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2020-11-17 09:46:54   •   ID: 2187

Crossing the Strait of Gibraltar by rafting early Humans?

Figure 1
Figure 1 show a Large Cutting Tool / LCT-Cleaver made from Quartzite and Figure 2 an Acheulian Handaxe made from Basalt, found together in S-Spain / Iberian Peninsula in 1932, by F Sanchez, an Amateur collector of Stone Tools.

African LCTs-early and late: LCTs appear early in the East African Acheulian. At Konso (Ethiopia), the early Acheulean technology includes both large cutting tools (handaxes, cleavers, and knives) and heavy-duty tools (picks and core-axes) that are bifacially or unifacially worked. Here the early Acheulian appeared, radioisotopically dated, at 1,75 k.a.

Figure 3 shows a heavy Acheulian East African Cleaver from Olorgesailie- see: 1247 . About Giant Cores and Large Cutting tools see here: 1003 and here 1173 .

It has to be mentioned that the production of LTCs in Europe is a quasi-unique feature of the Iberian Acheulian, compared to sites in N/W-Europe- where Flake-Cleavers are rare although not totally absent -see here: 2017 .

After their beginnings in the early Pleistocene, African LTC-Cleavers were found until the late Middle Pleistocene. LCTs are for example a component of the South African Fauresmith Industry (400-200 k.a. BP) - see 2197 .

In the Near East they were rare after GBY (at 800 k.a. BP). Anyhow they have been found during the later Middle Pleistocene in Arabia.

Here the stratified Acheulean site at Saffaqah, situated in the Dawadmi region of the Nejd plateau is of some importance, offering a very late Acheulian on the Arabian Peninsula with an abundance of LCTs dated to ca. 190 k.a. - currently the youngest documented Acheulean in Southwest Asia.

Figure 2
In Northern Africa, especially in the Maghreb the earliest LCTs were in use since 1,3 my ago near Casablanca (Thomas Quarry), and many of them were part of Middle Pleistocene ensembles - for example again at Casablanca (Grotte des Ours, STIC Quarry, Thomas Quarry) in Morocco and at Sidi Zin near Kef in north-western Tunisia- see 1578 .

The temporary lag between the Acheulian of East and North Africa always remained Enigmatic and was suggested to be the consequence of a mayor ecological barrier between the two regions. Anyhow the new dating of the basal Acheulian Layers at Thomas Quarry at Casablanca are 1,3 mya old and, with this date, move considerably closer to the Acheulian beginnings in East and South Africa.

S-European LCTs-early and late: The earliest and about 942 to 641 kyr old ensemble with LCTs and Handaxes in South / West Europe is currently the Barranc de la Boella site (Catalonia, Spain). The age of the site depends on consistent biostratigraphical and magnetostratigraphical data.

Beside LCT-Acheulian finds from middle Pleistocene terraces (+40−20 m) of the large Iberian rivers, dated between MIS 11 to MIS 7/6, at least one very late in-situ site with large accumulations of LCT is known from Spain and exhibits specific African signatures. This site is Porto Maior in the Galicia Province.

At Porto Maior lithic tool-bearing deposits date back to 293–205 k.a. Beside Handaxes, Flake Cleavers resembling their African counterparts both in large size, density of deposition and typology are present.

Most of the artifacts are in primary position and dated by several methods to 293–205 k.a. This dates are not only interesting regarding a possible African origin of he LCT ensemble, but also to the fact that an early Middle Paleolithic without a bifacial component was already present in parts of Iberia at the same time-span.

Last but not Least this late date even may indicate that the Franco-Cantabrian „Vasconian“ from MIS5 is a final expression from a Flake-Cleaver centrated tradition, that started in Africa and moved over Iberia towards the French border over time.

How should we interpret the occurrence of LCTs in Africa and Europe?

  • as a convergence phenomenon in regions where large cobbles or blocks of suitable raw material were common? However, the argument does not explain the absence of LCTs from many European regions with suitable raw material


  • as a longstanding tradition, beginning in Africa followed by a later technological transfer to Europe through one of the known Afro-European corridors? -arguments for this opinion can be found below


One possible transcontinental connection between Eurasia and Africa is beside the Levantine corridor and the Bab al- Mandeb Strait, the Strait of Gibraltar.

It is a narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates Gibraltar and Peninsular Spain in Europe from Morocco in Africa.

Today the two continents are separated by 14,3 kilometers of ocean at the Strait's narrowest point.

The Strait's depth ranges between 300 and 900 meters which possibly interacted with the lower mean sea level during Pleistocene glacial conditions when the level of the sea is believed to have been lower by 110–180 meters.

Modeling a fall in sea level of about 150 meters indicates the emergence of several islands which would reduce the distance between Africa and Europe to 5+2 km.

During the early Pleistocene, important falls in sea levels occurred at 2,4 and 1,6 mya. According to Robers (1992), the fall in sea level could have reached ca 160m. Interestingly these two events also coincided with faunal changes between Africa and Europe.

Figure 3
Other events occured during the Middle Pleistocene and during the last Glacial (especially during the LGM).

Here I discuss the hypothesis, that the production of LCTs was indeed not a convergence phenomenon but a longstanding tradition.

I my view there are some evidence that there was probably a technological transfer between N- Africa and Iberia via the Strait of Gibraltar during low sea levels.

This happened in analogy to the „island hopping“ of premodern humans to the island of Flores (Java), which was never connected with the Asian mainland. Notably, Human dispersal to Flores across a considerable marine barrier has been proven as early as 880 k.a. ago.

  • Geographically, Cleavers in possible European corridors between the Near East / Arabia and Iberia are absent


  • the specific and sophisticated chaine operatoire of cleavers virtually excludes, not only in my view, a convergent evolution during different times and places


  • If we accept the early date from the Barranc de la Boella site, LCTs on the Iberian peninsular were present at the same time, they were also present in the Maghreb


However, recent multifactorial studies show that without the knowledge of rafting, there was probably no possibility to cross the Strait of Gibraltar during the Pleistocene:

Our results show that Africa could be left via the Bab-al-Mandab Strait without specific rafting technology. At low sea level, even passive drifting was sufficient to cross the strait. In contrast, the Gibraltar- and Sicily Strait were barriers to humans without rafting technology (Hölzchen et al. 2022).

We should not forget that we have always underestimated the technical possibilities of our ancestors and that the picture in this respect is constantly changing. Therefore: Why should they not have mastered rafting?



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