Ancient DNA finds answers to the mystery of cattle’s origin and domestication from prehistoric traces (Part 2)

Produced by: Science Popularization China

Author: Zhou Yue and Wang Caihui (School of Cultural Heritage, Northwest University)

Producer: China Science Expo

The previous issue mentioned how various types of cattle were domesticated, and this issue will bring you the origin and domestication of cattle (domestic cattle), and what efforts scientists have made from the perspectives of genetics and archaeology.

cattle

(Photo source: veer photo gallery)

In the early stages of the study, skeletal evidence was the main source of clues. By analyzing bone morphology, measurement data, and archaeological phenomena, researchers have comprehensively inferred that domestic cattle were domesticated from aurochs . To date, most academics believe that the earliest archaeological evidence of aurochs domestication comes from the Neolithic region of Southwest Asia, where aurochs remains dating back about 10,500 years with obvious traces of human activity were found.

The skull and reconstruction of a bull in the British Museum

(Image source: Diversity magazine)

Domestic cattle are generally smaller than aurochs and have different tooth wear patterns from aurochs. Combining morphological characteristics with evidence of human activity, a series of domestic cattle fossils were subsequently discovered in the Middle East (~8000 years ago), Europe (~7000 years ago), and the Mediterranean and Southeast Asia (~6000 years ago). This suggests that humans domesticated aurochs extensively in suitable environments in order to obtain a stable food source.

Comparison between aurochs and modern cattle

(Image source: Cambridge University Press blog)

The wild ancestor of domestic cattle - Aurochs

At this point, everyone must be wondering, what is aurochs? In fact, the story of aurochs can be traced back to the Pleistocene. Caesar once described it in "Black Forest": Aurochs are slightly smaller than elephants, huge in size, and extremely fast, and they are not inferior to humans or animals.

Aurochs in cave art

(Image source: Nature magazine)

However, with the development of human civilization, the fate of the aurochs took a dramatic turn. In Europe, hunting aurochs was not only a hunting activity, but also evolved into a symbol of strength and courage. Owning aurochs horns was even regarded as a sign of honor. Due to the above reasons, the aurochs became extinct by 1627. The aurochs are very different from domestic cattle, and their evolution process is not fully understood. Although the fossil record provides us with evidence of the existence of species, the impact of the environment and human activities on the preservation and distribution of fossils makes it difficult to reveal a more complex population history.

The development of genetics in recent years has provided new ideas for the study of animal origin and evolution. Therefore, researchers have also begun to try to use genetic methods to analyze the origin and domestication history of domestic cattle. Aurochs can be divided into three main subspecies: Eurasian aurochs, Indian aurochs, and North African aurochs . Common cattle and humped cattle were domesticated from Eurasian aurochs and Indian aurochs in the Near East and the Indus River Basin, respectively.

New insights from modern genetics

DNA (deoxyribonucleic acid) is the carrier of biological genetic information and records the genetic code of organisms. Modern genetic research shows that there are three main groups of domestic cattle, including Asian zebu, Eurasian common cattle and African common cattle . The main mitochondrial lineages of modern domestic cattle are T and I, belonging to the common cattle and zebu lineages respectively. Although there are significant genetic differences between common cattle and zebu, there is also a wide range of genetic connections between the two due to their common ancestors and hybridization events.

Zebu

(Photo source: veer photo library produced by: Science Popularization China

Author: Zhou Yue and Wang Caihui (School of Cultural Heritage, Northwest University)

Producer: China Science Expo

The previous issue mentioned how various types of cattle were domesticated, and this issue will bring you the origin and domestication of cattle (domestic cattle), and what efforts scientists have made from the perspectives of genetics and archaeology.

cattle

(Photo source: veer photo gallery)

In the early stages of the study, skeletal evidence was the main source of clues. By analyzing bone morphology, measurement data, and archaeological phenomena, researchers have comprehensively inferred that domestic cattle were domesticated from aurochs . To date, most academics believe that the earliest archaeological evidence of aurochs domestication comes from the Neolithic region of Southwest Asia, where aurochs remains dating back about 10,500 years with obvious traces of human activity were found.

The skull and reconstruction of a bull in the British Museum

(Image source: Diversity magazine)

Domestic cattle are generally smaller than aurochs and have different tooth wear patterns from aurochs . Combining morphological characteristics with evidence of human activity, a series of domestic cattle fossils were subsequently discovered in the Middle East (~8000 years ago), Europe (~7000 years ago), and the Mediterranean and Southeast Asia (~6000 years ago). This suggests that humans domesticated aurochs extensively in suitable environments in order to obtain a stable food source.

