Which culture domesticated the horse

These horse-riding pastoralists from the western steppe, known as the Yamnaya, may not have been responsible for bringing horse breeding and Indo-European languages into Asia, according to a study by an international, interdisciplinary team published today in the journal Science. Their analysis revolves around the Botai people, who lived on grasslands in what is now Kazakhstan between about 3, and 3, B. When archaeologists explored the remains of Botai villages, they uncovered a horse-crazy culture.

The archaeological evidence, which includes hundreds of thousands of horse bone fragments and pottery that seems to have contained horse milk, suggests that the Botai were the earliest group to tame and breed horses. One camp has long held that the Botai figured out horse breeding themselves; another suggests that they learned it from a group of horse herders, perhaps the Yamnaya, who encountered the Botai while traveling across the steppe from west to east.

To find out, researchers pitted the competing theories against one another, combining archaeological evidence with an analysis of the genomes of 74 ancient humans.

They analyzed DNA from across the ancient Eurasian steppe and studied samples that ranged from medieval times all the way back to the Mesolithic era. It turns out that the Botai and the Yamnaya didn't share many genetic similarities at all.

The Botai were most closely related to a group of Paleolithic hunter-gatherers, not people of the western steppes like the Yamnaya. Instead of getting the scoop on horse breeding from western herders, the Botai may have learned to domesticate horses on their own through hunts before transitioning to pastoral life in their horse-centered farming villages.

The findings open up big questions about whose horses ended up evolving into modern-day steeds. Olsen was not involved with the research. Since the archaeological record suggests a swift transition to horse domestication, she says, the lack of evidence that the Botai mixed with other cultures is even more mysterious. The ancient DNA study also challenges the idea that as the Yamnaya moved east around 5, years ago, they brought Indo-European languages with them deep into Asia.

These new criteria, derived through careful comparison of natural history collections, included new bone formation to the diastema of the lower jaw, a feature thought to occur in very low levels in wild animals, and the erosion of cementum and enamel along the anterior margin of the lower second premolar.

While such cementum erosion occurs in both wild and domestic animals, by comparing wild and domestic animals with known life and work histories, Bendrey 6 found that metal bits often produce a version of this damage that is parallel-sided in shape, and is often more invasive than natural wear causing exposure of dentine. These new lipid values and paleopathological finds were further supported by metric comparisons of metapodial bones, which appeared to show that the Botai horses were the domestic E.

Together, these new finds underscored an emerging consensus that Botai represented the first step in the domestication story, which persists to the present day. Botai horse tooth cited as conclusive evidence of bit wear in Outram et al. Although the consensus forged by these discoveries was robust, recent discoveries necessitate a reevaluation of some or all of the Botai domestication argument.

In a key finding, Gaunitz and colleagues 11 revealed that despite the previously identified morphological patterns in metapodial shape, all analyzed Botai specimens were in fact E. The contextual nature of most of the existing evidence for domestication at Botai, however, may not support this interpretation. Many assumptions underpinning this earlier work—such as the idea that vegetal matter found in pithouses was horse dung, that postholes were used to form corrals, or that summer seasonality of isotope values indicated horse milk—were contingent upon the presence of domestic horses, rather than empirically demonstrated.

Other recent biomolecular work, such as a recent study analyzing dental calculus of human remains from Botai 31 , found no evidence for dietary milk proteins of any kind.

Consequently, it seems that the argument for Botai domestication of E. How robust is the evidence for horse transport at Botai? A careful examination of published imagery of this tooth shows evidence of natural damage and disturbances in dental development that may undercut the argument linking the apparently parallel-sided anterior enamel and dentine exposure observed in a single second premolar from Botai with a bridle bit.

Specifically, although the enamel exposure visible along the anterior margin of this tooth does indeed appear parallel-sided at first glance, it actually consists of two adjoining, oval-shaped areas of exposure.

