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A day in the life of an excavation at Tam Pà Ling cave.
Credit: Kira Westaway (Macquarie University)
Something that creationists find puzzling, in their desperate search for certainty at the expense of truth, is how science continually reassesses and revisits what we think we know, and of course, how we change our collective mind when that produces new evidence.
An example of this was published recently in the journal Nature Communications, where a combined team of Laotian, French, Danish, American and Australian researchers showed the results of a reevaluation of the age of fossil early Homo sapiens, found in a cave in Northern Laos, and showed that early modern humans spread through the area, on their way into Southeast Asia and Australasia, much earlier than had originally been thought. This pushes the earliest Homo sapiens presence in the area back from 40,000 to 86,000 years ago.
The newer dating uses luminescence dating because Laotian law forbids damage to the specimens from what is a world heritage site.
Luminescence dating is a method used by archaeologists and geologists to determine the age of archaeological or geological materials. It relies on the principle that certain minerals, such as quartz and feldspar, accumulate energy from ionizing radiation in the environment over time. This energy is stored in the form of trapped electrons within crystal defects or lattice imperfections.The research is explained in a press release from Flinders University, Australia:
When these minerals are exposed to sunlight or heat, the trapped electrons are released and the energy is emitted as light. This phenomenon is known as luminescence. By measuring the amount of luminescence emitted from a sample and comparing it to the known radiation dose received by the material since its last exposure to light, scientists can estimate the time that has elapsed since the material was last heated or exposed to sunlight.
Luminescence dating is particularly useful for dating sediments and fired materials such as ceramics or burnt stones, which have been exposed to sunlight or heat in the past. It is commonly applied in archaeological research to determine the age of artifacts or the deposition age of sediments. The method can provide ages ranging from a few hundred years to several hundred thousand years.
There are two main types of luminescence dating techniques: thermoluminescence (TL) dating and optically stimulated luminescence (OSL) dating. Thermoluminescence measures the light emitted when a sample is heated, while OSL measures the light emitted when a sample is stimulated with a controlled light source.
By using luminescence dating, archaeologists can establish the chronology of archaeological sites and artifacts, as well as gain insights into human activities, environmental changes, and geological processes in the past. It is an important tool for dating materials beyond the range of radiocarbon dating and provides valuable information for understanding the history and development of human civilizations.
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A rare glimpse of our first ancestors in mainland Southeast AsiaFrom the team's open access paper in Nature Communications
What connects a fossil found in a cave in northern Laos with stone tools made in north Australia? The answer is, we do. When our early Homo sapiens ancestors first arrived in Southeast Asia on their way from Africa to Australia, they left evidence of their presence in the form of human fossils that accumulated over thousands of years deep in a cave.
The latest evidence from Tam Pà Ling cave in northern Laos, uncovered by a team of Laotian, French, American and Australian researchers and published in Nature Communications, demonstrates beyond doubt that modern humans spread from Africa through Arabia and to Asia much earlier than previously thought.
It also confirms that our ancestors didn’t just follow coastlines and islands. They travelled through forested regions, most likely along river valleys, too. Some then moved on through Southeast Asia to become Australia’s First People.
Three Australian Universities contributed to the project. The researchers at the Flinders Microarchaeology Laboratory showed that the sediment in the cave had been laid down in distinct layers over tens of thousands of years.Tam Pà Ling plays a key role in the story of modern human migration through Asia but its significance and value is only just being recognised.
Assistant Professor Fabrice Demeter, co-lead authors.
Lundbeck Foundation GeoGenetics Centre
Globe Institute
University of Copenhagen, Copenhagen, Denmark
The Flinders Microarchaeology Laboratory researchers supported the dating evidence with a detailed analysis of the sediments to assess the origin of the fossils.Far from reflecting a rapid dump of sediments the site represents a consistent and seasonally deposited stack of sediments.
Associate Professor Mike W. Morley, co-author
Flinders Microarchaeology Laboratory, Archaeology,
College of Humanities, Arts and Social Sciences,
Flinders University, Adelaide, SA, Australia
They used a number of techniques including micromorphology, which examines sediments under a microscope to establish the integrity of the layers. This key component of the new chronology helped establish that there was a fairly consistent accumulation of sedimentary layers over a long period.
The results of our microarchaeological analyses have drawn for us a better appreciation of the ground conditions in Tam Pà Ling in the past, therefore allowing for more precise interpretations of how and when these early modern human fossils were buried in this part of the cave.
Vito C. Hernandez, co-author
PhD student
Flinders Microarchaeology Laboratory, Archaeology,
College of Humanities, Arts and Social Sciences,
Flinders University, Adelaide, SA, Australia.Since the first excavation and the discovery of a skull and mandible in 2009, the cave has been controversial. Evidence of our earliest journeys from Africa into Southeast Asia is usually dominated by island locations such as Sumatra, Philippines and Borneo.It gives us great pride and joy to be part of a laboratory that is exploring and using cutting edge techniques in archaeological science and contributing to a greater understanding of the prehistory of modern humans in the Australasian region!
Meghan S. McAllister-Hayward.
PHD Student and 2021 International Student Awards winner
Flinders Microarchaeology Laboratory, Archaeology,
College of Humanities, Arts and Social Sciences,
Flinders University, Adelaide, SA, Australia.
