Physical anthropologist claims (again) that Homo floresiensis was cretin Homo sapiens

This hypothesis has been proposed before by the same team and then rejected. However I feel obliged to mention it as I'm sure that some readers will find it interesting and also because, if real, it would mean that LB1 is not an Homo erectus (maybe a cretin H. erectus?) nor a new species but a marginal representative of our own expansion in Eurasia and beyond.

However I am skeptic, specially because Oxnard fails to compare with Homo erectus.

Cretinism is a severe chronic medical condition caused by low iodine intake. Iodine is mostly ingested with drinking water and also from sea salt, but not refined table salt (unless enriched).

Judge yourself anyhow:

Charles Oxnard et al. Post-Cranial Skeletons of Hypothyroid Cretins Show a Similar Anatomical Mosaic as Homo floresiensis. PLoS ONE 2010. Open access.

Late human evolution maps

Kambiz Kamrani at Anthropology.net mentions this site of a colleague and also his own dedicated page on human fossils. Both are very interesting and, using their data, I made some maps in order to better understand the chronology of recent human evolution in the range between 1.3 million years ago (oldest estimate for Neanderthal-Sapiens divergence, cf. Aida Gómez) and 60,000 years ago, when the expansion of these two species towards Asia was surely already in action.

As Asian fossils, excepted West Asia, are not relevant for my purpose (they are all Homo erectus senso lato with no transition happening there at all) I have used a base map that only includes the Western parts of the Old World.

Note: I used median ages but, when these overlapped too much with two of my arbitrary time frames, I placed them in the two relevant maps (check for safety but they are likely to be the same specimen.


1. 1.3 million years to 800,000 years ago:


While most of the findings are Homo erectus (purple dots), the likely first known individuals in the H. sapiens and H. neanderthalensis lines appear already, at the end of the period, at Atapuerca (H. antecessor) and Saldanha Bay (H. rhodesiensis).


2. 800-600,000 years ago:


We can appreciate in this period an expansion of H. rhodesiensis to the Horn of Africa and transition to H. heidelbergensis at Atapuerca (c. 600,000 years ago according to fossilized.org).


3. 600-400,000 years ago:

The expansion of Homo heidelbergensis becomes apparent in this period. Restricted to Europe however. Notice how in spite of these changes there are still many specimens categorized as H. erectus around the Mediterranean.


4. 400-200,000 years ago:


While it looks a dull map on first sight, most significant here is the existence of a fossil that may be transition between H. rhodesiensis and H. sapiens. This one is Lake Eyasi, in Tanzania (red-orange hue, not easy to appreciate possibly), dated to c. 240,000 years ago.


5. 200-60,000 years ago:



Whoa! Everything goes a lot faster now: Neanderthals and Sapiens everywhere! Well, each in their specialized area: Sapiens in and around the tropics, Neanderthals in the fresh regions of the North. Even the map caption becomes small as the earliest Neanderthal and Sapiens fossils (controversial chronology) show up in Central and East Asia respectively. I reflected this with a mere two color-coded arrows.

The oldest uncontroversial fossil of H. sapiens is Omo II (c. 195 Ka ago), followed by Herto (Idaltu) and Jebel Irhoud, in Morocco (both c. 160 Ka ago).

Molecular clock and the Denisova hominin

Yesterday I echoed the sequencing of ancient mtDNA from a finger tip at Denisova cave in Altai, dated to c. 40,000 years ago, when the area was also populated by H. sapiens and H. neanderthalensis.

I thought that would be about enough but as I read more and more discussions there seems to be some major confusion sparked by the use of molecular clock estimates, which the paper estimates in only 300-700 Ka for Neanderthal most recent common ancestor, hence producing a 1300-900 Ka estimate for the MRCA of us and the Denisova hominin, aka "X Woman". This, some say, calls for a major revision of the history of hominin migrations out of Africa because we know of no such migration.

Nonsense!

The problem is caused by the use of a quick-ticking version of the molecular clock, because there's absolutely no archaeological reason to claim that Neanderthal and Sapiens MRCA is dated to only 700 Ka much less 300.