The exposed area of enamel is also interrupted by a series of small circular pits in the enamel, producing small areas of exposed dentine, which Outram et al. However, this photo shows that each of the pits in the Botai tooth margin are exceedingly small in diameter—far smaller than any we have observed in archaeological horse remains from Mongolia, even those controlled with organic bits Small, circular pitting is also a characteristic sign of pit-form enamel hypoplasia—a dental defect caused by disruption of normal enamel matrix secretion, which results in pockets of thin or poorly developed enamel.

These observations raise the possibility that, in a large assemblage of wild horses, natural processes rather than human activity could produce similar features to those identified in the Botai assemblage.

To characterize the frequency of damage found on the Botai tooth cementum banding, as well as the frequency of enamel hypoplasia, and pitting of the enamel along the anterior margin of the second premolar in wild populations, we analyzed a sample of 72 lower second premolars and 81 upper second premolars of wild equids Equus spp.

All of these sites preserve abundant equid remains, which are late Pleistocene in age All of the specimens were examined with a hand lens using oblique lighting. Our study sample included worn and unworn teeth. For those specimens showing hypoplastic defects, we noted the location of the defect on the tooth crown. We identified the type of defect s present on the anterior margin of the tooth i. We treated isolated teeth as separate individuals, unless there was evidence that isolated teeth were associated i.

We calculated the percentage of specimens i. We note that one obstacle to the study of enamel hypoplasia in the cheek teeth of equids and other hypsodont ungulates is the presence of cementum covering the tooth crown 36 , Aged horses with teeth in extreme stages of wear often show abnormally large increases in tertiary cementum We excluded any specimens with a score of 5 from our analysis, because the cementum covering the tooth made it difficult to consistently evaluate whether enamel hypoplasia was present in the tooth.

For teeth with only one side of the tooth crown completely covered by cementum we scored the exposed sides of the tooth. Cementum did not pose a serious problem to the examination of enamel hypoplasia for many of the teeth we studied, because post-mortem weathering and degradation of cementum exposed the enamel underneath. We treated isolated teeth as separate individuals and associated teeth were treated as a single individual.

From this sample, we calculated the proportion of specimens displaying two or more well-defined cementum bands Table 2. We used the scoring system proposed by Bendrey 6 to determine the extent of new bone formation in the diastema.

Our results provide clear indication that pitting similar to that observed on the Botai horse is particularly common on the anterior margin of the lower second premolar of wild North American horses. Of these, 11 Furthermore, our evaluation of cementum banding, indicates that among wild horses, there is often a wide gradient in this trait—ranging from teeth that do not show any distinct cementum bands to those that show well-defined cementum bands.

Teeth with at least two or more well-defined cementum bands, as is the case in the Botai tooth, appear to be slightly more common in the upper second premolar These mandibles show faint changes, including the development of a well-defined ridge along the diastema and roughening of the bone.

Comparing our results to the Botai tooth provides strong indication that the osteological features taken for evidence of horse transport, may have been produced solely through natural processes. Although our analysis suggests that it is uncommon for enamel hypoplasia pits to co-occur in multiples on the anterior margin of the tooth, one wild horse in our sample, from Bluefish Cave I MgVo-1 in northern Yukon, exhibited two such pits, nearly identical to those attributed to bit wear at Botai, along with visible cementum banding Fig.

Based on available data, we are unable to speculate on whether enamel hypoplasia itself might occur in higher frequency or severity in domestic and wild samples. However, the high frequency of enamel hypoplastic defects with dentine exposed in North American horses suggests that dentine exposure—in the form of circular or oval pits—cannot be considered reliable evidence of transport damage.

Because of the different processes involved in bit wear and hypoplastic defects, the Botai tooth can potentially be evaluated in a non-destructive manner using recently developed visualization and virtual histological techniques In contrast to other types of enamel hypoplasia, pit-form hypoplastic defects are characterized by a scatter of isolated pits or single pits surrounded by unaffected enamel 34 , The rim of each pit, as seen on the surface of the tooth, is usually smooth In longitudinal histological sections, the rim of each pit appears smoothly curved and the striae of Retzius in the enamel forming the walls of the pit are also curved 34 , 35 , Frequently accentuated lines, i.

