Finding Harappan ancestors

Everybody from the Indian sub-continent must have some Harappan ancestry; either those who actually lived in the heyday of the Indus-Saraswati Valley Civilisation (3300 – 1300 BC) or those who dispersed through India as that civilisation declined and intermingled with the existing populations. This intermingling over about 1000 years, of Harappans with those already settled from previously blended populations (pre and post-Toba) is probably one of the key gene dispersal mechanisms on the sub-continent.

Excavations are still adding new details but what is quite clear is that while some Harappans may have moved north-east during its decline, most of them were absorbed into India.

Deciphering Harappan scriptThe Indus-Saraswati Valley civilisation reached its peak around 1,900 BCE. It had been flourishing there for over a millennium from about 3300 BCE. But various proto-Harappan cultures had existed in those fertile plains for almost 4,000 years before that (from about 7,000BCE). At their peak they occupied the entire Indus -Saraswati Valley and stretched as far as the Indo-Gangetic plain. At its peak there were some 1,000 settlements and at least 5 “great” cities that we now know of; Mohenjo-Daro, Harappa, Ganweriwala, Rakhigarhi and Dholavira. None of these are truly coastal and it is not improbable that one or perhaps two “great” coastal cities are now submerged and waiting to be discovered. Only about 10% of the known sites have been investigated and the Indus Valley script – which I call Harappan for convenience – has yet to deciphered.

… In my narrative it is the Harappans and their language which provided the nucleus for, and eventually became, the family of Dravidian languages. In fact it is probable that some of the roots of what became Hinduism came also with them. I would even suggest that the specialisation of functions (administrators, priests, traders, craftsmen and labour) that must have existed in the meticulously planned, water-resourceful, trading cities of the Indus-Saraswati Valley led to the foundation of guilds and a stratified society. That probably laid the foundations of the caste system which, in its perverted form, currently disgraces the subcontinent.

Andrew Robinson looks at the state of the decipherment of the Harappan script in Nature.

Nature 526, 499–501 (22 October 2015) doi:10.1038/526499a.

Where the Harappans probably went

Where the Harappans probably went

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80,000-120,000 year old modern humans in S China confirm many and older Out of Africa events

The single Out of Africa hypothesis was clearly grossly oversimplified as I have posted about before. The narrative I still find most likely is that there were multiple Out of Africa events for AMH by two main routes starting from about 130,000 years ago. One to the Northern end of the Arabian peninsula from what is now Egypt and one from the Horn of Africa to the Southern part of the Arabian peninsula. Settlements did establish themselves around the now submerged portion of Arabia and the Persian Gulf.  There was at least one wave, and probably many waves, of modern humans which, prior to the Toba explosion 74,000 years ago, found its way to the western parts of SE Asia (now Burma, Malaysia and perhaps as far as Laos) but id not reach Australia. Much of that wave perished with Toba, but some few survived and mixed with those who came later. Now a new paper shows that there must also have been an early  (c. 80,000+ years ago), expansion along a route from the fertile crescent into Southern China, probably displacing the homo erectus cousins of the Neanderthals who were extant there. (This could even be the “unknown” hominids concurrent with Neanderthals and Denisovans). Possibly they were constrained to move East by the Neanderthals who then occupied central Asia and Europe.

The Great Expansion which started some 60,000 -70,000 years ago eastwards from Africarabia, after the Toba explosion, was then the one which reached Australia about 60,000 years ago. It was this population which also expanded into central Asia in two or more great streams; one Westwards into Europe and one Northwards and Eastwards across the steppes of Russia and across Northern China. The mixed with the pre-modern hominids they came across. I speculate that it was in fact their superior social skills (group size, specialisation of skills, trade behaviour and language) which led to their eventual dominance and the gradual decline and absorption of all the homo species they came across.

