Will The Oil Age Be A Brief Historical Blip?

You don't have to be a die hard Peak Oil purist to agree with the gist of the implications of the graph above, posted at an NPR blog and based on an original presentation slide by Stephen Mayfield.

As noted by Wikipedia on Peak Oil:

Optimistic estimations of peak production forecast the global decline will begin by 2020 or later, and assume major investments in alternatives will occur before a crisis, without requiring major changes in the lifestyle of heavily oil-consuming nations. . . . Pessimistic predictions of future oil production operate on the thesis that either the peak has already occurred, that oil production is on the cusp of the peak, or that it will occur shortly. The International Energy Agency (IEA) says production of conventional crude oil peaked in 2006.

Peak oil production in the United States hit in 1970, but was pretty much irrelevant because oil trades in a world market. The U.S. has been a net oil importer since the early 1990s.

The United States isn't the only country in the world that has hit a localized peak in oil production as the illustration below from Wikipedia illustrates:

Some localized peak oil predictions are right around the corner: Iraq: 2018, Kuwait: 2013, and Saudi Arabia: 2014. In my grandchildren's world, most of the Middle Eastern oil powers will have greatly diminished oil wealth.

Whether peak oil is almost upon us or is, very optimistically (e.g. in the opinion of the most optimistic oil industry experts), a century out, in the big picture, the message is basically the same viewed through a long historical lens (and one could reasonably extend the chart above all the way back to 8,000 BCE when agriculture was begun for an even longer run historical perspective).

Most of the optimistic predictions assume that much of the new high cost oil production will come from "unconventional sources such as heavy crude oil, oil sands, and oil shale" that are made more attractive at higher oil prices. Even the optimists aren't predicting a sustained return to an era of oil prices of less than $40 per barrel (in 2008 dollars), and often half that, seen from roughly 1877 to 1972 and again from about 1986 to 2003. Instead, they predict a continued flow of increasingly expensive oil for a very long time. The current price for barrel of oil is about $100 which translates into gasoline prices of a bit under $4 a gallon at the pump in Colorado.

We learned how to make oil powered machines and oil based materials, we drilled and extracted vast amounts of easily available petroleum, and we very rapidly have burned through much of this non-renewable resource and continue to do so without seriously reducing our consumption of it. This use pattern has lasted about a century, and maybe it can last another, but it isn't sustainable.

For an oil economy to be sustainable, it needs to use biofuels or oil obtained from converting coal to a petroleum-like liquid fuel (such as the fuel produced in the Fischer–Tropsch process used by Germany and Japan during World War II). Rentech, Inc. has a proto-type plant in Commerce City, Colorado that produces about 10 barrels of fuels per day using the process from natural gas, and half a dozen other operations produce liquid fuels from natural gas or biomass using the process as well. There are a few small operations in the U.S., including one in Pennsylvania, that do small scale conversions from "waste coal" but only one Sasol plant in South Africa (which is coal rich, but oil poor) currently makes petroleum-like fuels from a combination of coal and natural gas on a large scale commercial basis using the technique.

You can extract more petroleum from deep wells, oil shale and the like, but this approach inevitably is still going to produce diminishing oil reserve growth and higher extraction costs. These options can bend the peak oil curve forward a little, but once the cost of extraction exceeds the cost of producing biofuels or converting coal or using other alternatives to oil (like fuel cell and battery powered vehicles), the technological capacity to extract more petroleum becomes irrelevant. The bottom line is that they aren't making any more new oil, so sooner or later, we're going to run out if we keep consuming it at a high rate as a core basis of our technological culture. Moreover, there is no more oil anywhere else in the solar system, since no place but Earth has ever had the biomass that broke down to produce petroleum.

The good news is that this imposes a natural limit on the amount of global warming inducing pollutants that combustion of petroleum can produce. And, petroleum consumption is the harder fossil fuel to refrain from using without being forced by resource constraints to do so, because it has fewer good substitutes. Our demand for coal is currently almost exclusively for electricity production, and that has easier substitutes that require innovation only by large, sophisticated electrical utilities, not by average people whose electricity consumption experience is unchanged by the fuel used to produce it.

The bad news is that to the extent that our standard of living is a product of cheap energy from petroleum, the future could bring real hardship as this one time economic boost is no longer available. Economists have attempted to estimate that impact, but given the uncertainties of technological developments and the inseparability of oil from our current economy's functioning, the efforts are speculative at best.

An economy based on cheap oil may be as transient as the brief period in the history of the Americas and of Australia when there was a brief burst of abundance arising from megafauna hunting until those fauna went extinct.

READ MORE - Will The Oil Age Be A Brief Historical Blip?

What Are The Causes of Phonemic Diversity?

Atkinson's Serial Founder Effect Hypothesis

Quentin Atkinson ("Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa", Science 4/15/2011) has made headlines with his bold assertion that "the number of phonemes used in a global sample of 504 languages is also clinal and fits a serial founder–effect model of expansion from an inferred origin in Africa. This result, which is not explained by more recent demographic history, local language diversity, or statistical non-independence within language families, points to parallel mechanisms shaping genetic and linguistic diversity and supports an African origin of modern human languages."

