some time calibration for episodes of occupation, abandonment and resettlement. Issues of human biology can be addressed to some extent from ancient genetics, where suitable bones are available. However, the ‘Our Way Model’ is driven by climate modelling and archaeology. It outputs an historical estimate of ‘human existence potential’ (HEP) that includes predictions of carbon storage in plants and animals – i.e.  potential food resources – expressed as regional population density in Europe. The technical details are complex, but Shao et al.’s conclusions are quite striking.

Maps of estimated anatomically modern human population density during the first six thousand years of Aurignacian migration and palaeoclimate record from the Greenland NGRIP ice core, with shaded warm episodes – red spots indicate the time of the population estimates above. (Credit: Shao et al. Fig. 1)

Climate change in the later stages of cooling towards the last glacial maximum at ~20 ka was cyclical, with ten Dansgaard-Oeschger cold stadial events capable of ‘knocking back’ both population density and the extent of settlement. In the first two millennia expansion from the Levant into the Balkans was slow. From 43 to 41 ka the pace quickened, taking the Aurignacian culture into Western Europe, with an estimate total European AMH population of perhaps 60 thousand. A third phase (41 to 39 ka) shrank the areas and densities of population during a prolonged cold period. The authors suggest that survival was in Alpine refuge areas that AMH people had occupied previously. Starting at around 38 ka, a lengthy climatic warm period allowed the culture to spread to its maximum extent reaching southern Britain and the north and east of the Iberian Peninsula. Perhaps by then the AMH population had evolved better strategies to adapt to increasing frigid conditions. But by that time the Neanderthals had disappeared from Europe freeing up territory and food resources. That too may have contributed to the expansion and the sustenance of an AMH total population of between 80 and 100 thousand during the second phase of the Aurignacian.

It’s as well to remember that this work is based on a model, albeit sophisticated, based on currently known data. Palaeoanthropology is extremely prone to surprises as field- and lab work progresses …

See also: New population model identifies phases of human dispersal across Europe. EurekaAlert, 4 September 2024; Kambani, K. 2024. The Dynamics of Early Human Dispersal Across Europe: A New Population Model. Anthropology.net, 4 September 2024.

Was the earliest human ancestor a European?

Charles Darwin famously suggested that humans evolved from apes, and since great apes (chimpanzees, bonobos and gorillas) live in Africa he reckoned it was probably there that the human ‘line’ began. Indeed, the mitochondrial DNA of chimpanzees (Pan troglodytes) is the closest to that of living humans. Palaeoanthropology in Africa has established evolutionary steps during the Pleistocene (2.0 to 0.3 Ma) by early members of the genus Homo: H. habilis, H. ergaster, H. erectus; H. heidelbergensis and the earliest H. sapiens. Members of the last three migrated to Eurasia, beginning around 1.8 Ma with the individuals found at Dmanisi in Georgia. The earliest African hominins emerged through the Late Miocene (7.0 to 5.3 Ma): Sahelanthropus tchadensi, Orrorin tugenensis and Ardipthecus kadabba. Through the Pliocene (5.3 to 2.9 Ma) and earliest Pleistocene two very distinct hominin groups appeared: the ‘gracile’ australopithecines (Ardipithecus ramidus; Australopithecus anamensis; Au. afarensis; Au. africanus; Au. sediba) and the ‘robust’ paranthropoids (Paranthropus aethiopicus; P. robustus and P. boisei). The last of the paranthropoids cohabited East Africa with early homo species until around 1.4 Ma. Most of these species have been covered in Earth-logs and an excellent time line of most hominin and early human fossils is hosted by Wikipedia.

All apes, including ourselves, and fossil examples are members of the Family Hominidae (hominids) which refers to the entire world. A Subfamily (Homininae) refers to African apes, with two Tribes. One, the Gorillini, refers to the two living species of gorilla. The other is the Hominini (hominins) that includes chimpanzees, living humans and all fossils believed to be on the evolutionary line to Homo. The Tribe Hominini is defined to have descended from the common ancestor of modern humans and chimps, and evolved only in Africa. As the definition of hominins stands, it excludes other possibilities! The Miocene of Africa before 7.2 Ma ‘goes cold’ as regards the evolution of hominins.  There are, however fossils of other African apes in earlier Miocene strata (8 to 18 Ma) that have been assigned to the Family Hominidae, i.e. hominids, of which more later.