Wu Liu et al, The earliest unequivocally modern humans in southern ChinaNature (2015)Published online14 October 2015, doi:10.1038/nature15696

AbstractThe hominin record from southern Asia for the early Late Pleistocene epoch is scarce. Well-dated and well-preserved fossils older than ~45,000 years that can be unequivocally attributed to Homo sapiens are lacking1, 2, 3, 4. Here we present evidence from the newly excavated Fuyan Cave in Daoxian (southern China). This site has provided 47 human teeth dated to more than 80,000 years old, and with an inferred maximum age of 120,000 years. The morphological and metric assessment of this sample supports its unequivocal assignment to H. sapiens. The Daoxian sample is more derived than any other anatomically modern humans, resembling middle-to-late Late Pleistocene specimens and even contemporary humans. Our study shows that fully modern morphologies were present in southern China 30,000–70,000 years earlier than in the Levant and Europe5, 6, 7. Our data fill a chronological and geographical gap that is relevant for understanding when H. sapiens first appeared in southern Asia. The Daoxian teeth also support the hypothesis that during the same period, southern China was inhabited by more derived populations than central and northern China. This evidence is important for the study of dispersal routes of modern humans. Finally, our results are relevant to exploring the reasons for the relatively late entry of H. sapiens into Europe. Some studies have investigated how the competition with H. sapiens may have caused Neanderthals’ extinction (see ref. 8 and references therein). Notably, although fully modern humans were already present in southern China at least as early as ~80,000 years ago, there is no evidence that they entered Europe before ~45,000 years ago. This could indicate that H. neanderthalensis was indeed an additional ecological barrier for modern humans, who could only enter Europe when the demise of Neanderthals had already started.

The 47 human teeth found in Fuyan Cave, Daoxian, China. photo S. XING AND X-J. WU

DiscoveryNews:

The teeth, excavated from Fuyan Cave in Daoxian, southern China, represent the earliest unambiguous evidence for Homo sapiensoutside of Africa.

“They are indeed the earliest Homo sapiens with fully modern morphologies outside of Africa,” lead author Wu Liu of the Chinese Academy of Sciences told Discovery News. “At the Levant (much of the eastern Mediterranean), we also have human remains from the sites of Qafzeh and Skhul (in Israel) with similar ages, but these fossils have been described as retaining some primitive features and, thus, are not fully modern.” …….

…….. Some researchers have even proposed an “Out of Asia” instead of “Out of Africa” migration path for the first Homo sapiens.

While the new findings do not resolve that question, they do reveal that our species was in southern China up to 70,000 years before it was in the eastern Mediterranean and Europe. The newly unearthed remains also offer evidence that China during the Pleistocene Era was likely inhabited by multiple groups of humans: our species and another more primitive lineage(s). Prior fossil discoveries show that the primitive Denisovans, for example, were in northern Asia.

Further complicating the mix is that Neanderthals were also living outside of Africa at the same time. The researchers suspect that the Neanderthals’ presence might have even deterred our species’ migration into Europe, since it took Homo sapiens so long to get there. Intriguingly, Neanderthals went extinct, or perhaps were absorbed into the Homo sapiens population, shortly after our species landed on what was Neanderthal turf. …….

The southern China cave where the teeth were found unfortunately provides no clues on what the culture of Homo sapiens was like there 80,000–120,000 years ago. No prehistoric tools or other telltale artifacts have been found so far at the site……..

The single Out of Africa event for modern humans is clearly far too simplistic. It is also clear that there were many back to Africa movements as well. Humans expanded sometimes because their old habitats were no longer viable. But, it seems, humans also explored and expanded into new territories from regions of plenty and where they maintained some contact with where they had come from. Probably, just because they could.

See also

Chinese teeth support pre- and post-Toba dispersals of modern humans

Multiple Out of Africa events

Related: Out of Africarabia posts

Posted in AMH, Denisovans, Neanderthals, Peopling the world | Tagged , , , , | 1 Comment

Earliest common ancestors could not have been mitochondrial Eve and Y-chromosomal Adam

The Creation myth of course claims that we are all descended from the genes of just two individuals (really one, since Adam’s rib couldn’t possibly have had different genes to the rest of him). And since creation was on 23rd of October, 4004 BC according to Bishop James Ussher, the human race must have come to be as a consequence of a great deal of incest among the descendants of Adam and Eve.

