Grantee Spotlight: Alba García de la Chica

Alba García de la Chica is a PhD candidate from the University of Barcelona. She was awarded a Leakey Foundation Research Grant during our fall 2017 cycle for her project entitled “Behavioral, hormonal and life-history correlates of pair bonding in owl monkeys.”

Alba García de la Chica at the Owl Monkey Project research site in Argentina.

The study of monogamy and pair-bonding have been central topics of anthropological and primatological theory and research. This long-held interest is based on the observation that, regardless of the social or mating system, pair bonds are an integral component of human social behavior, and men and women consistently form special relationships based on persistent emotional attachments. When and how pair-bonding behavior evolved in the hominid lineage remains a controversial topic, but there is consensus among researchers that the appearance of adult bonds in human evolution has played a central role in the formation of early human societies.

A pair of owl monkeys (Aotus azarae).

Over the years, researchers have examined numerous hypotheses that explain the evolution of pair bonds in our lineage. Is it because the presence of males reduces infanticide risk? Or because males and females benefit from cooperative parental care? Could it be that it is the competition between females for resources that is important? At the bottom of all these questions is the need to understand why males, who presumably have much higher reproductive potential, are benefiting more from a relationship with only one of them.

 

To answer these questions, we first need to understand the selective pressures that males and females face. Among monogamous primate taxa, there is an assumed low intensity of intrasexual competition, but in the owl monkey population I study in northeast Argentina (Aotus azarae), both sexes experience intense competition. This is so because in our population both males and females leave their natal groups at around three years of age, becoming solitary “floaters” who look for reproductive opportunities among established pairmates. In 22 years of study, we have never seen two solitary floaters become a pair, and all those who have achieved a reproductive position have done so by replacing one of the resident adults within an established group. Since these replacements occur through a very aggressive process at similar rates for males and females, it suggests that both sexes experience intense intrasexual competition. Thus, to maintain their reproductive positions, resident adults need to guard and monitor their partners in order to prevent behavioral interaction with potential competitors.

 

My research goal is to investigate the proximate mechanisms that allow the maintenance of pair bonds and monogamy in a primate species with pair bonded individuals and shared parental care. My study will use long-term ecological, demographic and behavioral data in order to evaluate the role that competition between the floaters and the resident adults has in regulating the social and mating system of this taxon. One of the ways in which I am exploring this is through an examination of the role that vocal communication has in space usage and reproductive competition between floaters and pair-bonded residents. In the future, I hope to expand on this project by evaluating how variation in long distance calls may inform hypotheses about mate defense, mate attraction, and territory defense.

Fresh Clues to the Life and Times of the Denisovans

Richard ‘Bert’ Roberts, Vladimir Uliyanov and Maxim Kozlikin (clockwise from top) examining sediments in the East Chamber of Denisova Cave. Institute of Archaeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences, author provided.

Zenobia Jacobs, University of Wollongong; Bo Li, University of Wollongong; Kieran O’Gorman, University of Wollongong, and Richard ‘Bert’ Roberts, University of Wollongong

We know that some modern human genomes contain fragments of DNA from an ancient population of humans called Denisovans, the remains of which have been found at only one site, a cave in what is now Siberia.

Two papers published in Nature give us a firmer understanding of when these little-known archaic humans (hominins) lived.

Denisovans were unknown until 2010, when their genome was first announced. The DNA was obtained from a girl’s fingerbone found buried in Denisova Cave in the Altai Mountains of southern Siberia.

The new studies provide the first robust timeline for the Denisovan fossils and DNA recovered from the cave sediments, as well as the environments that the Denisovans experienced.

 

A few Neanderthal fossils have also been retrieved from the site, along with their genetic traces in the sediments at Denisova Cave, which was first excavated 40 years ago.

Location map of Denisova Cave and photo (inset) of cave entrance. Institute of Archaeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences/Bert Roberts, author provided.

Modern humans (Homo sapiens) arrived later, making the site unique in the world as home to three groups of humans at various times.

All fossils of Denisovans and Neanderthals, and hominin bones not assigned to either group, discovered at Denisova Cave. Next to each fossil is the specimen number (for example, Denisova 2 in the top-left corner). Zenobia Jacobs, author provided.

Who were the Denisovans?

We currently know much more about the DNA of Denisovans than we do about their physical appearance, as hominin fossils are exceedingly rare at the site.

