Group of British scientists claimed yesterday to have identified human footprints in central Mexico that are 40,000 years old, almost three times older than the most generally accepted evidence for human settlement in the Americas.
The team from universities in Liverpool, Bournemouth, and Oxford are convinced that the footprints are human and represent several adults and children who walked in freshly fallen volcanic ash in the Valsequillo Basin, about 80 miles south-east of Mexico City.
Working with international colleagues, they have applied dating techniques on the sediment itself and on finds including a land snail, a water snail and a mammoth tooth, all of which came back with an age of around 40,000 years.
The footprints had to be disentangled from animal tracks, more than 250 marks in all. Casts, which Matthew Bennett of Bournemouth University described as "unmistakably human" were produced from laser modelling at the site, employing a technique used to make industrial prototypes.
Although the findings were announced after two years of work at the British universities and elsewhere, they are controversial, defying the conviction of many scientists that humans arrived in the Americas not more than 15,000 years ago.
The tracks were made in gritty ash from the volcano, protected by later sediment layers, and underwater for long periods. The ash layer has since become as hard as concrete, and was locally quarried as a building material, which is how the footprints resurfaced.
Scientists partially excavated the quarry in the 1960s, and found ancient animal bones and hints of a very early habitation site, but with the technology of the day could not date them accurately.
The British team revisited the site two years ago. Silvia Gonzalez, from Liverpool John Moores University, first spotted the trail of marks, and described her instant conviction that they were human and very ancient as "like a thunderbolt in my mind".
4萬(wàn)年前人類(lèi)腳印將美洲人類(lèi)史提前
英國(guó)科學(xué)家日前宣布，他們?cè)谀鞲缰胁堪l(fā)現(xiàn)的人類(lèi)腳印已有大約4萬(wàn)年的歷史，從而*了此前有關(guān)美洲出現(xiàn)人類(lèi)的歷史不會(huì)超過(guò)1.5萬(wàn)年的結(jié)論。
據(jù)英國(guó)《衛(wèi)報(bào)》7月5日?qǐng)?bào)道，由英國(guó)利物浦大學(xué)、波恩茅斯大學(xué)和牛津大學(xué)的科學(xué)家組成的科研小組稱(chēng)，他們?cè)谀鞲绨l(fā)現(xiàn)的250多個(gè)足跡中，有三分之二屬于人類(lèi)的腳印，其中包括成年人和小孩的腳印。這些腳印是當(dāng)時(shí)人們?cè)谶€未凝固的火山巖上行走時(shí)留下的。
科協(xié)家通過(guò)放射性碳鑒定技術(shù)和激光學(xué)鑒定技術(shù)斷定，這些腳印屬于人類(lèi)，且約有4萬(wàn)年的歷史。除此之外，科學(xué)家還發(fā)現(xiàn)了一只蝸牛、一只水蝸牛和一顆猛犸的牙齒，并斷定它們也約有4萬(wàn)的歷史。
2003年9月，在墨西哥中部一個(gè)湖邊被廢棄的采石場(chǎng)中的火山巖上，科學(xué)家發(fā)現(xiàn)了這些人類(lèi)足跡，但當(dāng)時(shí)許多科學(xué)家都堅(jiān)信人類(lèi)到達(dá)美洲的歷史不會(huì)超過(guò)1.5萬(wàn)年。在經(jīng)過(guò)近兩年的爭(zhēng)論后，這一發(fā)現(xiàn)在近日才正式被公開(kāi)。其實(shí)早在上個(gè)世紀(jì)60年代，科學(xué)家就在此地發(fā)現(xiàn)了古代動(dòng)物的遺骨和早期人類(lèi)居住地的痕跡，但當(dāng)時(shí)的鑒定技術(shù)無(wú)法測(cè)定出這些發(fā)現(xiàn)物的準(zhǔn)確年代。
傳統(tǒng)史學(xué)觀點(diǎn)認(rèn)為，大約1.2萬(wàn)年前的“冰河期”晚期，美洲人祖先從歐亞大陸經(jīng)由“白令海峽”到達(dá)美洲。先前，也有科學(xué)家認(rèn)為，人類(lèi)來(lái)到美洲大陸的時(shí)間可能要比這一說(shuō)法早上數(shù)千年。但是，上述腳印的發(fā)現(xiàn)證明，人類(lèi)在4萬(wàn)年前曾居住在墨西哥中部。這*了史學(xué)家們長(zhǎng)期以來(lái)深信不疑的美洲人歷史不會(huì)超過(guò)1.5萬(wàn)年的結(jié)論。
The team from universities in Liverpool, Bournemouth, and Oxford are convinced that the footprints are human and represent several adults and children who walked in freshly fallen volcanic ash in the Valsequillo Basin, about 80 miles south-east of Mexico City.
