Reconstructing how Neanderthals grew, based on an El Sidrón child

How did Neanderthals grow? Does modern man develop in the same way as Homo neanderthalensis did? How does the size of the brain affect the development of the body? A study led by the Spanish National Research Council (CSIC) researcher, Antonio Rosas, has studied the fossil remains of a Neanderthal child's skeleton in order to establish whether there are differences between the growth of Neanderthals and that of sapiens.

Neanderthal children may have grown up as slowly as modern humans 
[Credit: © S.Plailly, E.Daynes/LookatSciences]

According to the results of the article, which are published in Science, both species regulate their growth differently to adapt their energy consumption to their physical characteristics.

"Discerning the differences and similarities in growth patterns between Neanderthals and modern humans helps us better define our own history. Modern humans and Neanderthals emerged from a common recent ancestor, and this is manifested in a similar overall growth rate," explains CSIC researcher, Antonio Rosas, from Spain's National Natural Science Museum (MNCN). As fellow CSIC researcher Luis Ríos highlights, "Applying paediatric growth assessment methods, this Neanderthal child is no different to a modern-day child." The pattern of vertebral maturation and brain growth, as well as energy constraints during development, may have marked the anatomical shape of Neanderthals.

Neanderthals had a greater cranial capacity than today's humans. Neanderthal adults had an intracranial volume of 1,520 cubic centimetres, while that of modern adult man is 1,195 cubic centimetres. That of the Neanderthal child in the study had reached 1,330 cubic centimetres at the time of his death, in other words, 87.5% of the total reached at eight years of age. At that age, the development of a modern-day child's cranial capacity has already been fully completed.

"Developing a large brain involves significant energy expenditure and, consequently, this hinders the growth of other parts of the body. In sapiens, the development of the brain during childhood has a high energetic cost and, as a result, the development of the rest of the body slows down," Rosas explains.

Neanderthals and sapiens

The cost, in terms of energy, of anatomical growth of the modern brain is unusually high, especially during breastfeeding and during infancy, and this seems to require a slowing down of body growth. The growth and development of this juvenile Neanderthal matches the typical characteristics of human ontogeny, where there is a slow anatomical growth between weaning and puberty. This could compensate for the immense energy cost of developing such a large brain.

Skeleton of the Neanderthal boy recovered from the El Sidrón 
cave (Asturias, Spain) [Credit: Paleoanthropology Group 
MNCN-CSIC]

In fact, the skeleton and dentition of this Neanderthal present a physiology which is similar to that of a sapiens of the same age, except for the thorax area, which corresponds to a child between five and six years, in that it is less developed. "The growth of our Neanderthal child was not complete, probably due to energy saving," explains CSIC researcher Antonio Rosas.

The only divergent aspect in the growth of both species is the moment of maturation of the vertebral column. In all hominids, the cartilaginous joints of the middle thoracic vertebrae and the atlas are the last to fuse, but in this Neanderthal, fusion occurred about two years later than in modern humans.

"The delay of this fusion in the vertebral column may indicate that Neanderthals had a decoupling of certain aspects in the transition from infancy to the juvenile phase. Although the implications are unknown, this feature could be related to the characteristic enlarged shape of the Neanderthal torso, or slower brain growth," says Rosas.

The Neanderthal child

The protagonist of this study was 7.7 years old, weighed 26 kilos and measured 111 centimetres at the time of death. Although the genetic analyses failed to confirm the child's sex, the canine teeth and the sturdiness of the bones showed that it to be a male. 138 pieces, 30 of them teeth (including some milk teeth), and part of the skeleton- including some fragments of the skull from the individual- identified as El Sidrón J1, have recovered.

(Left to Right) Antonio García-Tabernero, Antonio Rosas and Luis Ríos beside the Neanderthal child's skeleton 
[Credit: Andrés Díaz-CSIC Communications Department]

The researchers have been able to establish that our protagonist was right-handed and was already performing adult tasks, such as using his teeth as a third hand to handle skins and plant fibres. In addition, they know who his mother was, and that the child protagonist of this investigation had a younger brother in the group. Furthermore, this child was found to have suffered from enamel hypoplasia when he was two or three years old. Hypoplasia (white spots on the teeth, especially visible in the upper incisors), occurs when the teeth have less enamel than normal, the cause usually being malnutrition or disease.

Discovered in 1994, the El Sidrón cave, located in Piloña (in Asturias, northern Spain) has provided the best collection of Neanderthals that exists on the Iberian Peninsula. The team has recovered the remains of 13 individuals from the cave. The group consisted of seven adults (four women and three men), three teenagers and three younger children.

