Ancient genome study identifies traces of indigenous “Taíno” in present-day Caribbean populations

tdk25 — Mon, 19 Feb 2018 20:00:58 +0000

Researchers were able to use the tooth of a woman found in a cave on the island of Eleuthera in the Bahamas to sequence the first complete ancient human genome from the Caribbean. ̽��ֱ��woman lived at some point between the 8th and 10th centuries, at least 500 years before Columbus made landfall in the Bahamas.

̽��ֱ��results provide unprecedented insights into the genetic makeup of the Taíno – a label commonly used to describe the indigenous people of that region. This includes the first clear evidence that there has been some degree of continuity between the indigenous peoples of the Caribbean and contemporary communities living in the region today.

Such a link had previously been suggested by other studies based on modern DNA. None of these, however, was able to draw on an ancient genome. ̽��ֱ��new research finally provides concrete proof that indigenous ancestry in the region has survived to the present day.

Comparing the ancient Bahamian genome to those of contemporary Puerto Ricans, the researchers found that they were more closely related to the ancient Taíno than any other indigenous group in the Americas. However, they argue that this characteristic is unlikely to be exclusive to Puerto Ricans alone and are convinced that future studies will reveal similar genetic legacies in other Caribbean communities.

̽��ֱ��findings are likely to be especially significant for people in the Caribbean and elsewhere who have long claimed indigenous Taíno heritage, despite some historical narratives that inaccurately brand them “extinct”. Such misrepresentations have been heavily criticised by historians and archaeologists, as well as by descendant communities themselves, but until now they lacked clear genetic evidence to support their case.

̽��ֱ��study was carried out by an international team of researchers led by Dr Hannes Schroeder and Professor Eske Willerslev of Cambridge's Department of Zoology within the framework of the ERC Synergy project NEXUS1492. ̽��ֱ��findings are published in the journal Proceedings of the National Academy of Sciences (PNAS).

Schroeder, from the ̽��ֱ�� of Copenhagen who carried out the research as part of the NEXUS1492 project, said: “It’s a fascinating finding. Many history books will tell you that the indigenous population of the Caribbean was all but wiped out, but people who self-identify as Taíno have always argued for continuity. Now we know they were right all along: there has been some form of genetic continuity in the Caribbean.”

Willerslev, who has dual posts at St John’s College, ̽��ֱ�� of Cambridge, and the ̽��ֱ�� of Copenhagen, said: “It has always been clear that people in the Caribbean have Native American ancestry, but because the region has such a complex history of migration, it was difficult to prove whether this was specifically indigenous to the Caribbean, until now.”

̽��ֱ��researchers were also able to trace the genetic origins of the indigenous Caribbean islanders, showing that they were most closely related to Arawakan-speaking groups who live in parts of northern South America today. This suggests that the origins of at least some the people who migrated to the Caribbean can be traced back to the Amazon and Orinoco Basins, where the Arawakan languages developed.

̽��ֱ��Caribbean was one of the last parts of the Americas to be populated by humans starting around 8,000 years ago. By the time of European colonization, the islands were a complex patchwork of different societies and cultures. ̽��ֱ��“Taíno” culture was dominant in the Greater, and parts of the Lesser Antilles, as well as the Bahamas, where the people were known as Lucayans.

To trace the genetic origins of the Lucayans the researchers compared the ancient Bahamian genome with previously published genome-wide datasets for over 40 present-day indigenous groups from the Americas. In addition, they looked for traces of indigenous Caribbean ancestry in present-day populations by comparing the ancient genome with those of 104 contemporary Puerto Ricans included in the 1000 Genomes Project. ̽��ֱ��10-15% of Native American ancestry in this group was shown to be closely related to the ancient Bahamian genome.

Jorge Estevez, a Taíno descendant who works at the National Museum of the American Indian in New York and assisted the project team, said that as a boy growing up in the United States, he was told stories about his Taíno ancestors at home, but at school was taught that the same ancestors had died out. “I wish my grandmother were alive today so that I could confirm to her what she already knew,” he added. “It shows that the true story is one of assimilation, certainly, but not total extinction. I am genuinely grateful to the researchers. Although this may have been a matter of scientific inquiry for them, to us, the descendants, it is truly liberating and uplifting.”

Although indigenous Caribbean communities were island-based, the researchers found very little genomic evidence of isolation or inbreeding in the ancient genome. This reinforces earlier genetic research led by Willerslev, which suggests that early human communities developed surprisingly extensive social networks, long before the term had digital connotations. It also echoes ongoing work by researchers at the Faculty of Archaeology in Leiden and others indicating the connectedness of indigenous Caribbean communities.

