Saturday, August 15, 2015

The past is another country

Male figurine, pottery, c. 7,000–5,000 years ago, Greece, Archaeological Museum of Heraklion, Wikicommons


A very important recent finding is the recovery of the entire genomes of three prehistoric farmers who lived in northern Greece 7500-5500 years BP. The data have been analyzed and are expected to shed light on the ancestral relationships of the first Europeans and provide a wealth of information about functional and morphological characteristics. Already it is known that some of our Neolithic ancestors could not digest milk, i.e., they were intolerant to lactose, and had brown eyes and dark skin. (Anon, 2015)

This is one of several findings with a common theme: the farther back in time we go, the less familiar people look. And we don't have to go very far.

This fact came up in a column I wrote about the Americas. If we turn back the clock, Amerindians look more and more European, yet their genes say they're still Amerindian. We're just getting closer to the time when both groups were the same people. If we turn back the clock even farther, those "proto-Amerindians" give way to a very different sort of human, much like the inhabitants of Papua New Guinea (Frost, 2015).

What happened to those first Americans? They were "replaced." If you're looking for family entertainment, don't study history or prehistory.

Ironically, one of the comments on that column argued that European settlers had stolen this land from the Native Americans and had thus forfeited any moral right to complain about immigration. Well, one genocide doesn’t justify another. I would also venture to say that the universe cares little about our notions of morality. There is only survival or extinction. Everything else is sophistry.

Early and not-so-early Europeans

Ancient DNA is telling a similar story about early Europeans. As late as 8,000 years ago, only the hunting peoples of northern and eastern Europe had white skin and a diverse palette of hair and eye colors. Farther west and south, in Spain, Luxembourg, and Hungary, we find hunter-gatherers with a strange mix of brown skin and eyes of blue, green, or grey. Central Europe was also home to early farmers with white skin, dark hair, and brown eyes. If we go still farther south, beyond the Alps, we see faces and bodies that seem to evoke another continent (Gibbons, 2015; Olalde and Lalueza-Fox, 2015).

This is in line with earlier work on skeletal remains. Angel (1972) found that "one can identify Negroid (Ethiopic or Bushmanoid?) traits of nose and prognathism appearing in Natufian latest hunters [...] and in Anatolian and Macedonian first farmers." In the Middle East, the Natufians (15,000-12,000 BP) were anatomically more similar to present-day West Africans than to present-day Middle Easterners (Brace et al., 2006).

Many African-looking skulls and skeletons have been found in an arc of territory stretching from Brittany, through Switzerland and northern Italy, and into the Balkans. Most are from the Neolithic, but some are as recent as the Bronze Age and the early Iron Age (Boule and Vallois, 1957, pp. 291-292)

Does this mean that prehistoric Greek farmers were more closely related to sub-Saharan Africans than to present-day Greeks? The genome analysis isn't complete, but I think not. They may have looked un-European, but their genomes would probably place them a lot closer to present-day Europeans than to anyone else. We saw the same thing with Kennewick Man. His skull looked European, yet genetically he was closer to Amerindians.

Those prehistoric Greeks were descended from a wave of modern humans that entered Europe some 40,000 years ago. In the north and east, the new settlers encountered selection pressures that recolored and reshaped their most visible features, making them look very different from their African-like relatives to the south and west. Yet this new look came about through changes to just a tiny subset of the genome.

This is not to argue that "we're all pretty much the same under the skin." One could just as well say that humans and chimps are pretty much the same under the skin. They are, actually, if one looks only at flesh and blood. Nonetheless, a human is not a chimp with a body shave.

A second look at the spread of farming

This portrait of early Europeans is still incomplete, and some findings seem contradictory. For instance, why did those Greek farmers lack the alleles for white skin and lactose tolerance when the same alleles were present in Central European farmers from the same time period? In fact, it now seems that both traits evolved in Europe (Gibbons, 2015). A year ago, almost everyone pointed to those Central Europeans as proof that white skin and lactose tolerance must have come from the Middle East, along with farming itself.

