Ancient DNA shows first farmers in South-East Asia migrated from China 4,500 years ago S

hare Print Mail Other share options ABC Science By science reporter Belinda Smith Updated Friday at 23:57 First posted Friday at 04:21

 An Vietnamese woman in a field.

 Modern humans have lived in South-East Asia for 70,000 years, but the first farmers probably came from China. (Unsplash: Danh Vo) Scraps of DNA thousands of years old have given archaeologists the "smoking gun" they need to show the first farmers in South-East Asia were migrants from south China. Key points: The onset of South-East Asian agriculture 4,000 to 4,500 years ago coincided with production of tools and pottery made in South China styles Agricultural practices arose through migration of new farmer populations or by a gradual change in the Indigenous hunter-gatherer lifestyle DNA analysis of 18 ancient humans suggests the former; farmers migrated from China to South-East Asia more than 4,100 years ago Researchers extracted DNA from ancient bones found in modern-day Vietnam, Cambodia, Thailand and Myanmar to estimate when new genes started flowing into the Indigenous hunter-gatherer populations of the time. They found an influx of genes from South China coincided with the appearance of agriculture in South-East Asia around 4,100 to 4,500 years ago, alongside pottery and tools made in the southern Chinese style. A second gene "pulse" flowed from China to South-East Asia a couple of thousand years later. The genetic analysis corroborates and extends linguistic and archaeological evidence of human dispersal in the region, said Marc Oxenham, a bioarchaeologist at the Australian National University and co-author of the study, which was published in Science on Friday. "We have, if you like, uncovered a smoking gun of genetic movement and mixture," he said. "Whether it be piecing together the lifeways of ancient peoples through their pottery … or exploring their deeper genealogies by way of ancient DNA, [each] provides a series of independent threads that form a greater weave of what it was like to be an ancient South-East Asian." Ancient DNA tells a story South-East Asia has a rich and complex history of human occupation. The first hominins, most likely Homo erectus, first appeared on the scene more than 1.6 million years ago. Modern Homo sapiens — that is, those that looked like us — showed up much later, moving in at least 70,000 years ago. Over tens of thousands of years, these hunter-gatherer colonists diversified and evolved, Professor Oxenham said. "Today we still see their presence, or descendants, as Indigenous Australians, Papuans … and so forth." Around 4,500 years ago, farming appeared, along with tools and pottery made in the style of southern China populations. A farmer tends to a rice paddy. The appearance of rice paddies in South-East Asia coincided with Chinese-style pottery and tools. (Unsplash: Simon Fanger) Whether that signified the spread of ideas or people, no-one was sure, said University of Adelaide paleogeneticist Bastien Llamas, who was not involved in the study. "Are the farmers coming from somewhere else, bringing these new technologies with them?" he asked. "Or was it diffusion of the culture, so the hunter-gatherers slowly learned and adapted to the new ways to become farmers?" To find out, Professor Oxenham and his colleagues examined DNA harvested from human remains found at five ancient South-East Asian sites. The specimens' age ranged from around 4,100 years ago, during the Neolithic period, to the Iron Age, 1,700 years ago. But extracting genetic information from such old samples is easier said than done. In cells, genomic DNA is coiled up in long strands, but when an organism dies, those strands start to fall apart. Add heat and humidity — like, say, the tropical conditions of South-East Asia — and DNA crumbles even faster. Ancient butchered rhino suggests humans lived in the Philippines 700,000 years ago butchered rhino image How these early humans and animals arrived at the island is unknown, but they may have been carried across by a tsunami. Luckily, to trace ancestry, geneticists don't need an individual's entire genome. A few specific sections will do. So from 146 individuals, the researchers were able to extract those specific areas from 18. And when they compared the ancient South-East Asian DNA with that from surrounding areas, they found the distinct genetic signature of South China. So it's likely that farmers from China slowly spread through South-East Asia between 4,100 to 4,500 years ago, bringing their languages and agricultural, tool-making and pottery technology with them. A couple of thousand years later, another influx of South China farmers made the same journey, evidenced by a different "pulse" of genes flowing into South-East Asia. Ultimately, Professor Oxenham said, the genetic mixing between these new migrants and the Indigenous populations "create the diversity of what is now mainland and island South-East Asia: Thais, Malaysians, Vietnamese, Indonesians, Filipinos, etcetera".