Much has been made of using a ‘molecular clock’ to hint at the length of time since the mtDNA of living humans and chimps began to diverge from their last common ancestor. That is a crude measure at it depends entirely on assuming a fixed rate at which genetic mutation in primates take place. Many factors render it highly uncertain, until ancient DNA is recovered from times before about 400 ka, if ever. The approach suggests a range from 7 to 10 Ma, yet the evolutionary history of chimps based on fossils is practically invisible: the earliest fossil of a member of genus Pan is from the Middle Pleistocene (1.2 to 0.8 Ma) of Kenya. Indeed, we have little if any clue about what such a common ancestor looked like or did. So the course of human evolution relies entirely on the fossil sequence of earlier African hominins and comparing their physical appearances. Each species in the African time line displays two distinctive features. All were bipedal and had small canine teeth.  Modern chimps habitually use knuckle walking except when having to cross waterways. As with virtually all other primates, fossil or living, male chimps have large, threatening canines. In the absence of ancient DNA from fossils older than 0.4 Ma these two features present a practical if crude way of assessing to when and where the hominin time line leads.

In 2002 a Polish geologist on holiday at the beach at Trachilos on Crete discovered a trackway on a bedding plane in shallow-marine Miocene sediments. It had been left by what seems to have been a bipedal hominin. Subsequent research was able to date the footprints to about 6.05 Ma. Though younger than Sahelanthropus, the discovery potentially challenges the exclusivity of hominins to Africa. Unsurprisingly, publication of this tentative interpretation drew negative responses from some quarters. But the discovery helped resurrect the notion that Africa may have been colonised in the Miocene by hominins that had evolved in Europe. That had been hinted at by the 1872 excavation of Oreopithecus bambolii from an Upper Miocene (~7.6 Ma) lignite mine in Tuscany, Italy – a year after publication of Darwin’s The Descent of Man.

Lignites in Tuscany and Sardinia have since yielded many more specimens, so the species is well documented. Oreopithecus could walk on two legs, its hands were capable of a precision grip and it had relatively small canines. Its Wikipedia entry cautiously refers to it as ‘hominid’ – i.e. lumped with all apes to comply with current taxonomic theory (above). In 2019 another fascinating find was made in a clay pit in Bavaria, Germany. Danuvius guggenmosi lived 11.6 Ma ago and fossilised remains of its leg- and arm bones suggested that it could walk on two legs: it too may have been on the hominin line. But no remains of Danuvius’s skull or teeth have been found. There is now an embarrassment of riches as regards Miocene fossil apes from Europe and the Eastern Mediterranean (Sevim-Erol, A. and 8 others 2023. A new ape from Türkiye and the radiation of late Miocene hominines. Nature Communications Biology, v. 6, article  842.; DOI: 10.1038/s42003-023-05210-5). A number of them closely resemble the earliest fossil hominins of Africa, but most predate the hominin record there by several million years.

Phylogenetic links between fossils assigned to Hominidae found in Africa and north of the Mediterranean Sea. (Credit: Sevim-Erol et al. 2023, Fig 5)

Ayla Sevim-Erol of Ankara University, Turkiye and colleagues from Turkiye, Canada and the Netherlands describe a newly identified Miocene genus, Anadoluvius, which they place in the Subfamily Homininae dated to around 8.7 Ma. Fragments of crania and partial male and female mandibles from Anatolia show that its canines were small and comparable with those of younger African hominins, such as Ardipithecus and Australopithecus. But limb bones are yet to be found. Around the size of a large male chimpanzee, Anadoluvius lived in an ecosystem remarkably like the grasslands and dry forests of modern East Africa, with early species of giraffes, wart hogs, rhinos, diverse antelopes, zebras, elephants, porcupines, hyenas and lion-like carnivores. Sevim-Erol et al. have attempted to trace back hominin evolution further than is possible with African fossils. They compare various skeletal features of different fossils and living genera to assess varying degrees of similarity between each genus, applied to 23 genera. These comprised 7 hominids from the African Miocene, 2 early African hominins (Ardipithecus and Orrorin) and 10 Miocene hominids from Europe and the Eastern Mediterranean. They also assessed similarities with 4 living genera, Homo, orang utan (Pongo), gorilla and chimp (Pan).

The resulting phylogeny shows close morphological links within a cluster (green ‘pools’ on diagram) of non-African hominids with the African hominins, gorillas, humans and chimps. There are less-close relations between that cluster and the earlier Miocene hominids of Africa (blue ‘pool’) and the possible phylogeny of orang utans (orange ‘pool’). Sevim-Erol et al. note that African hominins are clearly more similar and perhaps more closely related to the fossils of Europe and the Eastern Mediterranean than they are to Miocene African hominids. This suggests that evolution among the non-African hominids ceased around the end of the Miocene Epoch north of the Mediterranean Sea. But it may have continued in Africa. Somehow, therefore, it became possible late in Miocene times for hominids to migrate from Europe to Africa. Yet the earlier, phylogenetically isolated African hominids seem to have ‘crashed’ at roughly the same time. Such a complex scenario cannot be supported by phylogenetic studies alone: it needs some kind of ecological impetus.

