RSS

Category Archives: ecology

Archaeologists: Dakar rally in Chile is a crime against patrimony

The College of Archaeologist of Chile has risen their voice against the Rally Dakar 2014 (which is not anymore held in Africa after much controversy but in South America) because it impacts and destroys many archaeological sites. 
According to the Chilean archaeological guild the rally is a clear crime under the article 38 of law 17288, which should be persecuted by the Council of Defense of the State (CDE). However this entity “has its hands tied” because the Rally is promoted by the National Sports Institute (IND). 
The Council of National Monuments (CMN) has documented not less than 207 archaeological sites damaged by previous editions of the rally up to 2012 (all rallies since 2009 have gone through Chilean, as well Argentine and sometimes Peruvian lands).
Since 2009 five legal actions have been initiated against this destructive competition, all of which have been dismissed by the courts. 
Source[es]: Diario de Antofagasta (via Paleorama).
Advertisements
 
Leave a comment

Posted by on May 11, 2013 in archaeology, Chile, ecology, Latin America

 

SE Iberian pollution in the Metal Ages

One of the earliest cases of overexploitation and pollution in Europe has been found in SE Iberia, a key center of Early Bronze in Western Europe (Argaric civilization). The sediments of a lake in Sierra Nevada (Andalusia), known as Laguna de Río Seco (pictured), have provided the evidence for important pollution c. 3900 years ago, just when the Bronze Age began in the region. This is attributed mostly not to industry but to increase in fires and deforestation.
However, as we get into the Late Bronze (post-Argaric culture) and Iron age (Iberian culture), the evidence speaks of a type of pollution which can only be attributed to manufacture: lead. This kind of pollution reached a peak c. 2900 years ago (beginnings of Iron Age) and then again in the Roman era (as well as in the Industrial Age).
It is worth mentioning that lead pollution has decreased in the last decades, caused no doubt by the environmental awareness of these times and derived normative, like banning lead from gasoline.
Sources: SINC[es], Paleorama en Red[es].
Ref. A. García Alix et al., Anthropogenic impact and lead pollution throughout the Holocene in Southern Iberia. Science of the Total Environment 2013. Pay per viewLINK [doi:10.1016/j.scitotenv.2013.01.081]

 

Mouth bacteria changed with civilization… for worse

A premise of Primitivism, which is not really a doctrine or philosophy but more like realistic approach to the human condition, is that our evolutionary past is shaped almost totally by hunter-gathering. That we are basically hunter-gatherers in a jump or maybe formal suit. Why? Because some 95% of the biological history of Homo sapiens, as a formed species is one of hunter-gathering, not of productive economy nor civilization. This percentage can be extended to maybe 99.5% if we consider the whole history of the genus homo, etc. And that is a lot. 
Do I digress? Well, maybe not so much after all. The evolutionary news today is in any case that the bacterial ecosystems in our mouths have been degenerating since Neolithic, and then again with Industrialization. As Not exactly rocket science (a National Geographic blog written by Ed Yong) explains the bacteria in our mouth is not all hostile but, at least for hunter-gatherers, often balanced: some bacteria may attack our teeth but then others protect and even repair them. Much like the better known bacteria of our guts, there is a general balance in which, naturally at least, symbiosis with the human needs tends to dominate. After all those bacteria live in our mouths and therefore need it to exist in good shape: they may not be exactly “aware” of their own needs or the benefits of harm they bring to us but evolution fixes it in the long run, of course. 
Epipaleolithic foragers from Poland with a rather thick plaque, plaque that retained in millennial hibernation the bacteria of their mouth, have provided evidence of Prehistoric hunter-gatherers having a healthy, balanced mouth bacterial ecology. 
Instead Medieval English, who were already eating many carbohydrates from cereals, illustrate with their plaque the beginning of mouth bacterial decadence. There are a total of 34 studied remains between these two dates, illustrating that this change happened exactly with the Neolithic Revolution.
The members of the modern research team used their own mouths as reference for the modern bacterial environment. The results were rather depressing: industrialization has created many refined, unbalanced, foods (white cereals and sugar especially) that cause our mouths to be the boon of dentists.
We are what we eat
(source)

A similar kind of bacterial ecology decadence was observed in a previous study between the guts of Burkinabe farmers’ children and those of Italian urban ones. The latter have ecosystems dominated by well-fed firmicutes, associated to obesity.