Myths aside, I was wondering – with all the new DNA evidence that is now being produced – how far back in time we need to go to find the earliest common ancestors of all humans alive today?

The Out of Africa, single migration theory postulated that all humans alive (outside of Africa) were descended from just one group – perhaps as small as 200 individuals – who left Africa around 70,000 years ago and then expanded to populate the world. According to this theory our earliest common ancestors were then mitochondrial Eve and Y-chromosomal Adam who lived in Africa between 100,000 and 200,000 years ago (but not concurrently). But this theory of a single “out of Africa event is now being shown to be unsatisfactory on a number of counts.

  1. It is silent about how many were left in Africa and why their evolution continued in such a similar manner to the little, genetically cramped group which left.
  2. it is becoming increasingly evident that though AMH originated in Africa, there were probably many “Out of Africa” events. There were also many earlier “Out of Africa” events of homo erectus which then led to the evolution of Neanderthals in central Asia and points west into Europe, and the Denisovans in central Asia and points south-eastwards. Furthermore, once AMH had appeared in Africa there were groups which left – more than once – before and after the Toba eruption (74,000 years ago).
  3. Populations outside Africa today all show a few percentage of either Neanderthals or Denisovans or of anther unknown ancient human species. This may have been another human species concurrent with the Neanderthals and the Denisovans. African AMH then had a number of admixture events with these other species outside of Africa (probably in central asia around 30,000 – 50,000 years ago) to give modern humans.
  4. There were probably many Back to Africa events of AMH groups from outside of Africa, back into Africa which also influenced the genetic pool within Africa. (But these back-mixture events were not sufficient to introduce detectable traces of Neanderthal and Denisovan genes into African AMH).

African AMH is thought to have first come into being around 200,000 years ago in Africa. But it is thought that the ancestors of the Neanderthals and the Denisovans left Africa about 500,000 years ago. This immediately means that mitochondrial Eve and Y-chromosomal Adam could not have been our earliest common ancestors.

Our earliest common ancestry must go back to a time before African AMH and to a time when the ancestors of Neanderthals and Denisovans were still in Africa. And that takes us back to the time of homo erectus and to not less than some 500,000 years ago.

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Genetic evidence that Yamnayans spread across Europe 5,000 years ago supports linguistic steppe hypothesis

A new paper reports that studies of DNA from 101 Bronze Age skeletons shows that Europeans came from nomadic tribes who invaded during the Bronze Age.

Morten E. Allentoftet al. Population genomics of Bronze Age Eurasia. Nature, 2015; 522 (7555): 167 DOI:10.1038/nature14507

Abstract: The Bronze Age of Eurasia (around 3000–1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We investigated this by using new, improved methods to sequence low-coverage genomes from 101 ancient humans from across Eurasia. We show that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a more recent onset of positive selection on lactose tolerance than previously thought.

Nature News reports on the paper:

A team led by palaeogenomicists Morten Allentoft and Eske Willerslev at the Natural History Museum of Denmark in Copenhagen has used these advances to sequence the genomes of 101 people who lived across Eurasia between about 3000 bc and ad 700 (ref. 2). “We could have stopped at 80,” says Allentoft. But “we thought, ‘Why the hell not? Let’s go above 100.’”

The sequences allowed the team to tackle questions that have vexed archaeologists for decades, says Allentoft. For example, researchers have disagreed over whether the cultural changes of the Bronze Age were the result of migration or simply the spread of ideas. Allentoft and his colleagues found evidence for migration, in the form of a massive shift in the genetic make-up of northern and central Europeans at the start of the Bronze Age. Before 3000 bc, their genomes resembled those of early farmers from the Middle East and even earlier European hunter-gatherers. By 2000 bc, their genomes looked more like those of people from the Yamnaya culture, which arose on the steppe around 2900 bc.