The Underlying Data

He reaches this conclusion by massaging data from three maps prepared by Ian Maddieson from secondary sources in the World Atlas of Language Structure.  The maps clearly show that phonemic diversity isn't random, but don't necessarily support Atkinson's hypothesis either.

The maps show the number of consonants, with bins of

Small 6-14 (91 languages) 
Moderately small 15-18 (121 languages)
Average 19-25 (182 languages)
Moderately large 26-33 (116 languages)
Large 33+ (53 languages),

vowels, with bins of

Small (2-4) (93 languages)
Average (5-6) (288 languages)
Large (7-14) (183 languages),

and tone systems, with bins of

No tones (307 languages)
Simple tone system (132 languages) 
Complex tone system (88 languages),

in 504 languages around the world.

The Problems With Aktinson's Hypothesis

Atkinson's hypothesizes about the time-depth of these relationships and their mechanism aren't very persuasive. 

Regional Trends Are Present

Clearly, each of these features exhibit strong regional trends. 

The Amazon is vowel rich, consonant poor and often has a tone system.  The Caucasian languages are short on vowels, rich in consonants and usually lack of tone system.  Indigenous Australian languages without exception are vowel poor, lack tone, and have few to a moderately large number of consonants.  Papuan languages tend to be tonal and consonant poor.

Many West African and East African and Southeast Asian languages have complex tone systems, large numbers of vowels, and moderately large inventories of consonants.  Many indigenous languages of the Pacific Coast in the Americas are vowel poor, have simple tone systems and and tend to have high numbers of consonants.

Europe, South Asia, and North Asia tend to lack tone, have moderate numbers of consonants, and have moderate to high numbers of vowels.

The Data Are Too Noisy To Represent A Serial Founder Effect

Gleaning a relatively clear serial founder effect from these relationships seems far fetched.  The data sets are simply too noisy for that.  One can see clusters where the phonemic features seem to coincide.  One can fairly infer that regional clusters of similar phonemic features have a common origin.  One can even fairly infer that some common reason may account for the fact that non-adjacent regional clusters are phonemically similar.

The Data Don't Closely Track Language Families

Certainly it is true that the features don't seem to track language families. 

For example, Uralic Saami language is consonant rich, while the nearby Uralic Finnish language is consonant poor.

The only New World languages definitively tied to the Old World are the Na-Dene languages and the Yenesian Ket language.  Central Siberian Ket is vowel rich, consonant poor, and lacks a tone system; Na-Dene languages tend to be vowel poor and consonant rich, and some of the Na-Dene languages have a tone system.  Whatever the total number of phonemes is in these related languages, the case that Na-Dene's phoneme set arose from phoneme loss from its parent language is implausible.  Its phoneme losses and gains seem to have counterbalanced each other.

Some Niger-Congo languages have complex tone systems, other than no tone systems at all.  Some Niger-Congo languages (particularly toward Nigeria) are consonant rich, others (particularly towards Ivory Coast and Liberia) are consonant poor.

Areal Effects Are Inconsistent

Indeed, a linguistic trait that follows strong regional patterns while not closely tracking language family relationships is pretty much the definition of an areal effect in linguistics. 

But the source of these areal effects is obscure and inconstant.

Sometimes, the areal effects cross immense linguistic relationship divides.  The phoneme set of Basque, which is more distant from the other languages of Europe than any other for many hundreds of miles, is quite similar to that of many nearby Indo-European languages.  Yet, the phoneme set of the Caucasian languages is dramatically different from those of any of its neighbors, although languages of the Caucasus mountains do seem to have phoneme set sizes similar to each other in some cases despite not being very closely related linguistically and together they are very different from that of neighboring languages.

The Data Aren't A Close Fit To Pre-Historic Migration Patterns

The regions of phonemic similarity don't obviously track paths of deep pre-historic migration.  For example, if they did, we would expect continuity of phonemic trends from Africa to South Asia to Southeast Asia reflecting a Southern route migration.  Instead, we see similarities between Africa and Southeast Asia that are interrupted in South Asia.

Most Papuan languages have few consonants, but a couple of them which are not particularly closely related to each other, at odds with very nearby members of their respective language Trans-Papuan language genuses, have large inventories of consonants, and no Trans-Papuan languages have an intermediate number of consonants.  One imagines a scenario here in which one group intentionally develops a different phoneme set from their close linguistic neighbors in Papua New Guinea for no reason other than to make their language harder for their neighbors to acquire, thereby cementing group identity.

The Data Don't, and Shouldn't Reflect Deep Time Depth

Nor do they seem to obviously reflect linguistic time depth on the scale of tens of thousands of years.  All languages of the New World should have similar linguistic time depth, but show very distinct intra-American regional clusters in phonemic diversity.  Papua New Guinea and Australia were settled by modern humans at about the same time, but have dramatically different phonemic profiles. 

