Imagine a year in Africa that summer never arrives. The sky takes on a gray hue during the day and glows red at night. Flowers do not bloom. Trees die in the winter. Large mammals like antelope become thin, starve and provide little fat to the predators (carnivores and human hunters) that depend on them. Then, this same disheartening cycle repeats itself, year after year. This is a picture of life on earth after the eruption of the super-volcano, Mount Toba in Indonesia, about 74,000 years ago. In a paper published this week in Nature, scientists show that early modern humans on the coast of South Africa thrived through this event.

The glass shards at Pinnacle Point were carried nearly 9000 km from the source in Indonesia [Credit: Erich Fisher]

An eruption a hundred times smaller than Mount Toba - that of Mount Tambora, also in Indonesia, in 1815 - is thought to have been responsible for a year without summer in 1816. The impact on the human population was dire - crop failures in Eurasia and North America, famine and mass migrations. The effect of Mount Toba, a super-volcano that dwarfs even the massive Yellowstone eruptions of the deeper past, would have had a much larger, and longer-felt, impact on people around the globe.

The scale of the ash-fall alone attests to the magnitude of the environmental disaster. Huge quantities of aerosols injected high into the atmosphere would have severely diminished sunlight - with estimates ranging from a 25 to 90 percent reduction in light. Under these conditions, plant die-off is predictable, and there is evidence of significant drying, wildfires and plant community change in East Africa just after the Toba eruption.

If Mount Tambora created such devastation over a full year - and Tambora was a hiccup compared to Toba - we can imagine a worldwide catastrophe with the Toba eruption, an event lasting several years and pushing life to the brink of extinctions.

In Indonesia, the source of the destruction would have been evident to terrified witnesses - just before they died. However, as a family of hunter-gatherers in Africa 74,000 years ago, you would have had no clue as to the reason for the sudden and devastating change in the weather. Famine sets in and the very young and old die. Your social groups are devastated, and your society is on the brink of collapse.

The effect of the Toba eruption would have certainly impacted some ecosystems more than others, possibly creating areas - called refugia - in which some human groups did better than others throughout the event. Whether or not your group lived in such a refuge would have largely depended on the type of resources available. Coastal resources, like shellfish, are highly nutritious and less susceptible to the eruption than the plants and animals of inland areas.

The research team has been excavating caves at Pinnacle Point, South Africa, for nearly 20 years. Glass shards from Mount Toba were discovered at the PP5-6 location [Credit: Erich Fisher]

When the column of fire, smoke and debris blasted out the top of Mount Toba, it spewed rock, gas and tiny microscopic pieces (cryptotephra) of glass that, under a microscope, have a characteristic hook shape produced when the glass fractures across a bubble. Pumped into the atmosphere, these invisible fragments spread across the world.

Panagiotis (Takis) Karkanas, director of the Malcolm H. Wiener Laboratory for Archaeological Science, American School of Classical Studies, Greece, saw a single shard of this explosion under a microscope in a slice of archaeological sediment encased in resin.

"It was one shard particle out of millions of other mineral particles that I was investigating. But it was there, and it couldn't be anything else," says Karkanas.

The shard came from an archaeological site in a rockshelter called Pinnacle Point 5-6, on the south coast of South Africa near the town of Mossel Bay. The sediments dated to about 74,000 years ago.

"Takis and I had discussed the potential of finding the Toba shards in the sediments of our archaeological site, and with his eagle eye, he found one," explains Curtis W. Marean, project director of the Pinnacle Point excavations. Marean is the associate director of the Institute of Human Origins at Arizona State University and honorary professor at the Centre for Coastal Palaeoscience at Nelson Mandela University, South Africa.

Marean showed the shard image to Eugene Smith, a volcanologist with the University of Nevada at Las Vegas, and Smith confirmed it was a volcanic shard.

"The Pinnacle Point study brought me back to the study of glass shards from my master's thesis 40 years earlier," says Smith.

