Wednesday, July 11, 2018
Eating bone marrow played a key role in the evolution of the human hand
The strength required to access the high calorie content of bone marrow may have played a key role in the evolution of the human hand and explain why primates hands are not like ours, research at the University of Kent has found.
In an article in The Journal of Human Evolution, a team lead by Professor Tracy Kivell of Kent's School of Anthropology and Conservation concludes that although stone tool making has always been considered a key influence on the evolution of the human hand, accessing bone marrow generally has not.
It is widely accepted that the unique dexterity of the human hand evolved, at least in part, in response to stone tool use during our evolutionary history.
Archaeological evidence suggests that early hominins participated in a variety of tool-related activities, such as nut-cracking, cutting flesh, smashing bone to access marrow, as well as making stone tools. However, it is unlikely that all these behaviours equally influenced modern human hand anatomy.
To understand the impact these different actions may have had on the evolution of human hands, researchers measured the force experienced by the hand of 39 individuals during different stone tool behaviours - nut-cracking, marrow acquisition with a hammerstone, flake production with a hammerstone, and handaxe and stone tool (i.e. a flake) - to see which digits were most important for manipulating the tool.
They found that the pressures varied across the different behaviours, with nut-cracking generally requiring the lowest pressure while making the flake and accessing marrow required the greatest pressures. Across all of the different behaviours, the thumb, index finger and middle finger were always most important.
Professor Kivell says this suggests that nut-cracking force may not be high enough to elicit changes in the formation of the human hand, which may be why other primates are adept nut-crackers without having a human-like hand.
In contrast, making stone flakes and accessing marrow may have been key influences on our hand anatomy due to the high stress they cause on our hands. The researchers concluded that eating marrow, given its additional benefit of high calorific value, may have also played a key role in evolution of human dexterity.
The manual pressures of stone tool behaviors and their implications for the evolution of the human hand by Erin Marie Williams-Hatala, Kevin G. Hatala, McKenzie Gordon and Margaret Kasper, all Chatham University, Pittsburgh, USA and Alastair Key and Tracy Kivell, University of Kent is published in the Journal of Human Evolution.
Monday, July 9, 2018
Discoveries by archaeology team give new clues on life in ancient Jewish village
Credit: Jim Haberman
"The mosaics decorating the floor of the Huqoq synagogue revolutionize our understanding of Judaism in this period," said Magness. "Ancient Jewish art is often thought to be aniconic, or lacking images. But these mosaics, colorful and filled with figured scenes, attest to a rich visual culture as well as to the dynamism and diversity of Judaism in the Late Roman and Byzantine periods."
The first mosaics in the Huqoq synagogue were discovered by Magness' team in 2012. Since then, Magness, director of the Huqoq excavations and Kenan Distinguished Professor of Early Judaism in the department of religious studies in Carolina's College of Arts & Sciences, assisted by Shua Kisilevitz of the Israel Antiquities Authority and Tel Aviv University have uncovered additional mosaics every summer. This year, the team's specialists and students focused their efforts on a series of mosaic panels in the north aisle. Magness said this series is part of the richest, most diverse collection of mosaics ever found in an ancient synagogue.
Along the north aisle, mosaics are divided into two rows of panels containing figures and objects with Hebrew inscriptions. One panel labeled "a pole between two" depicts a biblical scene from Numbers 13:23. The images show two spies sent by Moses to explore Canaan carrying a pole with a cluster of grapes. Another panel referencing Isaiah 11:6 includes the inscription "a small child shall lead them."
The panel shows a youth leading an animal on a rope. A fragmentary Hebrew inscription concluding with the phrase "Amen selah," meaning "Amen forever," was uncovered at the north end of the east aisle.
During this eighth dig, the team also continued to expose a rare discovery in ancient synagogues: columns covered in colorful, painted plaster still intact after nearly 1,600 years.
The mosaics have been removed from the site for conservation and the excavated areas have been backfilled. Excavations are scheduled to continue in the summer of 2019. Additional information and updates can be found at the project's website: http://www.
Mosaics uncovered by this project include:
- 2012: Samson and the foxes
- 2013: Samson carrying the gate of Gaza on his shoulders
- 2013, 2014 and 2015: a Hebrew inscription surrounded by human figures, animals and mythological creatures including cupids; and the first non-biblical story ever found decorating an ancient synagogue -- perhaps the legendary meeting between Alexander the Great and the Jewish high priest
- 2016: Noah's Ark; the parting of the Red Sea showing Pharaoh's soldiers being swallowed by giant fish
- 2017: a Helios-zodiac cycle; Jonah being swallowed by three successive fish; the building of the Tower of Babel
Friday, July 6, 2018
Ancient DNA testing solves 100-year-old controversy in Southeast Asian prehistory
Credit: Fabio Lahr
Southeast Asia is one of the most genetically diverse regions in the world, but for more than 100 years scientists have disagreed about which theory of the origins of the population of the area was correct.
