Genomics of the Iberian Peninsula

Fig. 1: Selected archaeological sites in western Europe and North Africa.

Great effort has been devoted to framing the spatiotemporal fea-tures of Neanderthal replacement, as this may help to resolve the processes that triggered population and technological turnovers6. This includes determining any directionality of technological and population changes that, according to genetic and archaeological data, become recurrent events in western Europe from the Late Pleistocene onwards, generally exhibiting an east to west trend. Mousterian technocomplex replacement by Aurignacian popula-tions is postulated to be one such east-to-west population turn-over1. This same directionality is documented for the Gravettian technocomplex that replaced the Aurignacian7, the genetically and culturally documented Magdalenian–Azilian transition in western Europe at the beginning of the Bölling–Alleröd interstadial8, and replacements within the Epigravettian cultures of southern Europe.Among European east–west population turnovers, the Mousterian–Aurignacian transition has perhaps received the most attention. This is because it is associated with the putative extinction of Neanderthals, given that Aurignacian technocomplex elements have now been securely associated with AMHs1.

In comparing the early stages of the Aurignacian dispersal (Fig. 1) with subsequent transitions, two spatiotemporal anomalies emerge. The first is recorded on the Italian Peninsula, where populations manufacturing the Uluzzian industry (for some authors, a develop-ment rooted in the Mousterian lithic tradition9) seemingly prevented the expansion of the early Aurignacian10. The second anomaly is documented in mid-southern Iberia, where the Aurignacian expan-sion is postulated to have been delayed to the point of failure11. The proposal that the Middle Palaeolithic technocomplex extended to the end of Marine Isotope Stage 3 (Gorham’s Cave, Gibraltar: ~32.5 calibrated thousand years before the present (cal ka BP11) has lent weight to the hypothesis that the EUP reached southern Iberia at a comparatively late date. This reinforced the validity of a particu-lar version of the east-to-west wave-of-advance mode that set apart the ‘Iberian South’ from the rest of the Peninsula.


Fig. 2: Representative lithic industries from Bajondillo site archaeological levels Bj/14–Bj/11.

To reliably pin down the Neanderthal–AMH transition in southern Iberia, 17 new dates restricted to levels covering the transition of the Mousterian to the Aurignacian at the site of Bajondillo in the Bay of Málaga (southern Spain) (Fig. 1, Supplementary Figs. 1–3 and Supplementary Table 1) have been integrated with previous radio-metric dates13, using a Bayesian approach. The Middle Palaeolithic at Bajondillo lasts for ~120 kyr14, as represented by 6 archaeological levels (that is, Bj/19–Bj/14) (Supplementary Fig. 1), the last of which features a Denticulate Mousterian (~50–46 cal ka)13 (Fig. 2).

The evidence that allows us to identify Bj/13 as Proto-Aurignacian or Early Aurignacian results from a combination of chronological and stratigraphic data, complemented by historiographic and tech-nological data (Fig. 2 and Supplementary Fig. 4). Stratigraphically, Bj/13 is firmly set above a well-defined Middle Palaeolithic pack-age and overlaid by another Aurignacian level (Bj/11) lying below a Gravettian deposit (Bj/10). The stratigraphic package is well structured in sedimentological and micromorphological terms, and shows no inconsistency in the seriation of absolute dates indepen-dent of the long- or short-lived nature of the samples (see below).

The range of dates obtained from the Bayesian model appears to be fully consistent with our hypothesis of the Bj/13 Aurignacian (43.4–40.0 cal ka BP) lying chronologically between Heinrich events 5 (50–47 cal ka BP) and 4 (40.2–38.3 cal ka BP). However, techno-logically, level Bj/11 (~37.6–32.4 cal ka BP; Fig. 2 and Supplementary Table 1) corresponds to an Evolved Aurignacian with blade and bladelet technologies and the characteristic tools of this techno-complex. Hearths also testify to differences between the Middle Palaeolithic and EUP. Hearths from Bj/16 and Bj/15 evidence an exclusive use of grasses (Gramineae) as fuel, with temperatures never reaching 500 °C, whereas those from EUP levels (that is, Bj/12 onwards) exhibit a more efficient pyrotechnology, with frequent use of wood, and temperatures well in excess of 550 °C20.At Bajondillo, all six of the new accelerator mass spectrom-etry (AMS) dates for the Mousterian from Bj/14 derive from short-lived (< 5 years) shells of marine and terrestrial molluscs, and range between > 50 and 46 cal ka BP, the youngest ages being based on a Bayesian model (Supplementary Table 1; the pulmo-nate samples derive from a garden snail taxon (Otala species) that feeds on fresh vegetal matter and thus does not exhibit the ‘old-shell effect’). These dates calibrate this level to during or immedi-ately after Heinrich event 5 (Fig. 3). The date obtained on a mussel from the latest Middle Palaeolithic level at the nearby Abrigo 3 site, 20 km away from Bajondillo Cave on the Bay of Málaga, falls squarely within this range of dates (that is, 50–43.1 cal ka BP21; Supplementary Fig. 2b).



