New geological datings place the first European hominids in the south of the Iberian Peninsula 1.3 million years ago

One of the most important controversies about human evolution and expansion is when and by what route the first hominids arrived in Europe from the African continent. Now, geological dating techniques at the Orce sites (Baza basin, Granada, Spain) place the human remains found in this area as the oldest in Europe, at approximately 1.3 million years old. These results reinforce the hypothesis that humans arrived in Europe through the south of the Iberian Peninsula, through the Strait of Gibraltar, instead of returning to the Mediterranean via the Asian route. The study, led by Lluís Gibert, researcher and lecturer at the University of Barcelona's Faculty of Earth Sciences, has involved the participation of researchers from the Berkeley Geochronology Centre and Murray State University (United States).

Analysis of a new sampling area

The new dating has been based on the analysis of the paleomagnetism of an area of the Orce region, which has never been sampled before and which has been protected from the erosion that this basin has suffered over the years. This technique is a relative dating method based on the study of the inversion of the magnetic poles of the planet due to the internal dynamics of the Earth. These changes do not have a specific periodicity, but they are recorded in the minerals and make it possible to establish time periods from the different magnetic events.

These new data are very precise thanks to the long sedimentary sequence that outcrops in Orce. "The uniqueness of these sites is that they are stratified and within a very long sedimentary sequence, more than eighty metres long. Normally, the sites are found in caves or within very short stratigraphic sequences, which do not allow you to develop long palaeomagnetic sequences in which you can find different magnetic reversals," says Lluís Gibert.

The researchers have been able to identify a magnetic polarity sequence "with five magnetic events that allow them to place the three Orce sites with human presence between the Olduvai and Jaramillo subchron, that is, between 1.77 and 1.07 million years ago (Ma)," says the researcher. Subsequently, they have applied a statistical age model to accurately refine the chronology of the different stratigraphic levels with a margin of error of only 70,000 years. The result of this innovative methodology is that the oldest site with human presence in Europe would be Venta Micena with an age of 1.32 Ma, followed by Barranco León, with an age of 1.28 and finally Fuente Nueva 3, with an age of 1.23 Ma. "With these data, the other major site on the peninsula, the Sima del Elefante in Atapuerca, would be relegated to second place, far behind Orce, between 0.2 and 0.4 Ma more modern," adds the researcher.

Fauna underpins the antiquity of the site

To complete the dating, the study has also analyzed the fauna found at the different sites in Orce, as this is different depending on the period, and compared it with that found at other Early Pleistocene sites in other parts of Europe.

In this sense, the paper presents a detailed analysis of the micromammals and large mammals from all the Orce sites, carried out by the expert Robert Martin, based on the palaeontological collections stored at the Museum of the Catalan Institute of Palaeontology Miguel Crusafont (IPS) in Sabadell. "The results indicate that the small and large fauna of Orce is more primitive than, for example, that of the Sima del Elefante, where the evidence shows that the rodent Allophaiomys lavocati is more evolved than the Allophaiomys recovered from the Orce sites," Gibert explains.Another relevant indicator of the age of the Orce sites is the absence of the ancestors of the pigs. "These animals are considered to be Asian immigrants and have not been found in any European site between 1 and 1.5 Ma, while they have been found in the Sima del Elefante, supporting that the Orce fauna is older," explains the researcher.

Evidence pointing to passage through Gibraltar

This new dating would be added, according to the researcher, to other evidence that would tip the balance in favour of the colonization of Europe through the Strait of Gibraltar, rather than the alternative route: the return to the Mediterranean via Asia, such as "the existence of a lithic industry with similarities to that found in the north of the African continent and also the presence of remains of African fauna in the south of the peninsula, such as those of Hippopotamus, found in the sites of Orce, and those of Theropithecus oswaldi, an African primate similar to a baboon, found in the Victoria cave, a site near Cartagena (Murcia), non-existent anywhere else in Europe."

"We also defend the hypothesis -- adds the researcher -- that they arrived from Gibraltar because no older evidence has been found at any other site along the alternative route."

These new data are very precise thanks to the long sedimentary sequence that outcrops in Orce.