Besides the fingerbone, a total of three teeth have been genetically identified as Denisovan. The DNA from a tiny fragment of long bone from the daughter of Denisovan and Neanderthal parents provides direct evidence that the two groups met and interbred at least once.

We know frustratingly little about the geographic distribution and demography of the Denisovans, except for the head-scratching finding that Aboriginal Australians and New Guineans are the only people alive today with substantial amounts of Denisovan DNA in their genome.

But while hominin fossils are few and far between at Denisova Cave, the deposits contain thousands of artifacts made from stone. The upper layers also contain artifacts crafted from other materials, including ornaments made of marble, bone, animal teeth, mammoth ivory and ostrich eggshell. There are also animal and plant remains that bear witness to past environmental conditions.

Selection of artifacts from Denisova Cave. a, Upper Palaeolithic; b, Initial Upper Palaeolithic; c, middle Middle Palaeolithic; and d, early Middle Palaeolithic. Institute of Archaeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences, author provided.

Dating the Denisovans

Despite the importance of Denisova Cave to studies of human evolution, the history of the site and its inhabitants has persisted as a puzzle, due to the lack of a reliable timescale for the cave deposits and their contents.

With the publication of the two new papers, some of the critical pieces of this puzzle now fall into place.

The new studies build on the detailed work carried out by our Russian colleagues over several decades in all three chambers of Denisova Cave. They have painstakingly documented the complex layering of the deposits, along with the excavated cultural, animal and plant remains.

Sediment profiles (stratigraphy) in Denisova Cave: a, Main Chamber; b, East Chamber. The string lines in each photo are 50 cm apart. Institute of Archaeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences, author provided.

We used optical dating to determine when the sediments were last exposed to sunlight and deposited in the cave. Optical dating has been applied to archaeological sites around the world, with the minerals quartz and potassium feldspar most often used.

We measured more than 280,000 individual grains of these minerals from more than 100 samples using a combination of well-established and new procedures.

This enabled us to carry out a variety of experimental cross-checks, identify parts of the deposit that had been disturbed, date the oldest sediment layers, and construct a robust chronology for the site.

Optical dating of sediments: a, Zenobia Jacobs in the red-lit laboratory at the University of Wollongong; b, Sample holder for 100 individual sand-sized grains; b, Sample holders loaded onto carousel for optical dating of individual grains; d, green laser beam used to stimulate quartz grains in optical dating. University of Wollongong/Erich Fisher, author provided.

To better constrain the ages of the hominin fossils, our colleagues at the University of Oxford, UK, and two of the Max Planck Institutes in Germany developed a new statistical (Bayesian) model.

The new studies show that hominins have occupied the site almost continuously through relatively warm and cold periods over the past 300,000 years, leaving behind stone tools and other artifacts in the cave deposits.

Fossils and DNA traces of Denisovans are found from at least 200,000 to 50,000 years ago, and those of Neanderthals from between 200,000 and 100,000 years ago. The girl with mixed ancestry reveals that the two groups of hominins met and interbred around 100,000 years ago.

Summary timeline for the archaeology, hominin fossils and hominin DNA retrieved from the sediments at Denisova Cave. All age ranges are shown at the 95.4% confidence interval. Bert Roberts, author provided.

Although Denisovans persisted at the site until 50,000 years ago, this does not preclude their later survival elsewhere. They were evidently a hardy bunch, living through multiple episodes of the cold Siberian climate before finally going extinct.

An incomplete history

We now know much more about the life and times of the Denisovans, but there are still many unanswered questions.

For example, we don’t know the nature of any encounters between them and modern humans, who were already present in other parts of Asia and in Australia by 50,000 years ago.

So while our understanding of the history of Denisovans has come a long way since 2010, there are still many missing pieces of this intriguing puzzle.The Conversation


Zenobia Jacobs, Professor, University of Wollongong; Bo Li, Principal Research Fellow in Archaeological Science, University of Wollongong; Kieran O’Gorman, PhD candidate, University of Wollongong, and Richard ‘Bert’ Roberts, Director, ARC Centre of Excellence for Australian Biodiversity and Heritage (CABAH), University of Wollongong

This article is republished from The Conversation under a Creative Commons license. Read the original article.

New Studies Reveal the History of Denisova Cave

New studies write the history of a famous Siberian cave and unearth the oldest jewelry in the region.

