Tuesday, June 11, 2019

Pathogens may have facilitated the evolution of warm-blooded animals


Six hundred million years ago, fever appeared in animals as a response to infections: the higher body temperatures optimized their immune systems. At the time, virtually all animal species were cold-blooded. They had to sit in warm patches of habitat for extended periods of time to achieve fever-range body temperatures. For Michael Logan, a Tupper Fellow at the Smithsonian Tropical Research Institute in Panama (STRI), pathogens may be the reason why warm-blooded creatures first emerged.


Pathogens may have facilitated the evolution of warm-blooded animals
By keeping their bodies warm at all times, birds and mammals may be effectively priming their
 immune systems to withstand virulent pathogens [Credit: Michael Logan]
At first glance, cold-blooded creatures or 'ectotherms' seem to have it easy. Because they cannot regulate their body temperature internally, they spend 30 times less energy than warm-blooded creatures or 'endotherms' of the same size. So, while mammals and birds are constantly investing their calories in maintaining a high, stable body temperature, reptiles and amphibians can just search for a warm spot in their surrounding environment if they want to get cozy. But if ectothermy is so great, why did mammals and birds develop a different strategy that is so costly?


Over the years, scientists have proposed three different models for why endotherms evolved high, stable body temperatures. One claims that it aids physiological processes; another, that it helps animals maintain activity over longer periods of time; and the third, that it enables parents to take care of precocial offspring. However, none of these models have found strong support and the evolutionary history of endothermy remains somewhat of a mystery.

Although these various hypotheses may have some truth to them, for Logan, the trigger must have been something that profoundly impacted the ability of animals to survive and reproduce, otherwise endothermy would be too costly a strategy and would not be favored by natural selection. In a recent paper, published in the journal Ideas in Ecology and Evolution, he explains this theory.


Pathogens may have facilitated the evolution of warm-blooded animals
The ability to mount a rapid fever response to a pathogen means warm-blooded creatures 
are not limited by the thermal variation in their habitats [Credit: Michael Logan]
"My hypothesis is that by keeping their bodies warm at nearly all times, mammals and birds effectively prime their immune systems to withstand virulent pathogens, and that this may be part of the reason the extremely costly strategy of endothermy evolved in the first place," Logan said.


In this context, endothermy may offer critical advantages over ectothermy. The ability to mount a rapid fever response to a pathogen means endotherms are not limited by the thermal variation in their habitats. Meanwhile, cold-blooded creatures depend on external sources of heat to reach fever-like temperatures. They are subject to fluctuations in environmental conditions, and in searching for the ideal microclimate required to initiate fever, they may struggle to forage or mate and may be exposed to predators.

"This hypothesis has emerged from recent discoveries in the fields of immunology and animal physiology, but we still need to rigorously test it with data and experiments," Logan said. "For example, my model predicts that species that maintain the warmest, most stable body temperatures (all else remaining equal) should also experience the highest frequency of disease outbreaks or the most virulent pathogens."

Source: Smithsonian Tropical Research Institute [June 04, 2019]
Read more at https://archaeologynewsnetwork.blogspot.com/2019/06/pathogens-may-have-facilitated.html#zdYzTgeuO3OBcR3e.99
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Ancient DNA sheds light on Arctic hunter-gatherer migration to North America ~5,000 years ago

The first humans in North America arrived from Asia some time before 14,500 years ago. The next major stream of gene flow came about 5000 years ago, and is known to archaeologists as Paleo-Eskimos. About 800 years ago, the ancestors of the present-day Inuit and Yup'ik people replaced this population across the Arctic. By about 700 years ago, the archaeological evidence for the Paleo-Eskimo culture disappeared. Their genetic legacy in living populations has been contentious, with several genetic studies arguing that they made little contribution to later North Americans.


Ancient DNA sheds light on Arctic hunter-gatherer migration to North America ~5,000 years ago
An ancient population of Arctic hunter-gatherers, known as Paleo-Eskimos, made a significant 
genetic contribution to populations living in Arctic North America today 
[Credit: Kerttu Majander, Design by Michelle O'Reilly]
In the current study, researchers generated genome-wide data from 48 ancient individuals and 93 modern individuals from Siberia, Alaska, the Aleutian Islands and Canada, and compared this with previously published data. The researchers used novel analysis methods to create a comprehensive model of population history that included many ancient and modern groups to determine how they might be related to each other.


