Science is Rewriting the History of Horse Domestication
Throughout history, no animal has had a bigger impact on human societies than the horse. However, the exact time and method of horse domestication (taming and breeding) have remained a mystery to scientists.
Over half a million years ago, early humans used wooden spears to hunt horses, the first weapons ever made, and used horse bones to make simple tools. Later, in the Paleolithic era (the early Stone Age) over 30,000 years ago, ancient artists painted wild horses in caves across Eurasia (a region covering Europe and Asia).
After horses were first domesticated, they became essential to herding societies in the grasslands of Inner Asia (the central region of Asia, including countries like Kazakhstan and Mongolia). Horses helped people advance in technology, leading to inventions like the chariot, saddle, and stirrup (equipment for riding). Horses became the main way people travelled, communicated, farmed, and fought wars across much of the ancient world. Over time, horses reached almost every part of the world, even briefly reaching Antarctica.
As horses spread, they changed environments, social structures (the way societies are organised), and economies (systems of trade and money) on a massive scale. They were crucial to human societies until the invention of machines replaced their roles.
Because horses have played such a huge role in shaping human history, understanding when, why, and how they were first domesticated is important for understanding our world today. However, finding out this information has proven to be quite difficult. In my new book, "Hoof Beats: How Horses Shaped Human History," I bring together new archaeological (the study of ancient cultures through their remains) evidence that challenges what scientists thought they knew about horse domestication.
A Hypothesis about DomesticationOver the years, many different times and places around the world have been suggested as the possible origin of horse domestication—from Europe tens of thousands of years ago to regions like Saudi Arabia, Anatolia (modern-day Turkey), China, or even the Americas.
However, the most widely accepted idea has been the Indo-European hypothesis, also known as the "Kurgan hypothesis." This theory suggests that around the fourth millennium B.C. (4,000 to 3,000 B.C.), people from the steppes (vast grasslands) of western Asia and the Black Sea region, known as the Yamnaya, who built large burial mounds called "kurgans," began riding horses. This newfound mobility (the ability to move around easily) supposedly led to large migrations (movements of people) across Europe and Asia, spreading Indo-European languages and cultures.
But what evidence supports this Kurgan hypothesis about the first horse domestication? A lot of the most important clues come from the bones and teeth of ancient horses, studied through a field called archaeozoology (the study of ancient animal remains). Over the past 20 years, archaeozoologists have found data suggesting that horses were first domesticated by the Botai culture in Kazakhstan. This idea is supported by the large number of horse bones found at Botai sites dating back to the fourth millennium B.C.
There was also other indirect evidence, like ancient post holes (holes that held wooden posts) that may have been part of horse enclosures, and ceramic fragments (pieces of pottery) with horse fat residue. This fat seemed to come from the summer months when horses could have been milked.
The strongest evidence for early horse domestication was the wear patterns on Botai horse teeth and jawbones. These looked like the wear caused by a bridle or bit (equipment used to control a horse), which is common in both modern and ancient ridden horses.
Together, the data strongly suggested that horse domestication happened in northern Kazakhstan around 3500 B.C. This location isn't exactly where the Yamnaya lived, but it's close enough to fit with the Kurgan hypothesis.
However, there were parts of the Botai story that didn’t quite make sense.
New Questions and ToolsFrom the beginning, several studies showed that the mix of horse remains found at Botai was different from those found in later horse-herding societies. At Botai, the remains of male and female horses were found in almost equal numbers, and most were of healthy breeding age. Regularly killing off healthy, breeding-age horses would have quickly destroyed a breeding population, which seemed unlikely. This kind of mix is more common among wild animals that are hunted, not domesticated. Some Botai horses even had arrowheads stuck in their bones, suggesting they were killed through hunting rather than controlled slaughter.
These unresolved questions have hung over the theory linking the Botai culture to the first horse domestication.
In recent years, with the rapid improvement of archaeological and scientific tools, many assumptions about the Botai, Yamnaya, and the early history of horse domestication have been challenged.
In 2018, DNA sequencing showed that Botai horses were not the ancestors of domestic horses but were instead related to Przewalski’s horse, a wild species from the steppes (vast grassy plains) that has never been domesticated in recorded history.
Later, when we re-examined the skeletal features (bones) of horses linked to riding at Botai, we found similar wear patterns in Ice Age wild horses from North America, which had definitely never been ridden. While riding can cause visible changes to a horse’s teeth and jawbones, we argued that the small changes seen in Botai horses could easily be natural variations (differences).
This raised a big question: Were horses ever used for riding at Botai at all?
Moving Beyond the Kurgan HypothesisOver the past few years, trying to make sense of the evidence about horse domestication has become more and more confusing.
