Out of North Eurasia

With the onset of the glacial maximum c. 20,000 years ago, and the ponding up of the Ob River, humans circulated less easily from one end of the steppe-tundra belt to the other. This barrier separated ancestral Europeans from ancestral East Asians.

Outside Africa, people seem to have the same amount of Neanderthal admixture, be they Europeans, East Asians, or Papua/New Guineans. How come?

Perhaps the admixture was a one-time event that occurred just as modern humans began to spread out of Africa and into the Middle East. Only there did they encounter an ‘almost-modern’ population that had long bordered and probably intermingled with the Neanderthals to the north. Our ancestors thus received Neanderthal admixture indirectly, via a partially hybridized population. As they spread beyond this transitional zone, they encountered archaic hominins that differed much more from them in appearance and behavior. Admixture accordingly decreased.

The above explanation is parsimonious but still leaves a few loose ends. According to an unpublished study by Sarah Joyce and Jeffrey Long, archaic admixture occurred in two stages: an early one in the Middle East, when modern humans first spread out of Africa, and a later one, when modern humans first spread from Asia to Oceania (Dalton, 2010).

This leads us to an alternate explanation: all of the archaic hominins throughout Eurasia, including the Neanderthals, were related to each other. The second admixture looks Neanderthal because it came from a related archaic population somewhere on the Asia/Oceania boundary.

Did archaic admixture also occur separately in Europe and East Asia? Not if we believe the Joyce and Long study. Moreover, there is growing evidence that ancestral Europeans and ancestral East Asians were one and the same people until 22,500 years ago, long after the Neanderthals had gone extinct (Laval et al., 2010). This might seem surprising. Modern humans were already in Eurasia by 40,000 BP, if not earlier. How could these early Eurasians have stayed together as a single breeding population for the next twenty thousand years?

They didn’t. The modern humans who initially settled the south and east of Asia were later pushed out and/or absorbed. Today, their descendants are limited to a few relic groups: the Veddas of Sri Lanka, the Andaman Islanders, the Semang of the Malayan Peninsula, and the Aetas of the Philippines.

Present-day Europeans and East Asians descend largely from a small nomadic population that once roamed Eurasia’s northern tier—a belt of steppe-tundra that stretched from southwestern France to Beringia during the last ice age. This population then split in two about 20,000 years ago at the glacial maximum: on the one hand, an immense ice sheet spread south and east from Scandinavia; on the other, large glacial lakes formed along the Ob (Rogers, 1986; Crawford et al, 1997). Chronologically, this barrier to east-west gene flow matches the dating by Laval et al. (2010) of the split between ancestral Europeans and ancestral East Asians.

Even before the ice age ended some 10,000 years ago, these two northern groups had been spreading south, initially into the Middle East on the west and into the Americas on the east. Later expansions encompassed not only the rest of Asia but also North Africa and Oceania. Today, a common northern origin is suggested by linguistic similarities. There seems to be a core Eurasiatic macrophylum, principally Indo-European, Uralic, and Altaic, that stretches across the northern tier of Eurasia. To the south are other related language families, principally Afro-Asiatic, Dravidian, and Amerindian, that have nonetheless undergone more change, due to linguistic ‘founder effects’ or to lexical and grammatical borrowing from pre-existing southern languages (Rogers, 1986; Wikipedia – Eurasiatic languages, Nostratic languages).

But how did these northerners replace humans who were not only ‘modern’ like themselves but also native to southern latitudes? After all, the southerners were playing on their own turf. They had been adapting to their own climate and ecosystem for much longer. What happened to the home team advantage?

Some answers are offered by Hoffecker (2002, p. 135). Among early modern humans, tools and weapons were more complex at arctic latitudes than at tropical latitudes. “Technological complexity in colder environments seems to reflect the need for greater foraging efficiency in settings where many resources are available only for limited periods of time.” Arctic humans coped with resource fluctuations and high mobility requirements by planning ahead and by developing untended devices (e.g., traps and snares) and means of food storage.

In addition, these increased cognitive demands fell on both men and women. Paternal and maternal investment were much more equal than in the tropical zone, where women could provide for their families year-round with less male assistance (Kelly, 1995, pp. 268-269; Martin, 1974, pp. 16-18). Indeed, because the arctic zone compelled men to shoulder most of the food provisioning, women were free to enter a new range of tasks: food processing (e.g., butchery and carcass transport); shelter building; garment making; leather working; transport of material goods; etc. (Waguespack, 2005). It was this technological revolution that ultimately led to what we now call ‘civilization’ (Frost, 2008).

Of course, none of this could have been foreseen at the time. Northern Eurasians were simply pre-adapted for what came later. They were especially able to exploit the shift to agriculture and the ensuing need for seasonal planting, harvesting, and food storage, as well as more complex forms of social organization. This was their competitive edge over humans farther south.

References

Cavalli-Sforza, L.L., A. Piazza, P. Menozzi, and J. Mountain. (1988). Reconstruction of human evolution: Bringing together genetic, archaeological, and linguistic data, Proceedings of the National Academy of Science USA, 85, 6002-6006.

Crawford, M.H., J.T. Williams, and R. Duggirala. (1997). Genetic structure of the indigenous populations of Siberia. American Journal of Physical Anthropology, 104, 177-192.

Dalton, R. (2010). Neanderthals may have interbred with humans. Genetic data points to ancient liaisons between species. Naturenews, April 20.
http://www.nature.com/news/2010/100420/full/news.2010.194.html

Frost, P. (2008). The path to civilization? Evo and Proud, March 10, 2008.
http://evoandproud.blogspot.com/2008/03/path-to-civilization.html

Green, R.E., J. Krause, A.W. Briggs, T. Maricic, U. Stenzel, M. Kircher, et al. (2010). A draft sequence of the Neandertal genome, Science, 328, 710-722.
http://www.sciencemag.org/cgi/reprint/328/5979/710.pdf

Hoffecker, J.F. (2002). Desolate Landscapes. Ice-Age Settlement in Eastern Europe. New Brunswick: Rutgers University Press.

Kelly, R.L. (1955). The Foraging Spectrum. Diversity in Hunter-Gatherer Lifeways. Washington: Smithsonian Institution Press.

