Research press release


Scientific Reports

Evolution: Prehistoric human populations prospered before the agricultural boom

ヒト集団の大規模な成長と活動は、農業の発達によって促進されたが、新石器時代より前から大きく拡大し始めたのか、その後だったのかについては論争が続いている。ヒトは、新石器時代に作物を栽培し、動物を家畜化し始めている。農業は、約1万2000~1万1000年前に西アジアの肥沃な三日月地帯で発生し、その後の数千年間に他の地域で独自に発達したと考えられている。今回、L Jinたちは、世界各地でのヒトの人口増加パターンを比較するために、1000ゲノムプロジェクトで得られたアフリカ、ヨーロッパ、南北アメリカの11集団の900点以上のミトコンドリアゲノムを解析した。その結果、Jinたちは、拡大するヒト系統を同定し、過去の人口統計学的変動を再現した。アフリカ、ヨーロッパ、南北アメリカのいずれの大陸でも、農業が登場するまでに、主要なヒト系統の大部分が融合していた。


Major prehistoric human population expansions in three continents may have begun before the Neolithic period - around 15-11,000 years ago in Africa, from around 13,000 years ago in Europe and around 12-8,000 years ago in the Americas. The findings are published in Scientific Reports.

The development of agriculture facilitated extensive human population growths and activities, but whether these major expansions began before or after the Neolithic era, a period during which humans started to grow crops and domesticate animals, remains controversial. Agriculture is thought to have first developed in the Fertile Crescent of West Asia around 12-11,000 years ago, and was then developed independently over the next few thousand years in other regions. To compare global patterns of population growth, Li Jin and colleagues analyzed over 900 mitochrondrial genomes generated by the 1000 Genomes Project, representing 11 populations in Africa, Europe and the Americas. They identified the expansion lineages and were able to reconstruct the historical demographical variations. On all three continents, most of the major lineages coalesced before the first appearance of agriculture.

The data imply that major population expansions took place after the Last Glacial Maximum (the peak of the last ice age) but before the Neolithic period. The authors suggest that the milder climate after the Last Glacial Maximum may have offered a more amiable environment and may have been an important factor in prehistoric human expansions. The increase in population size was probably one of the driving forces that led to the introduction of agriculture, turning it from a supplementary food source to the primary one.

doi: 10.1038/srep00745


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