Previous studies have been carried out by a multidisciplinary team led by the paleoanthropologist Antonio Rosas (CSIC's National Museum of Natural Sciences), the geneticist Carles Lalueza-Fox (Institute of Evolutionary Biology, run by CSIC and the Pompeu Fabra University) and by the archaeologist Marco de la Rasilla (University of Oviedo).

Source: Spanish National Research Council (CSIC) [September 22, 2017]

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Ancient human DNA in sub-Saharan Africa lifts veil on prehistory

The first large-scale study of ancient human DNA from sub-Saharan Africa opens a long-awaited window into the identity of prehistoric populations in the region and how they moved around and replaced one another over the past 8,000 years.

Mount Hora in Malawi, where the oldest DNA in the study, from a woman who lived more than 8,000 years ago, 
was obtained [Credit: Jessica C. Thompson/Emory University]

The findings, published Cell by an international research team led by Harvard Medical School, answer several longstanding mysteries and uncover surprising details about sub-Saharan African ancestry—including genetic adaptations for a hunter-gatherer lifestyle and the first glimpses of population distribution before farmers and animal herders swept across the continent about 3,000 years ago.

"The last few thousand years were an incredibly rich and formative period that is key to understanding how populations in Africa got to where they are today," said David Reich, professor of genetics at HMS and a senior associate member of the Broad Institute of MIT and Harvard. "Ancestry during this time period is such an unexplored landscape that everything we learned was new."

Reich shares senior authorship of the study with Ron Pinhasi of the University of Vienna and Johannes Krause of the Max Planck Institute for the Science of Human History and the University of Tübingen in Germany.

"Ancient DNA is the only tool we have for characterizing past genomic diversity. It teaches us things we don't know about history from archaeology and linguistics and can help us better understand present-day populations," said Pontus Skoglund, a postdoctoral researcher in the Reich lab and the study's first author. "We need to ensure we use it for the benefit of all populations around the world, perhaps especially Africa, which contains the greatest human genetic diversity in the world but has been underserved by the genomics community."

Long time coming

Although ancient-DNA research has revealed insights into the population histories of many areas of the world, delving into the deep ancestry of African groups wasn't possible until recently because genetic material degrades too rapidly in warm, humid climates.

Technological advances—including the discovery by Pinhasi and colleagues that DNA persists longer in small, dense ear bones—are now beginning to break the climate barrier. Last year, Reich and colleagues used the new techniques to generate the first genome-wide data from the earliest farmers in the Near East, who lived between 8,000 and 12,000 years ago.

Genomic time-lapse

Almost half of the team's samples came from Malawi, providing a series of genomic snapshots from the same location across thousands of years.

This visual abstract depicts the findings of Skoglund et al. In their paper, the prehistory of African populations is explored 
by genome-wide analysis of 16 human remains providing insight into lineages, admixture, and genomicadaptions 
[Credit: Skoglund et al./Cell 2017]

The time-series divulged the existence of an ancient hunter-gatherer population the researchers hadn't expected.

When agriculture spread in Europe and East Asia, farmers and animal herders expanded into new areas and mixed with the hunter-gatherers who lived there. Present-day populations thus inherited DNA from both groups.

The new study found evidence for similar movement and mixing in other parts of Africa, but after farmers reached Malawi, hunter-gatherers seem to have disappeared without contributing any detectable ancestry to the people who live there today.

"It looks like there was a complete population replacement," said Reich. "We haven't seen clear evidence for an event like this anywhere else."

The Malawi snapshots also helped identify a population that spanned from the southern tip of Africa all the way to the equator about 1,400 years ago before fading away. That mysterious group shared ancestry with today's Khoe-San people in southern Africa and left a few DNA traces in people from a group of islands thousands of miles away, off the coast of Tanzania.

"It's amazing to see these populations in the DNA that don't exist anymore," said Reich. "It's clear that gathering additional DNA samples will teach us much more."

"The Khoe-San are such a genetically distinctive people, it was a surprise to find a closely related ancestor so far north just a couple of thousand years ago," Reich added.

The new study also found that West Africans can trace their lineage back to a human ancestor that may have split off from other African populations even earlier than the Khoe-San.

Missing links

The research similarly shed light on the origins of another unique group, the Hadza people of East Africa.

"They have a distinct appearance, language and genetics, and some people speculated that, like the Khoe-San, they might represent a very early diverging group from other African populations," said Reich. "Our study shows that instead, they're somehow in the middle of everything."

The Hadza, according to genomic comparisons, are today more closely related to non-Africans than to other Africans. The researchers hypothesize that the Hadza are direct descendants of the group that migrated out of Africa, and possibly spread within Africa as well, after about 50,000 years ago.