For example, in 2023, archaeologists noticed that hip and leg problems found in the skeletons of people from the Yamnaya and early Eastern European burials were similar to those seen in people who rode horses, which would support the Kurgan hypothesis. But these bone problems can also be caused by other types of animal transport, like riding in cattle-drawn carts, which were also found in Yamnaya-era sites.
So, how should archaeologists understand these mixed signals?
A clearer picture might be closer than we think. A detailed genetic study (study of DNA) of early Eurasian horses, published in June in the journal Nature, showed that Yamnaya horses were not ancestors of the first clearly domestic horses, known as the DOM2 lineage. And Yamnaya horses showed no signs of controlled breeding, such as genetic changes linked with inbreeding (breeding between closely related animals).
Instead, the first DOM2 horses appeared just before 2000 B.C., long after the Yamnaya migrations and just before the first archaeological evidence of horses being buried with chariots.
Currently, all the evidence seems to suggest that horse domestication probably took place in the Black Sea steppes, but much later than the Kurgan hypothesis suggests. Human control of horses seems to have started just before horses and chariots spread rapidly across Eurasia in the early second millennium B.C.
Of course, there are still more questions to be answered. In the latest study, the researchers noted some odd patterns in the Botai data, especially fluctuations in genetic estimates for generation time (how long it takes for a population to reproduce). Could this mean that Botai people kept the wild Przewalski’s horses in captivity, but only for meat, without using them for transportation? Perhaps. Future research will tell us more.
Either way, from these mixed signals, one thing is clear: The early history of humans and horses is ready for a new retelling.
SummaryThis article explains how new scientific discoveries are changing what we know about when and how humans first domesticated (tamed and bred) horses. Scientists used to think that horse domestication started with the Yamnaya people in western Asia about 5,500 years ago. However, recent studies, including DNA evidence, suggest that domesticated horses appeared much later, around 4,000 years ago, and not from the Yamnaya horses. The new research shows that early horses may not have been used for riding or carrying goods as much as previously thought. This means that the early story of how humans and horses first came together is more complex and needs to be rewritten.
Glossary
Throughout history, no animal has had a bigger impact on human societies than the horse. However, the exact time and method of horse domestication (taming and breeding) have remained a mystery to scientists.
Over half a million years ago, early humans used wooden spears to hunt horses, the first weapons ever made, and used horse bones to make simple tools. Later, in the Paleolithic era (the early Stone Age) over 30,000 years ago, ancient artists painted wild horses in caves across Eurasia (a region covering Europe and Asia).
After horses were first domesticated, they became essential to herding societies in the grasslands of Inner Asia (the central region of Asia, including countries like Kazakhstan and Mongolia). Horses helped people advance in technology, leading to inventions like the chariot, saddle, and stirrup (equipment for riding). Horses became the main way people travelled, communicated, farmed, and fought wars across much of the ancient world. Over time, horses reached almost every part of the world, even briefly reaching Antarctica.
As horses spread, they changed environments, social structures (the way societies are organised), and economies (systems of trade and money) on a massive scale. They were crucial to human societies until the invention of machines replaced their roles.
Because horses have played such a huge role in shaping human history, understanding when, why, and how they were first domesticated is important for understanding our world today. However, finding out this information has proven to be quite difficult. In my new book, "Hoof Beats: How Horses Shaped Human History," I bring together new archaeological (the study of ancient cultures through their remains) evidence that challenges what scientists thought they knew about horse domestication.
A Hypothesis about DomesticationOver the years, many different times and places around the world have been suggested as the possible origin of horse domestication—from Europe tens of thousands of years ago to regions like Saudi Arabia, Anatolia (modern-day Turkey), China, or even the Americas.
However, the most widely accepted idea has been the Indo-European hypothesis, also known as the "Kurgan hypothesis." This theory suggests that around the fourth millennium B.C. (4,000 to 3,000 B.C.), people from the steppes (vast grasslands) of western Asia and the Black Sea region, known as the Yamnaya, who built large burial mounds called "kurgans," began riding horses. This newfound mobility (the ability to move around easily) supposedly led to large migrations (movements of people) across Europe and Asia, spreading Indo-European languages and cultures.
But what evidence supports this Kurgan hypothesis about the first horse domestication? A lot of the most important clues come from the bones and teeth of ancient horses, studied through a field called archaeozoology (the study of ancient animal remains). Over the past 20 years, archaeozoologists have found data suggesting that horses were first domesticated by the Botai culture in Kazakhstan. This idea is supported by the large number of horse bones found at Botai sites dating back to the fourth millennium B.C.
There was also other indirect evidence, like ancient post holes (holes that held wooden posts) that may have been part of horse enclosures, and ceramic fragments (pieces of pottery) with horse fat residue. This fat seemed to come from the summer months when horses could have been milked.