"Our study is unique, not only in that it greatly expands the number of ancient genomes from this region, but because it is the first study to comprehensively describe all of these populations in one single coherent model," states Stephan Schiffels of the Max Planck Institute for the Science of Human History.

The researchers were able to show that a substantial proportion of the genetic heritage of all ancient and modern American Arctic and Chukotkan populations comes from Paleo-Eskimos. This includes people speaking Eskimo-Aleut languages, such as the Yup'ik, Inuit and Aleuts, and groups speaking Na-Dene languages, such as Athabaskan and Tlingit speakers, in Canada, Alaska, and the lower 48 states of the United States.


Ancient DNA sheds light on Arctic hunter-gatherer migration to North America ~5,000 years ago
The excavation of the Middle Dorset individual from the Buchanan site on southeastern 
Victoria Island, Nunavut, Central Canadian Arctic [Credit: T. Max Friesen]
Based on the researchers' analysis, Paleo-Eskimos interbred with people with ancestry similar to more southern Native peoples shortly after their arrival to Alaska, between 5,000 and 4,000 years ago. The ancestors of Aleutian Islanders and Athabaskans derive their genetic heritage directly from the ancient mixture between these two groups.


The researchers also found that the ancestors of the Inuit and Yup'ik people crossed the Bering Strait at least three times: first as Paleo-Eskimos to Alaska, second as predecessors of the Old Bering Sea archaeological culture back to Chukotka, and third to Alaska again as bearers of the Thule culture. During their stay in Chukotka that likely lasted for more than 1000 years, Yupik and Inuit ancestors also admixed with local groups related to present-day Chukchi and local peoples from Kamchatka.

Paleo-Eskimo ancestry is particularly widespread today in Na-Dene language speakers, which includes Athabaskan and Tlingit communities from Alaska and northern Canada, the West Coast of the United States, and the southwest United States.


Ancient DNA sheds light on Arctic hunter-gatherer migration to North America ~5,000 years ago
Attu Island, Aleutian Islands, Alaska [Credit: Jason Rogers]
"For the last seven years, there has been a debate about whether Paleo-Eskimos contributed genetically to people living in North America today; our study resolves this debate and furthermore supports the theory that Paleo-Eskimos spread Na-Dene languages," explains David Reich of Harvard Medical School and the Howard Hughes Medical Institute.


"One of the most striking case examples from our study is the ancient DNA we generated from the ancient Athabaskan site of Tochak McGrath in interior Alaska, where we worked in consultation with the local community to obtain data from three approximately seven hundred year old individuals. We found that these individuals, who lived after the time when the Paleo-Eskimo archaeological culture disappeared across North America, are well modeled as a mixture of the same two ancestry components as those found in Athabaskans today, and derived more than 40% of their ancestry from Paleo-Eskimos.

The researchers hope that the paper will provide an example of the value of genetic data, in the context of archaeological knowledge, to resolve long-standing questions.

"Determining what happened to this population was not possible from the archaeological record alone," explains Pavel Flegontov of the University of Ostrava. "By analyzing genetic data in concert with the archaeological data, we can meaningfully improve our understanding of the prehistory of peoples of this region. We faced challenging analytical problems due to the complex sequence of gene flows that have shaped ancestries of peoples on both sides of the Bering Strait. Reconstructing this sequence of events required new modelling approaches that we hope may be useful for solving similar problems in other regions of the world."

Watch “Future of the Past - Paleo Eskimos” on #Vimeo https://vimeo.com/334621261

The study is published in the journal Nature.

Source: Max Planck Institute for the Science of Human History [June 05, 2019]
Read more at https://archaeologynewsnetwork.blogspot.com/2019/06/ancient-dna-sheds-light-on-arctic.html#E4FIcAGTsSFFMSh0.99
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Herd of dinosaurs discovered in underground opal mine


WHAT THE HELL WERE THE DINOSAURS DOING IN AN OPAL MINE
MINING OPAL PERHAPS

Scientists have revealed that fossils from an underground opal mine near Lightning Ridge, outback NSW (Australia), include remains from a herd of dinosaurs, among them a new dinosaur species and the world's most complete opalized dinosaur.