Another discovery lay in wait in East Africa.

Scientists had predicted the existence of an ancient population based on the observation that present-day people in southern Africa share ancestry with people in the Near East. The 3,000-year-old remains of a young girl in Tanzania provided the missing evidence.

Reich and colleagues suspect that the girl belonged to a herding population that contributed significant ancestry to present-day people from Ethiopia and Somalia down to South Africa. The ancient population was about one-third Eurasian, and the researchers were able to further pinpoint that ancestry to the Levant region.

"With this sample in hand, we can now say more about who these people were," said Skoglund.

The finding put one mystery to rest while raising another: Present-day people in the Horn of Africa have additional Near Eastern ancestry that can't be explained by the group to which the young girl belonged.

Natural selection

Finally, the study took a first step in using ancient DNA to understand genetic adaptation in African populations.

It required "squeezing water out of a stone" because the researchers were working with so few ancient samples, said Reich, but Skoglund was able to identify two regions of the genome that appear to have undergone natural selection in southern Africans.

One adaptation increased protection from ultraviolet radiation, which the researchers propose could be related to life in the Kalahari Desert. The other variant was located on genes related to taste buds, which the researchers point out can help people detect poisons in plants.

The researchers hope that their study encourages more investigation into the diverse genetic landscape of human populations in Africa, both past and present. Reich also said he hopes the work reminds people that African history didn't end 50,000 years ago when groups of humans began migrating into the Near East and beyond.

"The late Stone Age in Africa is like a black hole, research-wise," said Reich. "Ancient DNA can address that gap."

Source: Cell Press [September 21, 2017]

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Solving the Easter Island population puzzle

Easter Island, known as Rapa Nui by its inhabitants, has been surrounded in mystery ever since the Europeans first landed in 1722. Early visitors estimated a population of just 1,500-3,000, which seemed at odds with the nearly nine hundred giant statues dotted around the Island. How did this small community construct, transport and erect these large rock figures?

Easter Island Moai [Credit: Arian Zwegers/Flickr]

A new study, published in the open-access journal Frontiers in Ecology and Evolution, hopes to unravel this mystery by giving the best estimate yet of the maximum population size sustained by Easter Island in its heyday.

"Despite its almost complete isolation, the inhabitants of Easter Island created a complicated social structure and these amazing works of art before a dramatic change occurred," says Dr. Cedric Puleston, lead author of this study, based at the Department of Anthropology, University of California, Davis, USA. "We've tried to solve one piece of the puzzle - to figure out the maximum population size before it fell. It appears the island could have supported 17,500 people at its peak, which represents the upper end of the range of previous estimates."

He adds, "If the population fell from 17,500 to the small number that missionaries counted many years after European contact, it presents a very different picture from the maximum population of 3,000 or less that some have suggested."

Previous archaeological evidence implies the indigenous people numbered far greater than the 1,500-3,000 individuals encountered in the 18th century. The population history of the island remains highly controversial. In addition to internal conflict, the population crash has been attributed to "ecocide," in which the Island's resources were exhausted by its inhabitants, reducing its ability to support human life.

Puleston and his colleagues examined the agricultural potential of the Island before these events occurred, to calculate how many people the Island could sustain.

"The project, funded by the U.S. National Science Foundation, involved a number of really good researchers, including archaeologists, a local expert in Rapa Nui culture, a soil scientist, a biogeochemist, and a population biologist, to get a thorough picture of what the island was like before European contact," he explains.

"We examined detailed maps, took soil samples around the Island, placed weather stations, used population models and estimated sweet potato production. When we had doubts about one of these factors we looked at the range of its potential values to work out different scenarios."

They found 19% of the Island could have been used to grow sweet potatoes, which was the main food crop. By using information on how birth and death rates at various ages depend on food availability, the researchers calculated the population size that level of production could sustain.

"The result is a wide range of possible maximum population sizes, but to get the smallest values you have to assume the worst of everything," says Puleston. "If we compare our agriculture estimates with other Polynesian Islands, a population of 17,500 people on this size of island is entirely reasonable."

He concludes, "Easter Island is fascinating because it represents an extreme example of a natural experiment in human adaptation, which began when people from a single cultural group spread quickly across the islands of the Pacific. The different environments they encountered on these islands generated a tremendous amount of variation in human behavior. As an extremely unusual case, in both its cultural achievements and its ecological transformation, Easter Island is remarkable and important. It retains an air of mystery, but it's a real place and has a real history lived by real people. Dispelling that mystery brings us closer to understanding the nature of humanity."