By Nicola Jones

Lush vegetation now covers the hillside entrance to Denisova Cave. Photo by Richard Roberts.

An extinct branch of hominins called the Denisovans is one of the most elusive members of our extended family tree: So far there have been only four individuals found in a single Siberian cave. Now researchers have done the painstaking work of dating the fossils, sediments, and artifacts found in that famous cave, including what might be the first evidence for crafts made by our long-lost cousins.

The Denisova Cave in the foothills of Russia’s Altai Mountains has a long history of occupation and has proven to be a gold mine for anthropologists trying to untangle the relationship between hominin groups living in Eurasia hundreds of thousands of years ago. The cave—which has three chambers and is about the size of a modern four-bedroom home—was used as recently as the 1700s by a hermit named Denis, which is where it got its modern name (in Russian, “the cave of Denis”). Its earlier inhabitants have proven harder to pin down.

Researchers have been finding and studying fossils from this cave since at least the 1970s. In 2010, the genetic analysis of a fragment of pinky finger bone prompted the identification and naming of the Denisovans, a sister group to Neanderthals. The two split ways about 400,000 years ago. So far, Denisovan remains haven’t been confirmed anywhere else in the world, although DNA studies suggest that they once lived widely across Asia.

Although thousands of tiny fossils have been found inside the Denisova Cave, many of these are from animals and only about a dozen individual hominins have been identified from bone and teeth—including three other Denisovans, three Neanderthals, and some unidentified hominins. Last year, genetic work revealed that one of the cave’s fossils is from the first-known offspring of a Denisovan and a Neanderthal, news that won headlines around the world.

With so few remains and artifacts, and no fire pits, it seems that the people of the time preferred to live in the open air and only came into the cave periodically, perhaps during heavy rain, says Bence Viola, a paleoanthropologist at the University of Toronto. “There are a lot of unpleasant creatures in there: hyenas, bats, pigeons. It can be disgusting,” says Viola. The cave’s location in chilly Siberia has made it a good place for preserving DNA. “The Altai is nice and cold, and the caves are like big fridges,” says Viola.

But dating all the tiny scraps found in the cave has proven tricky because they are mostly smaller than a centimeter across and older than can be reliably dated using radiocarbon dating, which works best for things 50,000 years old or younger. “It requires a huge amount of investment from a range of different people and techniques, so it inevitably takes a long time and effort to bring it together,” says archaeologist and earth scientist Zenobia Jacobs of the University of Wollongong in New South Wales, Australia.

This week, two papers published in Nature lay bare the history of the cave. Archaeologist Katerina Douka of the Max Planck Institute for the Science of Human History in Jena, Germany, and colleagues, including Viola, analyzed results from a combination of techniques, including radiocarbon dating, genetics, and optical dating, to track fossils and artifacts. Optical dating works by measuring how much stored energy remains in some minerals, including quartz, from the last time they were exposed to sunlight. Meanwhile, Jacobs and co-authors used optical dating on more than 100 samples of cave-floor sediments to fill in the complete timeline of hominin occupation, along with clues about the area’s climate based on animal and plant remains.

Together the works suggest that hominins have been living sporadically in this cave for about 300,000 years. Fossils and DNA traces in the soil show both Denisovans and Neanderthals living in the cave between about 200,000 and 90,000 years ago, says Jacobs, with Denisovans staying as late as about 50,000 years ago. The overlapping dates make sense, given the presence of a hybrid in the cave. “You could say it was a Denisovan cave, and the Neanderthals just visited for a while,” says Sharon Browning, a biostatistician at the University of Washington, Seattle, who has worked on Denisovan remains but wasn’t involved with either new study. “Though the Neanderthal occupation appears to have extended for tens of thousands of years, so it was a long visit.”

Perhaps most exciting is some pendants made from deer and elk teeth, and bone points that might have been used to pierce clothing for sewing. These have been dated at 43,000–49,000 years old, making them the oldest such artifacts in northern Eurasia. Older jewelry has been found elsewhere—shell beads discovered in Israel are at least 100,000 years old. But these ancient pendants could possibly be the first evidence of Denisovans making arts and crafts. Alternatively, the jewelry could come from modern humans, who are known to have been living elsewhere in Eurasia at that time.