Professor Corinne Hofman from Leiden ̽��ֱ�� and PI of the NEXUS1492 project, said: "Archaeological evidence has always suggested that large numbers of people who settled the Caribbean originated in South America, and that they maintained social networks that extended far beyond the local scale. Historically, it has been difficult to back this up with ancient DNA because of poor preservation, but this study demonstrates that it is possible to obtain ancient genomes from the Caribbean and that opens up fascinating new possibilities for research."

A thousand-year-old tooth has provided genetic evidence that the so-called “Taíno”, the first indigenous Americans to feel the full impact of European colonisation after Columbus arrived in the New World, still have living descendants in the Caribbean today.

It has always been clear that people in the Caribbean have Native American ancestry, but it was difficult to prove whether this was specifically indigenous to the Caribbean, until now.

Eske Willerslev

Image courtesy of the Library of Congress

First encounter. Columbus landing in the New World

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Habitable planets could exist around pulsars

sc604 — Tue, 19 Dec 2017 15:03:33 +0000

Pulsars are known for their extreme conditions. Each is a fast-spinning neutron star - the collapsed core of a massive star that has gone supernova at the end of its life. Only 10 to 30 kilometres across, a pulsar possesses enormous magnetic fields, accretes matter, and regularly gives out large bursts of X-rays and highly energetic particles.

Surprisingly, despite this hostile environment, neutron stars are known to host exoplanets. ̽��ֱ��first exoplanets ever discovered were around the pulsar PSR B1257+12 - but whether these planets were originally in orbit around the precursor massive star and survived the supernova explosion, or formed in the system later remains an open question. Such planets would receive little visible light but would be continually blasted by the energetic radiation and stellar wind from the host. Could such planets ever host life?

For the first time, astronomers have tried to calculate the ‘habitable’ zones near neutron stars - the range of orbits around a star where a planetary surface could possibly support water in a liquid form. Their calculations show that the habitable zone around a neutron star can be as large as the distance from our Earth to our Sun. An important premise is that the planet must be a super-Earth, with a mass between one and ten times our Earth. A smaller planet will lose its atmosphere within a few thousand years under the onslaught of the pulsar winds. To survive this barrage, a planet’s atmosphere must be a million times thicker than ours - the conditions on a pulsar planet surface might resemble those of the deep ocean floor on Earth.

̽��ֱ��astronomers studied the pulsar PSR B1257+12 about 2300 light-years away as a test case, using the X-ray Chandra space telescope. Of the three planets in orbit around the pulsar, two are super-Earths with a mass of four to five times our Earth, and orbit close enough to the pulsar to warm up. According to co-author Alessandro Patruno from Leiden ̽��ֱ��, “ ̽��ֱ��temperature of the planets might be suitable for the presence of liquid water on their surface. Though, we don't know yet if the two super-Earths have the right, extremely dense atmosphere.”

In the future, Patruno and his co-author Mihkel Kama from Cambridge's Institute of Astronomy would like to observe the pulsar in more detail and compare it with other pulsars. ̽��ֱ��European Southern Observatory’s ALMA Telescope would be able to show dust discs around neutron stars, which are good predictors of planets. ̽��ֱ��Milky Way contains about one billion neutron stars, of which about 200,000 are pulsars. So far, 3000 pulsars have been studied and only five pulsar planets have been found.

Reference:
A. Patruno & M. Kama. ‘Neutron Star Planets: Atmospheric processes and habitability.’ Accepted for publication in Astronomy & Astrophysics.

Adapted from a NOVA press release.

It is theoretically possible that habitable planets exist around pulsars - spinning neutron stars that emit short, quick pulses of radiation. According to new research, such planets must have an enormous atmosphere that converts the deadly x-rays and high energy particles of the pulsar into heat. ̽��ֱ��results, from astronomers at the ̽��ֱ�� of Cambridge and Leiden ̽��ֱ��, are reported in the journal Astronomy & Astrophysics.

Amanda Smith, ̽��ֱ�� of Cambridge

Artistic impression of a habitable planet near a pulsar (right)

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

̽��ֱ�� of Cambridge - Leiden ̽��ֱ��

Ancient genome study identifies traces of indigenous “Taíno” in present-day Caribbean populations

Habitable planets could exist around pulsars