This was before Tam Pà Ling, an upland cave site more than 300 kilometres from the sea in northern Laos, started divulging its secrets. The skull and jawbone were identified as belonging to Homo sapiens who had migrated through the region. But when?
As is usual in questions of human dispersal, the debate comes down to timing. But this evidence was hard to date.Without luminescence dating this vital evidence would still have no timeline and the site would be overlooked in the accepted path of dispersal through the region Luckily the technique is versatile and can be adapted for different challenges.
Associate Professor Kira E. Westaway.
School of Natural Sciences
Faculty of Science and Engineering
Macquarie University, Sydney, NSW, Australia.
The human fossils cannot be directly dated as the site is a World Heritage area and the fossils are protected by Laotian law. There are very few animal bones or suitable cave decorations to date, and it is too old for radiocarbon dating. This placed a heavy burden on the luminescence dating of sediments to form the backbone of the timeline.
Luminescence dating relies on a light-sensitive signal that is reset to zero when exposed to light but builds up over time when shielded from light during burial. It was originally used to constrain the burial sediments that encased the fossils.
These techniques returned a minimum age of 46,000 years – a chronology in line with the expected timing of Homo sapiens’ arrival in Southeast Asia. But the discovery didn’t end here.
From 2010 to 2023, annual excavations (delayed by three years of lockdowns) revealed increasingly more evidence that Homo sapiens had passed through en route to Australia.
Seven pieces of human skeleton were found at intervals through 4.5 metres of sediment, pushing the potential timeline far back into the realms of the earliest Homo sapiens migrations to this region.Having direct dating of the fossil remains confirmed the age sequence obtained by luminescence, allowing us to propose a comprehensive and secure chronology for a Homo sapiens presence at Tam Pà Ling.
Professor Renaud Joannes-Boyau.
Geoarchaeology and Archaeometry Research Group (GARG)
Southern Cross University, Lismore, NSW, Australia
In this study, the team overcame these issues by creatively applying strategic dating techniques where possible, such as the uranium-series dating of a stalactite tip that had been buried in sediment, and the use of uranium-series dating coupled with electron-spin resonance dating techniques to two rare but complete bovid teeth, unearthed at 6.5 metres.
The team supported the dating evidence with a detailed analysis of the sediments to assess the origin of the fossils using micromorphology, a technique that examines sediments under a microscope to establish the integrity of the layers. This key component of the new chronology helped establish that there was a consistent accumulation of sedimentary layers over a long period.
Fig. 1: Photograph of the TPL 6 frontal bone.
Fig. 2: Photograph of TPL 7 tibial fragment.
Fig. 3: Stratigraphic sections of the main excavation (trench 3) at Tam Pà Ling.
a Anterior view of the left superciliary arch and supraorbital margin, and portions of the frontal squama and temporal line; b endocranial surface including some of the left orbital plate and frontal crest; c left lateral view.
Fig. 2: Photograph of TPL 7 tibial fragment.
a Medial view indicating the inferior portion of the tibial tuberosity; b left lateral view indicating the interosseous crest; c posterior view indicating the vertical line; d anterior view; e distal view; f proximal view.
Fig. 3: Stratigraphic sections of the main excavation (trench 3) at Tam Pà Ling.
Profile 1 on the right is located at the base of the slope directly facing the entrance of the cave, and Profile 2, which is ~5 m adjacent to the east wall.
AbstractSo, the story of how and when modern humand dispersed out of Africa into the rest of the world, just got a little more complete, and it's beginning to look like at least some left Africa considerably earlier than we first thought.
The timing of the first arrival of Homo sapiens in East Asia from Africa and the degree to which they interbred with or replaced local archaic populations is controversial. Previous discoveries from Tam Pà Ling cave (Laos) identified H. sapiens in Southeast Asia by at least 46 kyr. We report on a recently discovered frontal bone (TPL 6) and tibial fragment (TPL 7) found in the deepest layers of TPL. Bayesian modeling of luminescence dating of sediments and U-series and combined U-series-ESR dating of mammalian teeth reveals a depositional sequence spanning ~86 kyr. TPL 6 confirms the presence of H. sapiens by 70 ± 3 kyr, and TPL 7 extends this range to 77 ± 9 kyr, supporting an early dispersal of H. sapiens into Southeast Asia. Geometric morphometric analyses of TPL 6 suggest descent from a gracile immigrant population rather than evolution from or admixture with local archaic populations.
Freidline, S.E., Westaway, K.E., Joannes-Boyau, R. et al.
Early presence of Homo sapiens in Southeast Asia by 86–68 kyr at Tam Pà Ling, Northern Laos.
Nat Commun 14, 3193 (2023). https://doi.org/10.1038/s41467-023-38715-y
Copyright: © 2023 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
I'll leave creationists to work out how this fits in with their infantile, evidence-free superstition of magic creation of humans in the Middle East, without ancestors, about 6, 000 years ago, followed by a genocidal flood with just eight survivors about 4,000 years ago. A flood, moreover that left multiple anual layers of sediment in a cave in Laos, for at least 86,000 years, burying the remains of the anatomically-modern humans living there at that time.
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