Laval, G., E. Patin, L.B. Barreiro, and L-Quintana-Murci. (2010). Formulating a historical and demographic model of recent human evolution based on resequencing data from noncoding regions, PloS ONE 5(4) : e10284

Martin, M.K. (1974). The Foraging Adaptation — Uniformity or Diversity? Addison‑Wesley Module in Anthropology 56.

Rogers, R.A. (1986). Language, human subspeciation, and Ice Age barriers in Northern Siberia. Canadian Journal of Anthropology, 5, 11‑22.

Waguespack, N.M. (2005). The organization of male and female labor in foraging societies: Implications for early Paleoindian archaeology. American Anthropologist, 107, 666-676.

Wikipedia. (2010). Eurasiatic languages,
http://en.wikipedia.org/wiki/Eurasiatic_languages

Wikipedia. (2010). Nostratic languages,
http://en.wikipedia.org/wiki/Nostratic_languages

Archaic admixture in Africans

Expansion of modern humans out of Africa and within Africa. Mellars (2006).

When we discuss the origins of modern humans, the term ‘Out of Africa’ is a bit misleading. Our common ancestors came not from Africa as a whole but from a relatively small area somewhere in East Africa. Beginning around 80,000 years ago, this area was the scene of several population expansions that culminated in a ‘big bang’ c. 60,000 BP (Watson et al., 1997). This was a sustained expansion that pushed out of Africa and into Europe, Asia, Oceania, and the Americas.

These modern humans spread at the expense of more archaic ‘hominins’: Neanderthals in Europe and West Asia, and other poorly known groups elsewhere. But the latter were not totally replaced, as seen in the 1 to 4% Neanderthal admixture of present-day Europeans, East Asians, and Papuans. This has led some people to quip that only Africans are pure Homo sapiens:

Better yet, and a blow to Caucasian and Asian racists, the comparison of the human and Neanderthal genome makes it clear that it is only Africans who are 100 percent Homo sapiens, while in European (including American and Australian settlers) and Asian populations one can find up to 4 percent DNA stemming from the archaic and often maligned Neanderthal species - a hominid that went extinct more than 20,000 years ago. (Camphausen, 2010)

Well, no. Sub-Saharan Africans actually have more archaic admixture. The difference is that it came not from Neanderthals but from archaic groups within Africa. About 13% of the sub-Saharan gene pool comes from an earlier expansion of pre-modern hominins that occurred c. 111,000 years ago and seems to correspond to the entry of Skhul-Qafzeh hominins into the Middle East (Watson et al., 1997). This higher level of admixture may have come about because archaic Africans were behaviorally and physically closer to modern humans than the Neanderthals were.

Nonetheless, these ‘Paleoafricans’ were clearly archaic. They lacked something that modern humans had. What was this disadvantage that ultimately removed them from the struggle for existence? The answer is much debated, but most authors posit a limited capacity for symbolic thinking and social organization:

[…] the African exodus was predated by a cultural revolution involving new stone blade technologies, skin working tools, ornaments and imported red ochre […] More advanced symbolic systems in language and religious beliefs could have provided a competitive advantage to a group by promoting coordination and cohesion. (Atkinson et al., 2009)

Thus, when we discuss human origins, the real split was not between Africans and non-Africans but rather between two groups of Africans: archaics and moderns. Dienekes (2005) uses the terms ‘Paleoafricans’ and ‘Afrasians’:

It is common to distinguish between Africans and non-Africans, with the former being much more genetically diverse than the latter. But, the real "gap" in human origins seems to be between the really old Africans ("Paleoafricans") and the rest ("Afrasians").

The Paleoafrican element is entirely confined to Africa, while the Afrasian one is found in both Africa and Eurasia. Indeed, modern humans can be entirely split into two groups: (i) a group of "pure" Afrasians which includes all non-Africans, and (ii) a group of Afrasian-Paleoafricans which includes all non-Caucasoid Africans. Human groups of entirely Paleoafrican origin, unhybridized with the younger Afrasians are no longer in existence.

All of this leads to an intriguing conclusion. Since present-day sub-Saharan Africans were used as a benchmark to estimate Neanderthal admixture in present-day Eurasians, and since Paleoafrican gene sequences should be less ‘derived’ and more similar to Neanderthal gene sequences, Neanderthal admixture in present-day Eurasians is probably a bit higher than the estimated 1 to 4%.

References

Atkinson, Q.D., R.D. Gray, and A.J. Drummond. (2009). Bayesian coalescent inference of major human mitochondrial DNA haplogroup expansions in Africa, Proceedings of the Royal Society B, 276, 367–373

Camphausen, R.C. (2010). Evidence for interbreeding with Neanderthals, only Africans pure, Digital Journal, May 10, 2010,
http://www.digitaljournal.com/article/291798

Dienekes. (2005). The mitochondrial time depth of humanity, Dienekes’ Anthropology Blog, May 14, 2005.
http://dienekes.blogspot.com/2005/05/mitochondrial-time-depth-of-humanity.html

Mellars, P. (2006). Why did modern human populations disperse from Africa ca. 60,000 years ago? A new model, Proceedings of the National Academy of Sciences (USA), 103, 9381-9386.
http://www.pnas.org/content/103/25/9381.abstract

Watson, E., P. Forster, M. Richards, and H-J. Bandelt. (1997). Mitochondrial footprints of human expansions in Africa, American Journal of Human Genetics, 61, 691-704.

The puzzle of Neanderthal admixture

Skhul V – one of the Skhul-Qafzeh hominins. Were they the middleman between Neanderthal genes and the modern human genome?

When I initially published my last post, I pooh-poohed the rumors about the reconstructed Neanderthal genome. How could modern humans have Neanderthal DNA when no such admixture appeared in previous analyses of mtDNA, dentition, and noncoding DNA? Any Neanderthal admixture would have to be less than 1%.

I then logged on to Razib Khan’s site. The news had just broken: modern humans outside Africa are 1 to 4% Neanderthal. I hurriedly rewrote my post and spent the rest of the day eating crow.