Students excavating the site at Vleesbaai [Credit: Dr. Jayne Wilkins]

Early in the study, the team brought in expert cryptotephra scientist Christine Lane who trained graduate student Amber Ciravolo in the needed techniques. Racheal Johnsen later joined Ciravalo as lab manager and developed new techniques.

From scratch, with National Science Foundation support, they developed the Cryptotephra Laboratory for Archaeological and Geological Research, which is now involved in projects not only in Africa, but in Italy, Nevada and Utah.

Encased in that shard of volcanic glass is a distinct chemical signature, a fingerprint that scientists can use to trace to the killer eruption. In their paper in Nature, the team describes finding these shards in two archaeological sites in coastal South Africa, tracing those shards to Toba through chemical fingerprinting and documenting a continuous human occupation across the volcanic event.

"Many previous studies have tried to test the hypothesis that Toba devastated human populations," Marean notes. "But they have failed because they have been unable to present definitive evidence linking a human occupation to the exact moment of the event."

Most studies have looked at whether or not Toba caused environmental change. It did, but such studies lack the archaeological data needed to show how Toba affected humans.

The Pinnacle Point team has been at the forefront of development and application of highly advanced archaeological techniques. They measure everything on site to millimetric accuracy with a "total station," a laser-measurement device integrated to handheld computers for precise and error-free recording.

Naomi Cleghorn with the University of Texas at Arlington, recorded the Pinnacle Point samples as they were removed.

Cleghorn explains, "We collected a long column of samples - digging out a small amount of sediment from the wall of our previous excavation. Each time we collected a sample, we shot its position with the total station."

Sampling of Cryptotephra at Vleesbaai, South Africa [Credit: Dr. Jayne Wilkins]

The sample locations from the total station and thousands of other points representing stone artifacts, bone, and other cultural remains of the ancient inhabitants were used to build digital models of the site.

"These models tell us a lot about how people lived at the site and how their activities changed through time," say Erich Fisher, associate research scientist with the Institute of Human Origins, who built the detailed photorealistic 3D models from the data. "What we found was that during and after the time of the Toba eruption people lived at the site continuously, and there was no evidence that it impacted their daily lives."

In addition to understanding how Toba affected humans in this region, the study has other important implications for archaeological dating techniques. Archaeological dates at these age ranges are imprecise - 10 percent (or 1000s of years) error is typical. Toba ash-fall, however, was a very quick event that has been precisely dated. The time of shard deposition was likely about two weeks in duration - instantaneous in geological terms.

"We found the shards at two sites," explains Marean. "The Pinnacle Point rockshelter (where people lived, ate, worked and slept) and an open air site about 10 kilometers away called Vleesbaai. This latter site is where a group of people, possibly members of the same group as those at Pinnacle Point, sat in a small circle and made stone tools. Finding the shards at both sites allows us to link these two records at almost the same moment in time."

Not only that, but the shard location allows the scientists to provide an independent test of the age of the site estimated by other techniques. People lived at the Pinnacle Point 5-6 site from 90,000 to 50,000 years ago. Zenobia Jacobs with the University of Wollongong, Australia, used optically stimulated luminescence (OSL) to date 90 samples and develop a model of the age of all the layers. OSL dates the last time individual sand grains were exposed to light.

The photo shows a volcanic glass shard erupted 74,000 years ago from the Toba volcano in Indonesia found at an archaeological site nearly 9000 km away at Vleesbaai, South Africa [Credit: Racheal Johnsen]

"There has been some debate over the accuracy of OSL dating, but Jacobs' age model dated the layers where we found the Toba shards to about 74,000 years ago - right on the money," says Marean. This lends very strong support to Jacobs' cutting-edge approach to OSL dating, which she has applied to sites across southern Africa and the world.

"OSL dating is the workhorse method for construction of timelines for a large part of our own history. Testing whether the clock ticks at the correct rate is important. So getting this degree of confirmation is pleasing," says Jacobs.

In the 1990s, scientists began arguing that this eruption of Mount Toba, the most powerful in the last two million years, caused a long-lived volcanic winter that may have devastated the ecosystems of the world and caused widespread population crashes, perhaps even a near-extinction event in our own lineage, a so-called bottleneck.