The Mediterranean Basin at the end of the Miocene Epoch when the only water was in the deepest parts of the basin. (Credit: Wikipedia, Creative Commons)

Following a ‘mild’ tectonic collision between the African continent and the Iberian Peninsula during the late Miocene connection between the Atlantic Ocean and the Mediterranean Sea was blocked from 6.0 to 5.3 Ma. Except for its deepest parts, seawater in the Mediterranean evaporated away to leave thick salt deposits. Rivers, such as the Rhône, Danube, Dneiper and Nile, shed sediments into the exposed basin. For 700 ka the basin was a fertile, sub-sea level plain, connecting Europe and North Africa over and E-W distance of 3860 km. There was little to stop the faunas of Eurasia and Africa migrating and intermingling, at a critical period in the evolution of the Family Hominidae. One genus presented with the opportunity was quite possibly the last common ancestor of all the hominins and chimps. The migratory window vanished at the end of the Miocene when what became the Strait of Gibraltar opened at 5.3 to allow Atlantic water. This resulted in the stupendous Zanclean flood with a flow rate about 1,000 times that of the present-day Amazon River. An animation of these events is worth watching

The first Europeans at the Ukraine-Hungary border

Until this year, the earliest date recorded for the presence of humans in Europe came from the Sierra de Atapuerca in the Province of Burgos, northern Spain. The Sima del Elefante cave yielded a fossil mandible of a human dubbed Homo antecessor from which an age between 1.2 to 1.1 Ma was estimated from a combination of palaeomagnetism, cosmogenic nuclides and stratigraphy. Stone tools from the Vallonet Cave in southern France are around the same age. There is a time gap of about 200 ka before the next sign of human ventures into Europe, probably coinciding with an extreme ice age. They reappear in the form of stone tools and even footprints that they left between 1.0 to 0.78 Ma in ancient river sediments beneath the crumbling sea cliffs of Happisburgh in Norfolk, England. Although no human fossils were preserved, they too have been assigned to H. antecessor.

Topographic map of Europe (click to see full resolution in a new window). The Carpathian Mountains form an arc surrounding the Pannonian Basin (Hungarian Plains) just below centr. Korolevo and other Homo erectus and H. antecessor sites are marked by red spots (Credit: Wikipedia Commons)

In 1974 Soviet archaeologists discovered a site bearing stone tools by the River Tisza at Korolevo in the Carpathian Mountains close to the borders between Ukraine, Romania and Hungary. Korolevo lies at the northeastern edge of the Pannonian Basin that dominates modern Hungary. Whoever left the tools was on the westward route to a huge, fertile area whose game might support them and their descendants. The route along the Tisza leads to the River Danube and then to its headwaters far to the west. Going eastwards leads to the plains north of the Black Sea and eventually via Georgia to the Levant. On that route lies Dmanisi in Georgia, famous for the site where remains of the first hominins (H. erectus, dated at ~1.8 Ma) to leave Africa were found (see: Consider Homo erectus for what early humans achived). The tools from Korolevo are primitive, but have remained undated since 1974. 50 years on, Roman Garba of the Czech Academy of Sciences with colleagues from Czechia, Ukraine, Germany, Australia, South Africa and Denmark have finally resolved their antiquity (Garba, R. and 12 others 2024. East-to-west human dispersal into Europe 1.4 million years ago. Nature v. 627, p. 805–810; DOI: 10.1038/s41586-024-07151-3). Without fossils it is not possible to decide if the tool makers were H. erectus or H. antecessor.

The method used to date the site is based on radioactive 10Be and 26Al formed from oxygen and silicon in quartz grains by cosmic ray bombardment while the grains are at the surface. Since the half life of 26Al (0.7 Ma) is less than that of 10Be (1.4 Ma), after burial the 26Al/10Be ratio decreases and is a guide to the age of the sediment layer that contains the quartz grains. In this case the ag is quite precise (1.42 ± 0.28 Ma). The decreasing age of H. erectus or H. antecessor sites from the 1.8 Ma of Dmanisi in Georgia in the east, through 1.4 Ma (Korolevo) to 1.2 in Spain and France could mark the slow westward migration of the earliest Europeans. It is tempting to suggest possible routes as Garba et al. have. But such sparse and widely separated sites can yield very little certainty. Indeed, it is equally likely that each known site marks the destination of separate migrations at different times that ended in population collapse. The authors make an interesting point regarding the Korolevo population. They were there at a time when three successive interglacials were significantly warmer than the majority during the Early Pleistocene. Also glacial cycles then had ~41 ka time spans before the transition to 100 ka about 1 Ma ago. Unfortunately, no information about the ecosystem that the migrants exploited is available