One theory believed the indigenous Hòabìnhian hunter-gatherers who populated Southeast Asia from 44,000 years ago adopted agricultural practices independently, without the input from early farmers from East Asia. Another theory, referred to as the 'two-layer model' favours the view that migrating rice farmers from what is now China replaced the indigenous Hòabìnhian hunter-gatherers.
Academics from around the world collaborated on new research just published in Science which found that neither theory is completely accurate. Their study discovered that present-day Southeast Asian populations derive ancestry from at least four ancient populations.
DNA from human skeletal remains from Malaysia, Thailand, the Philippines, Vietnam, Indonesia, Laos and Japan dating back as far as 8,000 years ago was extracted for the study - scientists had previously only been successful in sequencing 4,000-year-old samples from the region. The samples also included DNA from Hòabìnhian hunter-gatherers and a Jomon from Japan - a scientific first, revealing a long suspected genetic link between the two populations.
In total, 26 ancient human genome sequences were studied by the group and they were compared with modern DNA samples from people living in Southeast Asia today.
The pioneering research is particularly impressive because the heat and humidity of Southeast Asia means it is one of the most difficult environments for DNA preservation, posing huge challenges for scientists.
Professor Eske Willerslev, who holds positions both at St John's College, University of Cambridge, and the University of Copenhagen, led the international study.
He explained: "We put a huge amount of effort into retrieving ancient DNA from tropical Southeast Asia that could shed new light on this area of rich human genetics. The fact that we were able to obtain 26 human genomes and shed light on the incredible genetic richness of the groups in the region today is astonishing."
Hugh McColl, PhD student at the Centre for GeoGenetics in the Natural History Museum of Denmark of the University of Copenhagen, and one of the lead authors on the paper, said: "By sequencing 26 ancient human genomes - 25 from South East Asia, one Japanese J?mon - we have shown that neither interpretation fits the complexity of Southeast Asian history. Both Hòabìnhian hunter-gatherers and East Asian farmers contributed to current Southeast Asian diversity, with further migrations affecting islands in South East Asia and Vietnam. Our results help resolve one of the long-standing controversies in Southeast Asian prehistory."
Dr Fernando Racimo, Assistant Professor at the Centre for GeoGenetics in the Natural History Museum of the University of Copenhagen, the other lead author, said: "The human occupation history of Southeast Asia remains heavily debated. Our research spanned from the Hòabìnhian to the Iron Age and found that present-day Southeast Asian populations derive ancestry from at least four ancient populations. This is a far more complex model than previously thought."
Some of the samples used in the two and a half year study were from The Duckworth Collection, University of Cambridge, which is one of the world's largest repositories of human remains. Professor Marta Mirazón Lahr, Director of the Duckworth Laboratory and one of the authors on the paper, said: "This study tackles a major question in the origins of the diversity of Southeast Asian people, as well as on the ancient relationships between distant populations, such as Jomon and Hòabìnhian foragers, before farming. The fact that we are learning so much from ancient genomes, such as the one from Gua Cha, highlights the importance of amazing collections such as the Duckworth."
Ancestral people of Chaco Canyon likely grew their own food
Credit: Samantha Fladd/UC
A multidisciplinary team of experts from the University of Cincinnati determined that the sandy soils of Chaco Canyon were not too salty to grow crops such as maize, beans and squash for the more than 1,200 people who occupied this beautiful but harsh landscape during its most prolific years.
Researchers have long debated whether the people who lived here between 800 and 1300 AD were self-sufficient or relied partially or entirely on imported food to survive. These ancestral Puebloans built elaborate adobe structures, some of them four stories tall and recessed among cliff faces under the hot New Mexico sun.
Some previous research suggested that the desert soils simply were too saline for agriculture. The implication was that Chaco Canyon could not support a large resident population without lots of outside help. Alternately, researchers speculated that Chaco Canyon, a place of religious importance, maintained a small resident population that served and benefited from a larger population of visitors making pilgrimages.
