The Proto-Indo-Europeans were the speakers of the Proto-Indo-European language (PIE), an unattested but now reconstructed prehistoric language.

Knowledge of them comes chiefly from the linguistic reconstruction, along with material evidence from archaeology and archaeogenetics. Linguistic reconstruction is fraught with significant uncertainties and room for speculation, and PIE speakers cannot be assumed to have been a single, identifiable people or tribe. Rather, they were a group of loosely related populations ancestral to the later, still partially prehistoric, Bronze Age Indo-Europeans.

The Proto-Indo-Europeans in this sense likely correspond to populations of the Copper Age, or roughly the 5th to 4th millennia BC. Mainstream scholarship places them in the general region of the Pontic-Caspian steppe in Eastern Europe and Central Asia. Some scholars would extend the time depth of PIE or pre-PIE to the Neolithic or even the last glacial maximum and suggest alternative location hypotheses.

By the mid-2nd millennium BC offshoots of the Proto-Indo-Europeans had reached Anatolia, the Aegean, Northern India, and likely Western Europe.

Culture

The following traits of the Proto-Indo-Europeans and their environment are widely agreed-upon but still hypothetical due to their reconstructed nature. Some of the basic facts are:

• stockbreeding and animal husbandry, including domesticated cattle, horses, and dogs

• agriculture and cereal cultivation, including technology commonly ascribed to early farming communities

• a climate with winter snow

• transportation by or across water

• the solid wheel, used for carts, but not yet chariots with spoked wheels The Oxford introduction to Proto-Indo-European and the Proto-Indo-European world - J. P. Mallory, Douglas Q. Adams, Oxford University Press, 2006, ISBN 0199296685, p249

• worship of a sky god,The Oxford Companion to Archaeology - Edited by Brian M. Fagan, Oxford University Press, 1996, ISBN 0-19-507618-4, p347 - J.P. Mallory *dyeus ph₂tēr (lit. "sky father"; > Ancient Greek Ζευς (πατηρ) / Zeus (patēr); *dieu-ph₂tēr > Latin Jupiter)

• oral heroic poetry or song lyrics that used stock phrases such as imperishable fame

• a patrilineal kinship system based on relationships between men

The Proto-Indo-Europeans were a patrilineal society, probably half-nomadic, relying on animal husbandry, notably of cattle and sheep. They domesticated the horse – (cf. Latin equus). The cow () played a central role, in religion and mythology as well as in daily life. A man's wealth would have been measured by the number of his animals (small livestock), (cf. English fee, Latin pecunia).

They practiced a polytheistic religion centered on sacrificial rites, probably administered by a priestly caste. Burials in barrows or tomb chambers apply to the kurgan culture, in accordance with the original version of the Kurgan hypothesis, but not to the previous Sredny Stog culture nor to the contemporary Corded Ware culture, both of which cultures are also generally associated with PIE. Important leaders would have been buried with their belongings in kurgans, and possibly also with members of their household or wives (human sacrifice, suttee).

There is evidence for sacral kingship (see Sanskrit Devarajah), suggesting the tribal king at the same time assumed the role of high priest (cf. Germanic king). Many Indo-European societies know a threefold division of priests, a warrior class, and a class of peasants or husbandmen. Such a division was suggested for the Proto-Indo-European society by Georges Dumézil.

If there was a separate class of warriors, it probably consisted of single young men. They would have followed a separate warrior code unacceptable in the society outside their peer-group. Traces of initiation rites in several Indo-European societies suggest that this group identified itself with wolves or dogs (see also Berserker, werewolf).

As for technology, reconstruction suggests a culture of the early Bronze Age, with bronze tools and weapons. Silver and gold were known. Sheep were kept for wool, and textiles were woven. The wheel was known, certainly for ox-drawn carts, and late Proto-Indo European warfare may also have made use of horse-drawn chariots.

The native name of this people cannot be reconstructed with certainty. Aryo- (interpreted by some as meaning "those who plow"), sometimes upheld as a self-identification of the Proto-Indo-Europeans (see Aryan), is attested as an ethnic designation only in the Indo-Iranian subfamily, since it appears on written inscriptions; however, the Proto-Indo-Europeans themselves had not yet adopted writing so there is no way to verify that Aryo- was their self-identification.

Origins

There have been many attempts to claim that particular prehistorical cultures can be identified with the PIE-speaking peoples, but all have been speculative. All attempts to identify an actual people with an unattested language depend on a sound reconstruction of that language that allows identification of cultural concepts and environmental factors which may be associated with particular cultures (such as the use of metals, agriculture vs. pastoralism, geographically distinctive plants and animals, etc).