This study shows that along the food-rich coastline of southern Africa, people thrived through this mega-eruption, perhaps because of the uniquely rich food regime on this coastline. Now other research teams can take the new and advanced methods developed in this study and apply them to their sites elsewhere in Africa so researchers can see if this was the only population that made it through these devastating times.

Source: Arizona State University [March 12, 2018]

There's a particular feeling of excitement that comes from receiving a gift. It's a feeling of the unknown, of anticipation – and then you unwrap the package and find something spectacular.

Reconstruction of a Permian swamp [Credit: Rose Prevec]

As palaeontologists, rocks are our idea of a great gift. That's because when you crack them open, you might well find a fossil. And we aren't talking about dinosaurs: our area of specialisation is palaeobotany. This involves hunting for plant fossils which can tell us a great deal about the landscapes of past ages.

South Africa is home to a range of lesser known and neglected plant fossils, called the glossopterids. These trees once grew in vast swamps along with ancient plant groups such as ferns, horsetail ferns and clubmosses. We know from a few scattered reports that this amazingly rich fossil resource extends across much of Africa, particularly in Namibia, Zimbabwe, Mozambique and further north into Zambia, Tanzania, Kenya and even Madagascar.

Some may wonder why fossils matter. Plants never get as much attention as South Africa's famous rich and diverse fossil heritage that range from some of the earliest evidence of life through to its famous hominid collections. Glossopteris, for instance, has not been well studied in South Africa. It's still poorly understood.

There has been work done in different parts of the world. However, it is not detailed and each region uses its own system to try and understand these fossil plants. South Africa is lagging behind: there are two employed palaeobotanists in the country, while entire research teams exist in other parts of the world.

Yet plants can reveal a great deal about past environments and climates. If we have any hope of understanding South Africa's ancient past, scientists need to be able to reconstruct entire ecosystems, starting at the bottom of the food chain. Glossopteris dotted ancient landscapes before dinosaurs ever walked the earth, and before a single flower had bloomed. As such, it should be closely studied.

What we know

About 300 million years ago Earth entered what's known as the Permian period. During this time, and until about 252 million years ago, the Glossopteris plant became a common sight throughout Gondwana. This was a super continent that included regions known today as Africa, Antarctica, Australia, India and South America.

The presence of Glossopteris was used as supporting evidence for the revolutionary theory of "continental drift" during the mid 20th century. They literally reveal how the world we recognise today took shape.

Glossopteris leaves [Credit: Albany Museum]

Glossopteris was easy to recognise because of its distinctive leaves; the name means "tongue-fern"in Greek, because of its shape. Fossil evidence suggests that the plants probably grew in diverse habitats and came in different forms. These ranged from short shrubs to trees as tall as a five-story building.

Scientists suggest that at least some of these plants were deciduous because their leaves are often found preserved in thick mats thought to be the result of seasonal shedding. At that point, they became not only important for understanding our history: they started contributing to fuels and materials that are still used today.

Power plants

Dead material from these plants accumulated in swamp environments, was buried, and over time formed South Africa's vast coal reserves.

Under normal conditions, when plants die or shed their leaves these fall to the ground and decompose. Under special environmental conditions – such as those that occurred in the vast Permian swamps of Gondwana (which were a bit like today's mangrove swamps) – the process differs. Once Glossopteris shed their leaves, the plant material accumulated in acidic water with high levels of tannins and low oxygen concentrations.

This retarded the activity of the bacteria, fungi and other organisms that would otherwise lead to decomposition. Over time layers of mud, silt and sand washed into the swamp and buried the waterlogged peat layers. Millions of years passed. During this period the mud, silt, sand and the encased plant material experienced great pressure and high temperatures. It was compressed and changed into rock, and underwent various chemical changes.

The result? Coal seams. This is why coal is referred to as a fossil fuel. It is also a reminder that coal is finite.