But UC's soil analysis suggests that the most significant challenge for growing crops was irrigation. That's where ancestral Puebloans demonstrated particularly adroit farming skills and perceptive land management, said Jon-Paul McCool, a UC graduate and lead author of the study.
"The major limitation is water. You couldn't rely on rain for field agriculture," McCool said. "You'd have to gather and control water, which we know people in the region did."
McCool earned PhD and master's degrees in geography and museum studies at UC and now teaches at Valparaiso University.
Chaco Canyon has evidence of constructed canals -- water-diversion channels designed to direct rainfall to farm fields.
"If you have a population of 1,200 people, how did they survive?" McCool asked. "The part I'm interested in is the interrelationships between people and their environment and how each of them influences the other."
The study was published in June in the journal PLOS ONE.
One prevailing theory is that residents of Chaco Canyon depended heavily on outside assistance for sustenance. But the most likely resource for imported agriculture was in the Chuska Mountains on the Arizona border, more than 50 miles from Chaco Canyon.
Traveling great distances in a dry environment is commonplace in other parts of the world. But what makes travel in the ancient Southwest especially taxing is that every step was taken on foot -- human foot.
Ancient North Americans had no camels, horses, mules, llamas, alpacas, oxen or sled dogs to carry supplies. There were precious few navigable waterways. So if you wanted to bring something on such a trip, you were carrying it every step, said Nicholas Dunning, a professor of geography in UC's McMicken College of Arts and Science.
"You have to go to the Andes before you find a native beast of burden in the New World," Dunning said. "So if you're using human porters, you quickly reach a point of diminishing returns."
Dunning said the study was able to determine that the soils could support agriculture in Chaco Canyon and that irrigation canals found at the site were built at least as early as the eighth century.
"The evidence is compelling that they produced most of the food that they consumed in Chaco Canyon and devised sophisticated irrigation strategies to do it," Dunning said.
Today, Chaco Canyon sees about 9 inches of rain per year, four times less than the breadbasket of the American Midwest. To make the most of this precious resource, ancestral Puebloans built elaborate canals to divert rainfall to their farm fields.
UC researchers re-examined soil samples taken from sites in and around Chaco Canyon. While some of these sites indeed did have saline levels too high to support agriculture, that was the exception, researchers found.
Instead, researchers found that the desert soils were not much different from soils in other parts of the Southwest where agriculture was practiced.
"The evidence is persuasive that they grew their own food," Dunning said.
"My experience in traditional societies is farmers and agricultural populations are very risk averse," Dunning said. "So you tend to think in ways of making sure you have enough to eat yourself each year along with seed for next year."
UC's team consisted of geologists, archaeologists and biologists. They spent weeks each summer studying different aspects of Chaco Canyon. Many of the study sites are accessible only by foot so researchers would hike in at dawn before the afternoon heat became too oppressive. A collapsible tent shelter provided some relief from the sun.
Researchers could drink as much as four liters of water each workday, packing in provisions and packing out soil samples. Dunning said New Mexico's evening sky was full of stars.
"The skies were extraordinary. We were there for the Perseid meteor shower," Dunning said. "The environment is quite amazing. We would set off for work before dawn. We wanted to be at the excavation sites before the sun came up because the morning was the only decent time to work."
UC's research is adding to what scientists already know about ancestral Puebloans in New Mexico. These former occupants of Chaco Canyon left behind evidence of having traded goods with people from distant places. Archaeologists have found seashells from California and macaw feathers and cacao from Mexico.
Co-author and UC research associate Samantha Fladd thinks it is improbable that residents would rely on regular deliveries of staple goods from places so far away, especially if they could grow food themselves.
"It seems highly unlikely that this would be a sustainable system," Fladd said.
"It makes more sense to me that there would be trade relationships where populations would help each other in bad years. To rely on one location for most of your food would not be the most sustainable system," she said. "I would be skeptical you would see that much patronage."
Fladd said a round trip between Chaco Canyon and the Chuska Mountains would take as long as a week, depending on how many supplies were carried.
The people of Chaco Canyon left behind petroglyphs carved into the rock -- drawings of animals, people and symbols. These included the famed "Sun Dagger," a notch in a slot canyon that casts a dagger-shaped beam of light onto a shaded rock face upon which is a carved petroglyph spiral that marks the sun dagger's path across the wall over the four seasons.
They also were known for their turquoise carvings, including a famous frog figure among the collection of the National Park Service.
UC professor emeritus Vernon Scarborough, one of the paper's co-authors, spent his career studying ancient land-use strategies around the world. Chaco Canyon demonstrates how people were able to engineer their landscape in a resourceful and sustainable way, he said.