The strongest evidence for early horse domestication was the wear patterns on Botai horse teeth and jawbones. These looked like the wear caused by a bridle or bit (equipment used to control a horse), which is common in both modern and ancient ridden horses.
Together, the data strongly suggested that horse domestication happened in northern Kazakhstan around 3500 B.C. This location isn't exactly where the Yamnaya lived, but it's close enough to fit with the Kurgan hypothesis.
However, there were parts of the Botai story that didn’t quite make sense.
New Questions and ToolsFrom the beginning, several studies showed that the mix of horse remains found at Botai was different from those found in later horse-herding societies. At Botai, the remains of male and female horses were found in almost equal numbers, and most were of healthy breeding age. Regularly killing off healthy, breeding-age horses would have quickly destroyed a breeding population, which seemed unlikely. This kind of mix is more common among wild animals that are hunted, not domesticated. Some Botai horses even had arrowheads stuck in their bones, suggesting they were killed through hunting rather than controlled slaughter.
These unresolved questions have hung over the theory linking the Botai culture to the first horse domestication.
In recent years, with the rapid improvement of archaeological and scientific tools, many assumptions about the Botai, Yamnaya, and the early history of horse domestication have been challenged.
In 2018, DNA sequencing showed that Botai horses were not the ancestors of domestic horses but were instead related to Przewalski’s horse, a wild species from the steppes (vast grassy plains) that has never been domesticated in recorded history.
Later, when we re-examined the skeletal features (bones) of horses linked to riding at Botai, we found similar wear patterns in Ice Age wild horses from North America, which had definitely never been ridden. While riding can cause visible changes to a horse’s teeth and jawbones, we argued that the small changes seen in Botai horses could easily be natural variations (differences).
This raised a big question: Were horses ever used for riding at Botai at all?
Moving Beyond the Kurgan HypothesisOver the past few years, trying to make sense of the evidence about horse domestication has become more and more confusing.
For example, in 2023, archaeologists noticed that hip and leg problems found in the skeletons of people from the Yamnaya and early Eastern European burials were similar to those seen in people who rode horses, which would support the Kurgan hypothesis. But these bone problems can also be caused by other types of animal transport, like riding in cattle-drawn carts, which were also found in Yamnaya-era sites.
So, how should archaeologists understand these mixed signals?
A clearer picture might be closer than we think. A detailed genetic study (study of DNA) of early Eurasian horses, published in June in the journal Nature, showed that Yamnaya horses were not ancestors of the first clearly domestic horses, known as the DOM2 lineage. And Yamnaya horses showed no signs of controlled breeding, such as genetic changes linked with inbreeding (breeding between closely related animals).
Instead, the first DOM2 horses appeared just before 2000 B.C., long after the Yamnaya migrations and just before the first archaeological evidence of horses being buried with chariots.
Currently, all the evidence seems to suggest that horse domestication probably took place in the Black Sea steppes, but much later than the Kurgan hypothesis suggests. Human control of horses seems to have started just before horses and chariots spread rapidly across Eurasia in the early second millennium B.C.
Of course, there are still more questions to be answered. In the latest study, the researchers noted some odd patterns in the Botai data, especially fluctuations in genetic estimates for generation time (how long it takes for a population to reproduce). Could this mean that Botai people kept the wild Przewalski’s horses in captivity, but only for meat, without using them for transportation? Perhaps. Future research will tell us more.
Either way, from these mixed signals, one thing is clear: The early history of humans and horses is ready for a new retelling.
SummaryThis article explains how new scientific discoveries are changing what we know about when and how humans first domesticated (tamed and bred) horses. Scientists used to think that horse domestication started with the Yamnaya people in western Asia about 5,500 years ago. However, recent studies, including DNA evidence, suggest that domesticated horses appeared much later, around 4,000 years ago, and not from the Yamnaya horses. The new research shows that early horses may not have been used for riding or carrying goods as much as previously thought. This means that the early story of how humans and horses first came together is more complex and needs to be rewritten.
Glossary
- Domestication: The process of taming an animal and keeping it as a pet or on a farm.
- Paleolithic: Relating to the early phase of the Stone Age, lasting about 2.5 million years, when primitive stone tools were used.
- Eurasia: A large geographical region that includes both Europe and Asia.
- Steppes: Large areas of flat, unforested grassland.
- Mobility: The ability to move easily and quickly.
- Archaeozoology: The study of ancient animal remains found at archaeological sites.
- Przewalski’s horse: A rare and endangered species of wild horse from the steppes of central Asia.
- Genomic sequencing: A process used to determine the complete DNA sequence of an organism's genome.
- Inbreeding: Breeding between closely related individuals, which can lead to a higher chance of offspring having genetic problems.