Reference paper:  Christina J. Adler et al., Sequencing ancient calcified dental plaque shows changes in oral microbiota with dietary shifts of the Neolithic and Industrial revolutions. Nature 2013. Pay per viewLINK [doi:10.1038/ng.2536]

 

Reliability of Greenland ice cores questioned for Younger Dryas only

It seems now that the main proxy to understand Northern Hemisphere glaciation, the Greenland ice cores, is not as straightforward as scientists used to think. At least that is what a new study claims in relation to the Younger Dryas (only):
Zhengyu Liu, Younger Dryas cooling and the Greenland climate response to CO2. PNAS 2012. Pay per view (6-month embargo or depending on world region).


Abstract

Greenland ice-core δ18O-temperature reconstructions suggest a dramatic cooling during the Younger Dryas (YD; 12.9–11.7 ka), with temperatures being as cold as the earlier Oldest Dryas (OD; 18.0–14.6 ka) despite an approximately 50 ppm rise in atmospheric CO2. Such YD cooling implies a muted Greenland climate response to atmospheric CO2, contrary to physical predictions of an enhanced high-latitude response to future increases in CO2. Here we show that North Atlantic sea surface temperature reconstructions as well as transient climate model simulations suggest that the YD over Greenland should be substantially warmer than the OD by approximately 5 °C in response to increased atmospheric CO2. Additional experiments with an isotope-enabled model suggest that the apparent YD temperature reconstruction derived from the ice-core δ18O record is likely an artifact of an altered temperature-δ18O relationship due to changing deglacial atmospheric circulation. Our results thus suggest that Greenland climate was warmer during the YD relative to the OD in response to rising atmospheric CO2, consistent with sea surface temperature reconstructions and physical predictions, and has a sensitivity approximately twice that found in climate models for current climate due to an enhanced albedo feedback during the last deglaciation.

The problem is that, when compared with other records, the Greenland Ice cores’ oxygen isotope ration does not hold. The explanation is complex and related to CO2 levels, the North American Ice Sheet (which was already in retreat) and the different composition of oxygen isotopes when they arrived from the Pacific Ocean.

From the Archaeology News Network:

Working with UW-Madison climatologist Zhengyu Liu, collaborators at the National Center for Atmospheric Research and others, Carlson found their computer climate model breaking down on the Younger Dryas.
While it could reliably recreate temperatures in the Oldest Dryas — a similar cooling period about 18,000 years ago — they just couldn’t find a lever in the model that would simulate a Younger Dryas that matched the Greenland ice cores.
“You can totally turn off ocean circulation, have Arctic sea ice advance all the way across the North Atlantic, and you still will have a warmer climate during the Younger Dryas than the Oldest Dryas because of the carbon dioxide,” Carlson says.
By the time the Younger Dryas rolled around, there was more carbon dioxide in the air — about 50 parts per million more. The warming effects of that much CO2 overwhelmed the rest of the conditions that make the Oldest and Younger Dryas so alike, and demonstrates a heightened sensitivity for Arctic temperatures to rising greenhouse gases in the atmosphere.
The researchers zeroed in on the Northern Hemisphere’s temperature outlier, Greenland ice cores, and found that the conversion of oxygen isotope ratio to temperature typically used on the ice cores did not account for the sort of crash climate change occurring during the Younger Dryas. It assumes prevailing winds and jet streams and storm tracks are providing the moisture for Greenland precipitation from the Atlantic Ocean.

“The Laurentide ice sheet, which covered much of North America down into the northern United States, is getting smaller as the Younger Dryas approaches,” Carlson says. “That’s like taking out a mountain of ice three kilometers high. As that melts, it allows more Pacific Ocean moisture to cross the continent and hit the Greenland ice sheet.” The two oceans have distinctly different ratios of oxygen isotopes, allowing for a different isotope ratio where the water falls as snow.