In retrospect, I now realize I had put too much faith in the existing data. I had also ignored the warning signs. The HBD community correctly decoded the silence that had fallen over Pääbo’s research team, as well as a remark made by Linda Vigilant.

Despite the crow-phagia, this is good news. It means the end to a long and bitter conflict between proponents of two models of human origins: ‘Out of Africa’ versus multiregionalism. Anthropologists may still disagree, but the room for disagreement has greatly shrunk from what it was only a week ago. We can now move on.

The winning model is a weak version of Out of Africa. Modern humans are largely descended from a series of population expansions that began around 80,000 years ago somewhere in eastern Africa and culminated c. 60,000 BP in a ‘big bang’ that would create 96-99% of the gene pool outside Africa. The remaining 1-4% came from archaic Europeans and Asians, i.e., Neanderthals in Europe and West Asia, and other hominins elsewhere (Almas in Siberia? Hobbits in southeast Asia?). This admixture seems to have occurred in two stages: an early one in the Middle East, when modern humans began spreading out of Africa, and a later one, when modern humans began to spread from Asia to Oceania (Dalton, 2010). Curiously, the admixture looks Neanderthal in both cases.

Did this admixture contribute anything useful? We still don’t know. Some academics had identified the new variant of the microcephalin gene as being probably of Neanderthal origin, but this variant is absent from the reconstructed Neanderthal genome. To date, Pääbo’s team is of the opinion that “the Neanderthal DNA does not seem to have played a great role in human evolution” (Wade, 2010).

Surprisingly, the same level of Neanderthal admixture was found in a French subject, a Chinese subject, and a Papuan subject. This seems to suggest that Neanderthal admixture happened when modern humans began spreading out of Africa, probably in southwest Asia. But why was there no further admixture in Europe, where the two populations co-existed much longer? If there had been, we would see more Neanderthal admixture in present-day Europeans, but we don’t.

There are several possible explanations:

1. Noise in the data obscures the higher level of Neanderthal admixture in present-day Europeans. The picture should become clearer once we have sequenced 100% of the Neanderthal genome, and not the current 60% (Richard Green in an interview on CBC).

2. Early modern Europeans were replaced by Middle Eastern immigrants when farming replaced hunting and gathering (Green et al., 2010).

3. In Europe, early modern humans greatly outnumbered the Neanderthals. Subsequent admixture thus had little effect (Green et al., 2010).

4. In East Asia and Oceania, ‘Neanderthal admixture’ is actually a proxy for something else. These regions had non-Neanderthal archaic populations that were probably more closely related to the Neanderthals than to modern humans. If so, ‘Neanderthal admixture’ in these regions may correspond, more or less, to admixture with other archaic humans (my idea).

5. Neanderthal genes entered modern Eurasian populations indirectly, via an intermediate Middle Eastern population that already had Neanderthal admixture (because of prolonged contact) while being fairly close to modern humans in appearance and behavior. Modern humans may thus have more readily intermixed with them but not with Neanderthals in Europe. The latter were so different in appearance and behavior that admixture would have been minimal (my idea).

I’m inclined toward the last two explanations. Explanation #4 would explain why the later admixture in Asia/Oceania seems to have been as ‘Neanderthal’ as the early admixture in the Middle East. Unfortunately, to test this explanation, we must first reconstruct the genome of archaic humans from the Asia/Oceania transition zone. This will be difficult, if not impossible, given the accelerated degradation of DNA in the tropics.

Explanation #5 is also tempting. Not long before modern humans began spreading out of Africa, the Middle East was home to a population with both modern human and Neanderthal characteristics, as attested by remains from Skhul and Qafzeh in northern Israel. These hominins first appeared in the Levant some 120,000 years ago, perhaps as part of an earlier out-of-Africa expansion into south Asia. Their technology was Mousterian and Neanderthal-like, but their anatomy was relatively modern with some archaic features (Kidder et al., 1992; Pearson, 1998). These “almost-moderns” existed on the periphery of a range centered on the African continent. Only a bit farther north were the Neanderthals of Europe and West Asia.

When the climate cooled during the Early Pleniglacial (70,000-55,000 BP), the southern limit of the Neanderthal range shifted accordingly. Neanderthals then occupied the Levant until the arrival of modern humans some 50,000 years ago (Grun & Stringer, 1991; Schwarcz et al., 1989; Valladas et al., 1987).

What happened to the Skhul-Qafzeh hominins? They probably moved farther south, perhaps to the Hejaz. Such a location would have been athwart the main line of expansion of modern humans as they spread out of Africa. Unfortunately, despite many interesting sites, there has been no dating so far of early human occupation in Saudi Arabia (Petraglia & Alsharekh, 2003).

References

Dalton, R. (2010). Neanderthals may have interbred with humans. Genetic data points to ancient liaisons between species. Naturenews, April 20.
http://www.nature.com/news/2010/100420/full/news.2010.194.html

Green, R.E., J. Krause, A.W. Briggs, T. Maricic, U. Stenzel, M. Kircher, et al. (2010). A draft sequence of the Neandertal genome, Science, 328, 710-722.
http://www.sciencemag.org/cgi/reprint/328/5979/710.pdf

Grun, R., and C.B. Stringer. (1991). Electron spin resonance dating and the evolution of modern humans, Archaeometry, 33, 153-199.

Kidder, J.H., R.L. Jantz, and F.H. Smith. (1992). Defining modern humans: A multivariate approach, in G. Bräuer and F.H. Smith (eds.) Continuity or Replacement. Controversies in Homo Sapiens Evolution, pp. 157-177, Rotterdam: A.A. Balkema.

Pearson, O.M. (1998). Postcranial Morphology and the Origin of Modern Humans, Ph.D. dissertation, State University of New York at Stony Brook, Ann Arbor: University Microfilms International.

Petraglia, M.D. and A. Alsharekh. (2003). The middle palaeolithic of Arabia: implications for modern human origins, behaviour and dispersals, Antiquity Journal, 77, 671–684.
http://repository.ksu.edu.sa/jspui/handle/123456789/5520

Schwarcz, H.P., B. Blackwell, P. Goldberg, and A.E. Marks. (1979). Uranium series dating of travertine from archaeological sites, Nahal Zin, Israel, Nature, 277, 558-560.