See also: Prostak, S. 2024. 1.4-Million-Year-Old Stone Tools Found in Ukraine Document Earliest Hominin Occupation of Europe. Sci News, 7 March 2024. (includes map showing possible routes of early human dispersal)

Sophisticated Neanderthal art now established

Note: Earth-Pages will be closing as of early July, but will continue in another form at Earth-logs

The first detailed description and analysis of the amazing cave paintings of Western Europe that have been attributed to anatomically modern humans (AMH) were made in the early 20th century by the Jesuit priest Abbé Henri Breuil. As well as that those of Lascaux and Altamira, which have been dated, many works in Spanish caves have not. Art ascribed to AMH includes figurative work depicting a wide range of Late Pleistocene animals, abstract and perhaps symbolic designs, and ‘signatures’ of individual people in the form of direct prints or stencils of hands. The earliest known graphic work made by modern humans is a 100 ka-old baton of ochre with a zig-zag set of sharp incisions found with ochre-filled shells possibly for body painting at Blombos Cave in South Africa.

Evidence for pre-AMH work in Europe is sparse and widely  judged to be ambiguous; for instance 50 ka-old ochre-stained and pierced shells associated with Neanderthal remains in Spain.  Hints at even earlier origins for art lie in the geometrically etched bivalve shells excavated by Eugene Dubois at the site in Java where he discovered Homo erectus crania in 1891. They have recently been dated at around half a million years old.  Occasionally, radiometric dating of drawings has revealed quite meagre red dots that are slightly older than the widely accepted date of first entry of AMH into Europe (~40-45 ka) and may have been made by Neanderthals. Of course, there are many European cave paintings associated with dates earlier than the extinction of Neanderthals (around 30 ka) that may have been made by them, but which are generally ascribed to AMH by assuming that only our species has the wit to make them.  Even the sophisticated Châtelperronian stone tools and rough ornaments associated with undeniable Neanderthal remains are considered by many paleoanthropologists to show skills copied from AMH.

This AMH-centric view of art depends on two outlooks: simple prejudice that any beings markedly different in appearance from us were intellectually inferior – generally condemned as racist if applied to different groups of living humans; lack of incontrovertible and unambiguous evidence to the contrary. Both are set to be rigorously challenged by the growing use of sophisticated radiometric U-Th dating of the thin films of chemically precipitated calcite (flowstone or speleothem) that often coat the walls of caves and are at least as old as the art that they cover. A German-Spanish-British team has applied the technique to artwork and painted stalactites on the walls of three caves in Spain known to have been occupied by hominins over the last 100 ka (Hoffmann, D.L and 13 others 2018. U-Th dating of carbonate crusts reveals Neandertal origin of Iberian cave art. Science, v. 359, p. 912-915; doi: 10.1126/science.aap7778. See also: Appenzeller, T. 2018. Europe’s first artists were Neandertals. Science, v. 359, p.852-853; doi: 10.1126/science.359.6378.852). One cave that was analysed is that at La Pasiega in Cantabria whose art was sketched by Abbé Breuil. The team’s results are dramatic: all the dated samples pre-date 40 Ka, the oldest at 79.66±14.90 ka being from La Pasiega. Precisely dated art includes hand stencils, painted stalactites, geometric patterns and line drawings of animals. Many of the caves’ artworks remain to be dated, including some well-executed animals and strange, possibly symbolic designs.

Symbolic Neanderthal art in La Pasiega cave, Spain – left: recent photograph; right: sketch produced Abbé Breuil in 1913. The red, ladder-like symbol has a minimum age of 64 ka but it is unclear if the animals and other symbols were painted later. (credit: Hoffmann et al. 2018, Supplementary Data Figure S4)

The implications of this work are far-reaching. Handprints and stencils are common throughout the archives of European cave art and seem generally to be the oldest at each site. The dating method is yet to applied to the bulk of cave art, much of which is encased in speleothem, so it is quite possible that ‘dual authorship’ may be discovered in some caves. It now seems clear that Neanderthals invented permanent art independently of AMH, and since art is a form of communication that has implications for the ability to speak as well as to think ‘outside-the-box’. The 177 ka corral-like enclosures made of stalactites and associated hearths deep within Bruniquel Cave seem more likely to have ritual significance, far from the light of day, for the Neanderthals that made them. The finds throw doubt on the implausibility of Neanderthal invention of so-called ‘transitional’ technologies, such as the Châtelperronian. Finally, fully modern humans in Africa and Neanderthals in Europe were doing much the same things over roughly the same time period; genetically and physically they parted company about 450 to 400 ka ago; both were capable of artistic symbolism and fulfilled that potential. That implies that their common ancestor may have passed on the proclivity, as might their predecessor H. erectus who created the etched mollusc shells of Trinil half a million years ago.