Comparison between aurochs and modern cattle

(Image source: Cambridge University Press blog)

The wild ancestor of domestic cattle - Aurochs

At this point, everyone must be wondering, what is aurochs? In fact, the story of aurochs can be traced back to the Pleistocene. Caesar once described it in "Black Forest": Aurochs are slightly smaller than elephants, huge in size, and extremely fast, and they are not inferior to humans or animals.

Aurochs in cave art

(Image source: Nature magazine)

However, with the development of human civilization, the fate of the aurochs took a dramatic turn. In Europe, hunting aurochs was not only a hunting activity, but also evolved into a symbol of strength and courage. Owning aurochs horns was even regarded as a sign of honor. Due to the above reasons, the aurochs became extinct by 1627. The aurochs are very different from domestic cattle, and their evolution process is not fully understood. Although the fossil record provides us with evidence of the existence of species, the impact of the environment and human activities on the preservation and distribution of fossils makes it difficult to reveal a more complex population history.

The development of genetics in recent years has provided new ideas for the study of animal origin and evolution. Therefore, researchers have also begun to try to use genetic methods to analyze the origin and domestication history of domestic cattle. Aurochs can be divided into three main subspecies: Eurasian aurochs, Indian aurochs, and North African aurochs. Common cattle and humped cattle were domesticated from Eurasian aurochs and Indian aurochs in the Near East and the Indus River Basin, respectively.

New insights from modern genetics

DNA (deoxyribonucleic acid) is the carrier of biological genetic information and records the genetic code of organisms. Modern genetic research shows that there are three main groups of domestic cattle, including Asian zebu, Eurasian common cattle and African common cattle . The main mitochondrial lineages of modern domestic cattle are T and I, belonging to the common cattle and zebu lineages respectively. Although there are significant genetic differences between common cattle and zebu, there is also a wide range of genetic connections between the two due to their common ancestors and hybridization events.

Zebu

(Photo source: veer photo gallery)

Mitochondrial diversity studies have shown that the Near East and the Indus River Basin are the possible origin centers of common cattle and zebu cattle, respectively . In addition, based on nuclear genome data, some researchers believe that the desert area of ​​present-day Egypt is the third origin of domesticated cattle, and common cattle in Africa may have originated from here. Interestingly, some time later, the common cattle population in Africa underwent a replacement of zebu cattle components, which mainly entered from the Horn of Africa and the East Coast.

Ancient DNA reveals the evolution of domestic cattle

Modern genetic evidence has provided important insights into the evolutionary history of our domestic cattle, but we still know very little about the details of their history. Ancient samples contain a wealth of ancient genetic information, which is undoubtedly important material for revealing evolutionary details that modern samples cannot answer. Ancient DNA provides direct evidence of early domestication and wild ancestors, advancing our understanding of animal domestication. In recent years, the combination of archaeological materials and ancient DNA technology has enabled us to dig deeper into the genetic information of ancient samples and draw a more complete evolutionary story.

A combination of ancient and modern genetic studies suggests that common cattle were domesticated in the Fertile Crescent between 10,300 and 10,800 years ago and subsequently spread eastward and westward.

Regarding the westward spread, common cattle arrived in Anatolia 10,000 years ago and in Europe about 8,500 years ago. Cattle remains unearthed in Greece support this view. There are two routes for their migration and spread in Europe. One is to France, Spain and other places via the Mediterranean coast 7,900 to 7,700 years ago. The other is to Central Europe via the Danube River 7,500 years ago and to Northern Europe 1,000 years later.

Regarding the eastward spread, common cattle arrived in China, Mongolia and other places between 5,000 and 4,000 years ago and became the ancestors of common cattle in East Asia. Fossil evidence unearthed in northern China dating back 4,500 to 2,300 years ago further confirms this view.

The spread of common cattle

(Image source: Diversity magazine)

During the early stage of the spread of domestic cattle, aurochs and domestic cattle had extensive gene exchange in many regions of Eurasia, including Italy, the Near East, and China (Shanxi and Qinghai). Based on the whole genome data of cattle in Northeast China from 43,000 to 3,590 years ago, researchers speculated that the East Asian aurochs may be a unique subspecies. Moreover, as early as 3,800 to 3,400 years ago, gene exchange also occurred between East Asian aurochs and cattle on the Qinghai-Tibet Plateau.

The spread of zebu cattle was independent of that of ordinary cattle. About 4,500 years ago, zebu cattle migrated eastward to the Ganges Valley. Neolithic remains unearthed in India also support this view. About 4,200 years ago, zebu cattle began to infiltrate the Near East extensively from the Indus River Basin, and spread from the Indian coastal route to Southeast Asia and southern China about 3,500 to 2,500 years ago, and arrived in Indonesia 1,000 years ago.

In addition, researchers speculate that 4,200 years ago, climate change caused zebu cattle to spread into Europe; 4,000 years ago, male zebu cattle were introduced into East Africa through the Persian Gulf and South Arabia, which was reflected in the remains in Egypt and Somalia 3,500 years ago.