Valladas, H., J.L. Joron, G. Valladas, B. Arensburg, O. Bar-Yosef, A. Belfer-Cohen, P. Goldberg, H. Laville, L. Meignen, Y. Rak, E. Tchernov, A.M. Tillier, and B. Vandermeersch. (1987). Thermoluminescence dates for the Neanderthal burial site at Kebara in Israel, Nature, 330, 159-160.

Wade, N. (2010). Signs of Neanderthals mating with humans, New York Times, May 7, 2010.http://www.nytimes.com/2010/05/07/science/07neanderthal.html (read)

Ask the rhino

Linda Vigilant – Was she in on the Big Secret? Was the rhino?

The HBD blogosphere has been rife with speculation about the reconstruction of the Neanderthal genome. John Hawks, Razib Khan, and Steve Sailer felt that something big was in the offing. Above all, this something would resurrect the multiregional model of human origins.

Much of the stir centered on a recent study by Sarah Joyce that showed a higher-than-expected amount of variability in the microsatellite DNA of modern humans. Since this DNA is unaffected by natural selection, the unexplained variability must have come from an outside source, i.e., Neanderthals and other archaic humans.

Then there was this comment:

Linda Vigilant, an anthropologist at the Planck Institute, found Joyce's talk a convincing answer to "subtle deviations" noticed in genetic variation in the Pacific region.

"This information is really helpful," says Vigilant. "And it's cool." (Dalton, 2010)

Linda Vigilant works at the Planck Institute, where a team headed by Svante Pääbo is reconstructing the Neanderthal genome. Perhaps she was privy to something big that Pääbo had discovered but was waiting to disclose.

Now the hand-wringing is over. This morning, it's been revealed that modern Europeans and Asians are 1-4% Neanderthal. Does this mean the multiregional model has been vindicated?

First, let’s be clear about what we mean by the multiregional model. Originally, it meant that Homo sapiens evolved out of earlier, more archaic humans at different times and at different places. Modern Europeans are thus primarily descended from Neanderthals, East Asians from Peking Man, and so on.

That version is now dead as a dodo. No one accepts it anymore. If we look at mtDNA or dental traits, the Neanderthals are no closer to modern Europeans than they are to modern Africans or modern East Asians (Krings et al., 1999; Ovchinnikov et al., 2000; Tyrrell & Chamberlain, 1998). In addition Joyce’s findings were not corroborated by Laval et al. (2010), who failed to find evidence of admixture in the noncoding DNA of modern Europeans and modern East Asians. The latest findings have backtracked a bit on this consensus, but not a lot.

So the current multiregional model is a weak version of the original. The idea now is that sporadic admixture brought potentially valuable Neanderthal alleles into our gene pool. Natural selection then caused the alleles to spread and multiply among modern humans. There could thus have been considerable Neanderthal introgression into our gene pool at certain loci, despite very low levels of admixture (Hawks & Cochran, 2006; Hawks et al., 2007). Laval et al. (2010) concede this point in their recent study:

However, it is important to emphasize that our inferences are based on non-coding neutral regions of the genome and that adaptive introgression from archaic to modern humans may have occurred to a greater extent. Indeed, in contrast to neutral alleles, adaptive variants may attain high frequencies by natural selection after minimal genetic introgression. Future studies comparing coding-sequence variation in modern humans and extinct hominids (e.g. Neanderthals) should help to answer this question. (Laval et al., 2010).

What do I think? This ‘minimal multiregionalism’ suffers from two arguments that seem to me weak:

1. Microbes do it. Why not humans?

Different strains of bacteria regularly swap genes, thus allowing new and better variants to leapfrog from one strain to another. Such ‘lateral gene transfer’ is a powerful engine of evolutionary change because it spares different species the trouble of having to reinvent the wheel.

But what works in simple organisms or for simple traits does not necessarily work elsewhere. Yes, if the gene works more or less independently, you can plug it into another genome and get the same result, like the pigment gene that aphids have somehow taken from fungi. But this kind of ‘plug and play’ is harder to pull off with complex traits in complex organisms, like humans. A particular gene might work like fresh sliced bread in one species … and like burnt toast in another.

But perhaps some adaptive solutions are still essentially the same in different complex organisms, like Neanderthals and modern humans. This point is made by Greg Cochran:

Selection often stalls out (in the medium term) because genetic variety has been exhausted, but an injection of archaic genes would have facilitated adaptive change. Moreover, some of those archaic alleles must have been useful ( i.e. had a fitness edge), since archaic humans in Eurasia had had a long time to adapt to their non-African ecology. (Khan, 2010)

Cochran and Hawks seem to be particularly interested in alleles relating to brain function, like the microcephalin allele that they had earlier attributed to gene transfer (Hawks & Cochran, 2006; Hawks et al., 2007). The Neanderthal microcephalin gene has since been reconstructed and … it does not have that allele (Hawks, 2009).

Yet Cochran and Hawks remain undeterred. One reason why they don’t see the weaknesses in their hypothesis is their unwillingness to spell it out in detail. Why won’t they? Well, ask the rhino.

As I understand it, their hypothesis is that Eurasian populations are relatively smart because their ancestors received special brain alleles from the Neanderthal gene pool. If I’m right in my understanding, they’re probably wrong in theirs. Modern humans adapted to temperate and arctic Eurasian environments in ways that were unique and unparalleled. Neanderthal brainpower had nothing to do with it. Although the Neanderthals apparently borrowed cultural and technological adaptations from modern humans, there is no evidence of any borrowing in the other direction. In fact, these archaic humans seem to have had very little to offer our ancestors:

Despite the apparent advances over their predecessors, Neanderthal technological complexity falls at the low end of the scale for recent hunter-gatherers. Both in terms of the number of types and component parts of individual implements, the complexity of Neanderthal tools and weapons is significantly lower than that of hunter-gatherers in northern latitudes (and more typical of modern groups in temperate or equatorial regions). Technological complexity in colder environments seems to reflect the need for greater foraging efficiency in settings where many resources are available only for limited periods of time. More specifically, the Neanderthals seem to have lacked untended facilities (e.g., traps and snares) and devices for food storage, which are common technological strategies for coping with resource fluctuations and high mobility requirements among hunter-gatherers in high latitudes. (Hoffecker, 2002, p. 135)

2. If Europeans were part-Neanderthal, they’d have native rights

This is an interesting argument: “If we Europeans are even a little bit Neanderthal, no one could deny our special claim to the European continent. People like Gordon Brown and Ségolène Royal would stop saying we’re no more indigenous than newly arrived immigrants.”

