Posts Tagged ‘Holocene’

The next 100,000 years

June 1, 2013

In my other blog I try to address the life and times of the last 6,000 generations but trying to look forward to the next 6,000 is a fascinating thought experiment.

I was looking at the history of glacials and interglacials and just thinking that it was was terribly “unfair” that while I could imagine the future to my mind’s content, I could never know it. At least for even the distant past, we can look at surviving clues and by the logic that the past must have led to the present we can fill in the gaps and imagine what must have happened. The present constrains the past and helps to keep the imagination within narrow bounds. But for the future, the present  provides a starting point  and natural laws must also constrain any development of an unfolding future. But there are more natural laws we don’t know about than we do. And we haven’t a clue about all that we don’t know that we don’t know.

But I am still free to imagine what the next 100,000 years may bring.

As best we can judge, interglacials (defined as being when temperatures are higher than or equal to those at present)  have lasted upto 28,000 years and some seem to have been as short as 4,000 years. However most seem to last around 13,000 years. This interglacial period will surely end – whether within a 1000 years or in 10,000 – and a new glacial period will ensue.

http://roperld.com/science/sealevelvstemperature.htm

interglacials

But the next glacial will be different for humans and primarily because we have access to “abundant energy” (mainly based on fossil fuels and nuclear energy).

(more…)

Advertisements

We were lowly scavengers long before we became noble hunter-gatherers

May 10, 2013

There has always been an aura of romance about our ancient hunter-gatherer forbears. The term “noble savage” ( “bon sauvage”) only dates back to 1672 but the concept gained ground in the 18th and 19th centuries and the idea of “nature’s gentlemen” flourished in the sentimentality of that time. Jean M Auel’s hugely successful Earths Children series also paints a picture of rather noble hunter-gatherers. Hunters are of course intrinsically heroic and appending “gatherers” to their description does not take too much away. The heroic stature is only dissipated when we become fully settled agriculturists – mere farmers – in the Holocene. Farmer’s don’t conjure up images of nobility and heroism and of course when humans became traders they also get greed and deviousness added to their image.

But there is no perceived nobility or honor in scavenging. It is the image of the hyena versus that of the lion. But long before we became hunter-gatherers we were scroungers and scavengers. New archaeological findings indicates that we were hunter-scavengers some 2 million years ago. And we were scavengers before that and scroungers when we first split from the chimps.

Ferraro JV, Plummer TW, Pobiner BL, Oliver JS, Bishop LC, et al. (2013) Earliest Archaeological Evidence of Persistent Hominin Carnivory. PLoS ONE 8(4): e62174. doi:10.1371/journal.pone.0062174

My imagined time-line for the various phases of human development then becomes:

  • 8 million YBP           Human Chimpanzee divergence – Scroungers
  • 4 million YBP           Bipedalism – Scavengers
  • 2 million YBP           Stone tools – Hunter-scavengers
  • 600,000 YBP          Archaic Human – Neanderthal divergence
  • 200,000 YBP          Hunting teams, herd followers  Hunter-nomads
  • 60,000    YBP          Semi-permanent dwellings, Hunter-gatherers
  • 11,500     YBP          Settled agriculture Farmers
  • 5,000       YBP          Mercantile expansions Merchant-soldiers

Migration from India brought genes, tools and dingoes to Australia 4,200 years ago

January 15, 2013

It is generally assumed that the expansion of AMH from Africa (or Africarabia) reached S-E Asia around 70,000 years ago and Australia some 40,000 – 50,000 years ago. The Australian population then remained virtually isolated until quite recently. But a new genome-wide study suggests that there was migration from India to Australia some 4,200 years ago during the Holocene and that they brought stone-tools and the ancestor of the dingo with them. The study suggests that after the first migrants originally arrived in Sahul, the Australian, New Guinea and Mamanwa populations split from each other some 36,000 years ago. But by – an as yet unknown route – migrants from India arrived in Australia between 4,000 and 5,000 years ago.

