The Great London [Search results for Americas] 

By comparing the genes of current-day North and South Americans with African and European populations, an Oxford University study has found the genetic fingerprints of the slave trade and colonization that shaped migrations to the Americas hundreds of years ago.

The study published in Nature Communications found that:

• While Spaniards provide the majority of European ancestry in continental American Hispanic/Latino populations, the most common European genetic source in African-Americans and Barbadians comes from Great Britain.

• The Basques, a distinct ethnic group spread across current-day Spain and France, provided a small but distinct genetic contribution to current-day Continental South American populations, including the Maya in Mexico.

• The Caribbean Islands of Puerto Rico and the Dominican Republic are genetically similar to each other and distinct from the other populations, probably reflecting a different migration pattern between the Caribbean and mainland America.

• Compared to South Americans, people from Caribbean countries (such as the Barbados) had a larger genetic contribution from Africa.

• The ancestors of current-day Yoruba people from West Africa (one of the largest African ethnic groups) provided the largest contribution of genes from Africa to all current-day American populations.

• The proportion of African ancestry varied across the continent, from virtually zero (in the Maya people from Mexico) to 87% in current-day Barbados.

• South Italy and Sicily also provided a significant European genetic contribution to Colombia and Puerto Rico, in line with the known history of Italian emigrants to the Americas in the late 19th and early 20th century.

• One of the African-American groups from the USA had French ancestry, in agreement with historical French immigration into the colonial Southern United States.

• The proportion of genes from European versus African sources varied greatly from individual to individual within recipient populations.

'We found that the genetic profile of Americans is much more complex than previously thought,' said study leader Professor Cristian Capelli from the Department of Zoology.

The research team analysed DNA samples collected from people in Barbados, Columbia, the Dominican Republic, Ecuador, Mexico, Puerto Rico and African-Americans in the USA.

They used a technique called haplotype-based analysis to compare the pattern of genes in these 'recipient populations' to 'donor populations' in areas where migrants to America came from.

'We firstly grouped subsets of people in Africa and Europe who were genetically similar and used this fine scale resolution to find which combinations of these clusters resulted in the sort of mixtures that we now see in people across the Americas', said the study's first author, Dr Francesco Montinaro from the Department of Zoology.

'We can see the huge genetic impact that the slave trade had on American populations and our data match historical records', said study author Dr Garrett Hellenthal from the UCL Genetics Institute, 'The majority of African Americans have ancestry similar to the Yoruba people in West Africa, confirming that most African slaves came from this region. In areas of the Americas historically under Spanish rule, populations also have ancestry related to what is now Senegal and Gambia. Records show that around a third of the slaves sent to Spanish America in the 17th Century came from this region, and we can see the genetic evidence of this in modern Americans really clearly.'

These genetic findings also uncover previously unknown migration. ‘We found a clear genetic contribution from the Basques in modern-day Maya in Mexico’, said Professor Capelli. ‘This suggests that the Basque also took part in the colonisation of the Americas, coming over either with the Spanish conquistadores or in later waves of migration’.

'The differences in European ancestry between the Caribbean islands and mainland American population that we found were also previously unknown. It is likely that these differences reflect different patterns of migration between the Caribbean and mainland America.'

'These results show just how powerful a genetic approach can be when it comes to uncovering hidden patterns of ancestry. We hope to use the same approach to look at other populations with diverse genetic contributions, such as Brazilians,' said Professor Capelli.

Source: University of Oxford [March 24, 2015]

The human-dominated geological epoch known as the Anthropocene probably began around the year 1610, with an unusual drop in atmospheric carbon dioxide and the irreversible exchange of species between the New and Old Worlds, according to new research published today in Nature.

Previous epochs began and ended due to factors including meteorite strikes, sustained volcanic eruptions and the shifting of the continents. Human actions are now changing the planet, but are we really a geological force of nature driving Earth into a new epoch that will last millions of years?

Scientists at UCL have concluded that humans have become a geological power and suggest that human actions have produced a new geological epoch.

Defining an epoch requires two main criteria to be met. Long-lasting changes to the Earth must be documented. Scientists must also pinpoint and date a global environmental change that has been captured in natural material, such as rocks, ancient ice or sediment from the ocean floor. Such a marker -- like the chemical signature left by the meteorite strike that wiped out the dinosaurs -- is called a golden spike.