In fact the last migration out of Africa before H. sapiens we know of from the archaeological record is the Acheulean migration which is dated to c. 900,000 years ago. In my not so humble opinion, this is the real chronology of the divergence of Neanderthal and H. sapiens, a divergence that began most likely at the stage of H. ergaster.

Hence the Neanderthal-Sapiens MRCA must be an H. ergaster woman and should be dated to c. 900,000 or 1 million years ago.

That fixes all. Because, when we use this realistic reference, the MRCA of Denisova and the other hominins (Neanderthals and us) would have an age of 1.8 or 2 million years ago, which is precisely the time of the earliest H. erectus migration out of Africa.

So the Denisova hominin is, with all likelihood, an H. erectus or a descendant from this lineage (maybe by admixture with Neanderthals?) and everything fits nicely.

Everything but the short count molecular clock, which is obviously the one in need of a good fix, because it's demonstrating once and again that it only causes confusion and it always fails to fit well with the archaeological record.

X Woman

Not any fictional character but the quite unoriginal name given to the former bearer of a finger found in Denisova Cave (Altai, Russia) whose mtDNA has been analyzed now by Krause et al. (Paabo's team).

The result known so far (via Mundo Neandertal and El Neandertal Tonto, Qué Timo!) is that she is almost twice more distant from us than H. neanderthalensis. The most logical conclusion is that, in spite of using Mousterian industry and being neighbor of both Neanderthals and H. sapiens, she belonged probably to a deeper branch of H. erectus.

However everybody seems to be asking for caution... and yet comparing with H. floresiensis.

J. Krause et al., The complete mitochondrial DNA genome of an unknown hominin from southern Siberia. Nature, 2010. Pay per view.

For the archaeological context, it's interesting to read: A.P. Derevianko and S.V. Markin, The Middle and Upper Paleolithic of the Altai. 1997 (PDF).

Other news articles and blog reviews:
- Science News
- BBC
- Anthropology.net
- Dienekes'

Homo erectus in Europe even earlier

Recent research at Herault (SE France) has uncovered bones of our genus that date to c. 1.57 million years ago, pushing the earliest presence of Homo erectus (or maybe H. habilis or H. georgicus...) back several hundred thousand years.

Read more at Stone Pages-Aechaeo News.

African-style quartz tools in Crete from 130,000 BP

From Science News (found via Archaeology in Europe).

Archaeologists have found quartz tools in the Mediterranean island of Crete, dated to c. 130,000 BP, that resemble the type of tools used in Africa c. 800,000 BP (Acheulean I presume). For that reason they speculate, in spite of the late date, that the makers could have been part of the Homo erectus para-species, rather than H. sapiens or H. neanderthalensis, who lived nearby anyhow.

Whatever the species, what this finding makes clear is that ancient members of our genus were able to navigate, as Crete has never been connected to the mainland, since the Mediterranean Sea exists.

However, and very cautiously, I'd consider the possibility that they could be Homo sapiens, who are known to have lived in Palestine and North Africa not much later than this date.

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Update (Aug 19): Julien Riel-Salvatore mentions in his blog that the paper on this matter has finally appeared (LINK, pay per view). Importantly, he quotes:

The dating of the Palaeolithic in the Plakias region presents a considerable challenge, not least because of the long period of time that may have elapsed since the occupation of the earliest sites, during which postdepositional natural processes may have obscured the archaeological record. Additionally complicating the issue are the small number of sites, the lack of excavation, and the impact of modern development on the area, which has destroyed many sites.