Semitic Hebrew is consonant poor, while Ethio-Semitic Tigre is moderately consonant rich, despite the fact that the languages diverged from each other within the last four thousand years.  The Semitic Arabic dialects spoken closest Israel, which are some of the closest linguistic relatives of Hebrew, are in between.

Irish and Hindi have large numbers of consonants and average numbers of vowels, while most Indo-European languages have average numbers of consonants and large numbers of vowels.  Yet, Irish and Hindi each probably branched off the related Indo-European languages with more typical Indo-European phoneme sets within the last four thousand years.  The Indo-European Hittite language had a particularly low number of vowels (just four) despite being attested at about the same time that Hindi and Irish diverged from their most closely related, but phonemically distinct Indo-European languages, possibly as a substrate influence from vowel poor non-Indo-European languages in Anatolia.

The number of phonemes in English has changed between Old English and contemporary spoken English, and isn't the same even for all dialects of American English, which started to diverge from British English and from each other only in the last few hundred years.

Overall, the evidence seems to indicate that phoneme change can take place in time frames of several centuries, while language family relationships can be pretty clear for periods of several millennia, at least.

The Overall Patterns Couldn't Have Been Produced By Serial Founder Effects

Serial founder effects are hard pressed to explain why the Amazon is consonant poor and vowel rich, by the North Pacific Coast of North America has languages that are rich in consonants and short in vowels, while both have a mix of simple tone systems and languages without tone systems.  Both groups of languages, presumably, have similar time depth and derive from populations that would have been close in space to each other and genetically similar about 17,000 years ago.

The trends also have an immense amount of noise in them.  The Tibeto-Burman Naxi language of Southwest China, for example, is consonant rich, vowel rich and has a complex tone system, giving it the greatest amount of phonemic diversity possible in the data set.  So does the Yulu language of Sudan (a Nilo-Saharan language), and the Nilo-Saharan Ngiti language of the Congo.   A serial founder effect shouldn't put any languages with maximal phoneme sets so distant from each other.

Simply put, the cline that Atkinson proposes isn't the kind of cline one would associate with a serial founder effect.  It is a vague general trend with tenuous foundations that is inconsistent with a serial founder effect.   Whatever accounts for variation between languages in phonemic diversity, it is not a serial founder effect.

There Are Patterns To Phonemic Diversity

The problem is a fascinating puzzle, but Atkinson seems to be largely barking up the wrong tree to explain it. 

Climate Zone And Phoneme Mix

For example, without going into the matter with any particular preconceptions, one would notice that tropical areas tend to have high levels of tonality and rich vowel sets, while temperate and desert areas have low levels of tonality.  One might explain that by concluding that tropical areas have a rich array of bird sounds that locals have an evolutionary fitness reason to learn (culturally) or have a genetic ability to distinguish (or both), and that a well developed capacity to distinguish sounds of these kinds for non-linguistic purposes makes it more natural for these societies to use these kinds of sounds linguistically among themselves.  Consonant frequency might be a factor that allows a language to have a sufficient number of words by compensating for a lack of ability to make different tones and vowel sounds.

Is this the correct hypothesis?  I surely don't know.  But, it is a better statistical match to the data than Atkinson's hypothesis and is plausible enough to make sense.

Contact and Isolation

Unusually high phoneme inventories might be a marker of high levels of inter-linguistic contact.  The Nilo-Saharans who have the highest phoneme inventories in Africa are situated betwixt Afro-Asiatic and Niger-Congo language speakers and may be borrowing phonemes from the areal influences of both.  The Naxi who have the highest phoneme inventories in Asia are situated between Tibeto-Burmese speakers who have one set of phonemes and Southeast Asian language speakers who have another one.  Likewise, the presence of click consonants in some Bantu languages, presumably because the population previously spoke a Khoisan language before shifting to a Bantu superstrate language, reflects the kind of phoneme gain that can take place from linguistic contact.

Unusually low phoneme inventories might be a market of prolonged population isolation with low population densities in places like Australia.  Phoneme inventories can also occur when language learners in a new superstrate language can't accurately reproduce all of the sounds in the superstrate language.  This may be what happened in the case of Hittite and other Indo-European Anatolian languages.  One also sees it when the Japanese borrow words from languages with more phonemes than its own language has into Japanese.

The number of phonemes in a language is really a matrix of a smaller number of options for sound making. One might, for example, appropriately think of tone systems as multipliers of the number of phonemes in a language, rather than mere additional phonemes. Perhaps the appropriate way to count is to look at the number of combined tone-vowel/consonant sounds in a language (also perhaps modulated by rhythm or otherwise), rather than examining phoneme differences in isolation. Perhaps there is a phoneme set size towards which languages trend when not artificially reduced by small isolated populations (Hawaiian is another famous example phoneme loss in addition to Australia, for possibly similar reasons) and when not artificially increased by phoneme sharing at the boundaries of phoneme regions.