“The big question is: Who produced these bone points and pendants? That is something we just don’t know,” says Viola. “Sadly, the pendants don’t come with a name tag.”


Nicola Jones is a freelance science journalist living in Pemberton, British Columbia.

This work first appeared on SAPIENS under a CC BY-ND 4.0 license. Read the original here.

Bence Viola is a Leakey Foundation grantee.

The Diversity of Rural African Populations Extends to Microbiomes

New microbiome research funded in part by The Leakey Foundation points to a role for lifestyle, geography, and genetics, with surprising similarities to US populations in some cases.

A Maasai woman in a traditional outfit posing with her livestock. Photo by Alessia Ranciaro/Tishkoff Lab

Our microbiome, the complex community of bacteria, fungi, parasites, and other microorganisms in and on our bodies, reflects the way we live. If we own a pet, we likely share microbes with them. If we eat meat, the microbiome in our intestines may look different from that of a vegan.

In a growing field of study to determine how we acquire the microbes we carry within us and their influence on our health, most analyses have focused on people living in developed nations. But in the last several years, scientists have begun to investigate whether people in non-industrialized societies possess distinctly different microbiomes and, if so, what factors shape those differences.

A new report, published in the journal Genome Biology, has made significant strides in addressing these questions. Led by a team of geneticists from the University of Pennsylvania, in collaboration with researchers from Tanzania, Botswana, and the National Institutes of Health, the study is one of the largest to date to analyze the gut microbiomes of ethnically diverse Africans, with samples from 114 Botswanan and Tanzanian people from seven populations, as well as a comparison group from the United States.

The results point to the wide range of microbiome profiles across populations, which practice a variety of different lifestyles, from agropastoralist to pastoralist to hunter-gatherer. The magnitude of the differences is on par with the differences seen between industrialized and non-industrialized populations. Yet the researchers were also intrigued by unexpected similarities between groups.

“When we started this,” says geneticist Sarah Tishkoff, a Penn Integrates Knowledge Professor at Penn and senior author, “my hypothesis was that diet was going to be the driving factor in distinguishing the microbiome of these diverse populations. My biggest surprise was that that wasn’t the case.”

In fact, a subset of the samples from Bantu-speaking people living in farming communities in Botswana were nearly indistinguishable from those collected from people living in the Philadelphia area, samples collected by study coauthor Frederick Bushman, a microbiologist at Penn’s Perelman School of Medicine.

“The bacterial composition from some of the agropastoralists in Botswana was strikingly similar to the U.S. cohort,” says Matthew Hansen, a scientist in Tishkoff’s lab and co-lead author on the paper. “These are rural groups; they have a very different lifestyle but some factor is giving them a very similar microbiota to healthy Philadelphia-area residents.”

Previous efforts to examine the gut microbiomes of rural Africans have typically compared a single African population to one or more populations from industrialized nations. These earlier studies pointed to differences between groups; for example, a comparison of gut microbiomes between Italians and Hadza hunter-gatherers in Tanzania identified several groups of bacteria present in the Hadza that had not been previously identified in populations from Westerners.

But to get a more nuanced understanding of the factors influencing the microbial diversity in rural Africans, Tishkoff’s team collected samples from seven far-flung African populations. From Tanzania: Hadza hunter-gatherers, Maasai cattle-herders, Sandawe agropastoralists, who were hunter-gatherers until the late 19th century, and Burunge agropastoralists. And from Botswana: San hunter-gatherers, Bantu-speaking Herero pastoralists, and several groups of Bantu-speaking agropastoralists.

A nurse from the Kilimanjaro Christian Medical Center, works in the field with a study participant in Tanzania.
Photo credit: Alessia Ranciaro/Tishkoff Lab

Gathering the data, which required requesting residents of remote villages to provide fecal samples to the scientists, was by no means a simple process. Alessia Ranciaro, who helped lead data collection efforts for the work, says she and colleagues learned from early experiences how to navigate cultural and logistical hurdles to make the process smoother for both the participants and the scientists.

The researchers extracted DNA from the samples and sequenced a portion of the 16S ribosomal RNA gene, widely used in microbiome studies to help identify and compare bacteria.

“The analysis allows you to classify bacteria in a sample down to the genus level in many cases,” says Meagan Rubel, a doctoral student in Tishkoff’s lab who co-led the work. “But in the sample databases that we’re using, the bacteria has been classified based on industrialized or western groups, so people living these traditional lifestyles may have bacteria that we have never seen before.”