I have two responses. First, modern humans have inhabited Europe for some 35,000 years. If that length of residency doesn’t confer native rights, then no one anywhere has any—certainly not the Amerindians or the Inuit, who have been in the Americas for less than 15,000 years.

Which brings me to my second point. The currently dominant ideology—global capitalism—denies the very notion of native rights. It doesn’t matter whether your people have inhabited their land for 35,000 years or 35 million years. That’s just history, and we’ve come to the End of History. From now on, we’re all just individuals interacting in a global marketplace.

Eventually, this ideology will fall victim to its own contradictions. A market economy can exist with minimal state supervision only in a relatively homogeneous ‘high trust’ society. Liquidate that social environment, and you liquidate the economic environment that comes with it. At ‘best’, you’ll get a kind of totalitarian capitalism where everyone is deemed to be a potential thief or terrorist. At ‘worst’, the system will collapse, as communism did in Eastern Europe.

Of course, we shouldn’t wait passively for globalism to self-destruct. As thinking individuals with foresight, we should actively take part in the process. But such activism must start with an honest understanding of the world we live in. The lies of the current system cannot be fought with counter-lies. Europeans will not become more indigenous to their continent because they are found to have a few Neanderthal alleles here and there. They’re already indigenous, and that’s that.

Well, maybe the rhino can tell us more.

References

Dalton, R. (2010). Neanderthals may have interbred with humans. Genetic data points to ancient liaisons between species. Naturenews, April 20.
http://www.nature.com/news/2010/100420/full/news.2010.194.html

Hawks, J. (2010). Multiregional evolution lives! John Hawks Weblog, April 21, 2010.

http://johnhawks.net/weblog/reviews/evolution/introgression/joyce-dalton-interbreeding-2010.html

Hawks, J. (2009). The Neandertal genome FAQ, February 2009 edition, John Hawks Weblog, February 17, 2009.
http://johnhawks.net/weblog/reviews/neandertals/neandertal_dna/neandertal-genome-faq-2-2009.html

Hawks J., Cochran G., Harpending H.C., Lahn BT. (2007). A genetic legacy from archaic Homo. Trends Genet doi:10.1016/j.tig.2007.10.003

Hawks J., Cochran G. (2006). Dynamics of adaptive introgression from archaic to modern humans. PaleoAnthropology, 2006, 101-115. Open access

Hoffecker, J.F. (2002). Desolate Landscapes. Ice-Age Settlement in Eastern Europe. New Brunswick: Rutgers University Press.

Khan, R. (2010). Neandertal genomics paper coming? Discover magazine, April 27, 2010.
http://blogs.discovermagazine.com/gnxp/2010/04/neandertal-genomics-paper-coming/

Krings, M., Geisert, H., Schmitz, R.W., Krainitzki, H., & Pääbo, S. (1999). DNA sequence of the mitochondrial hypervariable region II from the Neandertal type specimen. Proceedings of the National Academy of Sciences USA, 96, 5581-5585.

Laval, G., E. Patin, L.B. Barreiro, and L-Quintana-Murci. (2010). Formulating a historical and demographic model of recent human evolution based on resequencing data from noncoding regions, PloS ONE 5(4) : e10284

Ovchinnikov, I.V., Götherström, A., Romanova, G.P., Kharitonov, V.M., Lidén, K., & Goodwin, W. (2000). Molecular analysis of Neanderthal DNA from the Northern Caucasus. Nature, 404, 490-493.

Sailer, S. (2010). The Neanderthal within. Steve Sailer’s iSteve Blog, May 2, 2010.
http://isteve.blogspot.com/2010/05/neanderthal-within.html

Tyrrell, A.J. & Chamberlain, A.T. (1998). Non-metric trait evidence for modern human affinities and the distinctiveness of Neanderthals. Journal of Human Evolution, 34, 549-554.

Cheap shots and collateral damage

Ségolène Royal and supporters

A University of New Mexico research team has announced that the human gene pool seems to have admixture from an outside source, most likely from the Neanderthals and other archaic humans. This conclusion was based on analysis of variation in microsatellite DNA from European, Asian, and Oceanic populations. Since microsatellite DNA is thought to be of neutral selective value, any variation must be due to the slow gradual accumulation of new mutations or admixture from outside our gene pool.

The researchers pinpointed two admixture events:

Using projected rates of genetic mutation and data from the fossil record, the researchers suggest that the interbreeding happened about 60,000 years ago in the eastern Mediterranean and, more recently, about 45,000 years ago in eastern Asia. (Dalton, 2010)

This analysis suffers from several problems. For one thing, it is based on rough estimates, i.e., the length of time that modern humans have existed outside Africa and the speed at which new mutations accumulate in microsatellite DNA. There is also the dubious assumption that this DNA is never affected by natural selection.

Nonetheless, this announcement has delighted anthropologists like John Hawks, Greg Cochran, and Alan Templeton who have long argued against the ‘Out of Africa’ model of human origins. As multiregionalists, they used to argue that modern humans evolved out of earlier archaic populations in Africa, Europe, and Asia. Thus, modern Europeans would primarily be descended from Neanderthals, Modern Asians from Peking man, and so on.

Today, the multiregional model is no longer accepted, and its proponents are now backing a compromise. Modern Europeans, for instance, would largely descend from the wave of humans that spread out of Africa 60,000 to 40,000 years ago, but they would still have some admixture from Neanderthals in their gene pool.

Will this debate ever be settled? Yes, and very soon. That’s the good news. In a few months, the reconstruction of the Neanderthal genome will be published. By comparing it with the genome of modern Europeans, we should find out whether any genes flowed from one to the other. Preliminary comparisons have already been done and to date have found … nothing.