Classes of Phonemes May Be The Most Suitable Level Of Analysis

Consonant and vowel count may be a poor measure in any case.  Many of the outlier cases in consonant number involve an entire classes of consonants or vowels found in one area, but not another, rather than individual phonemes. 

A lack of frictive consonants is a major factor in the low number of consonants found in Australia, Papuan languages, and low consonant languages of the Americas. 

High consonant count African languages are often notable for including labial-velar consonants (found elsewhere only in a small number of Papuan languages), and high vowel count in African languages are often notable for including a distinction between nasalized and non-nasalized vowels (otherwise found mostly in the Americas and sporadically elsewhere). The high consonant count in the Caucasian languages is largely attributable to the pharyngeal consonants used there, in some Afro-Asiatic languages, and in few other places.  Click consonants are also found only in one small, regional subset of Africans.

In contrast, distribution of the "th" sound is sporadic (and a poor fit for a serial founder effect).

Most of the cases of the losses of click sounds, labial-velar consonants, frictive consonants and perhaps even pharyngeal consonants and nasalized vowels, from parent languages that included them, might very well fit a serial founder effect model, since the distribution of these phonemic divergences are consistent with that model, while the distribution of the presence or absence of a "th" sound, linguistic tone systems and some kinds of vowel number variation may not. 

But, at any rate, the analysis probably needs to be conducted on a class of phoneme by class of phoneme basis, rather than on a total consonant set basis to make much sense as a phylogenetic tree.  Clearly, there were at least as many cases of independent phonemic invention in particular regions as there were cases of independent invention of plant and animal domestication complexes, and some kinds of phonemic invention (and linguistic invention generally) seem more prone to independent invention than others.

READ MORE - What Are The Causes of Phonemic Diversity?

The Clan of the Hippo Hunters

A trip to the Denver Zoo this weekend brought to my attention an underused tool for making sense of pre-history, along with population genetics, linguistic family relationships, archaeological evidence, the population genetics of domesticated plants and animals, cultural similarities, and ancient climate evidence. This is ancient wild plant and animal ranges.

Hippos and Rhinos

My attention was particularly focused on the historical range of the hippo and the rhino. In about 1942, both had a range that can be roughly summed up as the Sahel, East Africa, and Southern Africa to the south of the Congo Basin jungle and (at least for the hippo) the Nile River Basin. In the fifty years since then, the range of the rhino has contracted dramatically to scattered islands of wild populations, although the range of the hippo has contracted much less. Pygmy hippos are also found in the Congo basin. All of the non-pygmy hunter-gatherer societies of early Africa would have co-existed with the ancient rhinoceros.

I also found particularly interesting the ancient range of the hippo, which extended beyond Africa to essentially that part of Europe which was part of the Cardium Pottery Neolithic (about 14,000+ years after the mainland hippo went extinct) as well as additional swaths of Greece, Anatolia, Southern Persia, and the Western Coast of India right down to its Southern tip, although apparently, not into Eastern India. European hippos mostly went extinct before the last glacial maximum ca. 20,000 years ago, quite possibly as a result of modern human over hunting. But, dwarf hippos were found in Crete, Cyprus, Malta and Sicily until later dates, with the Cyprus Dwarf Hippopotamus surviving until the end of the Pleistocene or early Holocene (about ten thousand years after mainland European hippos went extinct).

It is customary to visualize early hunter-gatherer populations is mammoth hunters. But, at first, in addition to ancient members of the elephant family, there were also ancient relatives of hippos and rhinos for early hunter-gatherers to hunt. The woolly rhinoceros, for example, survived through about 8,000 B.C.E. in Western Siberia and had a range that reached as far east as Southern England in the Paleolithic. An Elasmotherium, which was an ancient rhinoceros that was the largest land animal to ever live, was dragged into a pair of caves in Southern Siberia approximately 50,000 years ago by some predator, human or otherwise.

It is easy to fall into the trap of thinking of the ancient world as similar to that of the current one and draw conclusions about human pre-history accordingly, but one has to remember that in the Out of Africa era that much of the territory that modern humans would have encountered was teaming with a wide variety of giant wild animals not adapted to human hunting techniques that would have been abundant sources of meat (although the giant predators who could have been a threat to early modern humans were more abundant as well).

For them, megafauna may have been a bit like oil is today, a resource that when used unsustainable would have eased human transition into a new technological era and wider range until exhausted.

Tapirs

The ancient range of the Tapir was also interesting. This pig-like relative of the hippo has New World varieties, found in Latin America, and is also found in Malaysia, probably because it arose prior to split of the Americas from the Old World due to continental drift. Its ancient range includes not only Southeast Asia (including all of the Sunda area that extends into Indonesia) and continues into India in a territory roughly conterminous with the region where Munda languages are spoken. The span is notable because it crosses the boundary between India and Burma has been a major barrier to East to West gene flow, roughly marking the divided between West Eurasian population genetics and East Eurasian population genetics, just as the Munda languages are an example of the Austroasiatic languages crossing this boundary.