Restoration of the Early Domestication History of Cattle

Previous studies have suggested that the domestication of cattle, especially the early domestication history, is far more complicated than we thought. Recently, Daniel G. Bradley's research team at Trinity College Dublin, Ireland, published a paper titled "The genomic natural history of the aurochs."

Paper title image

(Image source: screenshot of official website)

Using ancient genome information from 38 aurochs and 34 domestic cattle in Eurasia, scientists conducted a 47,000-year paleogenetic study, revealing the early evolution and domestication history of aurochs. This study provides a grand background on the genetic origin of "cattle" and greatly enriches our understanding of the evolution of aurochs.

Aurochs first appeared in Europe 650,000 years ago, and by the 100,000 years before the last glacial period, they had split into several different populations , including at least North Asian, Southwest Asian, and European populations. In the European population, two samples of aurochs (46,000 years ago and 47,000 years ago) have a close genetic relationship with samples after the last glacial period, indicating that the European population existed continuously before and after the last glacial period.

However, during the last ice age, due to the harsh climate, the habitat of aurochs in Europe was reduced to several "refuges" in southern Europe, including the Iberian Peninsula and the Balkan Peninsula. It is worth noting that most of the other ancient European samples are clustered together with the samples from the Iberian Peninsula, indicating that the aurochs populations in different refuges have different degrees of genetic contribution to other populations.

The North Asian population includes three Pleistocene-era aurochs, with a geographic range extending from western Russia (about 41,500 years ago) and Armenia (about 13,900 years ago) to Lake Baikal in the east (about 12,200 years ago). These three samples show ancestral lineages that have not undergone genetic mixing, and the authors speculate that ecological barriers prevented their contact with Europe. The aurochs in the Caucasus and Central Asia during the Holocene, however, show significant genetic mixing, which may be due to improved environmental conditions during the Holocene, which promoted exchanges between groups.

The Southwest Asian population includes two aurochs from central Turkey (about 7600 years ago) and Armenia (about 7100 years ago). In addition, aurochs from North Africa (Morocco, about 8800 years ago) also has a close genetic relationship with the Southwest Asian population, suggesting ecological continuity along the southern Mediterranean coast.

As mentioned above, the aurochs in East Asia may be a unique subspecies. In summary, the aurochs were widely distributed throughout Eurasia before domestic cattle were domesticated, which provided a population basis for the domestication of domestic cattle.

Cattle were first domesticated about 11,000 years ago by people living in southwest Asia, but genetic characteristics of that early population remain only faintly in modern cattle populations, reflecting a sharp decline in population numbers during the Ice Age.

Considering that the aurochs was one of the largest animals in ancient West Asia, it may have been a huge challenge to initially capture and control the reproduction of female cattle. Therefore, the authors speculate that humans domesticated the aurochs mainly through behaviors such as intentional provision of feed, rather than a passive domestication process in our traditional sense. The aurochs and domestic cattle still coexisted for thousands of years, and the genetic mixing of domestic cattle and undomesticated aurochs was widespread in the early spread of domestic cattle, and this mixing may have promoted adaptability.

Conclusion

Through the study of ancient cattle and domestic cattle remains, especially paleogenetic research, we have a deeper understanding of the origin and domestication history of domestic cattle. However, to reveal its evolutionary process more comprehensively, genome research on a wider range of older cattle samples is still needed. In the future, these studies will provide key evidence for revealing the complete history of domestic cattle domestication and help us understand the evolution of domestic cattle more comprehensively.

References:

1. Rossi C, Sinding MHS, Mullin VE, et al. 2024. The genomic natural history of the aurochs[J]. Nature, 2024: 1-6.

2.Chen S, Ren L, Gao Y, et al. 2024. Evidence of hybridization of cattle and aurochs on the Tibetan Plateau ~3750 years ago[J]. Science Bulletin, 69(18): 2825-2828.

3.Hou J, Guan X, Xia X, et al. 2024. Evolution and legacy of East Asian aurochs[J]. Science Bulletin, 69(21): 3425-3433.

4. Verdugo MP, Mullin VE, Scheu A, et al. 2019. Ancient cattle genomics, origins, and rapid turnover in the Fertile Crescent[J]. Science, 365(6449): 173-176.

5.Chen N, Cai Y, Chen Q, et al. 2018. Whole-genome resequencing reveals world-wide ancestry and adaptive introgression events of domesticated cattle in East Asia. Nat Commun, 9: 2337.

6. Chen SG, Gao Y, Chen NB, et al. 2024. Progress and prospects of archaeological and genetic studies on yak domestication in the Qinghai-Tibet Plateau[J]. Chinese Science Bulletin, 69(11): 1417-1428.