Now the bad news. The triumph of the ‘Out of Africa’ model will be heavily politicized. Although I support this model, I feel nothing but shame for the cheap shots that many other adherents have made. A common one has been to cast multiregionalists as ‘racists.’

This name-calling appears in a New York Times article that presents multiregionalists as “inheritors of a culturally infected biology” and its opponents as “supporting our better inclinations.” In an interview, paleontologist Chris Stringer clearly enjoyed being on the side of the angels, while snidely accusing the other side of racism. He recalled an encounter with Carleton Coon in a Harvard washroom where the aged professor referred to one of his critics as ''that . . . Jew Weiner.''

What irks me about this anecdote is not that it is unverifiable (washroom conversations are not published and Coon has long been dead), but simply its irrelevance. Suppose it could be shown that Carleton Coon had regularly sodomized his grad students. Or would microwave live kittens. Or had bad breath. What would that prove or disprove about the multiregional model? Nothing. This is ad hominem at its sleaziest.

In the same interview, Stringer went on to say that our species is so young that differences among humans can only be skin-deep:

Since so little time has passed since they [modern humans] decamped from Africa, dispersing to the far regions of the world -- 100,000 years being a mere paleontological moment -- ''only slight differences, if any, in intellect and innate behavior are likely to have evolved between modern human populations.'' We are ''all Africans under our skin.''

Uh, 100,000 years is not a mere paleontological moment. A population can undergo significant physical and genetic change in as little as eight generations. In fact, many animal species go back only to the last ice age (25,000-10,000 BP). Evolutionary change is due primarily to the intensity of natural selection and only secondarily to the passage of time. Indeed, the faster such change has occurred, the more important it must be, since it is being driven by intense natural selection and not by adaptively neutral processes like genetic drift or founder effects.

I can forgive journalists for not knowing the above. I find it harder to forgive Chris Stringer, who is fully aware of how fast natural selection can operate. There is no point in winning a debate if you inflict a lot of collateral damage in the process.

Clearly, there has been collateral damage. The catch phrase “We are all Africans” has taken on a life of its own, with almost 100,000 Google hits. In the last French election, Ségolène Royal cited the latest findings in paleontology when she proclaimed, “Nous sommes tous des Africains!” This cute expression is even appearing in high school textbooks.

And we’ll probably see it in newspaper headlines when the Neanderthal genome is finally published.

References

Dalton, R. (2010). Neanderthals may have interbred with humans. Genetic data points to ancient liaisons between species. Naturenews, April 20.
http://www.nature.com/news/2010/100420/full/news.2010.194.html

Hawks, J. (2010). Multiregional evolution lives! John Hawks Weblog, April 21
http://johnhawks.net/weblog/reviews/evolution/introgression/joyce-dalton-interbreeding-2010.html

Richards, R.J. (1997). Neanderthals need not apply, New York Times, August 17, 1997.
http://www.nytimes.com/books/97/08/17/reviews/970817.17richart.html

The puzzle of European hair and eye color

I’ve been fascinated by a puzzle of modern human evolution: the diverse palette of hair and eye colors that has developed in some populations (Frost, 2006; Frost 2008). Hair may be black, brown, flaxen, golden, or red, and eyes may be brown, blue, gray, hazel, or green. Both polymorphisms are largely confined to Europeans, especially those from the north and east.

This is an evolutionary puzzle for several reasons:

1. Hair color and eye color diversified through two separate processes that involved several gene loci (principally at MC1R for hair color and at OCA2-HERC2 for eye color).

2. Both processes occurred within the same geographic area.

3. Both processes occurred within a relatively narrow time frame, i.e., after the arrival of modern humans in Europe c. 35,000 years ago. Current estimates place this evolutionary change quite late in time, perhaps during the last ice age (25,000 - 10,000 BP).

For some anthropologists, this palette of hair and eye colors is a side effect of the lighter skin of Europeans. This lighter skin is, in turn, due to relaxation of selection for dark skin at non-tropical latitudes and a resulting accumulation of ‘loss of function’ alleles that affect not only skin color but also hair and eye color.

Yet relaxation of selection could not have produced so many new alleles over so little time. If selection is relaxed at loci for hair and eye color, close to a million years must elapse to produce the hair- and eye-color variability that Europeans now display, including ~ 80,000 years for the current prevalence of red hair alone (Harding et al., 2000; Templeton, 2002). This is much longer than the c. 35,000 years that modern humans have been in Europe. Moreover, the presumed initial cause—the whitening of European skin—seems to have occurred long after the arrival date of 35,000 BP (Norton & Hammer, 2007). As a Science journalist commented: “the implication is that our European ancestors were brown-skinned for tens of thousands of years” (Gibbons, 2007).

The puzzle is not resolved if Europeans turned white because of positive selection for lighter skin, as opposed to relaxation of selection for darker skin. Such a scenario would not have caused hair and eye color to diversify. In fact, most of the new alleles have little or no relationship with skin color. Only red hair and blue eyes are visibly associated with lighter skin.

There must have been positive selection for diversity of hair and eye color in and of itself. And this selection must have been very strong, given the relatively narrow time frame.

I have suggested that the likeliest explanation is sexual selection (Frost, 2006; Frost, 2008). This kind of explanation is consistent with several general facts:

1. Sexual selection typically creates brightly colored traits.

2. Such traits tend to be on or close to the face, because this part of the body attracts the most visual attention.

3. Intense sexual selection can produce color polymorphisms.

But why would sexual selection have been stronger among northern and eastern Europeans than among other human populations? To answer this question, we must understand why sexual selection should have differed in intensity among ancestral modern humans. In general, the differences were latitudinal, i.e., sexual selection differed primarily along a north-south axis.

Latitudinal differences in the ratio of men to women on the mate market

In the tropical zone, a woman could gather or grow enough food for herself and her children with little assistance. Because the cost of providing for a second wife was very low (often negative, i.e., a net gain), a man’s optimal reproductive strategy was to have as many wives as possible. There were thus too many men competing for too few women.

