When did humans first arrive in Southeast Asia?

When our team first found human skulls and chin bones in Tampà -ling Cave in northern Laos in 2009, some were skeptical about their origins and their real age.

When we A schedule has been published In 2012, skeptics remained based on the TamPà-ling evidence due to the arrival of modern humans, about 46,000 years ago.

In short, the site is not good at rap. One of the most interesting caves in Southeast Asia is often seen as a possible pathway on the dispersed path of humans in the region.

But, New research Posted in Natural CommunicationsWe report more human remains found in TamPàLing, and a more detailed, robust timeline for the website. This suggests that humans arrived in the region at least 68,000 years ago, possibly up to 86,000 years.

Lots of evidence, but it’s hard to date

Our Lao, French, American and Australian researchers dig in TamPàLing for many years. As we dig, we find more and more evidence Homo sapiens In early and earlier times.

First it is a finger bone, then about 2.5 meters deep, the chin bone, and then part of the rib. Eight pieces were found in the sediment of only 4.5 meters in total, which may not sound like a lot, but are archaeologically huge.

Of course, we think that this is enough to get TamPà-Ling in the early human arrival locations in Southeast Asia.

But there is still one obstacle: the cave is difficult to arrive. This prevents its meaning from being recognized, and without a compelling timeline, evidence of the cave will not be included in the debate about early human movements.

Many common dating methods are not available

There are some difficulties with dating tampàling.

First, human fossils cannot be stated directly because the site is a World Heritage Site and the fossils are protected by Laos’ laws.

Second, there are few animal bones and no suitable cave decorations, both of which can be used for dates.

Third, the entrance to the site is wide and steep. This means that any charcoal found in the cave may come from the outside and therefore has little to do with the age of the internal sediments.

This means that techniques such as the luminescent date must be used to determine the backbone of the schedule by the date of the sediment itself.

Signals for buried minerals

The luminescence date depends on the photosensitive signal accumulated in the buried sediment, resetting it to zero when exposed to light.

This technology mainly uses two minerals: quartz and feldspar.

Quartz can only be used in the younger level because it can limit the signals it can hold. In deeper layers, it can usually underestimate age, so in TamPà -ling we only use quartz with the first three meters of the sediment.

For lower levels (four to seven meters), we have to use feldspar to switch to dates to fill in the gaps in the age profile. Below six meters, feldstone cereals start the weather and we have to use tiny mineral particles to mix together, resorting to fine particles dating.

Dating teeth

In animal evidence, TamPàLing is relatively poor. However, the teeth of two cowhide animals were finally excavated from 6.5 meters deep, and two different techniques can be used to view them.

Uranium sequences date elements that change by measuring uranium and the inside of teeth through radioactive attenuation. The date of electron spin resonance depends on measuring the number of electrons in the tooth enamel.

Each technology provides fossils with individual digital ages. By combining both, we obtain reliable direct dates that can complement the luminous age.

Observe the sediment carefully

To make dating as strong as possible, we used every technique we could use, such as fixing the history of the uranium series in static burying it in sediment.

We also began supporting all dating evidence and conducting very detailed analysis of sediments to assess the origin of the fossils.

Micro-attitude is a technique to study sediments under a microscope to establish the integrity of the layers that buried fossils.

This is a key component of the new chronological order as it helps identify the long-term existence of fairly consistent sediment layers.

By 2022, we have accumulated a series of dating evidence that can be modeled to determine the exact age of each layer and the fossils they are buried.

Stop on the route of human transmission

Our latest chronology shows that humans exist near Tampà -Ling Cave for about 56,000 years. It also confirmed that the site did not reflect rapid sediments but contained stable accumulation of sediments over about 86,000 years.

The lowest fossil age is fragments of the leg bone depth of 7 meters, indicating that modern humans arrived in the region between 86,000 and 68,000 years ago.

TamPàLing’s evidence has been delayed Homo sapiens Arrive in Southeast Asia. This suggests that the location of the continent, as well as coastal and islands, may also be a viable spread route.

TamPàLing is just a stone’s throw from Cobra Cave The teeth were found About 150,000 years old belongs to Denisovan, a now-extinct relative of humanity that would otherwise be known only in the remains found in Siberia and Tibet. This suggests that the site may be located on a dispersed pathway among previously used humans.

TamPàling continues to reveal the puzzles of ancient human journeys around the world. Only time can tell how much it has in the store.

Kira Westaway is an associate professor at the School of Natural Sciences, Macquarie University. Meghan McAllister-Hayward is a PhD candidate. Mike W. Morley is an associate professor at Flinders University. Renaud Joannes-Boyau is an associate professor at Southern Inter-University. Vito C. Hernandez is a PhD candidate. This article is from dialogue.