Out of Africa and into an archaic human melting pot

Genetic analysis has revealed that the ancestors of modern humans interbred with at least five different archaic human groups as they moved out of Africa and across Eurasia.

Out of Africa and into an archaic human melting pot
A map showing where the ancestors of modern humans appear to have met and mixed
with archaic hominins [Credit: University of Adelaide]

While two of the archaic groups are currently known — the Neanderthals and their sister group the Denisovans from Asia ¬- the others remain unnamed and have only been detected as traces of DNA surviving in different modern populations. Island Southeast Asia appears to have been a particular hotbed of diversity.

Published in the Proceedings of the National Academy of Sciences, researchers from the University of Adelaide’s Australian Centre for Ancient DNA (ACAD) have mapped the location of past «mixing events» (analysed from existing scientific literature) by contrasting the levels of archaic ancestry in the genomes of present-day populations around the world.

«Each of us carry within ourselves the genetic traces of these past mixing events,» says first author Dr João Teixeira, Australian Research Council Research Associate, ACAD, at the University of Adelaide. «These archaic groups were widespread and genetically diverse, and they survive in each of us. Their story is an integral part of how we came to be.

«For example, all present-day populations show about 2% of Neanderthal ancestry which means that Neanderthal mixing with the ancestors of modern humans occurred soon after they left Africa, probably around 50,000 to 55,000 years ago somewhere in the Middle East.»

But as the ancestors of modern humans travelled further east they met and mixed with at least four other groups of archaic humans.

Out of Africa and into an archaic human melting pot
Proposed route of the ancestors of modern humans out of Africa and through Island Southeast Asia
[Credit: University of Adelaide]

«Island Southeast Asia was already a crowded place when what we call modern humans first reached the region just before 50,000 years ago,» says Dr Teixeira. «At least three other archaic human groups appear to have occupied the area, and the ancestors of modern humans mixed with them before the archaic humans became extinct.»

Using additional information from reconstructed migration routes and fossil vegetation records, the researchers have proposed there was a mixing event in the vicinity of southern Asia between the modern humans and a group they have named «Extinct Hominin 1».

Other interbreeding occurred with groups in East Asia, in the Philippines, the Sunda shelf (the continental shelf that used to connect Java, Borneo and Sumatra to mainland East Asia), and possibly near Flores in Indonesia, with another group they have named «Extinct Hominin 2».

«We knew the story out of Africa wasn’t a simple one, but it seems to be far more complex than we have contemplated,» says Dr Teixeira. «The Island Southeast Asia region was clearly occupied by several archaic human groups, probably living in relative isolation from each other for hundreds of thousands of years before the ancestors of modern humans arrived.

«The timing also makes it look like the arrival of modern humans was followed quickly by the demise of the archaic human groups in each area.»

Author: Robyn Mills | Source: University of Adelaide [July 15, 2019]

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Ancient Roman port history unveiled

Researchers successfully reconstructed anthropic influences on sedimentation, including dredging and canal gates use, in the ancient harbour of Portus — a complex of harbour basins and canals that formed the hub of commerce in the capital of the Roman Empire.

Ancient Roman port history unveiled
A team of international researchers led by La Trobe University and the University of Melbourne have, for the first time
worldwide, applied marine geology techniques at an ancient harbour archaeological site to uncover ancient
harbour technologies of the first centuries AD [Credit: La Trobe University]

The findings suggest that the Romans were proactively managing their river systems from earlier than previously thought — as early as the 2nd century AD.

The history was reconstructed using a range of high-resolution sediment analysis including piston coring, x-ray scanning, radiocarbon dating, magnetic and physical properties and mineral composition of the ancient harbour sediments.

La Trobe University Archaeology Research Fellow and marine geologist, Dr Agathe Lisé-Pronovost, said that ancient harbours can accumulate sediments more rapidly than natural environments, which is the case of Portus built in a river delta and where sediment accumulated at a rate of about one meter per century. Applying these methods allowed researchers to date and precisely reconstruct the sequence of events of the historical port, including dredging to maintain enough draught and canal gate use.

«Dating ancient harbour sediments is a major challenge, given ports are not only subjected to weather events throughout history, but the lasting effects of human activity,» Dr Lisé-Pronovost said.

«The methods we’ve applied have allowed us to address the dating issue and routine measurements of the sort could greatly improve chronostratigraphic analysis and water depth reconstruction of ancient harbour deposits.»

Dr Lisé-Pronovost and her team encourage geoarchaeologists to implement these innovative methods to their work.

The research has been published in Quaternary International.

Source: La Trobe University [July 15, 2019]

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2,000-year-old temple floor discovered at Malta’s Tas-Silġ excavations

The floor of a temple dating back to prehistoric times was uncovered in ongoing excavation works at Tas-Silġ, the Culture Ministry said.

2,000-year-old temple floor discovered at Malta's Tas-Silġ excavations
Credit: Heritage Malta

In a statement, it said the 2,000-year-old floor of the Temple of Ashtart was uncovered in a ‘farmhouse’ with various remains at the site.
The removal of the farmhouse floors have uncovered a series of floors and preparation layers, the ministry said.

2,000-year-old temple floor discovered at Malta's Tas-Silġ excavations
Credit: Heritage Malta

«The site at Tas-Silg contains the remains of over 4,000 years of structures, most of which were used for religious purposes,» Culture Minister Owen Bonnici said.
The Temple of Ashtart was made famous by Roman senator and orator Cicero when made reference to it in a prosecution speech against Caius Verres.

2,000-year-old temple floor discovered at Malta's Tas-Silġ excavations
Credit: Heritage Malta

Along the years, both the Missione Archeologica a Malta and the Department of Classics and Archaeology of the University of Malta have conducted extensive excavations at this site.
A ‘farmhouse’ located on the site is being restored and will be turned into a visitor centre equipped with digital interpretations.

These excavations are being carried out in collaboration with the Department of Classics and Archaeology of the University of Malta, which is utilising this dig to train its students in archaeological practices. Close collaboration is also held on this and other digs with the Superintendence of Cultural Heritage.

This project is just the first step in a long-term plan that Heritage Malta is currently implementing for the site. This includes the finalising of a management plan, and a conservation plan.

Author: Denise Grech | Source: The Times of Malta [July 15, 2019]

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