It has become popular to argue that farming spread out of the Middle East and into Central Europe through a process of population replacement. The argument seems logical. Because farming supports a larger population per unit of land area, immigrants from the Middle East should have overwhelmed the native hunter-gatherers of Europe by force of numbers. Apparently, things weren’t so simple. Early European farmers were a mixed bunch, and their relationship to the Middle East looks just as problematic. Farming did spread out of the Middle East, but the extent to which this diffusion was genetic or cultural is far from clear. Even the hard evidence looks soft when given a second look.

For instance, we know that a sharp genetic boundary separates late hunter-gatherers from early farmers in Europe. That's good evidence for population replacement. But when a Danish team used a more complete time series of ancient DNA samples, they found that the genetic boundary actually separated early farmers from somewhat later farmers. Haplogroup U, the supposed genetic signature of Europe's ancient hunter-gatherers, reached its current low level after the Neolithic, according to that time series (Melchior et al., 2010). The genetic boundary must therefore be partly due to something else than population replacement, perhaps new selection pressures.

Another piece of hard evidence is the cultural conservatism of hunter-gatherers, who generally prefer to die out than embrace farming and who especially dislike having to plan their lives over a yearly cycle. But that finding is based on tropical hunter-gatherers. Northern hunter-gatherers plan ahead over the coming year and are better able to make the leap. If we take the Mississippian culture of the American Midwest and Southeast (c. 800 -1600), we find that small groups of hunter-gatherers had little trouble making the shift not only to large-scale intensive maize farming but also to life in large towns of up to 40,000 people—all this in half a millennium.

Indeed, if we look at pre-Columbian America, we see that farming first developed in Mesoamerica and then spread north through cultural diffusion. There were very few cases of farmers demographically replacing hunter-gatherers. Why would the situation have been so different in prehistoric Europe? As a general rule, it seems that population replacement occurs only when there is a profound difference in mental makeup that cannot be easily changed.

A final question

Southern Europe and the Middle East were initially home to dark African-like people, who were then replaced by European-like people, apparently from the north, beginning around 12,000 ago. The process of replacement was still incomplete, however, during the time of those northern Greek farmers 7,500 to 5,500 years ago. That last date is very close to the dawn of history. Only a millennium and a half later, the Minoans were building the palace of Knossos. Are those African-like people remembered in European myths, legends, and folk tales?

h/t to Dienekes


Angel, J.L. (1972). Biological relations of Egyptian and eastern Mediterranean populations during Pre-dynastic and Dynastic times, Journal of Human Evolution, 1, 307-313. 

Anon. (2015). The Archeological Museum of Thessaloniki. Report on ancient DNA -Learn what eye color your ancestor had and what he ate in the Neolithic! Iefimerida

Boule, M. & Vallois, H.V. (1957). Fossil Men. New York: Dryden Press. 

Brace, C.L., N. Seguchi, C.B. Quintyn, S.C. Fox, A.R. Nelson, S.K. Manolis, and P. Qifeng. (2006). The questionable contribution of the Neolithic and the Bronze Age to European craniofacial form, Proceedings of the National Academy of Sciences U.S.A., 103, 242-247 

Dienekes. (2015). Prehistoric farmers from northern Greece had lactose intolerance, brown eyes, dark skin, Dienekes' Anthropology Blog, August 7 

Frost, P. (2015). Guess who first came to America? The Unz Review 

Gibbons, A. (2015). How Europeans evolved white skin, Science, Latest News, April 2 

Melchior, L., N. Lynnerup, H.R. Siegismund, T. Kivisild, J. Dissing. (2010). Genetic diversity among ancient Nordic populations, PLoS ONE, 5(7): e11898 

Olalde, I. and C. Lalueza-Fox. (2015). Modern humans' paleogenomics and the new evidences on the European prehistory, Science and Technology of Archaeology Research, 1


Anonymous said...