Source: Frontiers [September 20, 2017]

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X-Rays reveal secrets about ancient Peruvian mummy's history

Doctors at Driscoll Children's Hospital were hoping to take the wraps off some of the mysteries hidden inside an Peruvian mummy this morning. This archaelogical investigation was not done with trowels and shovels: this case, the digging was done with X-rays.

This 2,000-year-old mummy was taken to Driscoll Children's Hospital today for X-rays that can reveal information 
about its life in ancient times [Credit: Corpus Christi Museum of Natural History and Science]

"She was not my average patient!" said Suzi Beckwith, Diagnostic X-ray Coordinator at Driscoll Children's Hospital

For the past 60 years, the mummy has been kept at the Corpus Christi Museum of Natural History and Science. However now that museum wants to send the mummy back to Peru. They are trying to learn as much as they can about her, and X-rays can reveal a lot.

The museum already knows some of the mummy's past from records. They believe it is from the Inca Empire of Peru. When she was alive, the girl was 6- to 8-years-old girl, but that was back as far as 2,000 years ago.

Today, the museum and the hospital came together to see what secrets she is hiding inside.

"Because of the size of the mummy, I thought it was a baby," Beckwith said. "But looking at the X-rays, you see her legs are actually tucked in. So she's not a baby. she's a little girl.

X-rays can confirm gender, age, and even cause of death.

The X-rays showed the mummy's bones are in good condition, and can confirm other things like gender, age, 
and even cause of death [Credit: Corpus Christi Museum of Natural History and Science]

"We're looking for things that can help us give information to anthropologists in Peru, and then hopefully confirm cultural group that she belongs to, said Jillian Becquet, Collections Manager at the Corpus Christi Museum of Science and History.

Little is known about the girl's ancient life, where the mummy is from, or whether she was taken out of Peru legally.

Records do show the mummy was exhibited at the American Museum of Natural History in New York City, before arriving at the Corpus Christi Museum of Natural History and Science in 1957. The mummy was one of the museum's first artifacts. However, it was removed from display in the 1980s, and has sat in storage ever since.

"This person needs to be where her family buried her," Becquet said.

Now, the museum is trying to learn more about her past and identity, working with the Peruvian Embassy with the goal of sending the mummy home. 

"Whatever group was around her chose to do this very caring thing, to wrap her purposefully and bury her," Becquet said. "Somebody along the way disrespected that, and so we want that to be restored."

From here, Peruvian anthropologists will look over the data to verify the findings. As for if or when this mummy will be returned, will be up to the Peruvian government to decide.

Author: Jane Caffrey | Source: KrisTV [Septembter 18, 2017]

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Dawn of agriculture linked with poor start to life in ancient Atacama, Chile

Learning to cultivate crops and other agricultural food – rather than relying on hunter-gathering – is often thought of as a key milestone in the history of humanity.

Atacama [Credit: University of Otago]

However, new evidence from the University of Otago and the Universidad de Tarapaca in Chile indicates that the adoption of agriculture was associated with poor maternal and infant health in the ancient Atacama Desert.

This work provides the first direct evidence for maternal-foetal transfer of a nutritional deficiency in an archaeological sample.

Study lead author and PhD candidate Anne Marie Snoddy, of the Department of Anatomy, says agriculture does provide some evolutionary advantages, including increased resources for population growth.

“However, crop foods are quite poor in many nutrients needed by growing babies and their mothers. Women and children are particularly vulnerable to the negative effects of agricultural intensification and resource scarcity.”

The research team’s findings appear in the International Journal of Paleopathology.

“Our new paper sheds light on to the impact of the agricultural transition on these past people, showing rare evidence for newborns and foetuses, including a possible mother-baby pair, with signs of pathology related to food deficiencies.

“This kind of direct evidence of maternal-foetal transfer of a nutritional deficiency is not something we have ever seen in the archaeological record.”

This research aimed to assess if there was any impact on the reduction of dietary diversity with the adoption of agricultural food practices, by investigating disease evidence on the skeletons of individuals from a transitional Early Formative Period site (3,600-3,200 years before present).

All the infants at this site showed potential evidence for nutritional insufficiency in the form of scurvy (vitamin C deficiency).

“Scurvy leaves its signature on bones. Prolonged vitamin C deficiency causes poor bone formation and leaky blood vessels. Small amounts of blood collect at muscle attachment sites and this can cause abnormal bone to form,” Ms Snoddy says.

“By analysing the patterning of this abnormal bone formation throughout the skeleton, we can identify people who suffered from a period of vitamin C deficiency during their life, and this can give us information about the general quality of their diet. Scurvy is associated with low dietary diversity and generally poor nutrition.”