Hat tip: Pileta.

Some temperature proxies for the Younger Dryas
 

Iberian pine forest is 6000 years old

Pines from Tierra de Pinares (source)
Another curious snippet: the Castilian forest district of Tierra de Pinares (Land of Pine Forests), located at the border of the provinces of Segovia and Valladolid, happens to be at least 6000 years old, questioning the notion that it was a human creation. 
Since time immemorial the villages and towns of the area have lived with an economy largely centered on the exploitation of the resources of the pine tree (wood, resin, pine nut), what led many to suspect it was in fact a human design. However a new study of paleosoils has found that the maritime or resin pine (P. pinaster) has been there in large amounts since at least the Neolithic period, some 6000 years ago. 
The forest is an island of sorts among the wheat and sunflower fields that dominate the Castilian landscape, long ago probably more dedicated to cattle herding however. 

Cuéllar, above the “sea of pines” (green area behind).

Sources[es]: Pileta, SINC.

 
Leave a comment

Posted by on June 27, 2012 in ecology, Iberia, Neolithic

 

Bantu expansion damaged the Central African rainforests

Some 3000 years ago the sediments of the Congo river’s mouth were suddenly altered in an unexpected way: it is the signature of the first forest agriculture, which implied opening patches of the rainforest, allowing weathering of the soil.
The researchers analyzed the cores for elements like hydrogen that leave distinctive signatures in sediment. These geochemical markers correspond with past precipitation levels, which influence weathering. They also examined ratios of aluminum and potassium, which indicate weathering intensity, because potassium is a highly mobile element whereas aluminum is one of the most immobile. As expected, the weathering patterns closely followed precipitation levels—that is, until about 3000 years ago. At that point, Bayon says, the pattern became completely different. The sediment appeared to have undergone intense chemical weathering, which the climate alone could not explain. So the team began suspecting another factor was responsible. 

Hat tip to Stone Pages’ Archaeonews.

 
5 Comments

Posted by on March 3, 2012 in Africa, ecology, Iron Age, Neolithic, Prehistory

 

Ice-free pockets in Ice Age Scandinavia?

Norway spruce
New research suggests that there could have been some ice free pockets in Ice Age Scandinavia, generally believed to have been as completely covered in ice as Greenland is today, and that pine and spruce varieties may have survived in them for tens of thousands of years.

It seems that some modern Scandinavian trees do not have direct southern ancestors but also that there are sedimentary layers with their pollen belonging to the Ice Age. This challenges the generally accepted paradigm that imagined Scandinavia fully covered in snow-ice for much of the last Ice Age. 
For example, the excellent online resource Don’s Maps, shows the following ice cover for the Last Glacial Maximum, c. 20,000 years ago:

Based on Svendsen 2004
Author: Väino Poikalainen, horizontal stripes are lakes

A: The position of the polar timberline in present-day Europe
B: The position of the timberline at the most severe stage of the Würm Ice Age.
C: The limits of glacial debris deposited during the Würm (last) Ice Age.
D: The limits of glacial debris deposited during the Riss and Mindel (earlier) Ice Age.

From: Secrets of the Ice Age by Evan Hadingham, 1980

It seems now that this idea was wrong after all, not just pockets of forest are known to have existed in Central Europe in the LGM but also now it is claimed that even inside Scandinavia itself some forested areas survived all the time:

Two locations in Norway have proved particularly lucrative for the researchers. One of them, Andøya Island, in north-western Norway, is the source of material dated between 17,700 and 22,000 years-old. During the last ice age, the island was an ice-free pocket, one “refuges” on the edge of the enormous ice sheet, which blanketed at that time nearly all of Scandinavia.
“The other evidence, which supports the surviving conifers in the midst of an ice age, originates in Trøndelag, central Norway. One hypothesis is that trees were able to survive on the top of nunataks, the exposed ridges or peaks of mountains protruding from glacial cover, or in more sheltered areas close to the coast where proximity to the temperate conditions of the Atlantic Ocean favoured survival.

Source: Science Daily.