The farther away ancestral humans were from the tropics, the more women needed food (meat) provided by men. This was especially so in winter, when opportunities for food gathering were scarce. The cost of providing for a second wife was thus high, making polygyny impossible for all but the ablest hunters.

Alongside this trend of increasing female dependence on male providers was another north-south trend: male mortality increased farther away from the tropics because of longer hunting distances and the resulting increased risk of death due to accidents, exposure, starvation, etc.

Continental Arctic: optimal conditions for sexual selection of women

These two trends culminated in the continental Arctic. Here, women had few opportunities for food gathering at any time of year. They and their children depended almost wholly on meat that men provided through hunting. Here too, hunting distance was at a maximum. Men hunted wandering herds of herbivores, mainly reindeer, over very long distances. The high rate of male mortality, combined with the low rate of polygyny, limited the number of males available for mating. Result: a corresponding surplus of unmated females and intense sexual selection of women.

Today, this kind of environment is confined to the northern fringes of Eurasia and North America, but during the last ice age (25,000 – 10,000 BP) it lay further south and covered more territory. This was especially so in Europe, where the Scandinavian icecap had pushed the steppe-tundra zone down to the plains stretching from southwestern France through northern Germany and into eastern Europe. These temperate latitudes permitted a high level of bioproductivity and a comparatively large human population—the ancestors of today’s Europeans.

Sexual selection and color traits

When sexual selection is weak, the adaptive equilibrium is dominated by selection for a dull, cryptic appearance that reduces detection by predators. As sexual selection grows stronger, the equilibrium shifts toward a more noticeable appearance that retains the attention of potential mates, typically by means of vivid and/or novel colors.

One outcome may be a polymorphism of brightly colored phenotypes, due to the pressure of selection shifting to scarcer and more novel hues whenever a color variant becomes too common. This frequency dependence has been shown in humans. Thelen (1983) presented male participants with slides showing attractive brunettes and blondes and asked them to choose, for each series, the woman they would most like to marry. One series had equal numbers of brunettes and blondes, a second 1 brunette for every 5 blondes, and a third 1 brunette for every 11 blondes. Result: the rarer the brunettes were in a series, the likelier any one brunette would be chosen.

Among ancestral Europeans, this selection pressure may have caused a proliferation of new hair and eye colors to the detriment of our species norm of black hair and brown eyes. The selection was partly for novel colors. A rare color engages visual attention for a longer time than does a more common color (Brockmole & Boot, 2009). It may be that color rarity stimulates a mental algorithm that scans the visual environment for new or unusual objects.

In addition to color novelty, there also seems to have been selection for color brightness. Hair is carrot-red but not burgundy red. Eyes are light blue but not navy blue. Maan and Cummings (2009) argue that brighter colors have a stronger impact because they deliver a stronger signal that is more readily learned and retained in memory.

In a mate market already saturated with high-quality females, these eye-catching characteristics—color novelty and color brightness—may have made the difference between success and failure in finding a mate.

Other evidence for unusually strong sexual selection of European women

Hair and eye color polymorphism coincide geographically with other unusual physical traits. There is, for instance, the extreme whitening of the skin, which we do not see in other human populations at similar latitudes and which may have been driven by male targeting of lighter skin as a female-specific characteristic.

There also seems to have been selection to accentuate female-specific traits. Women of European descent have wider hips, narrower waists, and thicker deposition of subcutaneous fat than do women of other geographic origins (Hrdlička, 1898; Meredith & Spurgeon, 1980; Nelson & Nelson, 1986). Even before birth, Euro-American fetuses show significantly more sexual dimorphism than do African-American fetuses (Choi & Trotter, 1970).

In the same vein, Liberton (2009) has found that face shape differentiated between Europeans and sub-Saharan Africans in part through a selective force that has acted primarily on women, and not on both sexes. This too would be consistent with the selection pressure that seems to have diversified European hair and eye color.

References

Brockmole, J.R. & W.R. Boot. (2009). Should I stay or should I go? Attentional disengagement from visually unique and unexpected items at fixation, Journal of Experimental Psychology, 35, 808-815.

Choi, S.C., & Trotter, M. A. (1970). Statistical study of the multivariate structure and race‑sex differences of American White and Negro fetal skeletons. American Journal of Physical Anthropology, 33, 307‑312.

Frost, P. (2008). Sexual selection and human geographic variation, Proceedings of the 2nd Annual Meeting of the NorthEastern Evolutionary Psychology Society, The Journal of Social, Evolutionary & Cultural Psychology, 2 (supp.), 49-65, www.jsecjournal.com/NEEPSfrost.pdf

Frost, P. (2006). European hair and eye color - A case of frequency-dependent sexual selection? Evolution and Human Behavior, 27, 85-103 http://www.sciencedirect.com/science/journal/10905138

Gibbons, A. (2007). American Association Of Physical Anthropologists Meeting: European Skin Turned Pale Only Recently, Gene Suggests. Science 20 April 2007: 316. no. 5823, p. 364 DOI: 10.1126/science.316.5823.364a http://www.sciencemag.org/cgi/content/summary/316/5823/364a

Harding, R.M., Healy, E., Ray, A.J., Ellis, N.S., Flanagan, N., Todd, C., Dixon, C., Sajantila, A., Jackson, I.J., Birch‑Machin, M.A., & Rees, J.L. (2000). Evidence for variable selective pressures at MC1R. American Journal of Human Genetics, 66, 1351‑1361.

Hrdlička, A. (1898). Physical differences between White and Colored children. American Anthropologist, 11, 347‑350.

Liberton, D.K., K.A. Matthes, R. Pereira, T. Frudakis, D.A. Puts, & M.D. Shriver. (2009). Patterns of correlation between genetic ancestry and facial features suggest selection on females is driving differentiation. Poster #326, The American Society of Human Genetics, 59th annual meeting, October 20-24, 2009. Honolulu, Hawaii.

Maan, M.E. & M.E. Cummings. (2009). Sexual dimorphism and directional sexual selection on aposematic signals in a poison frog, Proceedings of the National Academy of Sciences (USA), 106, 19072-10977.

Meredith, H.V., & Spurgeon, J.H. (1980). Somatic comparisons at age 9 years for South Carolina White Girls and girls of other ethnic groups. Human Biology, 52, 401‑411.