Herd of dinosaurs discovered in underground opal mine
Artist's reconstruction of Fostoria dhimbangunmal 
[Credit: © James Kuether]
Dr. Phil Bell, lead researcher from the University of New England in Armidale, said he was stunned by the sheer number of bones found. "We initially assumed it was a single skeleton, but when I started looking at some of the bones, I realized that we had four scapulae (shoulder blades) all from different sized animals." It is the first dinosaur "herd" to be discovered in Australia.

The new dinosaur has been named Fostoria dhimbangunmal in honor of opal miner Robert Foster, who discovered the fossils in the 1980s. The species name, dhimbangunmal (pronounced bim-baan goon-mal), means "sheep yard" in the local Yuwaalaraay and Yuwaalayaay languages, in recognition of the Sheepyard locality where the bones were found.

In total, parts of four Fostoria skeletons were unearthed, ranging from small juveniles to larger animals that might have been five meters in length, prompting speculation they were part of a small herd or family.

Herd of dinosaurs discovered in underground opal mine
A fossil vertebrae of the newly discovered dinosaur species Fostoria dhimbangunmal 
discovered in opal [Credit: Robert A. Smith/Australian Opal Centre]
The bones, which are mostly grey potch opal, were found in the 1980s by opal miner Robert Foster at the Sheepyard opal field, near Lightning Ridge. Scientists from the Australian Museum in Sydney helped excavate the fossils, but the bones remained unstudied until donated to the Australian Opal Centre by Robert's children Gregory and Joanne Foster in 2015, under the Federal Government's Cultural Gift Program.

Jenni Brammall, paleontologist and special projects officer of the Australian Opal Centre, says, "Fostoria has given us the most complete opalized dinosaur skeleton in the world. Partial skeletons of extinct swimming reptiles have been found at other Australian opal fields, but for opalized dinosaurs we generally have only a single bone or tooth or in rare instances, a few bones. To recover dozens of bones from the one skeleton is a first."

Herd of dinosaurs discovered in underground opal mine
A fossilized toe bone of Fostoria dhimbangunmal found in opal 
[Credit: Robert A. Smith/Australian Opal Centre]
Fostoria was a two-legged plant-eating iguanodontian dinosaur closely related to the famous Muttaburrasaurus from central Queensland, which was discovered in 1980.

The discovery comes on the back of the new small plant-eating dinosaur also from Lightning Ridge, Weewarrasaurus pobeni, which was named by Dr. Bell and colleagues late last year.

"The rate of discovery is astounding. On average, there's at least one new dinosaur discovered around the world every week," Dr. Bell said. "With more palaeontologists and scientists looking further afield than ever before, it's an exciting time for dinosaur lovers everywhere, especially in Australia."

The new research was published in the Journal of Vertebrate Paleontology.

Source: University of New England [June 05, 2019]

Read more at https://archaeologynewsnetwork.blogspot.com/2019/06/herd-of-dinosaurs-has-been-discovered.html#fxpp5LTOLTLDmwto.99
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A JUG OF WINE, A LOAF OF BREAD, AND THOU MY BELOVED
Ancient DNA from Roman and medieval grape seeds reveal ancestry of wine making


 A grape variety still used in wine production in France today can be traced back 900 years to just one ancestral plant, scientists have discovered.


Ancient DNA from Roman and medieval grape seeds reveal ancestry of wine making
Waterlogged Roman grape seeds like these were genetically tested to investigate
grape varieties in the past [Credit: L. Bouby, CNRS/ISEM]
With the help of an extensive genetic database of modern grapevines, researchers were able to test and compare 28 archaeological seeds from French sites dating back to the Iron Age, Roman era, and medieval period.

Utilising similar ancient DNA methods used in tracing human ancestors, a team of researchers from the UK, Denmark, France, Spain, and Germany, drew genetic connections between seeds from different archaeological sites, as well as links to modern-day grape varieties.

It has long been suspected that some grape varieties grown today, particularly well-known types like Pinot Noir, have an exact genetic match with plants grown 2,000 years ago or more, but until now there has been no way of genetically testing an uninterrupted genetic lineage of that age.


