Ancient DNA finds answers to the mystery of cattle’s origin and domestication from prehistoric traces (Part 1)

Produced by: Science Popularization China

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

Producer: China Science Expo

Cattle play an important role in human culture and agricultural development, and are closely related to human life. As the largest and most powerful animal among domestic animals, cattle are often given multiple symbolic meanings. Cattle appeared in cave art murals during the Magdalenian period in Europe about 17,000 to 11,000 years ago. In China, cattle carry rich and profound cultural connotations as one of the twelve zodiac signs and the legend of "Laozi riding a green bull".

The Cow in Cave Art

(Photo source: veer photo gallery)

I ride a bull

(Photo source: veer photo gallery)

Despite this, our understanding of this "old friend" seems to be still limited.

This series of articles will be divided into two parts, leading everyone to learn about "cattle", including the common breeds such as cattle and buffalo, and combined with research papers related to "cattle", let everyone have a deeper understanding of them.

The taxonomic status of cattle

Cattle classification chart

(Picture source: self-made based on pictures from the Internet)

The extant cattle tribe (Bovini) can be further divided into the genera Bos, Bison, Bubalus, Syncerus and Pseudoryx.

The "cattle" we usually refer to are domestic cattle (Bos domesticus). In a broad sense, domestic cattle include all domesticated cattle, such as yellow cattle (Bos taurus), yaks (Bos grunniens) and water buffaloes (Bubalus bubalis), while in a narrow sense , domestic cattle only refer to yellow cattle (including common cattle (Bos taurus) and zebu cattle (Bos indicus)).

Kinship relationship diagram of members of the Niu family

(Image source: Knowledge is Power magazine)

Unlike groups of domestic animals that have descended from a single ancestor (such as domestic dogs and pigs), different species of domestic cattle are more distantly related than we thought. **Both cattle and yaks belong to the genus Bos, while buffaloes belong to the genus Bubalus. **Around 3 million years ago, cattle and buffalo split into two different groups, a degree of differentiation similar to the difference between cats and cheetahs. The split between cattle and yaks can be traced back to 1.6 million years ago.

How were cattle domesticated? Let’s start with the buffalo!

About 10,000 years ago, humans began an action that changed the world - domesticating animals. The "six domestic animals" we are familiar with all originated from humans' domestication of wild animals.

The origins of domesticated cattle are diverse. Taking the water buffalo as an example, studies have shown that the domestic water buffalo originated from the Asian wild water buffalo (Bubalus bubalis), and can be further divided into two types: river buffalo (Bubalus bubalis bubalis) and swamp buffalo (Bubalus bubalis carabanesis).

buffalo

(Photo source: veer photo gallery)

River buffalo originated in the Indian subcontinent and historically spread westward to the Balkans, Italy and Egypt, while swamp buffalo are mainly distributed in some areas of South Asia and Southeast Asia.

Research shows that swamp buffalo and river buffalo originated from different wild populations, namely wild buffalo populations in Southeast Asia 3,000 to 7,000 years ago and wild buffalo populations in India 6,300 years ago. Swamp buffalo were domesticated in southern China and northern Indochina about 8,000 years ago, and may have been introduced eastward through northwestern South Asia to China around 3,000 years ago. River buffalo were domesticated in western India 5,000 to 7,000 years ago, and then spread westward to the Mediterranean region.

Mitochondrial genome and Y chromosome studies based on modern samples indicate that swamp buffalo are more basal in the phylogenetic tree and have greater genetic diversity than river buffalo.

In addition, the study found a buffalo sample from Sri Lanka. Although it showed the characteristics of swamp buffalo in appearance, genetic evidence showed that it actually belonged to river buffalo. Combined with the high morphological similarity between swamp buffalo and wild Asian buffalo, the researchers speculated that river buffalo may have evolved from an ancestor similar to swamp buffalo. In addition, there is also genetic exchange between domesticated buffalo and wild buffalo.

How were cattle domesticated? Look at the yak!

The domestication of yaks is another story. We know that domestic yaks were domesticated from wild yaks, and their population history is closely related to human activities on the Qinghai-Tibet Plateau. Mitochondrial genome evidence from modern samples shows that there is a clear genetic differentiation between wild yaks and domestic yaks, among which the genetic diversity of domestic yaks is lower than that of wild yaks.

Yak

(Photo source: veer photo gallery)

The ancestor of the domestic yak is the primitive yak that appeared in the northeast of Eurasia more than 2.5 million years ago, while the "plateau giant" wild yak is the descendant of the primitive yak that migrated south into the heart of the Qinghai-Tibet Plateau during the Pleistocene period.

Modern genetic studies show that yak domestication began in the middle of the Holocene, about 7,300 years ago. The earliest archaeological evidence of domesticated yaks comes from the Lhasa River Valley in the southern Qinghai-Tibet Plateau 3,750 years ago. As humans settled on the plateau, the yak population increased rapidly, indicating that human domestication was crucial to the growth of the domestic yak population.

The domestication of yaks was different from the direct domestication of other species from wild populations, but rather through a gradual approach, in which cattle played a key role as an intermediate.

Modern genetic research has confirmed that domestic yaks and cattle in the Qinghai-Tibet Plateau share genes related to domestication selection, so some researchers have proposed that the domestication of yaks may have been achieved through hybridization with cattle, that is, the hybrid domestication model was adopted. This hybridization method not only successfully domesticated wild yaks into domestic yaks, but also enabled cattle to obtain genes for adapting to high-altitude hypoxia.

When talking about domestic cattle, we have to mention cattle (including common cattle and zebu cattle). As one of the most widely distributed and important large domestic animals in the world, cattle have undoubtedly made great contributions to human development. Therefore, the origin and domestication of cattle (cattle) have always been the focus of geneticists and archaeologists. This part will be discussed in detail in the next article, so stay tuned!

(Note: Latin parts in the text should be italicized)

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 Shungang, Gao Yu, Chen Ningbo, 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.