Similarity with hominids from the island of Flores

With these results, the researchers point to a "diachronism" between the oldest occupation of Asia, measuring 1.8 Ma, and the oldest occupation of Europe, which would be 1.3 Ma ago, so that African hominids would have arrived in southwestern Europe more than 0.5 Ma after leaving Africa for the first time about 2 Ma ago. "These differences in human expansion can be explained by the fact that Europe is isolated from Asia and Africa by biogeographical barriers that are difficult to overcome, both to the east (Bosphorus Strait, Dardanelles, Sea of Marmara) and to the west (Strait of Gibraltar). Humanity arrived in Europe when it had the necessary technology to cross maritime barriers, as happened before a million years ago on the island of Flores (Indonesia)," says Gibert. In this sense, the researcher adds that the Gibraltar route currently requires crossing up to fourteen kilometres of sea route, but "perhaps in the past this distance was shorter at certain times due to the high tectonic activity in this region and the fluctuations in sea level that favoured migrations."

"As cited in the paper -- he adds -- , we have identified other migrations of African fauna through Gibraltar at earlier times, 6.2 and 5.5 Ma ago when the Strait of Gibraltar was very narrow."

Human remains in Orce

A total of five human remains were found at the Orce sites since excavations began in 1982 by the palaeoanthropologist Josep Gibert. Firstly, two fragments of humerus bitten by hyenas were found at Venta Micena, as well as parts of a cranial fragment consisting of two parietals and an occipital, associated with an abundant Early Pleistocene fauna. The human provenance of these remains generated great controversy for years, although independent palaeoproteomic studies by the universities of Granada and San Francisco identified human proteins in the remains.

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4,000-year-old plague DNA found -- the oldest cases to date in Britain

Researchers at the Francis Crick Institute have identified three 4,000-year-old British cases of Yersinia pestis, the bacteria causing the plague -- the oldest evidence of the plague in Britain to date, reported in a paper published today in Nature Communications.

Working with the University of Oxford, the Levens Local History Group and the Wells and Mendip Museum, the team identified two cases of Yersinia pestis in human remains found in a mass burial in Charterhouse Warren in Somerset and one in a ring cairn monument in Levens in Cumbria.

They took small skeletal samples from 34 individuals across the two sites, screening for the presence of Yersinia pestis in teeth. This technique is performed in a specialist clean room facility where they drill into the tooth and extract dental pulp, which can trap DNA remnants of infectious diseases.

They then analysed the DNA and identified three cases of Yersinia pestis in two children estimated to be aged between 10-12 years old when they died, and one woman aged between 35-45. Radiocarbon dating was used to show it's likely the three people lived at roughly the same time.

The plague has previously been identified in several individuals from Eurasia between 5,000 and 2,500 years before present (BP), a period spanning the Late Neolithic and Bronze Age (termed LNBA), but hadn't been seen before in Britain at this point in time. The wide geographic spread suggests that this strain of the plague may have been easily transmitted.

This strain of the plague -- the LNBA lineage -- was likely brought into Central and Western Europe around 4,800 BP by humans expanding into Eurasia, and now this research suggests that it extended to Britain.

Using genome sequencing, the researchers showed that this strain of the Yersinia pestis looks very similar to the strain identified in Eurasia at the same time.

The individuals identified all lacked the yapC and ymt genes, which are seen in later strains of plague, the latter of which is known to play an important role in plague transmission via fleas. This information has previously suggested that this strain of the plague was not transmitted via fleas, unlike later plague strains such as the one that caused the Black Death.

Because pathogenic DNA -- DNA from bacteria, protozoa, or viruses which cause disease -- degrades very quickly in samples which might be incomplete or eroded, it's also possible that other individuals at these burial sites may have been infected with the same strain of plague.

The Charterhouse Warren site is rare as it doesn't match other funeral sites from the time period -- the individuals buried there appear to have died from trauma. The researchers speculate that the mass burial wasn't due to an outbreak of plague but individuals may have been infected at the time they died.