From the results they were able to obtain, broad patterns quickly emerged. Notably, the Botswanan samples differed from the Tanzanian ones. The gut microbiomes from Tanzanian populations tended to have a higher number of microbes in each sample, and individuals tended to share similar microbial profiles. In Botswana, on the other hand, samples tended to have fewer microbial species overall, and individuals’ microbiomes tended to be more different from one another. The latter pattern was also present in the U.S. samples.

While the analysis didn’t point to a “smoking gun” explaining this result, the researchers hypothesize that the reasons are tied to Botswana’s comparative national wealth and access to medical care.

“Botswana has diamonds and is relatively wealthy,” says Tishkoff. “They have a free medical system and a free educational system, which is very different from Tanzania.”

“You can imagine that within the spectrum of very different groups in African countries,” says Rubel, “there are groups undergoing these soft measures of industrialization that could be everything from increased access to clinical care to different kinds of foods. Antibiotic usage is something that can really change the gut microbiome, so people who have more access to that might be seeing marked shifts in their microbiome.”

Such shifts could help explain the similarities between Botswana and U.S. samples, though the researchers say more work needs to be done to confirm that is the case.

Overall, broad differences in the gut microbiome were readily apparent between the U.S. and most Africans. Within Africa, the frequency of some bacterial groups could differentiate populations by ethnicity and lifestyle. For instance, the two hunter-gatherer populations, the San and the Hadza, possessed different patterns of gut bacteria compared to pastoralist or agropastoralist groups. In addition, in the Maasai and Hadza populations, two groups in which the division of labor between men and women is particularly extreme, the researchers found significant sex differences in the microbiomes they analyzed.

To understand more about what the bacteria in the gut were actually doing, the researchers looked for molecular pathways that were abundant across the various microbial species in a given sample. In the U.S. samples, they identified pathways involved in breaking down environmental pollutants, such as bisphenol, which includes bisphenol A, better known as “the dreaded BPA in plastics,” says Rubel, as well as DDT, the insecticide responsible for thinning birds’ eggshells that has been banned in the U.S. since the 1970s.

They found evidence of DDT-breakdown pathways as well in the samples from Botswana, a country that has continued to use the chemical to control mosquitoes responsible for transmitted diseases such as malaria.

The findings raise a number of interesting questions, on which the researchers hope to shed more light with additional analyses and genetic and genomic sequencing in the future. They’re also probing the samples further to see whether the presence of gastrointestinal pathogens may play a primary role in influencing the gut microbiota of people in areas where such infections are prevalent.

“Our work expands a growing narrative,” says Rubel, “where microbiome trends seem to track with the level of industrialization across populations.”

The scientists note that even these remote African populations are not static in their lifestyle practices; development and its influences on the environment and traditional lifestyles may manifest in shifting microbiome patterns.

“What would be great to do is a longitudinal study of some of these groups,” says Hansen. “Over the next 20 years, their lives are certain to change rapidly, and it would be interesting to see if we find a shift in the microbiome as these lifestyle factors change.”


In addition to Hansen, Rubel, Ranciaro, Bushman, and Tishkoff, the study coauthors were the Perelman School of Medicine’s Aubrey G. Bailey, Simon R. Thompson, Michael C. Campbell, William Beggs, and Jaanki R. Dave; the University of Botswana’s Gaonyadiwe G. Mokone and Sununguko Wata Mpoloka; Tanzania’s Muhimbili University of Health and Allied Sciences’ Thomas Nyambo; and the National Institutes of Health’s Christian Abnet and Stephen J. Chanock.

The research was supported by The Leakey Foundation, the Lewis and Clark Fund, University of Pennsylvania,  National Institutes of Health (grants AI007532, ES022577, DK104339, and ES019851), and National Science Foundation (Grant 1540432).

Sarah Tishkoff is the David and Lyn Silfen University Professor and a Penn Integrates Knowledge Professor at Penn, with appointments in the Department of Genetics in the Perelman School of Medicine and in the Department of Biology in the School of Arts and Sciences.

Matthew Hansen is a research associate in the Tishkoff lab.

Meagan Rubel is a Ph.D. student co-advised by Tishkoff and Theodore Schurr, a professor in the Department of Anthropology in Penn Arts and Sciences.