Dr Nathan Wales, from the University of York, said: "From our sample of grape seeds we found 18 distinct genetic signatures, including one set of genetically identical seeds from two Roman sites separated by more than 600km, and dating back 2,000 years ago.

"These genetic links, which included a 'sister' relationship with varieties grown in the Alpine regions today, demonstrate winemakers' proficiencies across history in managing their vineyards with modern techniques, such as asexual reproduction through taking plant cuttings."

One archaeological grape seed excavated from a medieval site in Orléans in central France was genetically identical to Savagnin Blanc. This means the variety has grown for at least 900 years as cuttings from just one ancestral plant.


Ancient DNA from Roman and medieval grape seeds reveal ancestry of wine making
A vineyard by Pic Saint Loup Mountain in southern France 
[Credit: S. Ivorra CNRS/ISEM]
This variety (not to be confused with Sauvignon Blanc), is thought to have been popular for a number of centuries, but is not as commonly consumed as a wine today outside of its local region.

The grape can still be found growing in the Jura region of France, where it is used to produce expensive bottles of Vin Jaune, as well as in parts of Central Europe, where it often goes by the name Traminer.

Although this grape is not so well known today, 900 years of a genetically identical plant suggests that this wine was special - special enough for grape-growers to stick with it across centuries of changing political regimes and agricultural advancements.


Dr Jazmín Ramos-Madrigal, a postdoctoral researcher from the University of Copenhagen, said: "We suspect the majority of these archaeological seeds come from domesticated berries that were potentially used for winemaking based on their strong genetic links to wine grapevines.

"Berries from varieties used for wine are small, thick-skinned, full of seeds, and packed with sugar and other compounds such as acids, phenols, and aromas - great for making wine but not quite as good for eating straight from the vine. These ancient seeds did not have a strong genetic link to modern table grapes.

"Based on writings by the Roman author and naturalist, Pliny the Elder, and others, we know the Romans had advanced knowledge of winemaking and designated specific names to different grape varieties, but it has so far been impossible to link their Latin names to modern varieties. Now we have the opportunity to use genetics to know exactly what the Romans were growing in their vineyards."


Ancient DNA from Roman and medieval grape seeds reveal ancestry of wine making
Archaeological excavation of Roman farm at Mont Ferrier site in Tourbes, France. Grape seeds closely 
related to Pinot Noir and Savagnin Blanc were excavated from a well dating to the first century CE 
[Credit: M. Compan, Inrap]
Of the Roman seeds, the researchers could not find an identical genetic match with modern-day seeds, but they did find a very close relationships with two important grape families used to produce high quality wine.

These include the Syrah-Mondeuse Blanche family - Syrah is one of the most planted grapes in the world today - and the Mondeuse Blanche, which produces a high quality AOC (protected regional product) wine in Savoy, as well as the Pinot-Savagnin family - Pinot Noir being the "king of wine grapes".


Dr Wales said: "It is rather unconventional to trace an uninterrupted genetic lineage for hundreds of years into the past. Instead of exploring broad patterns in genetic ancestry, as in most ancient DNA projects, we had to think like forensics scientists and find a perfect match in the database.

"Large databases of genetic data from modern crops and optimized palaeogenomic methods have vastly improved our ability to analyse the history of this and other important fruits. For the wine industry today, these results could shed new light on the value of some grape varieties; even if we don't see them in popular use in wines today, they were once highly valued by past wine lovers and so are perhaps worth a closer look."

The researchers now hope to find more archaeological evidence that could send them further back in time and reveal more grape wine varieties.

The research was published in Nature Plants.

Source: University of York [June 10, 2019]
Read more at https://archaeologynewsnetwork.blogspot.com/2019/06/ancient-dna-from-roman-and-medieval.html#Bq472vmV85TxBYkq.99

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Dramatic change in ancient nomad diets coincides with expansion of networks across Eurasia

Read more at https://archaeologynewsnetwork.blogspot.com/2019/06/dramatic-change-in-ancient-nomad-diets.html#zB08oACl98r60SsO.99

 A meta-analysis of dietary information recorded in the bones of ancient animals and humans recovered from sites scattered across the Eurasian steppe, from the Caucasus region to Mongolia, demonstrates that pastoralists spread domesticated crops across the steppe through their trade and social networks.