Fig. 3: Comparison between the chronologies of the different archaeological levels at Bajondillo Cave and a selection of palaeoenvironmental proxies.


The oldest of the six AMS dates from Bj/13 (EUP) come from long-lived taxa (sample charcoal/Ua-18270) (Supplementary Table 1), which, although coherent among these taxa, may yield ages older than the deposit from which they were retrieved. Samples for Bj/13 that derive from short-lived (< 5 years) mussels and a terrestrial snail (Otala species) provide a Bayesian median age set between 42.5 and 41.2 cal ka BP (Fig. 3 and Supplementary Table 1). The taphonomic features (that is, fragmentation and thermoalteration) of all marine shells from Bj/13 document shellfish processing contemporane-ous with the deposit, reinforcing the autochthonous nature of the radiocarbon-dated samples, thus their reliability as chrono-indica-tors. The dates available from Bj/14 and Bj/13 (which were derived from the middles of the layers, away from their common bound-ary) show a potential discontinuity of ~2 kyr between these levels, one of which requires further research to be confirmed (Fig. 3 and Supplementary Table 1). The dates from Bj/13 coincide with others from early Aurignacian sites in Europe (Fig. 1), such as the Italian rock shelter of Riparo Mochi, as well as sites from Central Europe (~43-42.5 cal ka)23 and (~43.5 cal ka)24. Additionally, the most recent Middle Palaeolithic/Upper Palaeolithic chronological review from the Cantabrian area (northern Spain)25 and Central Spain26 yields essentially identical dates to those obtained at Bajondillo for the Middle Palaeolithic–Upper Palaeolithic transition. In North Africa, Upper Palaeolithic/Later Stone appear in Cyrenaica after ~43 ka (Haua Fteah), but only after 30 ka in the Maghreb (Grotte des Pigeons) (Fig. 1)8,12,17,27–34.

The new Bajondillo dates are crucial for several reasons. First, they confirm the presence of a chronologically early Aurignacian in southern Iberia at ~43 cal ka BP that now shows the first appear-ance of the EUP to be an essentially synchronous event throughout Europe (Fig. 3 and Supplementary Fig. 3). This suggests that the dis-persal of AMHs was much faster than hitherto postulated, and the expansion of the earliest Aurignacians in Europe is now increased westwards by > 1,000 km. These dates thus call into question both the gradual ‘wave-of-advance’ and the ‘Ebro frontier’ models. They also provide reference points for the attribution of early art work in Iberian caves—something that remains highly controversial35. The dates suggest either extremely high mobility of early Aurignacians or well-developed networks of interchange. For early AMHs, rapid dispersal was seemingly only possible over essentially ‘empty’ terri-tories (that is, either completely depopulated areas, as some studies suggest for southern Iberia at the time7, or areas featuring severely depleted human populations).The Aurignacian early expansion took place between Heinrich events 5 and 4 (Fig. 3 and Supplementary Fig. 3), when cold and steppic conditions prevailed throughout most of western Europe, including the Iberian hinterland36. In light of this, it might be no coincidence that a prevalence of European EUP sites has been reported along shores or neighbouring lowlands where milder con-ditions prevailed and more productive environments, in terms of living resources, existed (Fig. 1 and Supplementary Fig. 2c).

The Aurignacian from Bajondillo Cave conforms with this pattern and is not an isolated case in Iberia, where newly recorded Aurignacian sites south of the Ebro river, such as Foradada16, Cendres17 and Pego do Diabo12, are all located on the present-day coast or its adjoin-ing lowlands (Fig. 1), nor in Italy (Riparo Mochi and Serino; see Supplementary Information). Coasts and coastal lowlands as instrumental for human dispersal and colonizing events are not a phenomenon restricted to the European Aurignacian, since data emerging from southern Arabia37, Australia38,39 and South America40 all point in the same direction. In eastern and southern Iberia, trav-elling through coasts and coastal lowlands would have been con-siderably easier than travelling through one of the most rugged mountainous hinterlands in Europe. The enhanced mobility of Aurignacian populations can be inferred from their swift spread over western Europe from Glacial Interstadial 12 onwards, thus hinting at dispersals taking place across territories that were easy to traverse (Supplementary Fig. 2a,b)1.The onset of the Aurignacian cannot be detached from the demise of the Neanderthals. Inferences about the mobility and settlement patterns of southern Iberian Neanderthals are compli-cated due to the restricted number of Mousterian sites, as well as the prevalence of low sea-level stands during this period, which means that an undetermined, yet probably substantial, fraction of the evidence presently lies underwater. From this perspective Bajondillo Cave is of great relevance since, due to its topogra-phy, it was at all times located on or very close to the shore (that is, not more than 5 km distant; Supplementary Fig. 2a), but never flooded. The data from Bajondillo Cave and other coastal Iberian locations41 reveal that stasis, as exemplified by around 120 kyr14 of Neanderthal occupation with no clear traces of technological devel-opments, prevailed during the Iberian Mousterian.

Nature Ecology & Evolutionvolume 3, pages207–212 (2019)