What did pigs evolve from?

Pig is one of the oldest species on the earth, with a history of 36 million years, which is even older than human beings 10 times. As we all know, domestic pig Sus Scrofa Domesticus originated from the domestication of wild boar. At present, wild boars are mainly distributed in the southern part of Eurasia, that is, European wild boars are distributed in Tianshan Mountains in Europe, North Africa and Central Asia, and Asian wild boars are distributed in Chinese mainland, Taiwan Province Province, Java, Sumatra and New Guinea. In contrast, the distribution of domestic pigs is much larger, almost all over the world, and the varieties are varied and diverse. There are obvious differences in morphology and habits between domestic pigs and wild boars. The mandible, skull and lacrimal bone of domestic pigs are shortened, canine teeth are degenerated, nose moves up, face is sunken, face is widened, hindquarters are lengthened, weight is increased, body width is widened, gastrointestinal tract is developed, and abdominal circumference is enlarged. They are usually active during the day and rest at night, and their temperament is quite docile. People can't help asking, how did the fierce wild boar domesticate into domestic pigs with different shapes and habits? When and where did domestic pigs originate? Is it single origin or multi-origin? These are long-term concerns of academic circles. Over the years, scholars at home and abroad have made unremitting explorations on the origin and domestication of domestic pigs from different angles and achieved quite fruitful results. However, at the beginning of domestication, how to distinguish domestic pigs from wild boars was still at a loss. On the basis of reviewing the previous work, this paper tries to put forward new ideas around the above key issues, hoping to contribute to the in-depth study. Evidence of Animal Archaeology Since the birth of archaeology, the excavation results are changing with each passing day, which provides quite detailed physical data for exploring the origin of livestock. At present, exploring the origin of livestock mainly depends on the research results of animal archaeology. Generally speaking, judging whether animal bones unearthed from archaeological sites are domestic animals mainly depends on the following three principles: 1. Judging by the shape of bones, that is, comparing the size and shape of bones and teeth through observation and measurement, so as to distinguish domestic animals from wild animals. 2. Some animals in archaeological sites can be considered as domestic animals after conscious treatment by ancient humans. 3. The abnormal phenomena of animal age structure and bone morphology are organically combined with archaeological analysis to judge. It is reported that the world's earliest domestic pig was found in the Kayonu site in the southeast of Anatolia, the Asian part of Turkey, and its age was about 9,000 years ago. The earliest domestic pig found so far in China is generally believed to be the site of Cishan in Wu 'an County, Hebei Province, about 8000 years ago. The basis of this understanding is: 1, a complete pig bone with millet piled on it was found in the cave of this site; 2. Most pigs are between 1-2 years old; 3. The measurement data of upper and lower molars of pigs are similar to those of pigs unearthed in the late Neolithic site. 4. Stable carbon isotope analysis shows that pigs mainly eat C4 plants, which indicates that it is related to feeding. Regarding the preconditions for raising domestic pigs in the Neolithic Age, Mr. jing yuan thinks that there are the following three items: 1. The meat obtained by traditional hunting is obviously insufficient, so it is necessary to seek new meat resources; 2. There are a certain number of wild boar around the living environment, and it is easy to get domesticated objects; 3. There is a certain surplus of agricultural products, which provides enough feed for domestic pigs. It can be seen that the bamboo skin rock site in Guangxi where a large number of pig bones were unearthed is about 10 000 years ago. Because it does not meet the above conditions, it cannot be considered as the birthplace of domestic pigs. At the same time, relevant experts are actively discussing the pig bones unearthed from Jiahu site in Wuyang, Henan Province, about 9,000 years ago, and a clear conclusion should be reached soon.