"Chaco Canyon captures the ingenuity and creativity of the human spirit like few other places," Scarborough said.
"Our work and that of other colleagues is beginning to show the significance of low-tech adaptations in attempting to accommodate life on Earth," Scarborough said. "A greater understanding of just how these ancient, 'primitive' systems adapted and function merits a thoughtful assessment given the social and environmental stress we face globally today."
Scientists still aren't sure why the population of Chaco Canyon declined over the centuries. Chaco Canyon continued to be occupied intermittently after 1300.
"Every civilization comes to an end. But they went through a lot," McCool said. "What strategies allowed that civilization to continue? You're dealing with people who lived in a place for hundreds of years. What adaptations did they make to deal with changing circumstances?"
Fladd said when she goes to Chaco Canyon, she likes to hike up the Pueblo Alto trail. From the top of the mesa, she can survey all of Pueblo Bonito below her.
"I don't want to pretend I can understand their concerns 800 years ago," Fladd said. "But I am in awe of what they were able to do. It's a testament to how adaptable and creative they were."
Chaco Canyon has a long history of generating academic debates, in part because it's such a fascinating place. Chaco Canyon has been studied or referenced in thousands of research papers.
"Archaeology is a fun science because it requires a lot of imagination," Dunning said. "You're never dealing with complete data sets, so one has to fill in the holes. That's where the controversy comes in."
Our human ancestors walked on two feet but their children still had a backup plan
Credit: Jeremy DeSilva & Cody Prang
"For the first time, we have an amazing window into what walking was like for a 2½-year-old, more than 3 million years ago," says lead author, Jeremy DeSilva, an associate professor of anthropology at Dartmouth College, who is one of the world's foremost authorities on the feet of our earliest ancestors. "This is the most complete foot of an ancient juvenile ever discovered."
The tiny foot, about the size of a human thumb, is part of a nearly complete 3.32-million-year-old skeleton of a young female Australopithecus afarensis discovered in 2002 in the Dikika region of Ethiopia by Zeresenay (Zeray) Alemseged, a professor of organismal biology and anatomy at the University of Chicago and senior author of the study. Alemseged is internationally known as a leading paleontologist on the study of human origins and human evolution.
"Placed at a critical time and the cusp of being human, Australopithecus afarensis was more derived than Ardipithecus (a facultative biped) but not yet an obligate strider like Homo erectus. The Dikika foot adds to the wealth of knowledge on the mosaic nature of hominin skeletal evolution" explained Alemseged.
Given that the fossil of the tiny foot is the same species as the famous Lucy fossil and was found in the same vicinity, it is not surprising that the Dikika child was erroneously labeled "Lucy's baby" by the popular press, though this youngster lived more than 200,000 years before Lucy.
In studying the fossil foot's remarkably preserved anatomy, the research team strived to reconstruct what life would have been like years ago for this toddler and how our ancestors survived. They examined what the foot would have been used for, how it developed and what it tells us about human evolution. The fossil record indicates that these ancient ancestors were quite good at walking on two legs. "Walking on two legs is a hallmark of being human. But, walking poorly in a landscape full of predators is a recipe for extinction," explained DeSilva.
At 2½ years old, the Dikika child was already walking on two legs, but there are hints in the fossil foot that she was still spending time in the trees, hanging on to her mother as she foraged for food. Based on the skeletal structure of the child's foot, specifically, the base of the big toe, the kids probably spent more time in the trees than adults. "If you were living in Africa 3 million years ago without fire, without structures, and without any means of defense, you'd better be able get up in a tree when the sun goes down," added DeSilva. "These findings are critical for understanding the dietary and ecological adaptation of these species and are consistent with our previous research on other parts of the skeleton especially, the shoulder blade," Alemseged noted.
Ancient genome analyses reveal mosaic pattern of goat domestication thousands of years ago
Goat domestication was a mosaic --
not a singular -- process, with capture from the wild impacting genetic
diversity in different regions of the Fertile Crescent
An international team of scientists, led by geneticists from Trinity College Dublin, have sequenced the genomes from ancient goat bones from areas in the Fertile Crescent where goats were first domesticated around 8,500 BC. They reveal a 10,000-year history of local farmer practices featuring genetic exchange both with the wild and among domesticated herds, and selection by early farmers.
This genetic data - including 83 mitochondrial sequences and whole genome data from 51 goats - is published today by PhD Researcher in Genetics, Kevin Daly, and colleagues, in leading international journal Science.