The scholars of the 19th century who first tackled the question of the Indo-Europeans's original homeland (also called Urheimat, from German), were essentially confined to linguistic evidence. A rough localization was attempted by reconstructing the names of plants and animals (importantly the beech and the salmon) as well as the culture and technology (a Bronze Age culture centered on animal husbandry and having domesticated the horse). The scholarly opinions became basically divided between a European hypothesis, positing migration from Europe to Asia, and an Asian hypothesis, holding that the migration took place in the opposite direction.

In early 20th century scientific racism, the question was associated with the expansion of a supposed "Aryan race". The question is still contentious within some flavours of ethnic nationalism (see also Indigenous Aryans).

The Kurgan hypothesis is the most widely held theory and is based on linguistic, archaeological, and genetic evidence. It suggests PIE origin in the Pontic-Caspian steppe during the Chalcolithic.
A minority of scholars prefers the Anatolian hypothesis, suggesting origin in Anatolia during the Neolithic. Other theories (Armenian hypothesis, Out of India theory, Paleolithic Continuity Theory) have only marginal scientific support.

Urheimat hypotheses

In the 20th century, Marija Gimbutas created the Kurgan hypothesis, a modern variation of the traditional invasion theory. The name is after the kurgans (burial mounds) of the Eurasian steppes. The hypothesis is that the Indo-Europeans were a nomadic tribe of the Pontic-Caspian steppe (now Eastern Ukraine and Southern Russia) and expanded in several waves during the 3rd millennium BC. Their expansion coincided with the taming of the horse. Leaving archaeological signs of their presence (see battle-axe people), they subjugated the peaceful European Neolithic farmers of Gimbutas's Old Europe. As Gimbutas's beliefs evolved, she put increasing emphasis on the patriarchal, patrilinear nature of the invading culture, sharply contrasting it with the supposedly egalitarian, if not matrilinear culture of the invaded, to a point of formulating essentially feminist archaeology.

Her theory has found genetic support in remains from the Neolithic culture of Scandinavia, where bone remains in Neolithic graves indicated that the megalith culture was either matrilocal or matrilineal as the people buried in the same grave were related through the women. Likewise there is evidence of remaining matrilineal traditions among the Picts. A modified form of this theory by JP Mallory, dating the migrations earlier to around 4000 BC and putting less insistence on their violent or quasi-military nature, is still widely held.

The Anatolian hypothesis is that the Indo-European languages spread peacefully into Europe from Asia Minor from around 7000 BC with the advance of farming (wave of advance). The leading propagator of the theory is Colin Renfrew. However, this theory is contradicted by the fact that ancient Anatolia is known to have been inhabited by non-Indo-European people, namely the Hattians, Khalib/Karub, and Khaldi/Kardi. Also, the culture of the Indo-Europeans as inferred by linguistic reconstruction contradicts this theory, since the early Neolithic cultures in Anatolia had neither the horse, nor the wheel, nor metal, terms for all of which are securely reconstructed for Proto-Indo-European.

A scenario that could reconcile Renfrew's and the Kurgan hypotheses suggests that Indo-European migrations are somehow related to the disputed Black Sea deluge theory, the hypothesized submersion of the northeastern part of the Black Sea around 5600 BC: while a splinter group who became the proto-Hittite speakers moved into northeastern Anatolia around 7000 BC, the remaining population would have gone northward, evolving into the Kurgan culture, while others may have escaped far to the northeast (Tocharians) and the southeast (Indo-Iranians). While the time-frame of this scenario is consistent with Renfrew, it is incompatible with his core assumption that Indo-European spread with the advance of agriculture.

Using stochastic models of word evolution to study the presence or absence of different words across Indo-European languages, Gray & Atkinson suggest that the origin of Indo-European goes back about 8500 years, the first split being that of Hittite from the rest, supporting the Indo-Hittite hypothesis. They go to great lengths to avoid the problems associated with traditional glottochronology, and they carry out various sensitivity tests of their assumptions. However, their calculations rely entirely on Swadesh lists, and while the results are quite robust for well attested branches, their crucial calculation of the age of Hittite rests on a 200–word Swadesh list of one single language.

A more recent paper (Atkinson et al., 2005) analyzing 24 mostly ancient languages, including three Anatolian languages, produced the same time estimates and early Anatolian split. These claims are still controversial, however, and most traditional linguists consider these methods too inaccurate to prove the Anatolian hypothesis.

Another hypothesis connected with the Black Sea deluge theory suggests that PIE originated as the language of trade between early Neolithic Black Sea tribes. Under this hypothesis, University of Pennsylvania archaeologist Fredrik T. Hiebert proposes that the transition from PIE to IE dispersion occurred during the deluge.