The implication is that this apparent stark population genetic divide, rather than being a product of a natural geographic barriers (like the divide between Melanesia and Southeast Asia, the divide between Southern Europe and North Africa, the divide between North Africa and Subsaharan Africa, or the divide between South Asia and Siberia) may be of fairly recent origins, perhaps dating to the marginalization of Munda language populations during the expansion of Dravidian language speaking populations in the last few thousand years. Prior to that time, India might have had a more East Eurasian biased population genetic mix.

READ MORE - The Clan of the Hippo Hunters

Pre-Clovis Strata In New World Definitively Dated

A Texas archaeological dig has cleanly established the existence of a human settlement from around 15,500 to 13,200 years ago. This is about two thousand years earlier than the distinctive Clovis culture strata that is found across North America, and about a thousand years older than the oldest archaeological remains found in South America. This age is consistent with an entry of the earliest hominins to the Americas via the Beringian land bridge (where Alaska and its Aleutian Islands are today) and an expansion beyond Beringia when glacial melt would have opened a passage to the continental interior.

This site is notable because its dating is particularly "clean", because it clearly pre-dates the Clovis sites, and because it is in the interior of North America. It had seemed possible before this find, that earlier pre-Clovis sites fit a pattern that could have arguably been confined to the Pacific Coast of the Americas and their near vicinity, rather than also including the interior of the Americas and Eastern Coasts.

Open Question: Why do the earliest skeletons in the Americas seem to look different from later skeletons in the Americas?

The new find does not have bones, so ancient DNA and physical anthropology describing the people who inhabited the earliest strata of settlements in the Americas is not possible from this site. Some of the oldest skeletons in the Americas are from people who would have looked physically very different from modern Native Americans in all eras starting a few thousand years later, and somewhat similar to the very oldest East Asian skeletons. It isn't clear if the differences between the oldest skeletons and the later ones in physical type are a case of population replacement, human evolution as a result of new conditions, or factors like disease that could produce a few fluke skeletons that have been misinterpreted as seemingly belonging to a different racial type.

It is clear from genetic evidence that the vast majority of Native American genes found today have their origin in a pretty small population that expanded almost everywhere at about the same time when humans first emerged onto the continent from Beringia. The biggest divide in Native American genetics seems to suggest, however, that the genetic mix in the Native American groups that settled the North American interior is somewhat different than the genetic mix in the Native American groups that settled the Pacific Coast. It isn't clear if this was a product of random founder effects, or if there was some degree of population structure in the Beringian source population for the Americas.

It also isn't clear if there were one or more subsequent waves of people who arrived from Asia, perhaps by boat or perhaps in separate waves of migration that were closely spaced in time (the Na-Dene are often seen as a candidate population that could have given rise to the genetic difference between North America and South America), outside of the circumpolar region, that had a minor but detectable impact of Native American population genetics.

Finally, we can't rule out the possibility that the wave of humans arriving in the New World via the Beringian land bridge initially included modern humans from Asia of both an "archaic race" (paleoindians) and a more "modern race" and that the archaic modern humans vanished due to some combination of failure to adapt to the New World, conflict between the two populations that they lost, and admixture to the point where they were diluted into invisibility in modern Native American gene pools.

The plausiblity of a scenario with a "lost race" that inhabited the Americas as the same time as the ancestors of modern Native Americans is enhanced by the fact that we know that at least two other human populations, the Vikings, and a paleo-Eskimo population that arrived after the closing of the Beringian land bridge and then were replaced by the Eskimos, arrived in the Americans only the disappear without leaving a notable genetic trace in contemporary Native American populations.

Open Question: When did human first arrive in America?

The new find does, however, help us to bette calibrate the amount of genetic mutation that is observed in the Americas in indigeneous populations to a time of divergence.

That task is complicated by the fact that we don't know how much time the proto-Native Americans spent as a genetically distinct population in Beringia and Northest Asia before entering into the interior of the Americas. In particular, it isn't entirely clear if the proto-Native American population was drawn from pre-Last Glacial Maximum populations of Northeast Asia, post-Last Glacial Maximum populations of Northeast Asia, or a mix of the two. In one scenario, there was a population that entered Beringia, was trapped their by ice in both directions for many thousands of years, and then expanded out afterwards (Beringia's weather would have been mild for its lattitude due to ocean currents and prevailing winds). In another scenario, the stayover of the proto-Native Americans in Beringia en route to the Americas would have been relatively brief.

But, in all of the scenarios not ruled out by contrary genetic evidence or other evidence, the proto-Native American population would have been in a bottleneck situation in Beringia for some period of time before rapidly expanding out into virgin territory across all parts of North America and South America. So, timing of the "breakout" into the Americas can still be inferred by the amount of genetic diversity in different regions of the Americas, without knowing too much about how long that population was in the Americas. And, in theory, one can look at the amount of genetic differences between all American populations and plausible source populations in Asia, to estimate the age of the most recent common ancestor of the two populations. By subtracting the apparent expansion date of the Native American popluations of about 15,000 years ago, from the apparent age of the most recent common ancestor of the Asia souce populations and the American populations, it ought to be possible to estimate how long a distinct proto-Native American population was genetically isolated either in Berginia itself or in some territory in Northeast Asia.