Several approaches to dating were attempted, and our research on this topic continues. At Preveli 2, east of the Preveli Gorge, Palaeolithic artifacts are associated with a flight of marine terraces resulting from relatively high sea levels in the Pleistocene that were preserved by subsequent rock uplift. The lowest late Pleistocene marine terraces resulting from high stands of the sea at Preveli (14 ± 1 masl) and Schinaria (21 ± 1 masl) have 2-sigma calibrated radiocarbon ages of 45,400 ± 1,600 and 49,120 ± 2,890 years b.p., respectively, and are correlated with Marine Isotope Stages 3.3 and 3.4, both eustatic high stands. The higher terraces, at 59 and 96 masl, are unquestionably older. How much older? Assuming similar rates of rock uplift (1.4 ± 0.1 m/kyr) determined from the age-elevation relationships of the dated terraces at 14 and 21 masl, it is possible to estimate the approximate ages of the terraces associated with artifacts. This correlation provides an approximate age for the lithic artifacts. The higher terrace, at 96 masl, may belong to Marine Isotope Stage 5, possibly early 5e, ca. 110,000 b.p. Artifacts associated with the terrace at 59 masl could correlate with Marine Isotope Stage 5a, ca. 70,000 b.p. It should be stressed that these are rough approximations and these ages are probably minima that represent a terminus ante quem. If the uplift rate is changed, the terraces and the artifacts associated with them could be much older.

At Preveli 3, Preveli 7, Timeos Stavros 1, and Schinaria 5, Palaeolithic artifacts were found in outcrops of paleosols that exhibit the characteristics of the oldest maturity stage for such features, that is, Maturity Stage 6, or in geological terms, Marine Isotope Stage 6. Together these observations suggest an age of ca. 190,000–130,000 b.p. and serve as a terminus ante quem for the artifacts embedded within them. The stone tools were incorporated in the paleosols as part of a process described by Runnels and van Andel in Epirus: “the top of the Bt horizon itself would move gradually upward as a result of slow deposition, so engulfing any artifacts laid down on former land surfaces above it.” In other words, the Bt horizon, especially as much of the clay comes from eolian sources, will increase in thickness through time, slowly engulfing clasts, such as stone tools, that were formerly in the A horizon.

In sum, the dating of the Palaeolithic sites is based on geological data derived from the study of marine terraces on the southwestern coast of Crete and our identification of paleosols, and these data place the Palaeolithic lithic artifacts firmly in the Pleistocene, ca. 130,000 b.p. or earlier. The chronology can be further refined, however, and a dating program currently in progress may provide data for doing so.

Kenyan tool discovery could push Homo age back to two million years

Just a quick mention of these interesting findings. The tools found by Thomas Plummer's team in Kenya are the oldest Olduwayan style tools found in what used to be a savannah habitat (there are older ones but belong to jungle ecosystem). For this reason the researchers are quite confident that they do belong to members of the genus Homo. The oldest dates considered at the moment were of some 1.8 million years.

Thomas W. Plummer et al., Oldest Evidence of Toolmaking Hominins in a Grassland-Dominated Ecosystem. PLoS ONE, 2009 (free access like all PLoS materials).
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Acheulean spread from Africa to Eurasia

Important paper the one that David Beard mentions at Archaeology in Europe:

Stephen J. Lycett, Understanding Ancient Hominin Dispersals Using Artefactual Data: A Phylogeographic Analysis of Acheulean Handaxes. PLoS ONE, 2009. (Open Access).

Lycett analyzes the structure of Acheulean handaxes of Africa and Eurasia and concludes that there is very strong support (>94% likelihood) for an out-of-Africa scenario.

In all maximum parsimony trees, Eurasian axes appear as derived from African ones, possibly indicating that a migration (H. erectus or H. ergaster, depending on your naming preferences) from Africa to Eurasia happened along that techno-cultural spread.

Acheulean was first developed in Africa, some 1.6 million years ago. The most ancient confirmed date for Eurasian Acheulean is that of 'Ubeidiya (Palestine), dated to c. 1.4 million years ago though often thought of as a penetration without further consquences, followed by European ones (southern Spain, c. 900,000 BP) and more recent ones (c. 780,000 BP) in Palestine and other European areas (c. 600,000 BP). South Asian Acheulean is less well dated but most findings seem to be older than 800,000 BP.

However in Lycett trees, South Asian handaxes' typology appears consistently as older than European one (but more recent than the African types). He does not seem to have analyzed the very old Iberian or Palestinian tools though.
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