Though this coincides with the height of the Indus Valley civilization in 2600 BC, I think it is more likely that any ocean-based, island-hopping migration at this time would have started – at least geographically – from S-E India rather than from the Indus Valley civilization in N-W India. But coastal navigation around the Indian coastline of that time would have been well within the capabilities of the Indus valley inhabitants. This is also the period when proto-Dravidian was the language across most of India (including in the Indus valley civilization) and it would be interesting if there are any traces in language which match this genetic data.

Genome-wide data substantiate Holocene gene flow from India to Australia, by Irina Pugach, Frederick Delfin, Ellen Gunnarsdóttir, Manfred Kayser, and Mark Stoneking, Proceedings of the National Academy of Sciences, 

http://www.pnas.org/content/early/2013/01/09/1211927110

Abstract:The Australian continent holds some of the earliest archaeological evidence for the expansion of modern humans out of Africa, with initial occupation at least 40,000 y ago. It is commonly assumed that Australia remained largely isolated following initial colonization, but the genetic history of Australians has not been explored in detail to address this issue. Here, we analyze large-scale genotyping data from aboriginal Australians, New Guineans, island Southeast Asians and Indians. We find an ancient association between Australia, New Guinea, and the Mamanwa (a Negrito group from the Philippines), with divergence times for these groups estimated at 36,000 y ago, and supporting the view that these populations represent the descendants of an early “southern route” migration out of Africa, whereas other populations in the region arrived later by a separate dispersal. We also detect a signal indicative of substantial gene flow between the Indian populations and Australia well before European contact, contrary to the prevailing view that there was no contact between Australia and the rest of the world. We estimate this gene flow to have occurred during the Holocene, 4,230 y ago. This is also approximately when changes in tool technology, food processing, and the dingo appear in the Australian archaeological record, suggesting that these may be related to the migration from India.

BBC reports:

“For a long time, it has been commonly assumed that following the initial colonization, Australia was largely isolated as there wasn’t much evidence of further contact with the outside world,” explained Prof Mark Stoneking, from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

“It is one of the first dispersals of modern humans – and it did seem a bit of a conundrum that people who got there this early would have been so isolated.”

To study the early origins of Australia’s population, the team compared genetic material from Aboriginal Australians with DNA from people in New Guinea, South East Asia and India.

By looking at specific locations, called genetic markers, within the DNA sequences, the researchers were able to track the genes to see who was most closely related to whom.

They found an ancient genetic association between New Guineans and Australians, which dates to about 35,000 to 45,000 years ago. At that time, Australia and New Guinea were a single land mass, called Sahul, and this tallies with the period when the first humans arrived.

But the researchers also found a substantial amount of gene flow between India and Australia.

Prof Stoneking said: “We have a pretty clear signal from looking at a large number of genetic markers from all across the genome that there was contact between India and Australia somewhere around 4,000 to 5,000 years ago.”

He said the genetic data could not establish the route the Indians would have taken to reach the continent, but it was evidence that Australia was not as cut off as had been assumed.

“Our results show that there were indeed people that made a genetic contribution to Australians from India,” Prof Stoneking explained.

The researchers also looked at fossils and other archaeological discoveries that date to this period.

They said changes in tool technology and new animals could possibly be attributed to the new migrants.

Prof Stoneking said: “We don’t have direct evidence of any connection, but it strongly suggestive that microliths, dingo and the movement of people were all connected.”

New paper – “Warming since 1850 is mainly the result of natural climatic variations”

September 13, 2012

A new paper in Global and Planetary Change byNorwegian researchers has identified persistent cyclic variations in temperature records from Svalbard and Greenland. They find that some of the identified cycles correspond to variations in the Moons’ orbit around Earth and some correspond to solar variations. They find that warming since 1850 is mainly the result of natural climatic variations and conclude that the persistence of cycles makes climate forecasting feasible for limited time ranges.

And if  “warming since 1850 is mainly the result of natural climatic variations” then it just confirms that the theory that anthropogenic carbon dioxide emissions are responsible for global warming remains in the realm of speculation.

Identifying natural contributions to late Holocene climate change

by Ole Humlum, Jan-Erik Solheim and Kjell Stordahl

http://dx.doi.org/10.1016/j.gloplacha.2011.09.005

(more…)


%d bloggers like this: