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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Huge genetic diversity among Papuan New Guinean peoples revealed

The first large-scale genetic study of people in Papua New Guinea has shown that different groups within the country are genetically highly different from each other. Scientists at the Wellcome Trust Sanger Institute and their colleagues at the University of Oxford and the Papua New Guinea Institute of Medical Research reveal that the people there have remained genetically independent from Europe and Asia for most of the last 50,000 years, and that people from the country’s isolated highlands region have been completely independent even until the present day.

Traditional Enga cultural show in Wabag, Papua New Guinea 
[Credit: Michal Knitl/Shutterstock]

Reported in the journal Science, the study also gives insights into how the development of agriculture and cultural events such as the Bronze or Iron Age could affect the genetic structure of human societies.

Papua New Guinea is a country in the southwestern Pacific with some of the earliest archaeological evidence of human existence outside Africa. Largely free from Western influence and with fascinating cultural diversity, it has been of enormous interest to anthropologists and other scientists seeking to understand human cultures and evolution.

Male Huli tribe member in Tari area of Papua New Guinea in traditional clothes and face paint 
[Credit: Amy Nichole Harris/Shutterstock]

With approximately 850 domestic languages, which account for over 10 per cent of the world’s total, Papua New Guinea is the most linguistically diverse country in the world. To discover if the linguistic and cultural diversity was echoed in the genetic structure of the population, researchers studied the genomes of 381 Papuan New Guinean people from 85 different language groups within the country.

The researchers looked at more than a million genetic positions in the genome of each individual, and compared them to investigate genetic similarities and differences. They found that groups of people speaking different languages were surprisingly genetically distinct from each other.

Woman of a Papuan tribe in traditional clothes and coloring in New Guinea Island 
[Credit: Byelikova Oksana/Shutterstock]

Anders Bergström, the first author on the paper from the Wellcome Trust Sanger Institute, said: "This is the first large-scale study of genetic diversity and population history in Papua New Guinea. Our study revealed that the genetic differences between groups of people there are generally very strong, often much stronger even than between major populations within all of Europe or all of East Asia."

Professor Stephen J. Oppenheimer, second author of the paper from the Wellcome Trust Centre for Human Genetics, University of Oxford, said: "We found a striking difference between the groups of people who live in the mountainous highlands and those in the lowlands, with genetic separation dating back 10,000-20,000 years between the two. This makes sense culturally, as the highland groups historically have kept to themselves, but such a strong genetic barrier between otherwise geographically close groups is still very unusual and fascinating."

Locations of people studied from Papua New Guinea. Each language group is represented by a circle; the area indicates
 the number of genotyped individuals, and the color indicates the top-level language phylum. The study found that 
people speaking different languages were strongly genetically distinct from each other 
[Credit: Science doi: 10.1126/science.aan3842]

Human evolution in Europe and Asia has been greatly influenced by the development of agriculture around 10,000 years ago. When small bands of hunter-gatherers settled into villages and started farming, they expanded and over time gave rise to more genetically homogenous (similar) societies. However, despite the independent development of agriculture in Papua New Guinea at about the same time, the same process of homogenization did not occur here. This may indicate that other historical processes in Europe and Asia, such as the later Bronze and Iron Ages, were the key events that shaped the current genetic structure of those populations.

Dr Chris Tyler-Smith, corresponding author on the paper from the Wellcome Trust Sanger Institute, said: "Using genetics, we were able to see that people on the island of New Guinea evolved independently from rest of the world for much of the last 50,000 years. This study allows us to glimpse a different version of human evolution from that in Europe and Asia, one in which there was agriculture but no later Bronze Age or Iron Age. Papua New Guinea might show the genetic, cultural and linguistic diversity that many settled human societies would have had before these technological transformations."

Source: Wellcome Trust Sanger Institute [September 14, 2017]

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Nothing but the tooth: What dental remains from Homo naledi can tell us

Anthropologists just love to sink their teeth into a good mystery, and some recent research from NC State and Vassar College has done just that – by looking at what dental development in Homo naledi fossils can tell us about this human relative and the evolution of our own species, Homo sapiens.

H. naledi teeth in mandible [Credit: Alice Harvey]

In 2013, paleoanthropologists discovered the fossilized remains of at least 15 individual hominins, or human relatives, within the Dinaledi chamber of the Rising Star cave system near Johannesburg, South Africa. The remains were from an entirely new species, dubbed Homo naledi by the researchers. Recently, these fossils were determined to be around 200,000 – 300,000 years old, meaning that H. naledi walked the earth at the same time as other hominins like Neanderthals and possibly the earliest members of H. sapiens.

Chris Walker, assistant professor of anatomy at NC State, and Zach Cofran, a biological anthropologist from Vassar College, were researchers on the original team that studied the H. naledi fossils. Recently the duo had the opportunity to examine the dental remains of the youngest members of H. naledi to see if this extinct species grew more like humans or our extinct relatives.

Humans are unique among primates in how long it takes us to fully develop from child to adult. Chimpanzees, our closest living relatives, develop a bit faster than we do. Tooth formation and eruption patterns – the rate and order in which baby and adult teeth grow and emerge – also differ between humans and chimps. Scientists surmise that this difference may be related to the differences in developmental timing between the two species. Most evidence to date has suggested that the human-like pattern emerged quite recently in our evolutionary history and that our extinct relatives were generally more like chimps than humans with respect to dental development.

Walker and Cofran used CT scans of the mandibles of two H. naledi youngsters – one an infant and one an older child – to determine how the species’ teeth formed and emerged. What they discovered was surprising.

“Overall, we found a mixture of human and chimp patterns, although the eruption sequences in particular were human-like,” Walker says. “Given that H. naledi was alive so recently, similarities to humans aren’t necessarily shocking. But given the numerous primitive anatomical features of H. naledi – including a small brain, which is suggestive of a relatively fast, more chimp-like developmental pace – our findings are somewhat unanticipated. Even Neanderthals, a group that is much more anatomically similar to modern humans than H. naledi, have a more primitive dental eruption sequence.”

The uniqueness of the finding may actually raise more questions than it answers regarding H. naledi, and it potentially affects how anthropologists gauge the development times and life histories of ancient hominin species.

“A prolonged period of growth and development is a defining feature of humans, but we don’t know when this trait evolved,” says Cofran. “We’ve relied on teeth to make inferences about growth and development in extinct species because they preserve well in fossil samples and dental maturation has previously been linked to aspects of life history. But this finding, with the similarities between modern humans and H. naledi, raises questions about the adaptive significance of tooth emergence sequences.”

Walker and first author Cofran published their findings in Biology Letters.

Author: Tracey Peake | Source: North Carolina State University [September 13, 2017]

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When ancient fossil DNA isn't available, ancient glycans may help trace human evolution

Ancient DNA recovered from fossils is a valuable tool to study evolution and anthropology. Yet ancient fossil DNA from earlier geological ages has not been found yet in any part of Africa, where it's destroyed by extreme heat and humidity. In a potential first step at overcoming this hurdle, researchers at University of California San Diego School of Medicine and Turkana Basin Institute in Kenya have discovered a new kind of glycan -- a type of sugar chain -- that survives even in a 4 million-year-old animal fossil from Kenya, under conditions where ancient DNA does not.

Partial upper jaw of Australopithecus anamensis, a primitive hominin, recovered from the bone bed 
excavated at the Allia Bay site [Credit: Meave Leakey, PhD]

While ancient fossils from hominins (human ancestors and extinct relatives) are not yet available for glycan analysis, this proof-of-concept study, published in Proceedings of the National Academy of Sciences, may set the stage for unprecedented explorations of human origins and diet.

"In recent decades, many new hominin fossils were discovered and considered to be the ancestors of humans," said Ajit Varki, MD, Distinguished Professor of Medicine and Cellular and Molecular Medicine at UC San Diego School of Medicine. "But it's not possible that all gave rise to modern humans -- it's more likely that there were many human-like species over time, only one from which we descended. This new type of glycan we found may give us a better way to investigate which lineage is ours, as well as answer many other questions about our evolution, and our propensity to consume red meat."

Glycans are complex sugar chains on the surfaces of all cells. They mediate interaction between cells and the environment, and often serve as docking sites for pathogens. For millions of years, the common ancestors of humans and other apes shared a particular glycan known as Neu5Gc. Then, for reasons possibly linked to a malarial parasite that exploited Neu5Gc as a means to establish infection, a mutation that probably occurred between 2 and 3 million years ago inactivated the human gene encoding the enzyme that makes the molecule. The loss of Neu5Gc amounted to a radical molecular makeover of human ancestral cell surfaces and might have created a fertility barrier that expedited the divergence of the lineage leading to humans.

Today, chimpanzees and most other mammals still produce Neu5Gc. In contrast, only trace amounts can be detected in human blood and tissue -- not because we make Neu5Gc, but, according to a previous study by Varki's team, because we accumulate the glycan when eating Neu5Gc rich red meat. Humans mount an immune response to this non-native Neu5Gc, possibly aggravating diseases such as cancer.

In their latest study, Varki and team found that, as part of its natural breakdown, a signature part of Neu5Gc is also incorporated into chondroitin sulfate (CS), an abundant component in bone. They detected this newly discovered molecule, called Gc-CS, in a variety of mammalian samples, including easily detectable amounts in chimpanzee bones and mouse tissues.

Like Neu5Gc, they found that human cells and serum have only trace amounts of Gc-CS -- again, likely from red meat consumption. The researchers backed up that assumption with the finding that mice engineered to lack Neu5Gc and Gc-Cs (similar to humans) had detectable Gc-CS only when fed Neu5Gc-containing chow.

Excavation of the bone bed at the Allia Bay site, East Turkana, in 1996. A cross section of the bone bed 
can be seen passing diagonally from the center of the image to the right hand corner. This is the site 
where researchers collected a 4-million-year-old bovid fossil that contained Gc-CS 
[Credit: Meave Leakey, PhD]

Curious to see how stable and long-lasting Gc-CS might be, Varki bought a relatively inexpensive 50,000-year-old cave bear fossil at a public fossil show and took it back to the lab. Despite its age, the fossil indeed contained Gc-CS.

That's when Varki turned to a long-time collaborator -- paleoanthropologist and famed fossil hunter Meave Leakey, PhD, of Turkana Basin Institute of Kenya and Stony Brook University. Knowing that researchers need to make a very strong case before they are given precious ancient hominin fossil samples, even for DNA analysis, Leakey recommended that the researchers first prove their method by detecting Gc-CS in even older animal fossils. To that end, with the permission of the National Museums of Kenya, she gave them a fragment of a 4-million-year-old fossil from a buffalo-like animal recovered in the excavation of a bone bed at Allia Bay, in the Turkana Basin of northern Kenya. Hominin fossils were also recovered from the same horizon in this bone bed.

Varki and team were still able to recover Gc-CS in these much older fossils. If they eventually find Gc-Cs in ancient hominin fossils as well, the researchers say it could open up all kinds of interesting possibilities.

"Once we've refined our technique to the point that we need smaller sample amounts and are able to obtain ancient hominin fossils from Africa, we may eventually be able to classify them into two groups -- those that have Gc-CS and those that do not. Those that lack the molecule would mostly likely belong to the lineage that led to modern humans," said Varki, who is also adjunct professor at the Salk Institute for Biological Studies and co-director of the UC San Diego/Salk Center for Academic Research and Training in Anthropogeny (CARTA).

In a parallel line of inquiry, Varki hopes Gc-CS detection will also reveal the point in evolution when humans began consuming large amounts of red meat.

"It's possible we'll one day find three groups of hominin fossils -- those with Gc-CS before the human lineage branched off, those without Gc-CS in our direct lineage, and then more recent fossils in which trace amounts of Gc-CS began to reappear when our ancestors began eating red meat," Varki said. "Or maybe our ancestors lost Gc-CS more gradually, or only after we began eating red meat. It will be interesting to see, and we can begin asking these questions now that we know we can reliably find Gc-CS in ancient fossils in Africa."

Leakey is also hopeful about the role Gc-CS could play in the future, as an alternative to current approaches.

"Because DNA rapidly degrades in the tropics, genetic studies are not possible in fossils of human ancestors older than only a few thousand years," she said. "Therefore such ancient glycan studies have the potential to provide a new and important method for the investigation of human origins."

Author: Heather Buschman | Source: University of California - San Diego [September 11, 2017]

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First primates were built for leaping, fossil ankle suggests

A 52-million-year-old ankle fossil suggests our prehuman ancestors were high-flying acrobats. These first primates spent most of their time in the trees rather than on the ground, but just how nimble they were as they moved around in the treetops has been a topic of dispute.

This tiny ankle bone belonged to one of the earliest members of the primate family tree. The 52-million-year-old fossil 
suggests that the first primates were expert leapers. Discovered more than 30 years ago by paleontologist 
Marc Godinot, the fossil is now housed at the Muséum National d'Histoire Naturelle in Paris 
[Credit: Douglas Boyer, Duke University]

For years, scientists thought the ancestors of today's humans, monkeys, lemurs and apes were relatively slow and deliberate animals, using their grasping hands and feet to creep along small twigs and branches to stalk insects or find flowers and fruits.

But a fossil study published in the Journal of Human Evolution suggests the first primates were masters at leaping through the trees.

Paleontologists working in a quarry in southeastern France uncovered the quarter-inch-long bone, the lower part of the ankle joint.

The fossil matched up best with a chipmunk-sized creature called Donrussellia provincialis.

Previously only known from jaws and teeth, Donrussellia is thought be one of the earliest members of the primate family tree, on the branch leading to lemurs, lorises and bush babies.

Duke University assistant professor Doug Boyer and colleagues studied scans of Donrussellia's ankle and compared it to other animals, using computer algorithms to analyze the 3-D digital shape of each tiny bone.

They were surprised to find that Donrussellia's ankle was not like those of other primates, but was more similar to those of treeshrews and other nonprimate species.

The team's analyses also suggest the animal didn't just clamber or scurry along small branches. Instead, it may have been able to bound between trunks and branches, using its grasping feet to stick the landing.

The researchers say that -- contrary to what many scientists thought -- the first primates may have evolved their acrobatic leaping skills first, while anatomical changes that allowed them to cling to slender branch tips and creep from tree to tree came later.

"Being able to jump from one tree to another might have been important, especially if there were ground predators around waiting to snag them," Boyer said.

Author: Robin Ann Smith | Source: Duke University [September 11, 2017]

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Monkey tool use threatens prey numbers, say researchers

Using tools to search for food is affecting primate prey numbers and could potentially lead to prey species extinction, new Oxford research suggests.

Using tools to search for food is affecting primate prey numbers and could potentially lead to prey species extinction, 
new Oxford research suggests [Credit: Amanda Tan]

Once thought to be a skill unique to humans, recent studies have shown that some animals, such as monkeys, apes, birds and otters, are able to use tools to find food that would otherwise be inaccessible to them.

Tool use has been a gift and a curse for human society, on the one hand allowing people to progress to become one of the most successful species on the planet, but on the other endangering and pushing many prey species to the brink of extinction, particularly in the case of ocean overfishing.

In new research published in the journal eLife and funded by the European Research Council, scientists from the Department of Anthropology and Archaeology at Oxford University have assessed whether tool use can negatively affect prey species in the same way it does in human society. Using the primate species macaques (Macaca fascicularis) as an example, the findings reveal that these monkeys not only use tools but experience the same adverse effects, such as prey decline, which could eventually lead to a loss of tool skills. The paper was presented today at the British Science Festival.