These findings from Greece may have some bearing on the enigmatic "Basal Eurasian" ancestry that has been inferred as an admixed component in later Neolithic farming populations.

How much has been published so far on the autosomal DNA of these Neolithic Greeks? Unfortunately, we don't yet have genomes of the Natufian farmers either. But it would be significant if both proved to be markedly more "Basal Eurasian" than other, later agriculturalists.

This also brings to mind older anthropological texts that posited a very ancient residue of dark-skinned, curly-haired people in Southern Arabia - not related to recently introduced African slaves, but more like the Dravidian peoples of southern India. As far back as 1870, Thomas Henry Huxley even posited a connection between the Dravidian peoples and the earliest Egyptians.

The "Basal Eurasian" phenomenon might hold the key to deciphering all of these mysteries. Let's hope some genomes from ancient Egypt, Mesopotamia, and the Levant turn up soon.

Beyond anon said...

What was selecting for that phenotype?

Razib speculates that it was a plague ...

Malcolm Smith said...

There is a reference to white skin and a palette of different colours in hair and eyes. Shouldn't that be "fair" skin? That suite of skin, hair, and eye colour is the norm over north and northwest Europe. But there is a vast swathe of territory where black hair and brown eyes goes with olive skin: not only southern Europe, but northern Africa, the Middle East, and all the way to China and Japan. (The latter have a yellowish tinge to their skin due to keratin, but otherwise their complexion is similar to that of much of Europe. We should, of course, compare people with the same level of sun exposure.) Where did the olive skin come from, and how long has it been around? It would appear to me that it is at least partly due to the fact that melanin can safely be lost at high latitudes.

Anonymous said...

"Olive" or light brown skin is generally caused by the presence of the older skin-lightening gene, SLC24A5, in the absence of the more recent variant, SLC45A2. SLC24A5 occurs at 90-100 percent levels throughout the Mideast and North Africa in addition to Europe. But SLC45A2 is more European-specific and more recent, c. 5000-6000 years old.

I'm not sure, but I think by "white," Peter means both fair and olive shades as distinguished from dark brown. This terminology can get a bit problematic because different people conceive of "light" and "dark" skin differently depending on their own background.

But the idea, insofar as I understand it, is that before the Neolithic, West Eurasian populations, in the main, lacked both of the gene variants responsible for depigmentation, and therefore would have possessed skin tones much darker than either present-day Europeans or Middle Easterners (probably more like South Indians). Then the first-wave depigmentation set in with the arrival of West Asian farmers, who would have had an "olive" coloring similar to modern Iraqis. Finally, once these farmers and their mixed descendants became settled in Central and Northern Europe, a second genetic sweep turned their prevailing pigmentation from light brown to pinkish-white (and their hair from darker to lighter brown and blond).

Anonymous said...

"Are those African-like people remembered in European myths, legends, and folk tales?"

Such as in the character of Humbaba of The Epic of Gilgamesh, perhaps?

Humbaba was "the guardian of the Cedar Forest, where the gods lived, by the will of the god Enlil, who "assigned [Humbaba] as a terror to human beings."

Humbaba was killed by Gilgamesh and Enkidu so that they could exploit the timber resources of the Cedar Forest, and some of the references to the event in The Epic of Gilgamesh seem to me to have overtones of genocide: "Humbaba is first mentioned in Tablet II of the Epic of Gilgamesh: after Gilgamesh and Enkidu become friends following their initial fight, they set out on an adventure to the Cedar Forest beyond the seventh mountain range, to slay Humbaba (Huwawa):
Defeated, Humbaba appeals to a receptive Gilgamesh for mercy, but Enkidu convinces Gilgamesh to slay Humbaba. In a last effort, Humbaba tries to escape but is decapitated by Enkidu, or in some versions by both heroes together; his head is put in a leather sack, which is brought to Enlil, the god who set Humbaba as the forest's guardian. Enlil becomes enraged upon learning this and redistributes Humbaba's seven splendors (or in some tablets "auras"). 'He gave Humbaba's first aura to the fields. He gave his second aura to the rivers. He gave his third aura to the reed-beds. He gave his fourth aura to the lions. He gave his fifth aura to the palace (one text has debt slaves). He gave his sixth aura to the forests (one text has the hills). He gave his seventh aura to Nungal."[5] No vengeance was laid upon the heroes, though Enlil says, "He should have eaten the bread that you eat, and should have drunk the water that you drink! He should have been honored."'