Pits that are caused by other factors such as flaking of poorly mineralized enamel 42 , 43 , 44 , cavitary lesions resulting from pre-eruptive enamel resorption 41 and enamel erosion from mechanical wear or abrasion e.

Consequently, damage caused by bits should be easily distinguishable from pit-form hypoplastic defects using histological approaches. Schematic diagram of two longitudinal histological sections showing the differences between A a pit-form hypoplastic defect and B a pit produced by other processes such as flaking of poorly mineralized enamel or enamel erosion due to mechanical wear. A In a pit-form hypoplastic defect the rim of the pit is smoothly curved and the striae of Retzius in the enamel forming the walls of the pit are also curved.

B A pit produced by flaking of poorly mineralized enamel or enamel erosion due to mechanical wear cross-cuts normal striae of Retzius and it usually lacks a smooth and curved rim. Interestingly, our results suggest a discrepancy in the frequency of enamel hypoplasia in the anterior margin of the upper and lower second premolars of the wild equid samples Table 1.

These teeth form at approximately similar times during ontogeny Therefore, disruptions in enamel secretion would be in theory expected to be correlated to some degree in upper and lower second premolars for a given individual. Although we were not able to analyze associated upper and lower second premolars in our sample, there is no indication of preservation bias, collecting bias, or sampling biases between upper and lower teeth in the samples we studied.

One possible explanation for this discrepancy in the frequency of enamel hypoplasia in the upper and lower teeth is different dental developmental geometries. Dental developmental geometry is a factor that is known to affect the expression and visibility of enamel hypoplasia Our new data suggest that, without careful consideration of other enamel and cementum patterns, criteria used to identify bit wear through enamel exposure can sometimes produce spurious results.

The Botai tooth presents a band of enamel exposure that is However, as indicated previously, despite appearances of parallel sides, the enamel exposure consists of two adjoining, oval-shaped areas of exposure. These exposed areas of enamel correspond with two well-defined bands of reduced cementum deposition, observed along the buccal and lingual sides of the tooth. We propose that reduced cementum deposition in this region of the tooth made the anterior side of the premolar more susceptible to cementum erosion from natural wear, resulting in the exposure of two tall, oval-shaped areas of enamel.

Multiple, well-defined cementum bands are relatively common in the lower In some cases, cementum bands appear to be the result of reduced cementum deposition, similar to the condition observed in the Botai tooth. However, in other cases they appear to result from increased cementum deposition on top and below the cementum band. Based on these observations, two alternative, although not mutually exclusive, mechanisms can potentially explain the formation of cementum bands.

The first of these is disruption of the secretory activity of cementoblasts, the cells that form cementum—if tooth eruption is more or less constant, disruption in the secretory activity of cementoblasts would lead to a reduction in the deposition of tertiary cementum for the duration of the disruption.

In either case, it would seem that the mechanism of cementum band formation is common enough in wild horses to warrant careful consideration by archaeologists interested in anthropogenic tooth damage.

Mandibular bone formation on wild Pleistocene horse specimen n o DhPg In light of our new data, arguments for horse domestication at Botai no longer appear to be supported by the available archaeological evidence. Without the presumption of horse transport, many aspects of the Botai assemblage are more efficiently explained by interpretation of the site as the result of regularized mass-harvesting of wild horses.

At Paleolithic sites across Europe, entire bands of horses—either mostly-female harem groups, all-male bachelor bands, or both—were commonly ambushed alongside natural water features where they were more effectively trapped and slaughtered This strategy appears to have been employed by the earliest hominin horse hunters, dating back nearly a half million years or more 47 , Group harvesting at Botai could easily explain unresolved questions in the assemblage, including apparent presence of entire carcasses, the predominance of prime-aged adult animals, and the recovery of bone arrowheads in situ with deceased horse remains, as well as the utter absence of other domestic fauna at Botai The relatively equal ratios of male and female animals found at Botai could imply that the site was used to harvest both bachelor bands and harem groups over its use history.