Nelson, J.K., & Nelson, K.R. (1986). Skinfold profiles of Black and White boys and girls ages 11‑13. Human Biology, 58, 379‑390.

Norton, H.L. & Hammer, M.F. (2007). Sequence variation in the pigmentation candidate gene SLC24A5 and evidence for independent evolution of light skin in European and East Asian populations. Program of the 77th Annual Meeting of the American Association of Physical Anthropologists, p. 179.

Templeton, A.R. (2002). Out of Africa again and again. Nature, 416, 45-51.

Thelen, T.H. (1983). Minority type human mate preference. Social Biology, 30, 162-180.

Population replacement in Algeria?

'Trans-Saharan' immigrant camp in Algeria

The 21st century will see a surge of emigration from sub-Saharan Africa that will eclipse the one that used to pour out of Europe into the Americas, southern Africa, Siberia, and Australia. Millions upon millions will be claiming new lands for themselves, just like Europeans of another age.

The biggest surprise will be their push into a wide range of territories, and not simply the homelands of the former colonial powers. Remember, this is not a game of ‘tit for tat.’ It is not some kind of just recompense for colonial wrongs, although its enablers will portray it as such. This is a game that predates our notions of justice and even humanity itself. In fact, it is as old as the oldest life forms.

One front of this population expansion will be Algeria, a Mediterranean country immediately north of sub-Saharan Africa. Until recently, it was a country of emigration, not immigration, its population growing almost entirely through natural increase. The last decade, however, has seen its demography become more and more ‘European’. On the one hand, the fertility rate has fallen to 2.27 children per woman—just enough to replace the existing population. On the other, immigration has become a significant source of population growth.

The current influx began in the mid-1990s. Initially, it flowed into the Saharan portion of Algeria from the neighboring states of Niger and Mali. Over the past decade, its sources have broadened to include all of West Africa and even Central and East Africa. This ‘trans-Saharan’ immigration is also spreading to the north of the country, i.e., the Mediterranean coast:

Further north, in Alger, between the migrants in the old Arab city (the Casbah), the old colonial center (the Port-Saïd quarter essentially), and those in the peripheral quarters (Dely Brahim, Chéraga), and even though the migrants keep a very low profile, there are at least 15,000. In Oran, Algeria’s western metropolis, though closer to the border, there are several thousand (between 3,000 and 5,000) whereas for Maghniyya, a town next to northern Morocco, […] the member of the legislative assembly for that town gives a figure of 3,000 migrants in a camp nearby (Oued Jordi) and 4,000 others in the town itself. (Bensaâd, 2009)

This is something new for Algerians:

The phenomenon of clandestine immigration in Algeria is relatively new for a country like our own, which has become, in only a few years, one of the desirable destinations for nationals of sub-Saharan countries, with some of them attempting to settle here. (Algerie-dz.com, 2005)

At first, it was thought that they were simply passing through on their way to Europe. Many were, but many more saw Algeria itself as their new home:

Some might think that these Black African immigrants are just passing through Algeria, while they wait to find a way to enter Europe. But in reality they say they have found what they want in Algeria. As proof, they have moved in with their families. (Algerie-dz.com, 2005)

Last year, the national gendarmerie estimated that 70% of all clandestine immigrants intend to settle in the country permanently (Algerie360.com, 2009).

Efforts are certainly being made to control the influx. Bensaâd (2009, p. 18) reports that 3,000 migrants are being expelled per month at Tin Zouatin, on the Mali border. And Tin Zouatin is just one of three ‘expulsion points.’ Even though Algeria has signed all of the international conventions on refugees, it has never granted anyone refugee status (Bensaâd, 2009, p. 20)

Yet the influx continues and anti-immigration sentiment is rising among Algerians. It is unclear, however, how this sentiment will translate into political action. The current administration is committed, at least superficially, to a paradigm that took shape during the independence struggle of the early 1960s, i.e., international socialism, pan-Africanism, and Third Worldism. There is a political opposition—the Islamists—but they too are committed to a universalist paradigm that could hardly be used to mobilize opposition to immigration. Remember, most of the trans-Saharan immigrants are also Muslims.

Algeria is thus caught in an ideological gridlock that will probably allow the influx to continue, at least for now. Will we eventually see population replacement? Such a scenario might seem unlikely. After all, Algeria’s fertility rate has not fallen below the replacement level and its gendarmerie has shown a degree of seriousness in dealing with clandestine immigration that would put many Western countries to shame.

Against this, it should be pointed out that the fertility rate has already fallen below replacement in neighboring Tunisia (1.84 children per woman), and this decline will likely spread to the rest of North Africa. Meanwhile, immigration cannot help but increase. First, there is the long porous border with sub-Saharan Africa, particularly with those regions that now have the highest rates of natural increase on the continent. Second, production of oil and natural gas will spur economic growth and create employment for immigrant workers. Third, the Algerian leadership is committed to maintaining at least an outward show of pan-African solidarity. This might explain the secrecy that seems to surround most immigration data (Bensaâd, 2009, pp. 17-21). Too much information could inflame public opinion or, as the demographer Ali Bensaâd puts it, force the Algerian authorities to address “a new societal reality for which they have no legal and social answers.”

So, yes, if current trends continue, we will eventually see population replacement. This process will be fueled not only by high levels of African immigration but also by the youthful age structure and high fertility of the immigrant population, which may pass the one-million mark as soon as five years from now. At that point, immigration control will start to break down, with clandestine immigrants simply melting away into the existing community. Algeria too will be entering the “age of interesting times.”

References

Algerie-dz.com (2005). L’Algérie, eldorado de l’immigration clandestine, Sept. 6, 2005
http://www.algerie-dz.com/article3318.html

Algerie360.com (2009). Immigration clandestine : En Algérie, 70% des clandestins se stabilisent, June 2, 2009 http://www.algerie360.com/algerie/immigration-clandestine-en-algerie-70-des-clandestins-se-stabilisent/

Bensaâd, A. (2009). Le Maghreb à l’épreuve des migrations subsahariennes. Immigration sur émigration, Paris : Éditions Karthala.