February 04, 2013

Late Neandertal survival in Iberia questioned

Neanderthal remains point to earlier extinction
In the latest study1, Higham and his former graduate student Rachel Wood, now at the Australian National University in Canberra, tried to date remains from 11 sites on the Iberian Peninsula using their decontamination methods. Previous efforts put the remains as young as 36,000 years old.

However, Wood and Higham found that just two of the sites — Jarama, outside Madrid, and Cueva del Boquete de Zafarraya, near the southern tip of Spain — contained bones with enough carbon to be dated. Their work suggests that these remains are more than 45,000 years old, with some older than 50,000 years, the practical limit of carbon dating. Wood says that the team’s study calls into question evidence that the last populations of Neanderthals found refuge in the Iberian Peninsula.
PNAS doi: 10.1073/pnas.1207656110

Radiocarbon dating casts doubt on the late chronology of the Middle to Upper Palaeolithic transition in southern Iberia

Rachel E. Wood et al.

It is commonly accepted that some of the latest dates for Neanderthal fossils and Mousterian industries are found south of the Ebro valley in Iberia at ca. 36 ka calBP (calibrated radiocarbon date ranges). In contrast, to the north of the valley the Mousterian disappears shortly before the Proto-Aurignacian appears at ca. 42 ka calBP. The latter is most likely produced by anatomically modern humans. However, two-thirds of dates from the south are radiocarbon dates, a technique that is particularly sensitive to carbon contaminants of a younger age that can be difficult to remove using routine pretreatment protocols. We have attempted to test the reliability of chronologies of 11 southern Iberian Middle and early Upper Paleolithic sites. Only two, Jarama VI and Zafarraya, were found to contain material that could be reliably dated. In both sites, Middle Paleolithic contexts were previously dated by radiocarbon to less than 42 ka calBP. Using ultrafiltration to purify faunal bone collagen before radiocarbon dating, we obtain ages at least 10 ka 14C years older, close to or beyond the limit of the radiocarbon method for the Mousterian at Jarama VI and Neanderthal fossils at Zafarraya. Unless rigorous pretreatment protocols have been used, radiocarbon dates should be assumed to be inaccurate until proven otherwise in this region. Evidence for the late survival of Neanderthals in southern Iberia is limited to one possible site, Cueva Antón, and alternative models of human occupation of the region should be considered.

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5 comments:

Rokus said...

Contrary to what the word "extinction" may suggest, this older dates for Neanderthal rather increases the transition period between late Neanderthal and their early modern human descendents. This period may be long enough for the transition to be smooth, evolution-driven and characterized by an increased bidirectional gene flow due to the attested cultural changes of this time.

terryt said...

"this older dates for Neanderthal rather increases the transition period between late Neanderthal and their early modern human descendents. This period may be long enough for the transition to be smooth"

Good point.

genetiker said...

Contrary to what the word "extinction" may suggest, this older dates for Neanderthal rather increases the transition period between late Neanderthal and their early modern human descendents.

That makes absolutely no sense.

This period may be long enough for the transition to be smooth

I wouldn't characterize losing the struggle for life as a "smooth transition". It's like saying the Titanic encountered "smooth sailing" in its voyage across the Atlantic.

John Hawks wants everybody to believe that Neanderthals were basically "just like us", but the reality is that they were intellectually inferior.

No humans wanted to mate with archaics, but the most inferior humans took what they could get.

Humans assimilated the few adaptive pieces of the archaics' DNA, and then proceeded to rapidly outcompete/exterminate them.

terryt said...

"but the reality is that they were intellectually inferior".

We don't 'know' that at all.

"No humans wanted to mate with archaics, but the most inferior humans took what they could get".

We also don't 'know' that. What we do know is that neanderthals have left some genes in modern humans. Presumably such genes would not have survived if the moderns that bred with neanderthals were 'the most inferior humans'.

eurologist said...

No humans wanted to mate with archaics, but the most inferior humans took what they could get.

IDK - Uba (Lycia Naff) in The Clan of the Cave Bear was kind of hot. ;)

More seriously, and in other words, if an average (but real) man had been in an all-men party for a couple of weeks, I think there would have been a 1/100 or better chance he'd encounter someone sufficiently attractive. I think it has more to do with situation and carpe diem than with inferiority.