Apart from being the major source of fuel in the production of South Africa's electricity, Glossopteris influences our lives in many ways. The carbon atoms harvested from the air as carbon dioxide by these trees during the process of photosynthesis, hundreds of millions of years ago, can also be found in petrol, waxes, plastics, and a host of other products used in everyday life.

New finds

South Africa has a huge potential for new fossil discoveries, with vast territories still waiting to be explored, yet very few researchers are studying fossil plants and insects.

We are part of a small group of researchers based at the Albany Museum in Grahamstown in the Eastern Cape province who are determined to change this by shedding more light on Glossopteris and fossil plants in general.

At the moment we're working on a few small road cuttings near a Northern Cape town called Sutherland. This is revealing a depth of knowledge about Permian ecosystems that has not been seen before in South Africa, and is very rare on a global scale.

New discoveries are not only about bringing a wonderful piece of the country's heritage to light. This work is also opening up new scientific fields and opportunities for skills development that the country desperately needs.

Author: Aviwe Matiwane And Rosemary Prevec | Source: The Conversation [March 08, 2018]

This article was originally published on The Conversation. Read the original article.

Homo naledi's relatively taller and more wear resistant molars enabled it to have a much more abrasive diet than other South African hominins. This is the result of a recent study published in the Journal of Human Evolution by researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, the University of Durham in the United Kingdom and the University of Arkansas in the United States. The researchers conclude that Homo naledi may have eaten a much grittier diet than other South African hominins.

Molar wear resistance of two older South African hominins (Australopithecus africanus and Paranthropus robustus) and Homo naledi: Darker colours indicate more wear resistant areas of the tooth, and lighter colours indicate less wear resistant areas [Credit: MPI f. Evolutionary Anthropology]

Mammals that eat foods that need to be cut, like leaves and grasses, have sharper, more complex molars (i.e. more cusps and crests) , while mammals that eat foods that need to be crushed, like fruits and nuts, have duller, less complex molars. The researchers used a technique known as dental topography to measure molar sharpness, complexity, and other aspects of tooth shape in South African hominins to reconstruct the diet of Homo naledi.

The researchers found no difference in sharpness or complexity between the molars of Homo naledi and other South African hominins, implying they ate foods with similar mechanical properties. However, Homo naledi did have relatively taller, more wear resistant molars than other South African hominins, suggesting its teeth were adapted to consume foods that wore its teeth faster. "We think that Homo naledi must have been eating foods covered in dust or grit, or possibly ate plants containing lots of defensive silica particles, known as phytoliths," said Michael Berthaume of the Max Planck Institute of Evolutionary Anthropology and Durham University, one of the authors of the study.

Protection from gritty diets

Plants produce phytoliths or 'plant stones' to try and prevent animals from eating too much of them. Animals such as grass-eating antelopes living in dry, and hence gritty, environments have high crowned molars to enable them to eat diets heavy in plant stones and grit without wearing their teeth away too much.

The findings of the present study suggest that Homo naledi may have evolved a similar strategy, and hence was eating a different diet to that of other South African hominins. "This lends support to the idea that Homo naledi, with its mixture of traits from earlier and later hominins, was ecologically distinct to other South African hominins," Berthaume added.

Source: Max Planck Society [March 07, 2018]

The acoustic qualities of a rock shelter may have been a key factor in its selection as a site for rock art and indicate a spiritual significance to the practice, according to a recent study, while scientists are also looking into whether some caves were chosen as artistic sites because of the view.

Scientists believe that rock art sites were chosen for their visual and acoustic properties [Credit: Curt Harrell]

Professor Margarita Díaz-Andreu and Dr. Tommaso Mattioli, both from the University of Barcelona, Spain, spent two years visiting rock art sites in France, Italy and Spain to compare acoustics and assess their relevance to the choice of location.

'In a cliff such as Baume Brune (in Vaucluse, France), with 43 shelters, why were only eight selected to be painted?' said Prof. Díaz-Andreu. 'There are other apparently similar ones nearby that were left empty. Why?'

