65,000 years of human occupation in Australia
克里斯托弗·克拉克森 Chris Clarkson
(澳大利亚昆士兰大学 University of Queensland)
澳洲是认识现代人类分布极其宝贵的地区，其原因众多。 首先，这个地区从来没有古老的人类居住，因此最古老的活动遗迹确属于第一批到达的现代人，这里是他们走出非洲漫长旅程的终点。其次，要到达澳洲和新几内亚，至少需要穿越65公里的大洋通道，这就需要有能够载人和充足的物资的远洋船只。第三，澳大利亚是世界上最干燥的大陆，拥有独特的动植物群，需要人类明显的适应和改变来开发新资源，采取新的居住和生存策略。 最后，遗传分析表明澳大利亚土著居民自从第一次到达此处以来就一直处于孤立状态，因此，这个大陆的文化和技术变化一定是独立于其他地方而发生的。
2012年和2015年，我们在两个漫长的季度发掘深度达3.5米。这个结果具有全球意义，因为这完全改变了我们对于最早人类到达澳洲及其广大区域的时间和性质的认识。 我们的研究结果加强了我们对现代人最初走出非洲并经亚洲到达太平洋边缘地带的科学认识。对发掘材料的研究包含了三大方面。第一，进行了该地区有史以来最全面的释光和放射性碳联合测年项目，由54个样品中的24800粒砂和50个AMS放射性碳样本进行年代测定。人类活动的新基准年代确定在65000 +/- 5000年，将现代人到达该地的年代前推了至少15000年。其次，对遗址结构进行了综合研究，包括对石质工具进行拼合，对燃烧遗迹和相关的炉灶遗迹进行评估，对体量大的沉积物块进行薄片分析，以确定过去活动面和随后的干扰状况。多管齐下的研究显示该遗址没有受到严重的扰动，活动遗迹也没有受到后沉积过程的重大影响。第三，对遗址重大发现的研究表明，第一批进入该地区的现代人使用了当时技术相当复杂的石器，且进行了艺术活动，之前还从未有类似发现。该遗址出土了世界上已知最古老的石斧，并且在该地区首次使用磨石研磨种子，也是该地区进行颜料加工和添加反射云母以制造反射涂料最古老的例子。
The question of when modern humans spread out of Africa and colonised Asia, Australia and the Pacific has been an ongoing problem for generations of archaeologists that has proved difficult to solve for many reasons. Firstly, genetic analyses suggest this exodus likely took place 60-80,000 years ago – well beyond the limits of radiocarbon dating. Determining how old sites from this period are must therefore turn to alternative dating techniques, each with their own strengths and weaknesses. Secondly, many archaic species of humans likely inhabited different parts of Asia at this time, such as Denisovans, Homo Floresiensis, Neanderthals, and perhaps even Homo erectus. Thus determining which sites were made by which species is extremely difficult. Thirdly, the route modern humans must have taken to populate island southeast Asia, the combined Pleistocene landmass of Sahul (Australia and New Guinea), and the many Melanesian islands, traversed lands now deeply inundated by post-glacial sea level rise. Thus many sites from this early colonising period must lie deep under water. Finally, sites from this period generally do not preserve skeletal remains, hence the makers of stone tools and other items remains enigmatic.
Australia is an extremely valuable region of the world for understanding this story of modern human dispersal for a number of reasons. Firstly, there were never any archaic humans living in this region, hence the oldest traces of occupation must attest to the first arrival of modern humans at the end point of the long journey out of Africa. Secondly, to reach Australia and New Guinea ocean crossings of at least 65km in length were required, necessitating ocean-going vessels capable of carrying many people and abundant supplies. Thirdly, Australia is the driest continent on earth and home to a unique flora and fauna, necessitating dramatic adaptations to exploit new resources and adopting new settlement and subsistence strategies. Finally, genetic analyses indicate that Australian Aborigines have remained largely isolated since first colonisation, hence cultural and technological changes on this landmass must have taken place independently of those elsewhere.
Our research aimed to determine when modern humans first reached Australia, by returning to the site of Madjedbebe (formerly known as Malakunanja II) and to undertake state-of-the-art excavations using appropriate dating techniques that can stretch beyond the radiocarbon barrier. Our team consisted of lithic specialists, luminescence dating experts, geoarchaeologists, usewear and residue experts, radiocarbon dating experts, anthracologists, archaeobotanists, archaeozoologists, malacologists, geomorphologists and palaeoclimate experts.
In 2012 and again in 2015, we excavated to 3.5m depth in two lengthy field-seasons. The results are globally significant because they have completely changed our understanding of the timing and nature of the first human occupation of Australia and the region more generally. Our results enhance our scientific appreciation of the initial dispersal of modern humans out of Africa and across Asia to the edge of the Pacific. The analysis of excavated material consisted of three major components. The first saw one of the most comprehensive combined luminescence and radiocarbon dating programs ever undertaken in the region, with ages determined for 24,800 sand grains from 54 samples and 50 AMS radiocarbon dates. A new baseline age for human occupation was established at 65,000 +/-5000 years, pushing back the age of modern human occupation in the region by at least 15,000 years. Second, extensive studies were undertaken to ascertain the structural integrity of the site, including refitting of stone tools, assessments of burning and associated hearths, and thin-section analysis of bulk sediment blocks to establish the presence of past occupation surfaces and subsequent disturbance. This multi-pronged investigation revealed the site was not significantly disturbed and that occupation deposits were not overly affected by post-depositional processes. Third, analysis of the remarkable finds from the site demonstrated that the first modern humans to enter the region employed stone tools that were highly sophisticated for the time and engaged in artistic practices not known before from this period. The site contains the oldest known stone axes in the world, the first use of seed-grinding grindstones in the region, and the oldest examples known in the region of pigment processing and admixture of reflective mica paint additives to make reflective paints.
In partnership with the local Mirarr Aboriginal traditional owners of the site, the research was published in Nature in July 2017 and received extensive global media attention and extensive television coverage. It demonstrates the profound antiquity of modern human occupation of Australia and expands our understanding of early technological capabilities, such as open-ocean crossings and the behavioural flexibility required to establish a viable human population in the unique Australian environment.