Led by Dr Lydia Luncz, a postdoctoral researcher at Oxford, the team used archaeological evidence to demonstrate that the macaques' use of tools to forage for shellfish in Khao Sam Roi Yot National Park in Thailand is affecting prey availability.

The researchers compared the availability, size and maturation stages of groups of shellfish between two islands inhabited by different-sized macaque populations against the stone artefacts uncovered on the island. In doing so, they were able to show how tool use has affected prey reproductive biology over time.

The findings show that this foraging behaviour has caused the monkeys to enter an 'ecological feedback loop', influencing both the size and amount of prey available over time. The evidence revealed an emerging pattern: both the size of the shellfish and the tools used to open them were found to be smaller on the island with many predators. If it continues, the researchers have speculated that these prey populations are likely to decline.

Without prey to forage on, the monkeys will also have no need to use the technique so might even experience a social regression and 'unlearn' how to use tools altogether.

Dr Luncz said: 'People often say that practice makes perfect – the more you do something the better you get at it. But the less you do it, the harder it becomes and the more you are likely to forget that skill completely. Our study shows that it is the same for monkeys. With no need to use the stones for foraging, the technique might be lost.

'As this is a learned social behaviour, in the long term there will be a generation of macaques that do not know how to use tools, and any associated benefit or trade with other species will be lost. Potentially, one day tool use might get reinvented by later generations, and it will be interesting to see how the skill is discovered and who they learn it from.

'This has interesting parallels to the evolution of human stone use, where stone technology might also have been lost and reinvented throughout history.'

The team will next build on this knowledge by visiting islands with monkey populations that do not currently use stone tools to dig for evidence that they may have done in the past.

Dr Luncz said: 'In archaeology, generally the deeper you dig the further you go back in time. The same methods used for human artefacts can tell us a lot about how species have evolved and adapted to environmental change over time.'

Source: University of Oxford [September 08, 2017]

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'Vampires' may have been real people with rare blood disorder

Porphyrias, a group of eight known blood disorders, affect the body's molecular machinery for making heme, which is a component of the oxygen-transporting protein, hemoglobin. When heme binds with iron, it gives blood its hallmark red color.

Mural of Vlad the Impaler, who was accused of being a vampire. Perhaps, instead, he suffered from 
a blood disorder called porphyria [Credit: Children's Hospital Boston]

The different genetic variations that affect heme production give rise to different clinical presentations of porphyria -- including one form that may be responsible for vampire folklore.

A clinical cause for nocturnal blood drinking?

Erythropoietic protoporphyria (EPP), the most common kind of porphyria to occur in childhood, causes people's skin to become very sensitive to light. Prolonged exposure to sunshine can cause painful, disfiguring blisters.

"People with EPP are chronically anemic, which makes them feel very tired and look very pale with increased photosensitivity because they can't come out in the daylight," says Barry Paw MD, PhD, of the Dana-Farber/Boston Children's Cancer and Blood Disorders Center. "Even on a cloudy day, there's enough ultraviolet light to cause blistering and disfigurement of the exposed body parts, ears and nose."

Staying indoors during the day and receiving blood transfusions containing sufficient heme levels can help alleviate some of the disorder's symptoms. In ancient times, drinking animal blood and emerging only at night may have achieved a similar effect -- adding further fuel to the legend of vampires.

Now, Paw and his team of international investigators report -- in a paper in the Proceedings of the National Academy of Sciences -- a newly discovered genetic mutation that triggers EPP. It illuminates a novel biological mechanism potentially responsible for stories of " vampires" and identifies a potential therapeutic target for treating EPP.

The nature of EPP's "supernatural" symptoms

To produce heme, the body goes through a process called porphyrin synthesis, which mainly occurs in the liver and bone marrow. Any genetic defects that impact this process can interrupt the body's ability to produce heme; the decreased heme production leads to a buildup of protoporphyrin components. In the case of EPP, type of protoporphyrin called protoporphrin IX accumulates in the red blood cells, plasma and sometimes the liver.