Armed with a specialised portable tool for measuring acoustics, the researchers showed the rock art sites studied have distinct acoustic features.

These take the form of either many echoes in the shelters where the art was found, or strong reverberations. At some sites, it was possible to hear sounds from great distances. Other undecorated shelters in the area lacked these special effects.

'We found that in all of the areas that we tested, the people who had chosen places to decorate had selected places with good acoustics,' said Prof. Díaz-Andreu. In two particular sites, the team demonstrated that the places that were decorated were those with more echoes.

Music

This suggests that the rock art sites were used for rituals, or religious ceremonies, and may or may not have involved music.

'As archaeologists we are obsessed with material culture,' said Prof. Diaz-Andreu, 'But in fact, sound and music are very important to the way in which we feel and the way we react. Sound has special properties that facilitate us to reach a type of mental state that is prone to enhance religious feelings.'

Dr. Jamie Hampson, a researcher at the University of York, UK, who works on a project exploring the modern-day use of rock art (see below), agreed that the rock art has spiritual significance. 'We've got a lot of ethnography from groups in South Africa in particular about the rock face being a veil between this world and the spirit world,' he said.

Prof. Díaz-Andreu and Dr. Mattioli believe that prehistoric humans may have used echolocation techniques such as tongue clicks, cane tapping and handclapping to select the shelters. However, this is impossible to prove.

'Clicking and handclapping do not leave a trace in the archaeological record,' Prof. Díaz-Andreu said.

Rock art is found at hundreds of thousands of sites throughout the world. Throughout history, people from all walks of life have used rock carvings, engravings and paintings to express themselves, and the oldest sites found are more than 65,000 years old.


Manual rubbings

Up until now, researchers have had to take manual rubbings of rock art to analyse in the lab. But this low-tech, 2-D and labour-intensive option meant that important data, such as colour and the 3-D nature of indentations in the rock, were missing.

Now, new zoomable 3-D digital models of rock art sites are providing archaeologists with better tools for analysing data – and they could shed light on why certain sites were chosen. They could also help archaeologists work out whether traces at certain sites are man-made or natural, and potentially identify the styles of individual artists.

Dr. Sue Cobb of the University of Nottingham, UK, led the 3-D-PITOTI project, which developed fully interactive virtual replicas of several rock art sites at Valcamonica, Northern Italy, in high detail.

She said: 'The archaeologists were looking for a way to analyse the content that they were studying in more detail and in different ways. They wanted a better way to view and compare small details of different rock art figures, identify families of figures, and make the 3-D rock art available to their fellow colleagues and the public.'

To build the models, the project team developed an entirely new scanning device to collect images of the rock surface. Specially designed to capture the colour of the rock art and intricate details, at the same time it is lightweight and portable enough to be easily transported across inaccessible areas, hence the nickname 'walking-stick scanner'.

The scanner is so powerful it can reconstruct surface points at 0.1 millimetre spatial resolution, and uses a high=powered flash.

A feature of the finished 3-D models is that you can zoom in and out from the images easily, and virtually fly over the sites. To achieve this effect, the team took photographs from near-range, mid-range and far-range locations to capture the rock art from a range of distances and angles.

The 3-D models can be viewed via a 3-D multi-user touch table, a multi-user 3-D wall display, or individual tablets. Tourists can use the models in museums and visitor centres, to view rock art that is inaccessible or highly vulnerable to damage.

As well as providing a faithful record of art that is one day likely to vanish from exposure to wind, rain and snow, the highly detailed 3-D models are helping scientists answer questions such as whether the view from a particular place was important in selecting the site for decoration.

'Archaeologists can compare rock art images located in different sites,' said Dr. Cobb. 'They ask—is there anything meaningful about those locations and the images of rock art that are placed at that site that can help us understand why that site was meaningful to people at that time?'

Modern-day use of rock art imagery

Rock art sites can be a big tourist draw and scientists have been looking at how the experience can best be managed. Dr. Jamie Hampson from the University of York found that visitor perceptions of artwork and the management of rock art sites in South Africa, Australia and the US were enhanced when there were indigenous tour guides and staff at the sites.