The findings echo those of a team that sequenced 69 ancient Europeans. Both groups speculate that the Yamnaya migration was at least partly responsible for the spread of the Indo-European languages into Western Europe.

Allentoft’s team found genetic traces of the Yamnaya in people who lived near the Altai Mountains in central Russia from 2900 bc to 2500 bc, potentially explaining why Indo-European languages are spoken so far into Asia. “It’s pretty clear that these eastern cultures in the Bronze Age are linked to the Yamnaya,” says Pontus Skoglund, a population geneticist at Harvard Medical School in Boston, Massachusetts. But he is not yet convinced that the culture’s wanderings explain the origins of all Indo-European languages.

So it would seem that hunter-gatherers mixed with farmers from the east who spread across Europe about 9,000 years ago. They formed the first agricultural settlements. Then came the invasion of the nomadic Yamnaya culture around 5,000 years ago. The Yamnayans were much more individualistic than the peoples they replaced and gave rise to the prominence of the nuclear family and the development of large family holdings of cleared lands, rather than the clusters of people in village settlements. They came on horses and brought livestock. But by about 4,000 years ago they too were overrun by the warlike Sintashta.

The genetic evidence of the spread of the Yamnaya culture, first westwards and then eastwards, suggests that proto-Indo-European starts here. This picture is not inconsistent with the Eurasian region being the origin of proto-Indo-European. But the genetic picture tends to support the “steppe hypothesis” rather than the “Anatolian hypothesis”.

Nature News: …… Scholars have long recognized an Indo-European language group that includes Germanic, Slavic and Romance languages as well as classical Sanskrit and other languages of the south Asian subcontinent. Yet the origins of this family of tongues are mired in controversy. 

…….  Some researchers hold that an early Indo-European language was spread by Middle Eastern farmers around 8,000–9,500 years ago (see ‘Steppe in time’). This ‘Anatolian hypothesis’ is supported by well-documented migrations into Europe, where agriculturalists replaced or interbred with the existing hunter-gatherers. In 2012, a team led by evolutionary biologist Quentin Atkinson of the University of Auckland in New Zealand produced a family tree of Indo-European tongues that also pointed to an Anatolian origin more than 8,000 years ago.

A competing theory posits that the languages emerged on the Eurasian steppe some 5,000–6,000 years ago, when the domestication of horses and invention of wheeled transport would have allowed herders there to rapidly expand their range. Proponents of the ‘steppe hypothesis’ note that linguistic reconstructions of a proto-Indo-European tongue include words associated with wheeled vehicles, which were not invented until long after Middle Eastern farmers had reached Europe. “Most linguists have signed up to the steppe hypothesis,” says Paul Heggarty, a linguist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

Could the Yamnaya culture be the origin of Indo-European languages?

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Our Neanderthal genes may have come mainly from their females

Nature reports on recent DNA studies which suggest that AMH – Neanderthal encounters took place also in Europe around 40, 000 years ago.

Early European may have had Neanderthal great-great-grandparent

It seems reasonable to assume that encounters began in central Asia / Middle East perhaps as early as 50-60,000 years ago and then moved westwards. AMH and Neanderthals could have coexisted at particular locations for as long as 5,000 years (250 generations) and it is more likely that Neanderthal populations declined as their habitat was encroached upon and taken over by the expanding AMH population. Not an intense war or even an intentional genocide of the Neanderthals but a gradual takeover of their territories as Neanderthals were pushed westwards and finally died out in Iberia some 30,000 years ago.

So I imagine bands of AMH and Neanderthals living in close proximity but largely with each group keeping to itself. When they encountered each other no doubt conflict occurred and the victors took spoils. For whatever reasons, AMH “won” the majority of these clashes and their territory grew while that of the Neanderthals shrank – westwards across central Asia and Europe. And in these clashes it is my speculation that the victors took the females of the vanquished as part of their spoils. Most probably AMH females joined Neanderthal bands and Neanderthal females joined AMH bands as spoils of war. But only the offspring of the Neanderthal females have left their mark because they had joined the line that would continue:

…. DNA analysis of a jawbone from a Romanian cave from about 40,000 years ago had a Neanderthal for a great-great- grandparent.