In practice, this isn't so easy, because the margin of error in dating the oldest human habitation sites discovered (roughly plus or minus 900 years) and the margin of error in estimating divergence times based on genetic evidence (roughly plus or minus a few thousand years) in large in relationship to the probable length of the time that this population was isolated pre-expansion, which is a few hundred years at the low end of theoretical expectation (i.e. about 14,500 years ago) and about seven thousand years at the high end of theoretical expectation (i.e. about 22,000 years ago).

Open Question: Where there pre-land bridge or post-land bridge waves of human migration to the Americas?

When glaciers melted, the land bridge between Asia and the Americas was submerged, effectively isolating the Americas from the rest of the world until the arrival of Columbus in 1492, with a handful of very limited exceptions:
* some circumpolar Eskimo and paleo-Eskimo interchange between North America and Siberia,
* a brief and failed interlude of Viking efforts to colonize a few places on the North Atlantic coast of North America about a thousand years ago, and
* a probable brief episode of contact (but not population exchange) between the Austronesians and the South Americans on the Pacific Coast that brough the kumara (a kind of South American origin yam) and some associated names for it that are used in South American languages, to the Polynesians sometime in the last two thousand years or so.

It isn't clear what lasting cultural impact, if any, this brief episode of Polynesian-South American contact had on the South Americans. There are musical similarites between South American music and the musics of some cultures in Southeast Asia and Melanesia, and this is one time that this musical culture could have arrived, but the music of Polynesian cultures does not share the traits found in both Southeast Asia and Melanesia on one hand, and South America on the other, so music as a cultural impact seems unlikely.

The circumpolar contacts are the only known contracts between the Americas and the rest of the world between the closing of the Beringian land bridge and 1492 CE, that are known to have had a genetic impact on modern Native American populations.

There are a couple of New World sites that claim much older ages (ca. 30,000 years ago), but there is considerable dispute over the methodology used to establish those dates from cinders that may or may not have had human origins and whose dating may or may not be reliable. If there were populations in the Americas that old, one also has to explain why modern humans expanding into the virgin territories of the Americas did not show the signs found in all other cases where that happened: megafauna extinction, widespread population expansion leaving archaeological traces, etc., yet did leave isolated traces at very far flung sites. And, one also has to presume a level of sea faring expertise greater than was known to be available in any candidate populations around that time. And, one has to explain the lack of the distinct population genetic signatures you would expect from that population.

Obviously, new discoveries can only push earliest Native American populations further back in time, but the knowledge we have of ancient climate and the timing of megafauna extinctions widely believed to be related to the arrival of humans in the Americas strongly disfavors a scenario in which humans arrived very much earlier. Even the sites with archaic modern human physical anthropology are quite close in time (within a few thousand years) of the sites with modern human physical anthropology quite simmilar to modern populations.

READ MORE - Pre-Clovis Strata In New World Definitively Dated

An Ancient Megadrought

Between the Last Glacial Maximum (the peak of the most recent full fledged ice age), and the Neolithic Revolution (the domestication of plants and animals), there were the worst droughts of the last 50,000 years in the regions that were home to most of the modern human population. The timing suggests that these droughts may have set in place key events from pre-history that followed including proto-farming of non-domesticated plants and the settlement of the Americas.

[O]ne of the most widespread and intense droughts of the last 50,000 years or more struck Africa and Southern Asia 17,000 to 16,000 years ago.

Between 18,000 and 15,000 years ago, large amounts of ice and meltwater entered the North Atlantic Ocean, causing regional cooling but also major drought in the tropics,
"The height of this time period coincided with one of the most extreme megadroughts of the last 50,000 years in the Afro-Asian monsoon region with potentially serious consequences for the Paleolithic humans that lived there at the time[.]" The "H1 megadrought," as it's known, was one of the most severe climate trials ever faced by anatomically modern humans.

Africa's Lake Victoria, now the world's largest tropical lake, dried out, as did Lake Tana in Ethiopia, and Lake Van in Turkey. The Nile, Congo and other major rivers shriveled, and Asian summer monsoons weakened or failed from China to the Mediterranean, meaning the monsoon season carried little or no rainwater.

What caused the megadrought remains a mystery, but its timing suggests a link to Heinrich Event 1 (or "H1"), a massive surge of icebergs and meltwater into the North Atlantic at the close of the last ice age.

Previous studies had implicated southward drift of the tropical rain belt as a localized cause, but the broad geographic coverage in this study paints a more nuanced picture. "If southward drift were the only cause," says Stager, lead author of the Science paper, "we'd have found evidence of wetting farther south. But the megadrought hit equatorial and southeastern Africa as well, so the rain belt didn't just move--it also weakened."

From here.