The Armenian hypothesis is based on the Glottalic theory and suggests that the Proto-Indo-European language was spoken during the 4th millennium BC in the Armenian Highland. It is an Indo-Hittite model and does not include the Anatolian languages in its scenario. The phonological peculiarities of PIE proposed in the Glottalic theory would be best preserved in the Armenian language and the Germanic languages, the former assuming the role of the dialect which remained in situ, implied to be particularly archaic in spite of its late attestation. Proto-Greek would be practically equivalent to Mycenean Greek and date to the 17th century BC, closely associating Greek migration to Greece with the Indo-Aryan migration to India at about the same time (viz., Indo-European expansion at the transition to the Late Bronze Age, including the possibility of Indo-European Kassites).

The Armenian hypothesis argues for the latest possible date of Proto-Indo-European (sans Anatolian), a full millennium later than the mainstream Kurgan hypothesis. In this, it figures as an opposite to the Anatolian hypothesis, in spite of the geographical proximity of the respective Urheimaten suggested, diverging from the timeframe suggested there by a full three millennia.

Genetics

The rise of archaeogenetic evidence which uses genetic analysis to trace migration patterns also added new elements to the origins puzzle. Luigi Luca Cavalli-Sforza and Alberto Piazza argue that Renfrew and Gimbutas reinforce rather than contradict each other. states that "It is clear that, genetically speaking, peoples of the Kurgan steppe descended at least in part from people of the Middle Eastern Neolithic who immigrated there from Turkey." Piazza & Cavalli-Sforza (2006) state that:

"if the expansions began at 9,500 years ago from Anatolia and at 6,000 years ago from the Yamnaya culture region, then a 3,500-year period elapsed during their migration to the Volga-Don region from Anatolia, probably through the Balkans. There a completely new, mostly pastoral culture developed under the stimulus of an environment unfavourable to standard agriculture, but offering new attractive possibilities. Our hypothesis is, therefore, that Indo-European languages derived from a secondary expansion from the Yamnaya culture region after the Neolithic farmers, possibly coming from Anatolia and settled there, developing pastoral nomadism."

400px|thumb|more detailed map of Haplogroup R1a distributionSpencer Wells suggests in a (2001) study that the origin, distribution and age of the R1a1 haplotype points to an ancient migration, possibly corresponding to the spread by the Kurgan people in their expansion across the Eurasian steppe around 3000 BC. About his old teacher's proposal, states that "there is nothing to contradict this model, although the genetic patterns do not provide clear support either", and instead argues that the evidence is much stronger for Gimbutas' model:

"while we see substantial genetic and archaeological evidence for an Indo-European migration originating in the southern Russian steppes, there is little evidence for a similarly massive Indo-European migration from the Middle East to Europe. One possibility is that, as a much earlier migration (8,000 years old, as opposed to 4,000), the genetic signals carried by Indo-European-speaking farmers may simply have dispersed over the years. There is clearly some genetic evidence for migration from the Middle East, as Cavalli-Sforza and his colleagues showed, but the signal is not strong enough for us to trace the distribution of Neolithic languages throughout the entirety of Indo-European-speaking Europe."

Y-chromosome DNA haplogroup R1a1, a lineage thought to have originated in the Eurasian Steppes north of the Black and Caspian Seas, is associated with the Kurgan culture, the Indo-European languages, as well as with the postglacial Ahrensburg culture which has been suggested to have spread the gene originally. Alternatively, it has been suggested that R1a arrived in southern Scandinavia during the time of the Corded Ware culture.Dupuy, B. et al. 2006. . Forensic Science International. 164: 10-19. The mutations that characterize haplogroup R1a occurred ~10,000 years bp. Its defining mutation (M17) occurred about 10,000 to 14,000 years ago. Ornella Semino et al. propose a postglacial spread of the R1a1 gene from the north of the Black Sea during the time of the Late Glacial Maximum, subsequently magnified by the expansion of the Kurgan culture into Europe and eastward.

R1a1 is most prevalent east of the Vistula: in Pakistan, India, central Asia, and to a lesser extent Poland, Russia, and Ukraine. It drops considerably to the west: R1a1 measurements read 6.2% in Germans (a 4X drop in Czechs and Slovakians' reading of 26.7%) and 3.7% in the Dutch. However, a study in which ancient DNA was extracted from Corded Ware Culture skeletal remains at a western German site showed that the males possessed the R1a lineage.

The present-day population of R1b, with extremely high peaks in Western Europe and measured up to the eastern confines of Central Asia, are believed to be the descendants of a refugium in the Iberian peninsula (Portugal and Spain) at the Last Glacial Maximum, where the haplogroup may have achieved genetic homogeneity.

See also

• Pre-Indo-Europeans

• Proto-Indo-European language

• Comparative linguistics

• Urheimat

• Armenian hypothesis

• Archaeogenetics

• Kurgan

• Aryan

• Aryan invasion

• Paleolithic Continuity Theory

Footnotes