'A lot of visitors point out how much more meaningful their experience is if they're accompanied by a guide who is part of an indigenous group in the area,' explained Dr. Hampson.

It's clear that for many indigenous people, rock art holds a symbolic and spiritual meaning. However, it is often used to create tourist memorabilia, without seeking permission from the relevant indigenous people. Certain images are considered sacred and are not suitable for this kind of use.

'So much of this is about respect and courtesy and taking all possible measures to ensure permission is granted before images are borrowed,' said Dr. Hampson.

The work done by Dr. Hampson's ROCKART project encouraged the employment of more indigenous staff at heritage sites, and raised awareness about image appropriation. The project also aided several Aboriginal corporations in Australia to set up and run their own rock art visitor centres, fueling entrepreneurship in remote areas.

Author: Catherine Collins | Source: Horizon: The EU Research & Innovation Magazine [March 01, 2018]

South Africa's history and economy has been built on its rich natural treasures of a number of precious metals, stones and minerals. The country's mineral deposits have been created over hundreds of millions of years through processes that are still not completely understood.

This is professor Rais Latypov in front of an example of the stratified chromite layers [Credit: Wits University]

One of these processes, that has troubled scientists and geologists for years, is the origin of chromitite layers hosted by layered intrusions -- a major source of chromium on our planet. This process has been a mystery for decades, as scientists tried to work out how layers of pure chromite form from magmas that are coming from Earth's mantle. These are supposed to be rich in a mineral called olivine -- not chromite.

"It has been widely believed that magmas sourced from the mantle cannot directly crystallise chromite, as the mantle rocks that are being melted are rich in olivine, and therefore these melts should crystallise olivine, not chromite," says Professor Rais Latypov from the School of Geosciences of the University of the Witwatersrand in South Africa, whose research team published a paper in Nature Communications.

"Together with a large group of my colleagues, I have been trying hard for several decades to find a mechanism that can explain the formation of these large chromite deposits in shallow crustal chambers but it turned out that we have been looking in the wrong place."

To find the answer to these questions, Latypov and his team have been studying layers of chromite in South Africa's Bushveld Complex, where over 80% of the global resources of platinum-bearing chromite deposits can be found.

They discovered that some basaltic magmas will form chromite after decompression as they rise up from the mantle through the crust towards the Earth's surface. The reduction in pressure, as the magma rises up from the mantle to the crust, is key to the crystallisation process of the chromite.


"When these magmas arrive into a shallow magma chamber, sitting only a few kilometres below the surface of the Earth, they are already saturated in pure chromite, and, on cooling, can crystallise layers of platinum-bearing massive chromitite.

Chromium is an important industrial element that substantially improves the physical and chemical properties of steels, increasing their strength and making them corrosion-resistant. The platinum that is associated with these rocks is used in catalytic converters within cars to break down toxic exhaust gases into relatively benign species.

These zebra-striped coloured layers of platinum-bearing chromite that are formed through this process can be seen clearly in the ridges at the top of the Bushveld Complex, near Steelpoort in Mpumalanga, which became exposed through erosion over the many millions of years since they formed. Some of these layers can be several meters thick and extend for hundreds of kilometres.

"The Bushveld Complex covers an area of 100s of square kilometres. It stretches from Steelpoort in Mpumalanga in the East, past Pretoria to the Pilanesberg in the West; and from Bethal, Mpumalanga in the South to north of Polokwane in Limpopo. We believe that the Bushveld chamber must have been operating as a flow-through system into which magmas were entering and depositing their chromite, before flowing out of the chamber and erupting as basalts via volcanoes, which have now been eroded away," says Latypov.

"It seems that the reduction of lithostatic pressure during the transfer of mantle-derived melts towards the surface plays a vital role in the formation of magmas that produce planetary resources, without which modern human society cannot develop in a sustainable manner."

Further research is being conducted on whether other magmatic deposits around the world, such as vanadium-bearing magnetite in layered intrusions, can also be related to lithostatic pressure reduction.