image: https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLE_37g2E-GZLtaT1oerjUnA73Tqw9LLRvKKPpVMSDkPOG3CkTlOnM7f5Y2minNJ9idqA6tpo1kaRR1IuTVwXtgctCSmS4kpSfh-bIEqqCpOGyPqMBgKOKXXDdbwqdjLkOpb0RnQ/s640/nomad-diets-02.jpg
Dramatic change in ancient nomad diets coincides with expansion of networks across Eurasia
Millet cultivation in Central Asia [Credit: © Spengler 2014]
Researchers from Kiel University sifted through previously published stable isotopic data and applied new quantitative analyses that calibrate human dietary intake against environmental inputs. The results have allowed them to better isolate the timing of the incorporation of agricultural products into the diets of pastoral nomads and, crucially, link burgeoning socio-political networks to this dietary transformation.

Through a big data project that explored over a thousand stable isotope data points, researchers were able to find evidence for an early transition to agriculture - based on dietary intake across Eurasia.


"Our understanding of the pace of crop transmission across the Eurasian steppe has been surprisingly unclear due in part to a focus on the excavation of cemeteries, rather than settlements where people threw out their food," says Alicia Ventresca Miller, lead author, formerly of Kiel University and currently at the Max Planck Institute for the Science of Human History.

"Even when settlement sites are excavated, the preservation of carbonized seed remains is often poor. This is what makes stable isotope analyses of human remains from this region so valuable - it provides direct insights into the dietary dynamics of ancient pastoralists who inhabited diverse environments."

Millet spreads across the Eurasian steppe

Millet, originally domesticated in China, appears to have been occasionally consumed at low levels by pastoralists inhabiting the far-flung regions of Siberia and southeastern Kazakhstan, possibly as early as the late third millennium. This initial uptake of millet coincided with the expansion of trans-regional networks across the steppe, when objects and ideas were first regularly exchanged over long-distances.

image: https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidtn75c1pGfMEpevlcPMuY3PAE1t67BxIcgjbH1a1YBVyjBtYaZc9NQNYCuMWRsKnQurIThB1BErK_8tqoXeVgC3q7VuvyPnLh5QOklaBaI7_CKyGM1fx5yutO7R4s0cs5gDLNQg/s640/nomad-diets-01.jpg
Dramatic change in ancient nomad diets coincides with expansion of networks across Eurasia
Map of millet and wheat/barley consumption over time: a) 1000-500 cal BC, 
b) 500-200 cal BC, and c) 200 BC-AD 400 [Credit: I. Reese 
& A. R. Ventresca Miller, 2017]
However, it was not until a thousand years later that millet became a regular feature of pastoralist diets. This timing coincides with the intensification of complex political structures at the transition to the Iron Age. Burgeoning socio-political confederations drove a marked increase in the exchange of costly prestige goods, which strengthened political networks - and facilitated the transfer of cultigens.


Wheat and Barley in the Trans-Urals

Despite taking part in these political networks, groups in the Trans-Urals invested in wheat and barley farming rather than millet. A dietary focus on wheat and barley may have been due to different farming techniques, greater water availability, or a higher value on these cultigens.

"Our research suggests that cultigens were converted from a rare luxury during the Bronze Age to a medium demarcating elite participation in political networks during the Iron Age," states Cheryl Makarewicz of Kiel University.

Regional variation in millet consumption

While herding of livestock was widespread, not all regions adopted millet. In southwest Siberia, dietary intake was focused on pastoral animal products and locally available wild plants and fish. In contrast, the delayed adoption of millet by populations in Mongolia during the Late Iron Age coincides with the rise of the Xiongnu nomadic empire.


"This is particularly interesting because it suggests that communities in Mongolia and Siberia opted out of the transition to millet agriculture, while continuing to engage with neighboring groups," explains Ventresca Miller.

This study shows the great potential of using the available isotope record to provide evidence for human dietary intake in areas where paleobotany is understudied. Further research should clarify the exact type of grains, for example broomcorn or foxtail millet, were fundamental to the shift in dietary intake and how networks of exchange linked different regions.

The findings are published in Scientific Reports.

Source: Kiel University [June 10, 2019]
Read more at https://archaeologynewsnetwork.blogspot.com/2019/06/dramatic-change-in-ancient-nomad-diets.html#zB08oACl98r60SsO.99
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