Hodell, D.A., Brenner, M. and Curtis, J.H. 2005. Terminal Classic drought in the northern Maya lowlands inferred from multiple sediment cores in Lake Chichancanab (Mexico). Quaternary Science Reviews 24: 1413-1427.
Background
Based on a single sediment core retrieved in 1993 from Lake Chichanacanab in the center of the northern Yucatan Peninsula of Mexico (19°50'-19°57'N, 88°45'-88°46'W), Hodell et al. (1995) provided evidence for a protracted drought during the Terminal Classic Period of Mayan civilization (AD 800-1000). Subsequently, based on two additional sediment cores retrieved from the same location in 2000, Hodell et al. (2001) determined that the massive drought likely occurred in two distinct phases (750-875 and 1000-1075).
What was done
In this most recent study, Hodell et al. (2005) returned to Lake Chichanacanab in March of 2004 and retrieved a number of additional sediment cores in some of the deeper parts in the lake, with multiple cores being taken from its deepest point. Depth profiles of bulk density data were then obtained by means of gamma-ray attenuation, as were profiles of reflected red, green and blue light via a digital color line-scan camera.
What was learned
In the words of the researchers, "the data reveal in great detail the climatic events that comprised the Terminal Classic Drought and coincided with the demise of Classic Maya civilization." In this regard, they report that "the Terminal Classic Drought was not a single, two-century-long megadrought, but rather consisted of a series of dry events separated by intervening periods of relatively moister conditions," and that it "included an early phase (ca 770-870) and late phase (ca 920-1100)." Last of all, they say that "the bipartite drought history inferred from Chichancanab is supported by oxygen isotope records from nearby Punta Laguna," and that "the general pattern is also consistent with findings from the Cariaco Basin off northern Venezuela (Haug et al., 2003), suggesting that the Terminal Classic Drought was a widespread phenomenon and not limited to north-central Yucatan."
What it means
Based on proxy temperature data from several places in North America, it would appear that the Terminal Classic Drought that led to the demise of Mayan civilization likely occurred during the climatic transition between the Dark Ages Cold Period and Medieval Warm Period, when increasing temperatures may have exacerbated land water loss via evaporation in the midst of a prolonged period of significantly reduced precipitation. See also, in this regard, our review of the study of Almeida-Lenero et al. (2005).
Seems a pretty fair summary.
[Update: More lengthy quickie post]
Mammoth news Extinct mammoth DNA decoded
Mammoths became extinct in the last few thousand years
Scientists have pieced together part of the genetic recipe of the extinct woolly mammoth.
The 5,000 DNA letters spell out a large chunk of the genetic code of its mitochondria, the structures in the cell that generate energy.
The research, published in the online edition of Nature, gives an insight into the elephant family tree.
It shows that the mammoth was most closely related to the Asian rather than the African elephant.
Study traces Egyptians’ stone-age roots
Some 64 centuries ago, a prehistoric people of obscure origins farmed an area along Egypt’s Nile River.
Barely out of the Stone Age, they produced simple but well-made pottery, jewelry and stone tools, and carefully buried their dead with ritual objects in apparent preparation for an afterlife. These items often included doll-like female figurines with exaggerated sexual features, thought to possibly symbolize rebirth.
Despite the simplicity of their possessions, a new study suggests these people, the Badarians, may have ultimately given rise to one of the world’s first major civilizations some 14 centuries later: the glittering culture of Egypt.
Indeed, the Egyptians seem to have been basically the same people from the end of the Stone Age through late Roman times, the research found.
Interesting article on the Badarians. We seem to recall other studies showing that there was a lot of continuity between modern and ancient Egyptians. That is, what you see among Egyptians today is probably what you would have seen in the New Kingdom as well.
Hobbits! They're everywhere! Hobbits may be earliest Australians
THE tiny hobbit-like humans of Indonesia may have lived in Australia before they became extinct about 11,000 years ago.
The startling claim comes from archaeologist Mike Morwood, leader of the team that in 2003 uncovered remains of the 1m-tall hominid at Liang Bua cave on Indonesia's Flores island.
They believe the pint-size person - known officially as Homo floresiensis and unofficially as the "Hobbit" - was wiped out by a volcanic eruption that spared their Homo sapiens neighbours.
Speaking at a public lecture in Perth, Professor Morwood from the University of New England in Armidale, NSW, raised the prospect that Hobbits colonised Australia before Aboriginal settlers arrived about 60,000 years go.
Eh, not much info there.