Pooja Swali, first author and PhD student at the Crick, said, "The ability to detect ancient pathogens from degraded samples, from thousands of years ago, is incredible. These genomes can inform us of the spread and evolutionary changes of pathogens in the past, and hopefully help us understand which genes may be important in the spread of infectious diseases. We see that this Yersinia pestis lineage, including genomes from this study, loses genes over time, a pattern that has emerged with later epidemics caused by the same pathogen."

Pontus Skoglund, group leader of the Ancient Genomics Laboratory at the Crick, said, "This research is a new piece of the puzzle in our understanding of the ancient genomic record of pathogens and humans, and how we co-evolved.

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One of Swedish warship Vasa's crew was a woman

When the human remains found on board the warship Vasa were investigated, it was determined that the skeleton designated G was a man. New research now shows that the skeleton is actually from a woman.

About thirty people died when Vasa sank on its maiden voyage in 1628. We cannot know who most of them were, only one person is named in the written sources. When the ship was raised in 1961 it was the scene of a comprehensive archaeological excavation, in which numerous human bones were found on board and examined.

“Through osteological analysis it has been possible to discover a great deal about these people, such as their age, height and medical history. Osteologists recently suspected that G could be female, on the basis of the pelvis. DNA analysis can reveal even more”, says Dr Fred Hocker, director of research at the Vasa Museum, in Stockholm, Sweden.

Since 2004 the Vasa Museum has collaborated with the Department of Immunology, Genetics and Pathology at Uppsala University in Sweden to investigate all of the remains from Vasa and find out as much as possible about each individual. Initially the project focused on confirming if certain bones belonged to a specific person. Marie Allen, professor of forensic genetics, has led the work.

“For us, it is both interesting and challenging to study the skeletons from Vasa. It is very difficult to extract DNA from bone which has been on the bottom of the sea for 333 years, but not impossible”, says Marie Allen. She continues:

“Already some years ago we had indications that skeleton G was not a man but a woman. Simply put, we found no Y-chromosomes in G’s genetic material. But we could not be certain and wanted to confirm the result”.

The result has now been confirmed thanks to an interlaboratory study with Dr Kimberly Andreaggi of the Armed Forces Medical Examiner System’sArmed Forces DNA Identification Laboratory (AFMES-AFDIL) in Delaware, USA. The AFMES-AFDIL is the American Department of Defense’s laboratory, specializing in human remains DNA testing from deceased military personnel. They have established a new testing method for the analysis of many different genetic variants.

“We took new samples from bones for which we had specific questions. AFMES-AFDIL has now analysed the samples, and we have been able to confirm that G was a woman, thanks to the new test”, says Marie Allen.

For Marie Allen and Kimberly Andreaggi, the analysis of the Vasa skeletons is a way to develop their forensic methods, which can then be used to analyse DNA in criminal investigations or to identify fallen soldiers.

For the Vasa Museum the results of the DNA analysis are an important puzzle piece in the museum’s research into the people on the ship. Dr. Anna Maria Forssberg, historian and researcher at the museum, explains:

“We want to come as close to these people as we can. We have known that there were women on board Vasa when it sank, and now we have received confirmation that they are among the remains. I am currently researching the wives of seamen, so for me this is especially exciting, since they are often forgotten even though they played an important role for the navy“.

More results are expected shortly from the new samples. Marie Allen and Kimberly Andreaggi will be able to say something about how individuals looked, what colour their hair and eyes had, and possibly where their families came from.

“Today we can extract much more information from historic DNA than we could earlier and methods are being continuously refined. We can say if a person was predisposed to certain illnesses, or even very small details, such as if they had freckles and wet or dry ear wax”, says Marie Allen.

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Earliest human remains in eastern Africa dated to more than 230,000 years ago

The age of the oldest fossils in eastern Africa widely recognised as representing our species, Homo sapiens, has long been uncertain. Now, dating of a massive volcanic eruption in Ethiopia reveals they are much older than previously thought.

The remains -- known as Omo I -- were found in Ethiopia in the late 1960s, and scientists have been attempting to date them precisely ever since, by using the chemical fingerprints of volcanic ash layers found above and below the sediments in which the fossils were found.