Alessia Ranciaro is a senior research scientist in the Tishkoff lab.

Frederic Bushman is the William Maul Measey Professor in Microbiology in the Perelman School of Medicine at Penn.


This article was provided by the University of Pennsylvania

Understanding Australopithecus sediba

Life reconstruction of Australopithecus sediba commissioned by the University of Michigan Museum of Natural History © Sculpture Elisabeth Daynes / Photo S. Entressangle.

The fossil site of Malapa in the Cradle of Humankind, South Africa, discovered by Lee Berger of the University of the Witwatersrand, Johannesburg, in August 2008, has been one of the most productive sites of the 21st century for fossils of early human ancestors or hominins. A new hominin species, Australopithecus sediba (Au. sediba), was named by Berger and his colleagues, following the discovery of two partial skeletons just under two million years old, a juvenile male individual– Malapa Hominin 1 (MH1)– and an adult female, Malapa Hominin 2 (MH2). The skeletons are under the custodianship of the University of the Witwatersrand, where they are being kept. Each partial skeleton is more complete than the famous “Lucy,” an Australopithecus afarensis or early hominin species found in 1974 in Ethiopia. Now, 10 years later after the discovery of Malapa, full descriptions of the hominin fossil material, as well as raw measurement data and surface scans of the fossils, available at Morphosource.org, are published in a special issue of the open access journal, PaleoAnthropology.

“The anatomies we are seeing in Australopithecus sediba are forcing us to reassess the pathway by which we became human,” explained co-editor and Leakey Foundation grantee Jeremy DeSilva, an associate professor of anthropology at Dartmouth, and co-author of four of the papers, including ones on the lower limb and computer animation of the walking mechanics.

The special issue is comprised of nine separate papers analyzing: the skull; vertebral column and thorax; pelvis; upper limb: shoulder, arm and forearm; hand; and lower limb fossils of Au. sediba; along with descriptions of body size and proportions; and walking mechanics, including a 3D computer animation of Au. sediba walking. The papers are co-authored by leading anthropologists, many of whom are Leakey Foundation grantees. The research draws on approximately 135 specimens from MH1, MH2 and what may be a third individual, all of which were uncovered between 2008 and 2016.

The researchers found that Au. sediba is a unique species, refuting earlier critics who questioned its validity as a species. They say that Au. sediba is distinct from both Australopithecus africanus, with which it shares close geographic proximity, and from early members of the genus Homo (e.g., Homo habilis) in both East and South Africa; yet, it also shares features with both groups, suggesting a close evolutionary relationship.

“Our findings challenge a traditional, linear view of evolution. It was once thought that a fossil species a million years younger than Lucy would surely look more human-like. For some anatomies of Australopithecus sediba, like the knee, that is true. But, for others, like the foot, it is not. Instead, what we’re witnessing here are parallel lineages, illustrating how different hominin experiments were unfolding early in our complex evolutionary history,” explained DeSilva.

These new research papers address critiques of Au. sediba from other colleagues while correcting some initial observations and testing new ideas regarding this extraordinary collection. For example, other researchers hypothesized that this was more than one species due to the differences in the size and shape of the vertebrae. “The differences in these vertebrae can simply be attributed to their developmental age differences: the juvenile individual’s vertebrae have not yet completed growth, whereas the adult’s vertebra growth is complete,” explained co-editor and Leakey Foundation grantee Scott A. Williams, an associate professor of anthropology in the Center for the Study of Human Origins at New York University, and co-author of two of the papers, including the one on the vertebral column.

The special issue also finds that Au. sediba was well adapted to terrestrial bipedalism or walking on just two feet but also spent significant time climbing in trees, perhaps for foraging and protection from predators.

This larger picture sheds light on the lifeways of Au. sediba and also (whether directly or indirectly) on a major transition in hominin evolution, that of the largely ape-like species included broadly in the genus Australopithecus to the earliest members of our own genus, Homo.


Consistent with the open research approach for Au. sediba by Lee Berger and the Evolutionary Studies Institute at the University of the Witwatersrand, co-editors DeSilva and Williams, who are also affiliated with the University, invite colleagues to study the Au. sediba material and test the hypotheses presented in these papers.


PaleoAnthropology (2018)

Guest Editors: Scott A. Williams, Jeremy M. DeSilva