READ MORE - An Ancient Megadrought

Friday Links of Interest

* Colorado's incarceration rate for women (93 per 100,000 population) is the third highest in the United States after Oklahoma (134 per 100,000), and Texas (98 per 100,000). The national average is 69 per 100,000. "In 2004, [Oklahoma] imprisoned more than 10 times as many women per capita as Massachusetts or Rhode Island."

* Microsoft's customer support website chronicles the ire of people who have had Bing hijack their systems.

* "[H]ow many offenders sentenced under the old 100-1 crack guidelines (and the amended version applicable from 2007 to 2010) would benefit from retroactive application of the new 18-1 crack guidelines that the passage of the Fair Sentencing Act produced"?

12,835 offenders sentenced between October 1, 1991, and September 30, 2009 (fiscal years 1992 through 2009), would be eligible to receive a reduced sentence if [the new sentencing guideline] were made retroactive. If these offenders were to receive reduced sentences . . . the dates on which they would be released would span more than thirty years....

Based on [additional] assumptions, the average sentence reduction for all impacted offenders with sufficient information to perform this analysis would be 22.7 percent (or 37 months, from 163 months to 126 months). Table 6 shows that 7,612 offenders (76.9%) would receive a sentence reduction of 48 months or less. Conversely, 286 offenders (2.9%) would receive a sentence reduction of more than 10 years.

A more modest adjustment to the crack sentencing guidelines in 2007 was applied retroactively. "The 2007 reduction benefited over 15,000 crack prisoners, though the amount of sentence reduction was only around 2 years of imprisonment."

The federal corrections budget would be reduced by about $1 billion if the sentencing guideline change mandated by the Fair Sentencing Act was made retroactive.

* Mohamad Hammoud was the first man convicted of charges including material support for terrorism after 9/11 (he was the first man charged under a 1996 law that makes it illegal to give money to designated terror groups and was found guilty and sentenced shortly after 9/11). He was sentenced to 155-years in prison "for smuggling cigarettes and sending $3,500 of the profits to Hezbollah." This was reduced this past January by Judge Graham Mullen on the grounds that this was "grossly disproportionate." But, the new sentence for the man who has served about ten years in prison so far is 30 years in prison after the original sentence was reversed on appeal. Thus, "the 37-year-old from Lebanon will spend an additional two decades in prison, then likely be deported." Hammoud plans to appeal the new sentence as well.

His attorneys wanted Hammoud to walk out of the courtroom with a sentence of the more than 10 years he already served. . . They contend he sent the money to a wing of Hezbollah that helps provide Middle Eastern communities with clean water and good housing, not the military wing labeled terrorists by the United States government for numerous attacks on Israel. . . . defense attorneys brought up more than a dozen cases in which people got sentences much shorter than Hammoud, including sentences of only a few decades for defendants that provided actual weapons and hundreds of thousands of dollars to terrorist organizations. "This is a case where people get seven years, eight years," Hammoud's attorney Stanley Cohen said.

From here.

* Twin studies, surprisingly, show a strong hereditary component to adolescent crime victimization:

[G]enetic factors explained a surprisingly significant 40 to 45 percent of the variance in adolescent victimization among the twins, while non-shared environments (those environments that are not the same between siblings) explained the remaining variance. But among adolescents who were victimized repeatedly, the effect of genetic factors accounted for a whopping 64 percent of the variance.

The study's author surmises that "genetically influenced traits such as low self control affect delinquent behavior, and delinquents, particularly violent ones, tend to associate with antisocial peers."

* Low prices of consumer electronics in the U.K. have caused criminals to shift from committing burglaries to muggings where small, high value items like iPods and laptop computers are stolen.

* High IQ people of modest means are considerably less likely to get higher education in Minnesota than in Sweden, while low IQ people from affluent families were more likely to get higher education in Minnesota than in Sweden. Higher education is free in Sweden to students with good grades and test scores, but money is still a barrier to these students in the United States.

Notably, Harvard and several other Ivy League schools have instituted sliding scale tuition arrangements so that they can continue to admit the most qualified applicants regardless of means. For example, Harvard limits tuition to 10% of the first $180,000 of family income and has ceased including student loans in undergraduate financial aid packages.

* Tree ring data from Mexico released last year showed that a "large ancient drought previously confirmed for the Southwest of the United States is shown to have extended into central Mexico (1149-1167 AD)."

[It] also provides the first independent confirmation of the so-called Terminal Classic drought, a megadrought some anthropologists relate to the collapse of the Mayan civilization. This decades-long dry period had been previously determined by analysis of lake and basin sediments in other areas of Mexico and the Caribbean. . . [The data] narrowed the event's timing to 897-922 AD and confirmed that it had a wider geographical impact than previously thought, extending into the highlands of Central Mexico, where other classic period cultures were located.

This parallels recent 2500 years of paleoclimate data from Europe that also shows a strong link between the major upheaval in European civilization in the last couple of thousand years and climate trends.