When protoporphin IX is exposed to light, it produces chemicals that damage surrounding cells. As a result, people with EPP experience swelling, burning and redness of the skin after exposure to sunlight -- even trace amounts of sunlight that pass through window glass.

Some genetic pathways leading to build-up of protoporphyrin IX have already been described, but many cases of EPP remain unexplained. By performing deep gene sequencing on members of a family from Northern France with EPP of a previously unknown genetic signature, Paw's team discovered a novel mutation of the gene CLPX, which plays a role in mitochondrial protein folding.

"This newly-discovered mutation really highlights the complex genetic network that underpins heme metabolism," says Paw, who was co-senior author on the study. "Loss-of-function mutations in any number of genes that are part of this network can result in devastating, disfiguring disorders."

Myth vs. reality

Paw suggests that identifying the various gene mutations that contribute to porphyria could pave the way for future therapies that could correct the faulty genes responsible for these related disorders.

"Although vampires aren't real, there is a real need for innovative therapies to improve the lives of people with porphyrias," says Paw.

Author: Kat J. McAlpine | Source: Boston Children's Hospital [September 07, 2017]

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How monkey fights grow

How does conflict spread through a society? One way to think of conflict spreading is to picture an epidemic, with aggressive individuals "infecting" others and causing them to join the fight.

A pigtail macaque shows its "game face" [Credit: A.J. Haverkamp]

While studying the dynamics of conflict in a monkey society, researchers Edward Lee (Cornell University), Bryan Daniels (ASU-SFI Center for Biosocial Complex Systems), David Krakauer (Santa Fe Institute), and Jessica Flack (Santa Fe Institute), found evidence for a more complicated structure behind conflict. Whereas the simple picture can be accurate for figuring out who will join a conflict, it is not enough to forecast how long the conflict will last. Their findings are published in a recent issue of the Journal of the Royal Society Interface.

Krakauer points out that if we view conflict as contagion, we might expect that the time it takes for a new conflict epidemic to die down would increase with each newly "infected" individual. In other words, each new participant simply adds to the total fight duration. Instead, Lee and colleagues found that fight durations grow more quickly as others join. It appears that it is not individuals who control the length of fights, but the relationships between pairs of individuals.

Imagine you are hosting a large dinner party. How long will you need to stay up? If the invitees are busy that week, each person might arrive at a different time but only stay for an hour. For each additional invitee, you simply add to the total duration of the party. But imagine that each person wants to talk with everyone else before leaving. If it is hard for more than a few conversations to happen at a time, then dinner will have to last until each pair of individuals has a chance to converse. This is how conflicts grow in duration, Lee says. More individuals mean more possibilities of conflict between pairs of individuals, and each of those pairwise relationships must be separately resolved.

Daniels says this finding suggests that "conflicts that grow big tend to get out of control," and "there are hints that a similar pattern may be at work in some human conflicts."

By studying statistical variation in the observed fights, the researchers found evidence that conflict duration is strongly affected by the first interaction, which sets the tone for the fight. If the first interaction is brief, then following episodes are likely to be just as brief. A long drawn out initial brawl, however, will be followed by similarly difficult episodes. This, Flack says, "is a signature of collective memory," meaning "the duration of the conflict is not just determined by individuals independently deciding whether to continue fighting or drop out, but through their joint memory for the past and subsequent collective decision-making."

Lee points out that interventions by uninvolved third-parties could be designed to stop conflicts that are likely to get out of control by watching closely how a fight starts and making a decision about when to intervene based on the features of this initial interaction. However, an open question is how much conflict to allow. Just as small fires in a forest clear out brush so that devastatingly large wildfires do not occur, small conflicts may play a useful role. By predicting how fights evolve, external monitors may be able to promote useful mild conflict but prevent harmful all-out brawls.

Source: Santa Fe Institute [September 07, 2017]

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