The most ancient depictions of Humbaba might be taken to suggest he wore a full-face mask.

Stephen said...

Interesting so I should update those images of white cavemen I have in my imagination, if the European type did not really arise until the bronze and iron age times associated with lactose tolerance and the Indo-European languages.

A pastoral origin of whites is curious as pastorialists often have the resources for multiple wives and plenty of vitamin D in the milk. But in a large polygamous family there would also be competition for parental resources that the cutest children will likely win. Access to milk and animals for carrying children reduces the age at which children can be weened shortening the period between pregnancies speeding up reproduction. So an increase population growth would speed up the cycle of tribal warfare in which prettier women would be more likely to survive, enough tribal warfare and there could be stiff competition for the position of concubine even with polygamy. If this be survival of the prettiest continued through the malthusian medieval economy with first born heirs and those with other resources having the pick of wives, then the further you go back in history the uglier people will be, perhaps famous bauties like Helen of Troy would seem quite plain to us. I remember reading some study about how other the last thousand years European skulls have gotten allot more pedomorphic.

DataExplorer said...

"Are those African-like people remembered in European myths, legends, and folk tales?"

The Sardinians have a carnival where people dress up with black masks, the uglier the better, and distinctive fur coats. They are called "Mamuthones". Look up the pictures on google. I bet this tradition is based on the original inhabitants of the island, or a group of people the original inhabitants encountered before they got to the island.

Peter Frost said...

"How much has been published so far on the autosomal DNA of these Neolithic Greeks?"

Nothing has been published in the scientific literature. All I have are interviews with the researchers and reports in the press (both in Greek).

"This also brings to mind older anthropological texts that posited a very ancient residue of dark-skinned, curly-haired people in Southern Arabia"

They may have been descendants of the "southern route" of modern humans, i.e., the expansion out of Africa through South Asia and into Southeast Asia (and perhaps East Asia and the Americas, but that's another controversy).

"What was selecting for that phenotype?"

It seems to have been a selection pressure that was stronger on women than on men. Women are fairer than men, and in Europe they display a greater natural diversity of hair and eye color. I've argued for sexual selection in several papers, the most recent one being:

Frost, P. (2014). The puzzle of European hair, eye, and skin color, Advances in Anthropology, 4, 78-88.

"But there is a vast swathe of territory where black hair and brown eyes goes with olive skin: not only southern Europe, but northern Africa, the Middle East, and all the way to China and Japan."

I've argued that the pressure of sexual selection on women was generally stronger in non-tropical environments (because of constraints on polygyny and higher male mortality due to longer hunting distances and greater dependence on hunting as a source of food). This selection pressure would have been most intense during the last ice age on the low-latitude steppe-tundra of northern and eastern Europe. This kind of environment was characterized by 1) almost total dependence on hunting as a source of food; 2) very long hunting distances and hence high male mortality; and 3) relatively high bioproductivity and a relative large human population, even during the glacial maximum (because the Atlantic made the climate moister and milder). The steppe-tundra of northern Asia was colder and drier and thus supported a smaller human population. There were consequently fewer mutations that sexual selection could act upon, and when such mutations did arise they could be lost, given the smallness of the population and the greater risk of local groups dying out during times of environmental stress, particularly at the peak of the glacial maximum.

"It would appear to me that it is at least partly due to the fact that melanin can safely be lost at high latitudes."

We see extreme whitening of the skin in northern and eastern Europe but not at the same latitudes among the native populations of Asia and North America.