Senior author Dr Sian Halcrow, of the Department of Anatomy, says there has been a focus archaeologically on the exploration of the pre-agricultural Chinchorro people and associated elaborate mummy burials.

However, recent research highlights periods of increasing infant mortality during the transitional period from hunter-gatherer to agricultural practices, and biological anthropologists are beginning to investigate the reasons for this.

“This work is important for the wider interpretation of the environmental context of the Atacama Desert, in northern Chile, in which these populations lived. This desert is one of the harshest environments in the world, with the least amount of rainfall (<2 mm per year) of any hot desert.

“The stresses on these people may have gotten worse with the adoption of agricultural food crops, which are poor sources of many important nutrients,” she says.

Ms Snoddy says the researchers interpreted that the vitamin C deficiency was possibly due to periodic food shortages from El Nino events in the area.

“In this paper, we argue that the extreme arid environment of the Atacama means that it is particularly ecologically unstable, with climate change causing major impact on both marine and land resources.”

Dr Halcrow says “importantly, the group’s latest findings also contribute to an understanding of the sensitive relationship between the ill health of the mother and infant in the past”.

“Ongoing work on bone and tooth chemistry and microfossil analyses of dental plaque may provide further insights into the transition to agriculture at this time.”

Source: University of Otago [September 15, 2017]

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Secrets of ancient Irish burial practices revealed

A new analysis of bones taken from a century-old excavation at Carrowkeel in County Sligo has revealed evidence of the burial practices and death rites of the ancient people of Ireland.

Some of the jawbones from the original Carrowkeel excavation a century ago, which were re-discovered 
in the Duckworth Laboratory at the Leverhulme Centre for Human Evolutionary Studies 
at University of Cambridge [Credit: IT Sligo]

The findings, which have been published in the journal Bioarchaeology International, are part of a project applying modern techniques and research questions to the human remains.

The team of researchers includes Sam Moore, lecturer in Prehistoric Archaeology at IT Sligo, and the group’s work focussed on the 5300 years-old Passage Tomb Complex at Carrowkeel. This site is one of the most impressive Neolithic ritual landscapes in Europe.

“The bones were analysed from an original excavation of Carrowkeel in 1911, led by Prof R.A.S. McAlister,” explains Sam.

“They were subsequently presumed missing or lost until a group of boxes with the name ‘Carrowkeel’ on them was discovered in the archive in the University of Cambridge in 2001. The bones date from between 3500 and 2900 BC."

A view of Cairn K at the Carrowkeel Passage Tomb site in County Sligo [Credit: IT Sligo]

The project was led by Dr Thomas Kador (University College London), with osteological research undertaken by Dr Jonny Geber from the Department of Anatomy at New Zealand’s University of Otago. The group also included Sligo based archaeologist Dr Robert Hensey and independent researcher Pádraig Meehan.

The team analysed bones from seven passage tombs that included both unburnt and cremated human remains from around 40 individuals.

Dr Geber says he and his colleagues determined that the unburnt bone displayed evidence of dismemberment.

“We found indications of cut marks caused by stone tools at the site of tendon and ligament attachments around the major joints, such as the shoulder, elbow, hip and ankle,” he says.

Cut marks on some of the human remains which were discovered at Carrowkeel. Cut marks, marked in white (above) 
and magnified (below), observed on a left humerus (upper arm) from Cairn K (a), the ilium of a left coxae (part of pelvis) 
from Cairn K (b), and a right femur (upper leg) from Cairn K (c) [Credit: Jonny Geber]

Dr Geber says the new evidence suggests that a complex burial rite was undertaken at Carrowkeel, which involved a funerary rite and placed a particular focus on the “deconstruction” of the body.

So why would people in pre-historic Ireland have performed such rituals?

“Attempting to understand the reasons these ancient communities dismembered the bodies is one of the real fascinations with this research,” says Sam Moore.

“In the societies of the past, ancestry had more to do with group identity. This appears to have held real importance in Neolithic Ireland.”

An aerial view of Carrowkeel in County Sligo, showing Cairns E & F in the foreground; 
Lough Arrow in the background [Credit: IT Sligo]

While evidence of similar pre-historic funerary rites has been uncovered in the UK, this is the first definitive discovery of similar practices during the same period on the island of Ireland.

The re-analysis of the bones uncovers high level of complexity and diversity of the funerary rites, which perhaps was not fully recognized previously.

The new study has been able to show that the Carrowkeel complex was a highly significant place in Neolithic society in Ireland, which had an important role in facilitating interaction with the dead and a spiritual connection with the ancestors.

Source: Institute of Technology Sligo [September 15, 2017]

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