Summer seasonality identified by Outram et al. If chosen for a favorable topographic position or location on a key ecological corridor or migration route, horse mass harvesting sites may have been regularly utilized in a particular time of year over long stretches of time.

A reappraisal of the pre-Botai archaeological record of humans and horses also supports this view. Many of the cultural modifications found in the Botai artifact assemblage—the decoration of horse bones, the use of horse bones as tools, and even the occasional ritual inhumation of horse remains—are fully consistent with hunter-gatherer cultures in which horse hunting plays an important role.

Horses are the most commonly depicted animal in Eurasian Paleolithic cave paintings 50 , and were a favorite muse for hunter-gatherer artists across the Pleistocene and into the Holocene—appearing on bones, ivory, or stone objects—and probably many organic artifacts that have not survived—as decorations or as dedicated votives The discoveries of ritual features and artwork at Botai or Eneolithic sites from the Black Sea region, while important, fail to effectively delineate a domestication relationship from the rich hunting tradition that preceded it.

How, then, to explain the apparent resurgence in the frequency of horses—a Pleistocene animal whose populations began to dwindle after the Last Glacial Maximum—during the 4th millennium BCE? A convergence of climate and human factors unrelated to horse domestication may have contributed. The late Neolithic witnessed a cooling trend across much of northern Eurasia 52 , 53 , 54 , 54 that could have boosted the population size and expanded the viable habitat of cold-adapted equids.

Program Contacts John E. Yellen, NSF, , email: jyellen nsf. Principal Investigators Sandra L. Olsen, Carnegie Museum of Natural History, , email: olsens carnegiemnh. The U. National Science Foundation propels the nation forward by advancing fundamental research in all fields of science and engineering. NSF supports research and people by providing facilities, instruments and funding to support their ingenuity and sustain the U. Each year, NSF receives more than 40, competitive proposals and makes about 11, new awards.

Those awards include support for cooperative research with industry, Arctic and Antarctic research and operations, and U. Get News Updates by Email. Connect with us online NSF website: nsf. Follow us on social Twitter: twitter. But experts have long puzzled over the deceptively simple question of where domestic horses actually came from. It took a two-continent collaboration among over a hundred scientists to home in on the answer: southern Russia.

The discovery provides strong evidence that of three main locations in contention—Anatolia, Iberia, and western Eurasian steppes—the last is likely the birthplace of modern domestic horses, Equus caballus.

Study leader Ludovic Orlando , a molecular archaeologist at University Paul Sabatier in Toulouse, France, and colleagues reconstructed ancient horse genomes from ancient horse skeletons found in sites ranging from Portugal to Mongolia.

One region in southern Russia, near the intersection of the Volga and Don Rivers, stood out. The cattle-herding region already had indirect archaeological evidence of horse domestication, but the new DNA research now shows that modern domestic horses can be traced to equines living here between 4, and 4, years ago. Because people in the Volga-Don region bred horses for domestication and quickly began migrating to new places with them, this new line of horses soon spread from western Europe to eastern Asia and beyond.

In Bronze Age Europe and Asia, about 5, to 4, years ago, people were probably domesticating horses. Archaeological and historical records suggest that quite suddenly, around 4, years ago, horse populations mysteriously shot up across Eurasia. Was climate change expanding grasslands and giving horses more habitat?

Were people across the world breeding herds at the same time? Or did these domesticated horses share a common source? Only in the last decade or so has the technology to test ancient DNA from preserved materials such as bones and hair become finely honed enough to investigate such broad questions.

For their research, Orlando and an international team of bone collectors scoured museums and archaeological sites, ultimately gathering enough material to test individual genomes from horse remains found across Europe and central Asia.