I take this grandparent to be a Neanderthal grandmother who was abducted by some marauding group of promiscuous humans only because the ensuing child survived to give rise to us and it is the human environment which has continued. The picture I have is that our Neanderthal genes today are due mostly to the Neanderthal females who were “impressed” into service by an aggressive and expanding human population. There may well have been Neanderthal male – human female offspring but they would more likely have been brought up in a Neanderthal environment, which – along with them -has not survived.

So I imagine the decline of the Neanderthals taking some 20-30,000 years as AMH expanded westwards  and the decline of the Denisovans probably starting a little later but taking somewhat less time. The encounters and admixing probably only occurred with the tribes and bands at the frontiers.

Imagined shrinking of Neanderthal territory

Imagined shrinking of Neanderthal territory

Maybe the DNA analyses will someday be sophisticated enough to be able to distinguish if it was mainly Neanderthal  females who have contributed to the current AMH gene pool or not.

But until then my story is that it was the Neanderthal females taken as spoils of war by expanding AMH tribes who have provided the majority of our Neanderthal genes.

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Scavenging came long before hunting

My layman’s belief is that before ancient humans came down from the trees they were primarily foragers (gatherers). They would have taken advantage of any scavenging opportunities that presented themselves and may – in isolated instances – have been driven to kill in defence, which subsequently provided a feeding opportunity. But they were primarily foragers rather than scavengers or hunters. Not so very different from the behaviour of primates today.

A new paper from the Smithsonian adds weight to the belief that ancient humans were scavengers first and hunters only later. Scavenging, as a major means of getting food , could have been prevalent 2 – 3 million years ago.

Briana L. Pobiner, New actualistic data on the ecology and energetics of hominin scavenging opportunitiesJournal of Human Evolution, Volume 80, March 2015, Pages 1–16

AbstractFor decades, the ‘hunting-scavenging debate’ has been an important research focus in Plio-Pleistocene hominin behavioral ecology. Here I present new data on potential scavenging opportunities from fresh carnivore kills on a conservancy in central Kenya. This ecosystem is dominated by felids (mainly lions) and has a different carnivore guild than in many earlier studies of scavenging opportunities that took place in areas such as Ngorongoro and Serengeti in Tanzania and Maasai Mara in Kenya, where lions face high levels of inter-specific competition from bone-crunching hyenas. I found that while scavenging opportunities vary among carcasses, most carcasses retained some scavengeable resources. Excluding within-bone resources, even the scavengeable meat on ‘defleshed’ larger sized prey carcasses is usually substantial enough to meet the total daily caloric requirements of at least one adult male Homo erectusindividual. I argue, as others have before me, that scavenging opportunities in a particular ecosystem will vary in part due to carnivore taxon, density and guild composition; prey size, biomass and community structure; and habitat (e.g., vegetation, physiography). We should expect variability in scavenging opportunities in different locales and should focus our research efforts on identifying which variables condition these differences in order to make our findings applicable to the diversity of ecological settings characterizing the past.

So the timeline I envisage for the development of human activity takes us from foraging to scavenging to hunting to herding to transient agriculture and finally to settled agriculture. The shift from scavenging to occasional hunting may be connected to the development of bipedalism, while active, organised hunting may be connected to the increasing control of fire. Certainly the ready availability of fire probably could have led to the feeling that all animals – no matter how large – could all be treated as prey. I have a picture in my mind of mammoth hunting taking off only because fire was available. Transient agriculture by peoples who led a predominantly nomadic life-style and where some plants and vegetables were intentionally cultivated during the few months of a summer camp may well have been established by about 40-50 thousand years ago. I take settled agriculture (and therefore the growth of cities) to have begun around 12,000 years ago.

Human activity timeline

Human activity timeline

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Once upon a story …….