More on Neanderthals, Denisovans and AMH genetic relatedness

Editorial from the Guardian Newspaper 26 February 2018.

Fracking unlikely in Europe

These days, leading British politicians burdened with power have a tendency to show outwardly that they are, if little else, earnest. When busy with economic and industrial policy they wear tailored day-glo hi-viz suits and shiny new hard hats. During the great 2015 floods of Northern England, their garb was off the peg North Face gear and green wellington boots. And, of course, for social policy a hoodie is de rigueur. Rosy-cheeked Prime Minister David Cameron has been extremely earnest about fracking for shale gas for several years, and in the petroleum industry the appropriate signal of a leading politician’s enthusiasm is to wear a rigger’s blue jumpsuit; ‘We’re going all out for shale’ Cameron has said. Given the explosive success of shale-gas exploitation in North America over the last decade that’s not very surprising, but do not expect to see him looking earnestly at an exploration rig again any time soon.

Cameron’s excitement began when in 2011 the Advanced Resources Institute (ARI) in Washington DC released the results of its consultancy for the US Department of Energy on global shale-gas prospects. The star prospect in Europe was Poland, well endowed with subsurface shales, which according to ARI, had more than 5 trillion cubic metres of technically recoverable reserves, enough to satisfy Polish consumption for more than 300 years. In 2013, ARI suggested 17 trillion m3 beneath Britain, albeit only 0.7 trillion that was amenable to fracking (about a decade’s worth of British gas consumption). But still the hype was maintained. An article in the 3 March 2016 issue of Nature (Inman, M. 2016. Can fracking power Europe. Nature, v. 531, p. 22-24) tempers enthusiasm a great deal more.

The Polish Geological Institute revised the country’s reserves down to a tenth of ARI’s estimate. After an initial frenzy of interest following the ARI report, when exploration licences covered a third of Poland, during 2013 and 2014 major companies relinquished licences for fracking en masse. Their exploratory activities had been disappointing because of the depth of burial (2-5 km compared with 1-2 km in the US) and unfavourably high clay content and strength of the target shales. The less thrilling ARI prospects for Britain did not excite major petroleum players at all, what interest there is being from ‘juniors’ such as Cuadrilla. The British Geological Survey, which has huge archives of geological information, both surface and subsurface, has assessed the three main British shale-gas ‘plays’ and comes up with a reserve figure of between 24 and 68 trillion m3. But that high figure is based on the situation in mid-west North American shale-gas fields, where the geology is a great deal simpler than here. In Britain, orogenies at the end of the Carboniferous and the outermost ripples of that which formed the Alps in late Mesozoic and Palaeogene times created far more deformation than beneath the central plains of North America. Widespread faults, even though few in Britain have large displacements, pose two sets of problems. As the minor earthquakes set off by fracking in the tectonically simple Fylde area of western Lancashire indicate, pumping fluids into faulted rock can release pent-up elastic strain. But such leakage into faults and smaller fractures may also cause the injection pressure to fall, making the fracking process less efficient.

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Fracking information sheet from the British Geological Survey

Inman reports that fracking is now moribund throughout Europe, partly because of the disappointing results and also because environmental concerns for densely populated regions have spurred widespread moratoria, including those in three of Britain’s four nations; Scotland, Wales and Northern Ireland. The only current European fracking activity is in England, conducted by a handful of junior companies. A stumbling block in England actually lies with the quality of subsurface data for what has been described at the most close examined geology in the world. Since the early 1980s there has been a succession of onshore licensing rounds for oil and conventional gas, the 14th of which is still active. The early ones were accompanied by a great deal of seismic reflection surveying, mainly using the truck mounted ‘Vibroseis’ method where the ground is mechanically thumped rather than subject to explosive shot firing that is favoured in sparsely populated areas. According to BGS, the guardians of the onshore seismic exploration repository, compared with the onshore seismic data available in North America that for Britain is ‘sparse, and fairly poor’.