An international team of scientists, led by the University of Cambridge, has reassessed the age of the Omo I remains -- and Homo sapiens as a species. Earlier attempts to date the fossils suggested they were less than 200,000 years old, but the new research shows they must be older than a colossal volcanic eruption that took place 230,000 years ago. The results are reported in the journal Nature.

The Omo I remains were found in the Omo Kibish Formation in southwestern Ethiopia, within the East African Rift valley. The region is an area of high volcanic activity, and a rich source of early human remains and artefacts such as stone tools. By dating the layers of volcanic ash above and below where archaeological and fossil materials are found, scientists identified Omo I as the earliest evidence of our species, Homo sapiens.

"Using these methods, the generally accepted age of the Omo fossils is under 200,000 years, but there's been a lot of uncertainty around this date," said Dr Céline Vidal from Cambridge's Department of Geography, the paper's lead author. "The fossils were found in a sequence, below a thick layer of volcanic ash that nobody had managed to date with radiometric techniques because the ash is too fine-grained."

As part of a four-year project led by Professor Clive Oppenheimer, Vidal and her colleagues have been attempting to date all the major volcanic eruptions in the Ethiopian Rift around the time of the emergence of Homo sapiens, a period known as the late Middle Pleistocene.

The researchers collected pumice rock samples from the volcanic deposits and ground them down to sub-millimetre size. "Each eruption has its own fingerprint -- its own evolutionary story below the surface, which is determined by the pathway the magma followed," said Vidal. "Once you've crushed the rock, you free the minerals within, and then you can date them, and identify the chemical signature of the volcanic glass that holds the minerals together."

The researchers carried out new geochemical analysis to link the fingerprint of the thick volcanic ash layer from the Kamoya Hominin Site (KHS ash) with an eruption of Shala volcano, more than 400 kilometres away. The team then dated pumice samples from the volcano to 230,000 years ago. Since the Omo I fossils were found deeper than this particular ash layer, they must be more than 230,000 years old.

"First I found there was a geochemical match, but we didn't have the age of the Shala eruption," said Vidal. "I immediately sent the samples of Shala volcano to our colleagues in Glasgow so they could measure the age of the rocks. When I received the results and found out that the oldest Homo sapiens from the region was older than previously assumed, I was really excited."

"The Omo Kibish Formation is an extensive sedimentary deposit which has been barely accessed and investigated in the past," said co-author and co-leader of the field investigation Professor Asfawossen Asrat from Addis Ababa University in Ethiopia, who is currently at BIUST in Botswana. "Our closer look into the stratigraphy of the Omo Kibish Formation, particularly the ash layers, allowed us to push the age of the oldest Homo sapiens in the region to at least 230,000 years."

"Unlike other Middle Pleistocene fossils which are thought to belong to the early stages of the Homo sapiens lineage, Omo I possesses unequivocal modern human characteristics, such as a tall and globular cranial vault and a chin," said co-author Dr Aurélien Mounier from the Musée de l'Homme in Paris. "The new date estimate, de facto, makes itthe oldest unchallenged Homo sapiens in Africa."

The researchers say that while this study shows a new minimum age for Homo sapiens in eastern Africa, it's possible that new finds and new studies may extend the age of our species even further back in time.

"We can only date humanity based on the fossils that we have, so it's impossible to say that this is the definitive age of our species," said Vidal. "The study of human evolution is always in motion: boundaries and timelines change as our understanding improves. But these fossils show just how resilient humans are: that we survived, thrived and migrated in an area that was so prone to natural disasters."

"It's probably no coincidence that our earliest ancestors lived in such a geologically active rift valley -- it collected rainfall in lakes, providing fresh water and attracting animals, and served as a natural migration corridor stretching thousands of kilometres," said Oppenheimer. "The volcanoes provided fantastic materials to make stone tools and from time to time we had to develop our cognitive skills when large eruptions transformed the landscape."

"Our forensic approach provides a new minimum age for Homo sapiens in eastern Africa, but the challenge still remains to provide a cap, a maximum age, for their emergence, which is widely believed to have taken place in this region," said co-author Professor Christine Lane, head of the Cambridge Tephra Laboratory where much of the work was carried out. "It's possible that new finds and new studies may extend the age of our species even further back in time."

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