Ever since the Holen (2017)
paper, that I covered here I have wondered which species of humans could
possibly have migrated to America during this era. Yes, who were the humans
that left the modified bones, teeth and cobbles at the Cerutti Mastodon (CM)
site? In their Supplementary information, section 9. “Asian origins of early
humans on the west coast of North America” Holen et al. engage in some
discussion on the matter (from their Supplementary Information, Section 9.
Asian origins of early humans on the west coast of North America):
“Hominins in Eurasia during MIS 5 include Homo sapiens, Homo
neanderthalensis, Homo sp. (Denisova), Homo floresiensis and Homo erectus80,
81. These taxa, except Homo floresiensis, could have dispersed into
northeastern Asia as temperatures increased at the end of MIS 6 and during the
Last Interglacial MIS 582. Plausible dispersal routes for hominins
to arrive on the west coast of North America at the end of MIS 6 include a land
route across Beringia prior to 135 ka83 and a coastal water route
along the coasts of Asia, Beringia and North America…
The continuous presence of hominins beginning ~300 ka in southern
Siberia at the end of the Lower Paleolithic, although many of the sites are not
well-dated84, provides a potential source of populations that could
disperse eastward. By adapting to conditions in southern Siberia, hominins
could have extended their range further northeast to cross Beringia during
interglacial intervals. The southern edge of the Beringian land bridge at its
maximum extent is estimated to have been close to 63° N, about 200 km further
north than the Diring Yuriakh site situated at 60° N in Siberia. The best age
estimate for the lower level of the site containing stone tools is based upon
TL dates of 267-366 ka85. However, the geoarchaeological position
and age (especially of the oldest stone artefacts) have been questioned86.
It is noteworthy that fossil remains of a cold-adapted female hominin, possibly
an archaic Homo sapiens, have been discovered in Manchuria, China (40° 34สน N).
Animal teeth at the site were dated to ~ 260 ka by electron-spin resonance and
uranium series dating87. It is not yet known how far north these
cold-adapted hominins dispersed, but they may be responsible for archaeological
sites like Diring Yuriakh and other Early Paleolithic sites in southern
Siberia.
At Denisova Cave (51.4° N) in southcentral Siberia, Homo
neanderthalensis is first evidenced by the appearance of Middle Paleolithic
stone tools in Stratum 22 with bracketing radio thermoluminescence (RTL) ages
of 282 ± 56 and 171 ± 43 ka88. Biostratigraphic and paleomagnetic
data (Blake polarity episode) correlate more recent Denisova Cave Middle
Paleolithic stone tool industries with MIS 586. Thus, there are several
possible hominin candidates (late Homo erectus, Neanderthals or archaic Homo
sapiens) resident in eastern Asia that could have entered North America via
Beringia and dispersed to the west coast of North America at 130 ka. Another
possibility is that the little-known Denisovans, related most closely to
Neanderthals89, and known only from DNA studies at Denisova Cave,
were the first hominins to reach North America.
The authors then examine the
evidence for sea-faring in ancient hominids and the possibility that the Skoglund
(2015) “population Y” were the humans that were in California 130,000 years ago
and conclude:
“The CM site currently is the only locality in North America that
supports such an early hominin dispersal. This speculative discussion poses the
challenge to initiate archaeological research in MIS 5e and MIS 6-age
geological deposits in North America.”
From the whole section, some of
which I have not quoted, the, authors have therefore established:
1. The climate in California
130,000 years ago was wetter and milder in comparison to other eras of the
Pleistocene, by reference to the relevant literature. For example, the wider distribution of
mammals, including mastodon and sloth above the arctic circle and at higher
altitudes in the Rocky Mountains and as witnessed by fossils found at the CM
site such as a capybara (Hydrochoerus) tooth, far north of its usual range.
2. Food was therefore, plentiful
for any incoming human migrants from Beringia to the Panamanian isthmus and
beyond during the timeframe in question (MIS5e).
3. The humans could be
candidates: “Hominins in Eurasia during MIS 5 include Homo sapiens, Homo
neanderthalensis, Homo sp. (Denisova), Homo floresiensis and Homo erectus80,
81. These taxa, except Homo floresiensis, could have dispersed into
northeastern Asia as temperatures increased at the end of MIS 6 and during the
Last Interglacial MIS 5.”
4. Although they discount archaic
modern humans (AMH), given the recent findings of much older, ca. 300,000BP
archaic modern humans from Jebel Irhoud (Richter, et al. 2017) and the
120,000BP Chinese teeth from Fuyan Cave in Daoxian, province (Lui et al. 2015) there
seems at least a possibility that Homo sapiens were the species that came to
America 130,000 years ago.
The candidate species therefore
are:
- Homo erectus
- Homo neanderthalensis
- Homo sp. “Denisovans”
- Archaic Homo sapiens
Here are a few mug shots:
Clockwise from top left:
Homo erectus from Wikipedia
(2017). Original caption reads: Dmanisi skull 3, Fossils skull D2700 and D2735
jaw, two of several found in Dmanisi in the Georgian Caucasus.
Homo neanderthalensis from North
Carolina School of Science and Mathematics (2017). Original caption reads:
Hominid Skull - Homo neanderthalensis La Chapelle-aux-Saints 1 "The Old
Man". Estimated Age: 60,000 years. Location: La Chapelle-aux-Saints,
France
Homo sp. “Denisovans” from
Discover magazine (2016). Original caption reads: A molar that belonged to an
ancient Denisovan. Max Planck Institute for Evolutionary Anthropology
Archaic Homo sapiens from Peter
Brown Palaeoanthropology (2017). Original caption reads: Dali is reasonably
complete and well preserved, with damage restricted to postdepositional crushing
and displacement of the palate and left maxilla. A large section of the right
parietal is missing, as are the maxillary teeth and left zygomatic arch. Wu
(1981, 1989) found that most of the cranial dimensions and morphological
features of Dali were intermediate between Homo erectus and H. sapiens, with
Dali assigned to archaic H. sapiens.
In future posts, I will consider each of the above species
of human and what the possibility/evidence of them reaching the Americas
130,000 years ago is.
References
Discover magazine (2016), retrieved from:
Holen, S. R., et. al. (2017) A 130,000-year-old archaeological
site in southern California, USA Nature 544, 479–483 doi:10.1038/nature22065
Can be accessed here: http://www.nature.com/nature/journal/v544/n7651/full/nature22065.html
And the Supplementary information can be downloaded from
here:
Liu, Wu, et al. "The earliest unequivocally modern
humans in southern China." Nature 526.7575 (2015): 696-699.
North Carolina School of Science and Mathematics (2017),
retrieved from:
Peter Brown Palaeoanthropology (2017). Retrieved from:
Richter, Daniel, et al. "The age of the hominin fossils
from Jebel Irhoud, Morocco, and the origins of the Middle Stone
Age." Nature 546.7657 (2017): 293-296.
Skoglund, P. et al. Genetic evidence for two
founding populations of the Americas. Nature 525, 104-108 (2015).