The study authors systematically compared the major environmental impacts of human activity over the past 50,000 years against these two formal requirements. Just two dates met the criteria: 1610, when the collision of the New and Old Worlds a century earlier was first felt globally; and 1964, associated with the fallout from nuclear weapons tests. The researchers conclude that 1610 is the stronger candidate.

The scientists say the 1492 arrival of Europeans in the Americas, and subsequent global trade, moved species to new continents and oceans, resulting in a global re-ordering of life on Earth. This rapid, repeated, cross-ocean exchange of species is without precedent in Earth's history.

They argue that the joining of the two hemispheres is an unambiguous event after which the impacts of human activity became global and set Earth on a new trajectory. The first fossil pollen of maize, a Latin American species, appears in marine sediment in Europe in 1600, becoming common over subsequent centuries. This irreversible exchange of species satisfies the first criteria for dating an epoch -- long-term changes to Earth.

The Anthropocene probably began when species jumped continents, starting when the Old World met the New. We humans are now a geological power in our own right -- as Earth-changing as a meteorite strike

The researchers also found a golden spike that can be dated to the same time: a pronounced dip in atmospheric carbon dioxide centred on 1610 and captured in Antarctic ice-core records. The drop occurred as a direct result of the arrival of Europeans in the Americas. Colonisation of the New World led to the deaths of about 50 million indigenous people, most within a few decades of the 16th century due to smallpox. The abrupt near-cessation of farming across the continent and the subsequent re-growth of Latin American forests and other vegetation removed enough carbon dioxide from the atmosphere to produce a drop in CO2. Thus, the second requirement of a golden spike marker is met.

The researchers have named the 1610 dip in carbon dioxide the 'Orbis Spike'. They chose the Latin word for 'world' because this golden spike was caused by once-disconnected peoples becoming globally linked.

Lead author, Dr Simon Lewis (UCL Geography and University of Leeds), said: "In a hundred thousand years scientists will look at the environmental record and know something remarkable happened in the second half of the second millennium. They will be in no doubt that these global changes to Earth were caused by their own species. Today we can say when those changes began and why. The Anthropocene probably began when species jumped continents, starting when the Old World met the New. We humans are now a geological power in our own right -- as Earth-changing as a meteorite strike."

He added: "Historically, the collision of the Old and New Worlds marks the beginning of the modern world. Many historians regard agricultural imports into Europe from the vast new lands of the Americas, alongside the availability of coal, as the two essential precursors of the Industrial Revolution, which in turn unleashed further waves of global environmental changes. Geologically, this boundary also marks Earth's last globally synchronous cool moment before the onset of the long-term global warmth of the Anthropocene."

The authors also considered the merits of dating the Anthropocene to 1964, which saw a peak in radioactive fallout following nuclear weapons testing. This marker is seen in many geological deposits, and by the 1960s human impact on the Earth was large. However, the researchers note that while nuclear war could dramatically alter Earth, so far it has not. While the fallout from nuclear bomb tests is a very good marker, the testing of nuclear weapons has not been -- in geological terms -- an Earth-changing event.

The beginning of the Industrial Revolution, in the late 18th century, has most commonly been suggested as the start of the Anthropocene. This linked a clear turning point in human history, and the rise of atmospheric carbon dioxide from fossil fuel use is a long-term global environmental change of critical importance. However, the researchers did not find a golden spike at that time because most effects were local, while the global exponential rise in carbon dioxide was too smooth an increase to form a precisely dated marker.

The authors' new paper ends by highlighting some implications of formally defining the Anthropocene.

Co-author, geologist Professor Mark Maslin (UCL Geography) said: "A more wide-spread recognition that human actions are driving far-reaching changes to the life-supporting infrastructure of Earth will have implications for our philosophical, social, economic and political views of our environment. But we should not despair, because the power that humans wield is unlike any other force of nature, it is reflexive and therefore can be used, withdrawn or modified. The first stage of solving our damaging relationship with our environment is recognising it."