At times of social stability and prosperity, like the rise of the Roman Empire between 300 B.C.E. and 200 C.E., Europe experienced warm, wet summers ideal for agriculture. Similar conditions accompanied the peak years of medieval Europe between 1000 C.E. and 1200 C.E. . . .

In the 3rd century C.E. . . . extended droughts matched the timing of barbarian invasions and political turmoil. Around 1300 C.E., on the other hand, a cold snap combined with wetter summers coincides with widespread famines and plague that wiped out nearly half of Europe's population by 1347. . . . In eras of prosperity, more trees were cut down for building and fuel, yielding more samples in the archaeological record. At other times, like the years after the Black Death and the so-called Migration Period between 300 C.E. and 600 C.E. when the Roman Empire was overwhelmed by tribes pushing in from the east, the number of wood samples dwindles to nearly nothing.

Krugman and Brad DeLong, meanwhile, have recently noted an interesting article from 1970 on the connection between the institutions of slavery and serfdom in Europe and the Black Death. Climate data may elucidate some of the unanswered questions from that analysis.

READ MORE - Friday Links of Interest

Native American Genetic Clusters

An open access PLOS article directing a computer to cluster Native Americans into seven clusters, further informed by language and geographical information produced the map above.

Previous analyses comparing genetic to linguistic differentiation in the Americas yielded equivocal results. Cavalli-Sforza et al. reported that, prior to the publication of their book, three of seven studies supported congruence between genes and languages. At that time, Ward et al. found that rates of linguistic diversification are faster that rates of genetic differentiation in mtDNA, and concluded that there is little congruence between linguistic and genetic relationships in the Americas. In more recent studies also using mtDNA, the hypothesis that language classifications reflect the genetic structure of Native American populations was also rejected. Lastly, an analysis of autosomal microsatellite markers in 28 Native American populations from the Human Genome Diversity Panel (HGDP) provided a qualitative correspondence between linguistic and genetic groupings. However, tests of correlation were not significant for these data.

In this study, linguistic data did corollate with autosomal genetics, something that the authors attribute to the fact that the latent cluster methodology that they used does not require any particular tree-like model to be generated. The linguistic data input in variants of the models used were as follows: "Model B used Greenberg's classification at the stock level (8 levels), Model C used Greenberg's classification at the group level (14 levels), and Model D used The Ethnologue classification at the family level (16 levels)."

Unsurprisingly, Ethnologue's more details account provided a better match to the genetic clusters. "Among the 16 families of The Ethnologue classification, only the Tupi, Choco and Chibchan families were not associated to a unique genetic cluster." The Choco (Waunana and Embera) and Chibchan (Cabacar, Guayme, Kogi and Arhuaco)correspond to the populations in the brownish-orange colored area that includes most of Central America and the northern coast of South America. The Tupi languages (Guarani, Karbana, Ache and Surui) include the three groups on the map in the general vicinity of Uruguay, and Surui in the vicinity of Bolivia.

Put another way, the yellow (Oto-Manguean Mixtec and Zapotec, Mixe-Zoque Mixe, Mayan Maya and Kaqchikel, Quechuan Inga and Quechua, Amaryan Amarya, Auraucanian Hulliche, Marco-Ge Kaingang, Arawakan Wayuu and Piapoco), green (Na-Dene Chipawyan, and Algic Cree and Ojibwa) and purple (Uto-Aztecan Pima) clusters were cases where every language cluster in the group fit entirely into a single genetic cluster, while the language groups outside those areas did not fit a single genetic cluster. The number of clusters chosen was arbitrary.

Analysis

While the authors don't articulate their conclusions in these terms, the implication of a situation where there are overlapping genetic and linguistic clusters that lack a tree-like structure seems to be that Native American languages may have been part of various Sprachbunds, rather than having a tree-like relationship to each other. This would be consistent with a scenario in which Native Americans speaking a very small number of common languages (perhaps just one or two) disperse rapidly across the Americas, and then remain more or less geographically fixed in place as their languages begin to random drift apart from each other influenced by neighbors.

An alternate interpretation, for the yellow regions at least, each of which were parts of Pre-Columbian Neolithic civilizations (the Incas on the Pacific Coast of South America, and successions of Olmecs, Mayans and Atzecs in the general vicinity of Mexico), is that the two Neolithic populations were fairly close genetically and that their Neolithic expansions created the genetic cluster, but did not extend to the rest of Central America and South America, which was unsuitable for their crops, and hence allowed the greater pre-Neolithic genetic diversity of Latin America to persist. The purple Uto-Aztecan cluster could have a similar source.

Perhaps also, the Central American and South American regions that do not cluster so neatly have a mix of settlers who came from the Andes and went East, and settlers who made their way along the Atlantic coast and forged inland.

In contrast, the green areas in North America may have had only a single wave of initial settlement that was relatively distinct from the Latin American regions; other evidence puts the Eastern and Western branches of Native Americans as the deepest genetic divide in a generally genetically unified population derived from a small founding population.

An earlier post at this blog on the same topic is found here.

READ MORE - Native American Genetic Clusters