Patagonian monsters: December 2014

Wednesday, December 31, 2014

Oldest Stone Tools in Turkey are 1.2 Ma and made by Homo erectus

The oldest stone tool in Turkey was discovered, and it was made by Homo Erectus. A paper by Maddy et al., reports that (I quote the Abstract):

Abstract Anatolia lies at the gateway from Asia into Europe and has frequently been favoured as a route for Early Pleistocene hominin dispersal. Although early hominins are known to have occupied Turkey, with numerous finds of Lower Palaeolithic artefacts documented, the chronology of their dispersal has little reliable stratigraphical or geochronological constraint, sites are rare, and the region's hominin history remains poorly understood as a result. Here, we present a Palaeolithic artefact, a hard-hammer flake, from fluvial sediments associated with the Early Pleistocene Gediz River of Western Turkey. This previously documented buried river terrace sequence provides a clear stratigraphical context for the find and affords opportunities for independent age estimation using the numerous basaltic lava flows that emanated from nearby volcanic necks and aperiodically encroached onto the contemporary valley floors. New 40Ar/39Ar age estimates from these flows are reported here which, together with palaeomagnetic measurements, allow a tightly-constrained chronology for the artefact-bearing sediments to be established. These results suggest that hominin occupation of the valley occurred within a time period spanning ∼1.24 Ma to ∼1.17 Ma, making this the earliest, securely-dated, record of hominin occupation in Anatolia.

The tool is a piece of stone about 5 cm (2 in.) long, fashioned by the hand of a Homo erectus in Anatolia. Far from their African homeland. A clear indication that H. erectus was alive and kicking at the time (1.2 Ma) and crafting advanced tools. By the way, Anatolia gives access to Georgia on the Northeast and, Europe to the West.

H. erectus remains were found close to this site some years ago (at Kocabas - see the full text of the paper here), but the dating was not clear, but estimated at 1.1 Ma. Now we can be sure that H. erectus was living here during this period.

The tool. From the paper

Happy 2015

I wish you all a Very Happy New Year. May 2015 be a positive year for each and everyone of us.

Thursday, December 4, 2014

Africans not so differentiated after all

A paper published in Nature on Dec. 3, 2014, deals with the genome of Africans [1]. I found it interesting because, against the usual mainstream belief on African diversity, it reports that: "overall differentiation among African populations was modest [...] This suggests that a large proportion of differentiation observed among African populations could be due to Eurasian admixture, rather than adaptation to selective forces (Supplementary Note 6). Genes known to be under selection were notably enriched among the most differentiated loci after masking of Eurasian ancestry". [1]

So the differences are due to Eurasian admixture! and those that were not of Eurasian origin, differed because they were being selected for positively. Clearly not the kind of scenario expected if the myth of a "molecular clock" was true.

The interesting part is that regarding SNP diversity: " A substantial proportion of unshared (11%–23%) and novel (16%–24%) variants were observed, with the highest proportion among Ethiopian populations" [1]. Note that they are Ethiopians not Sub Saharan Africans which are always mentioned as being the most diverse!

This higher diversity among "Ethiopian populations, possibly suggest[s] Eurasian gene flow", furthermore, analysis "supported evidence for substantial Eurasian and HG ancestry in SSA" (Sub Saharan Africans). The Eurasian admixture in Africans was substantial: "ranging from 0% to 50%".

An interesting discovery was that of the cause of diversity:

"On examining locus-specific Europe–Africa differentiation, enrichment of loci known to be under positive selection was observed among the most differentiated sites (P = 1.4 × 10−31). Furthermore, there was statistically significant enrichment for gene variants among these, indicating that this differentiation is unlikely to have arisen purely from random drift (P = 0.0002). Additionally, we found no evidence for background selection as the primary driver of differentiation among these loci (Supplementary Note 7)." [1]

In other words natural selection is acting to promote diversity and it is not due to "natural drift". No regularly ticking mutation clock here, what is acting is a clock ticking at higher and variable speed, prodded by Evolutionary adaptation to a changing environment.

Source

[1] Deepti Gurdasani, et al., (2014). The African Genome Variation Project shapes medical genetics in Africa. Nature (2014) doi:10.1038/nature13997

Homo erectus were not so dum after all!

A paper published in Nature [1] reported : "The manufacture of geometric engravings is generally interpreted as indicative of modern cognition and behaviour. Key questions in the debate on the origin of such behaviour are whether this innovation is restricted to Homo sapiens, and whether it has a uniquely African origin1. Here we report on a fossil freshwater shell assemblage from the Hauptknochenschicht (‘main bone layer’) of Trinil (Java, Indonesia), the type locality of Homo erectus discovered by Eugène Dubois in 1891 (refs 2 and 3). In the Dubois collection (in the Naturalis museum, Leiden, The Netherlands) we found evidence for freshwater shellfish consumption by hominins, one unambiguous shell tool, and a shell with a geometric engraving. We dated sediment contained in the shells with 40Ar/39Ar and luminescence dating methods, obtaining a maximum age of 0.54 ± 0.10 million years and a minimum age of 0.43 ± 0.05 million years. This implies that the Trinil Hauptknochenschicht is younger than previously estimated. Together, our data indicate that the engraving was made by Homo erectus, and that it is considerably older than the oldest geometric engravings described so far. Although it is at present not possible to assess the function or meaning of the engraved shell, this discovery suggests that engraving abstract patterns was in the realm of Asian Homo erectus cognition and neuromotor control"

Our distant ancestors were much smarter than believed until now. Symbolic representations have been believed to be a more recent acquisition (H. sapiens and, more reluctantly, Neanderthals).

A smarter H. erectus is interesting, it means that 500 kya they could have not only engraved mussel shells but also, dealt with the cold Arctic climate and walked across Beringia into the Americas.

430 - 540 ky old shell with human markings. From [1]