One of our first domesticates and a source of meat, milk and hides, goats now number almost a billion animals. They have been a partner animal since c. 8,500 BC. The earliest evidence for domestic goats occurs in the Fertile Crescent region of Southwest Asia, where crop farming and animal herding began. Before herding, local hunters targeted wild goats - also known as bezoar - and this local practice eventually became the basis of goat management and livestock keeping.
However, reading the past from examining modern genetics is difficult due to thousands of years of migration and mixture.
"Just like humans, modern goat ancestry is a tangled web of different ancestral strands. The only way to unravel these and reach reliably into the past is to sequence genomes from actual ancient animals; a kind of molecular time travel," said Professor of Population Genetics and ERC Advanced Investigator at Trinity College Dublin, Dan Bradley, who led the project.
Using genetic data from over 80 ancient wild and domestic goats, the group has charted the initial patterns of domestication, demonstrating a surprising degree of genetic differentiation between goats across the Fertile Crescent and the surrounding regions.
Research Fellow at Trinity, and joint first author of the paper, Pierpaolo Maisano Delser, said: "Goat domestication was a mosaic rather than a singular process with continuous recruitment from local wild populations. This process generated a distinctive genetic pool which evolved across time and still characterises the different goat populations of Asia, Europe and Africa today."
Using ancient samples, the group was able to analyse the genetic diversity of different goat populations back in time and reconstruct the history of early domesticates.
Domestic animals have changed human society and humans have also moulded livestock into hundreds of different types and breeds - this study has the earliest genetic discovery yet of this process. It seems that, like modern breeders, ancient farmers were interested in animal appearance.
PhD Researcher at Trinity, and first author of the paper, Kevin Daly, said: "Whole genome sequences from the past allowed us directly analyse some of the earliest goat herds. We found evidence that at least as far back as 8,000 years ago herders were interested in or valued the coat colour of their animals, based on selection signals at pigmentation genes." Furthermore, distinct but parallel patterns of this selection were observed in different early herds, suggesting this was a repeated phenomenon.
There are also indications that these early animals had been selected for liver enzymes that gave better tolerance to new toxins, possibly from fungus growing on fodder, and also production traits such as fertility and size.
First dogs in the Americas arrived from Siberia, disappeared after European contact
Credit: Photo courtesy Illinois State Archaeological Survey.
This is the first comprehensive genomic study of ancient dogs in the Americas to analyze nuclear DNA, which is inherited from both parents, along with mitochondrial DNA, which is passed down only from mothers to their offspring. By comparing genomic signatures from 71 mitochondrial and seven nuclear genomes of ancient North American and Siberian dogs spanning a period of 9,000 years, the research team was able to gain a clearer picture of the history of the first canine inhabitants of the Americas.
The oldest dog remains in the Americas date to about 9,000 years ago, many thousands of years after people began migrating over a land bridge connecting present-day Siberia and Alaska. The ancient dogs analyzed in the new study likely originated in Siberia, the researchers found. The dogs dispersed to every part of the Americas, migrating with their human counterparts.
These dogs persisted for thousands of years in the Americas, but almost completely vanished after European contact, the researchers found.
"This suggests something catastrophic must have happened, and it's likely associated with European colonization," said senior lead author Laurent Frantz, a lecturer at Queen Mary University and co-investigator at the University of Oxford. "But we just do not have the evidence to explain this sudden disappearance yet."
"By looking at genomic data along with mitochondrial data, we were able to confirm that dogs came to the Americas with humans, and that nearly all of that diversity was lost - most likely as a result of European colonization," said Kelsey Witt, who led the mitochondrial DNA genome work as a graduate student in the laboratory of University of Illinois anthropology professor Ripan Malhi, who also is an author of the study.
"Few modern dogs have any trace of these ancient lineages," said Witt, now a postdoctoral researcher at the University of California, Merced.
The team also discovered that the genomic signature of a transmissible cancer that afflicts dogs appears to be one of the last "living" remnants of the genetic heritage of dogs that populated the Americas prior to European contact.
"This suggests that this tumor originated in or near the Americas," Witt said.
The new findings reinforce the idea that early human and dog inhabitants of the Americas faced many of the same challenges after European contact, Malhi said.
"It is known how Indigenous peoples of the Americas suffered from the genocidal practices of European colonists after contact," he said. "What we found is that the dogs of Indigenous peoples experienced an even more devastating history and a near-total loss, possibly as a result of forced cultural changes and disease."
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