Working with international colleagues, they have applied dating techniques on the sediment itself and on finds including a land snail, a water snail and a mammoth tooth, all of which came back with an age of around 40,000 years.
The footprints had to be disentangled from animal tracks, more than 250 marks in all. Casts, which Matthew Bennett of Bournemouth University described as "unmistakably human" were produced from laser modelling at the site, employing a technique used to make industrial prototypes.
Although the findings were announced after two years of work at the British universities and elsewhere, they are controversial, defying the conviction of many scientists that humans arrived in the Americas not more than 15,000 years ago.
The tracks were made in gritty ash from the volcano, protected by later sediment layers, and underwater for long periods. The ash layer has since become as hard as concrete, and was locally quarried as a building material, which is how the footprints resurfaced.
Scientists partially excavated the quarry in the 1960s, and found ancient animal bones and hints of a very early habitation site, but with the technology of the day could not date them accurately.
The British team revisited the site two years ago. Silvia Gonzalez, from Liverpool John Moores University, first spotted the trail of marks, and described her instant conviction that they were human and very ancient as "like a thunderbolt in my mind".
4萬(wàn)年前人類(lèi)腳印將美洲人類(lèi)史提前
英國(guó)科學(xué)家日前宣布，他們?cè)谀鞲缰胁堪l(fā)現(xiàn)的人類(lèi)腳印已有大約4萬(wàn)年的歷史，從而*了此前有關(guān)美洲出現(xiàn)人類(lèi)的歷史不會(huì)超過(guò)1.5萬(wàn)年的結(jié)論。
據(jù)英國(guó)《衛(wèi)報(bào)》7月5日?qǐng)?bào)道，由英國(guó)利物浦大學(xué)、波恩茅斯大學(xué)和牛津大學(xué)的科學(xué)家組成的科研小組稱(chēng)，他們?cè)谀鞲绨l(fā)現(xiàn)的250多個(gè)足跡中，有三分之二屬于人類(lèi)的腳印，其中包括成年人和小孩的腳印。這些腳印是當(dāng)時(shí)人們?cè)谶€未凝固的火山巖上行走時(shí)留下的。
科協(xié)家通過(guò)放射性碳鑒定技術(shù)和激光學(xué)鑒定技術(shù)斷定，這些腳印屬于人類(lèi)，且約有4萬(wàn)年的歷史。除此之外，科學(xué)家還發(fā)現(xiàn)了一只蝸牛、一只水蝸牛和一顆猛犸的牙齒，并斷定它們也約有4萬(wàn)的歷史。
2003年9月，在墨西哥中部一個(gè)湖邊被廢棄的采石場(chǎng)中的火山巖上，科學(xué)家發(fā)現(xiàn)了這些人類(lèi)足跡，但當(dāng)時(shí)許多科學(xué)家都堅(jiān)信人類(lèi)到達(dá)美洲的歷史不會(huì)超過(guò)1.5萬(wàn)年。在經(jīng)過(guò)近兩年的爭(zhēng)論后，這一發(fā)現(xiàn)在近日才正式被公開(kāi)。其實(shí)早在上個(gè)世紀(jì)60年代，科學(xué)家就在此地發(fā)現(xiàn)了古代動(dòng)物的遺骨和早期人類(lèi)居住地的痕跡，但當(dāng)時(shí)的鑒定技術(shù)無(wú)法測(cè)定出這些發(fā)現(xiàn)物的準(zhǔn)確年代。
傳統(tǒng)史學(xué)觀點(diǎn)認(rèn)為，大約1.2萬(wàn)年前的“冰河期”晚期，美洲人祖先從歐亞大陸經(jīng)由“白令海峽”到達(dá)美洲。先前，也有科學(xué)家認(rèn)為，人類(lèi)來(lái)到美洲大陸的時(shí)間可能要比這一說(shuō)法早上數(shù)千年。但是，上述腳印的發(fā)現(xiàn)證明，人類(lèi)在4萬(wàn)年前曾居住在墨西哥中部。這*了史學(xué)家們長(zhǎng)期以來(lái)深信不疑的美洲人歷史不會(huì)超過(guò)1.5萬(wàn)年的結(jié)論。