This blog is about trying to put some (speculative) flesh on the bones of the preceding 6,000 generations which have led to me. I haven’t got very far because I’m still struggling with what should be the necessary (and sufficient) assumptions to make before starting on speculation. Initially I was focused on the period from 100,000 to 200,000 years ago when AMH came into being in Africa. I assumed a singular Out of Africa event sometime after that and a  rapid expansion from a small population in Arabia. I assumed they reached Australia by about 45,000 years ago and the Americas across the Bering Strait around 15,000 years ago. All this before the end of the last glacial age and the population explosion that settled agriculture brought.

But even these simple assumptions are now morphing. Archaeological evidence suggests that AMH reached Arabia prior to 100,000 years ago. Moreover they may have been many forays out of Africa into Arabia. There may have been two waves (at least) of expansion out of Arabia; one pre-Toba and one post-Toba. The explosion of DNA analysis work now indicates that all non-African humans have some Neanderthal DNA. Some have in addition some Denisovan DNA. Neanderthals (and Denisovans) had originated from archaic humans who had also originated in Africa and had spread over Eurasia. They disappeared as separate sub-species, not by some cataclysmic event but as they were gradually overwhelmed and “subsumed” into the main-stream which was – for whatever reason – much more successful. The main-stream species (now modern AMH) was irrepressibly promiscuous. It seems they mated with all other homo sub-species available (Neanderthal, Denisovan and possibly one other).  The recent articles (herehere and here) about current East Asians having about 20% more Neanderthal DNA than current Europeans suggest that the AMH – Neanderthal matings were not an isolated one-time incident, but occurred at least twice.

So I need to rebuild the framework of assumptions on which to construct my narrative and that means going back to the very foundations. It is not important to my narrative that any or all of these assumptions are proven – only that they are feasible. What is important though is that none of the assumptions be demonstrably false. My current set of “layman” assumptions – still being refined are:

  • The primate line diverges from a common ancestor to give the predecessors of gorillas and of humans/chimps at least 10 million years ago – in Africa.
  • Archaic humans and chimpanzees diverged from a common ancestor around 8 million years ago (and for my narrative it does not matter if it was 5 million or 10 million years ago but it would matter if it was only 1 million years ago).
  • This primate-human divergence occurred only once and only in Africa. Gorillas and chimps and bonobos are native only to Africa. If this or similar divergences took place in other locations as well any resulting species did not survive.
  • In due course the homo line gave rise to the bipedal homo erectus  around 3 million years ago – again only in Africa.
  • Homo erectus left Africa – probably many times whenever glacial periods allowed – and spread across Europe and Asia but did not make it to the Americas.
Homo Out of Africa

Homo Out of Africa

  • Neanderthals (in Eurasia), Denisovans (in East Asia) and possibly another sub-species (in South Asia?) evolved as the main-line from these archaic humans. Probably starting in the period from 600,000 years ago to about 400,000 years ago.
  • Some admixture may have taken place between these populations whose territories had some overlap.
  • In the meantime in Africa, modern humans evolved and separated from the archaic humans who – in other places – had evolved into the contemporary Neanderthals and Denisovans.
  • In due course around 300,000 years ago the ancestors of modern humans appeared and AMH had established themselves in Africa by around 200,000 years ago. Other streams of homo erectus had by then died out.
  • Then around 100 – 120,000 years ago populations of AMH had found their way into Arabia. There may have been many such excursions but possibly only one or two survived for any length of time.
  • Sometime before the Toba explosion 74,000 years ago, a wave of expansion eastwards had reached what is now SE Asia and had begun to penetrate north into Central Asia. Most of these settlers were extinguished by the Toba explosion but some few pockets may have survived. A small population in Arabia probably survived or were replenished by further migrations – when humid conditions allowed – from Africa.
  • Soon after the Toba event came a population explosion in a green Arabia/Persian Gulf/South Central Asia and the great expansion.
  • And the interactions with the Neanderthals and Denisovans would have come about during – and maybe due to – this expansion (70 – 30,000 years ago).

And the rest is history.

My assumed Out of Africarabia

 

 

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