An official decision on whether to formally recognise the Anthropocene, including when it began, will be initiated by a recommendation of the Anthropocene Working Group of the Subcommission of Quaternary Stratigraphy, due in 2016.

Source: University College London [March 11, 2015]

Bodies found in a 200 year-old Hungarian crypt have revealed the secrets of how tuberculosis (TB) took hold in 18th century Europe, according to a research team led by the University of Warwick.

A new study published in Nature Communications details how samples taken from naturally mummified bodies found in an 18th century crypt in the Dominican church of Vác in Hungary have yielded 14 tuberculosis genomes, suggesting that mixed infections were common when TB was at peak prevalence in Europe.

The research team included collaborators from the Universities of Warwick and Birmingham, University College London, the Hebrew University in Jerusalem and the Hungarian Natural History Museum in Budapest. Lead author Professor Mark Pallen, from Warwick Medical School, said the discovery was significant for current and future infection control and diagnosis.

Professor Pallen said: “Microbiological analyses of samples from contemporary TB patients usually report a single strain of tuberculosis per patient. By contrast, five of the eight bodies in our study yielded more than one type of tuberculosis – remarkably from one individual we obtained evidence of three distinct strains.”

The team used a technique called “metagenomics” to identify TB DNA in the historical specimens—that is direct sequencing of DNA from samples without growing bacteria or deliberately fishing out TB DNA. This approach draws on the remarkable throughput and ease of use of modern DNA sequencing technologies.

Gemma Kay, first author on the paper says: “Poignantly, we found evidence of an intimate link between strains from in a middle-aged mother and her grown-up daughter, suggesting both family members died from this devastating infection.”

The team used the 18th century sequences to date the origin of the lineage of TB strains commonly found in Europe and America to the late Roman period, which fits in with the recent controversial suggestion that the most recent common ancestor of all TB strains occurred as recently as six thousand years ago.

Professor Pallen said: “By showing that historical strains can be accurately mapped to contemporary lineages, we have ruled out, for early modern Europe, the kind of scenario recently proposed for the Americas—that is wholesale replacement of one major lineage by another—and have confirmed the genotypic continuity of an infection that has ravaged the heart of Europe since prehistoric times.”

Professor Pallen added that with TB resurgent in many parts of the world, the struggle to contain this ancient infection was far from over. He concludes: “We have shown that metagenomic approaches can document past infections. However, we have also recently shown that metagenomics can identify and characterize pathogens in contemporary samples, so such approaches might soon also inform current and future infectious disease diagnosis and control.”

For more photos of the Hungarian mummies visit the website Morbid Anatomy.

Source: University of Warwick [April 07, 2015]

The worst land grab in decades in the Brazilian Amazon is threatening the survival of isolated tribes that have no contact with the outside world, a rights group said Wednesday.

Ranchers and settlers in the remotest reaches of northwestern Brazil are voraciously cutting down rainforest to farm crops, encroaching on the ancestral lands of three uncontacted groups, said Survival International.

The land grab is also threatening another tribe, the Uru Eu Wau Wau, or "Harpy Eagle" people, that has only limited contact with the outside world, said the London-based group.

Warning the groups face "annihilation," it accused local politicians in the state of Rondonia of backing the deforestation, even though the area is officially designated as an indigenous reserve and sits within a national park, Pacaas Novas.

Because isolated peoples' immune systems have never been exposed to the outside world's diseases, the land grab risks causing devastating outbreaks, Survival said.

"Around the world, industrialized society is stealing tribal lands in the pursuit of profit. What's happening in Brazil is simply a continuation of the invasion and genocide which characterized the European colonization of the Americas," said the group's director, Stephen Corry.

The organization quoted a letter the Harpy Eagle tribe sent to Brazilian police, in which they call the land grab "extremely serious."

"We are very worried because the invasions are close to our villages and putting the lives of women, old people, children and men at risk," said the letter.

Experts estimate between 50 and 90 percent of the populations of Brazil's isolated tribes were wiped out when the government initiated contact with them in the 1970s and 80s—official policy at the time.

Today, the government tries to avoid any contact with isolated peoples, in order to protect them.

Brazil is home to some 900,000 indigenous people from 305 different ethnic groups.

Source: AFP [October 27, 2016]