Source: University of the Witwatersrand [March 01, 2018]

The lion population of Zimbabwe's Savé Valley Conservancy shows low genetic diversity despite improved numbers, according to a study published in the open-access journal PLOS ONE by Laura Tensen from the University of Johannesburg, South Africa, and colleagues based in the Savé Valley Conservancy.

Lion (Panthera leo) [Credit: Regina Hart, Flickr]

The African lion (Panthera leo) population in the Savé Valley Conservancy of the Lowveld region of Zimbabwe fell to less than ten known individuals, until the 2005 introduction of ten new lions helped it recover to around 200 in 2016. But since this population originated from just a few individuals, there are concerns about potential low genetic diversity due to inbreeding. The authors of the present study genotyped a sample of 42 Savé Valley lions, using mitochondrial and nuclear markers to compare the genetic diversity of this population to that of other African lion populations.

The researchers found that the Savé Valley lion population appears to be the least genetically diverse of those in Zimbabwe's Lowveld region, with evidence of inbreeding. The population also appeared genetically distinct from others, likely because factors such as human development may have prevented the populations mixing.

Lion populations with low genetic diversity are known to be at risk for reduced fertility and increased death rates compared to more diverse populations. Given their findings, the authors suggest the introduction of new unrelated lions into the Savé Valley population may become necessary to enhance its genetic diversity and ensure its long-term future.

Source: Public Library of Science [February 07, 2018]

More than 70 years ago two palaeontologists named Robert Broom and John Robinson discovered a skull at the Sterkfontein Caves near Johannesburg. They nicknamed the skull, which is believed to be about 2.5 million years old, "Mrs Ples".

A study of “Mrs” Ples’ tooth sockets has made scientists think differently about “her” sex [Credit: Ditsong National Museum of Natural History]

Its scientific name is Australopithecus africanus, and it's extremely significant because scientists believe it to be a distant relative of all humankind. The fossil represents part of the evidence demonstrating that Africa is the continent from which all humanity originated.

In the decades since then the skull's sex has become the subject of some debate. Not everyone has been convinced by Broom's insistence that "Mrs Ples" was a female of her species.

Our new research, just published in the South African Journal of Science, offers compelling proof that the naysayers were right. "Mrs" Ples was actually a "Mr".

We discovered this by making a careful study of her tooth sockets. In many primates, males can be distinguished from females because of differences in the size of their canine teeth. Simply put, adult males have larger canines than females.

Mrs Ples' teeth were not preserved. Her canine sockets were, and they were about the size one would expect for a female. But our study revealed that the sockets weren't naturally that small: they'd become smaller because of acid used during work done on the skull about 60 years ago. The acid digested away parts of the skull bone around the tooth sockets.

These findings, which form part of an ongoing debate about the iconic skull's sex, are further proof that science is a work in progress. Scientists don't always agree, and they don't always have the definitive answers. Sometimes it can take decades, or even centuries, to reach a resolution.

A disputed history

Soon after he and Robinson made their landmark discovery, Broom confidently claimed that Mrs Ples was female based on the size of her canine sockets. This was a visual deduction; at that time he did not have a substantial comparative sample for the species, so there was room for doubt.

Measurements of the canine socket were published in 1950 at a time when the fossils found at Sterkfontein were cleaned mechanically.

Initially, Broom used a hammer and chisel to remove the hard calcified sands that surrounded Mrs Ples in the caves. But later, in the 1960s, Robinson used acetic acid to remove further rock – and some fossils, Mrs Ples among them, were damaged in the process.

In 1983, Professor Yoel Rak from Tel Aviv challenged Broom's opinion. He pointed out that there were prominent ridges on Mrs Ples's snout, and argued that these were probably associated with the large roots of the canine teeth. Rak became the first to suggest that Mrs Ples ought to be called "Mr" instead.

This view was supported by subsequent research, which one of us – Francis Thackeray – was involved in.

Then opinions changed yet again. In 2012, Professor Fred Grine of the State University of New York re-examined the available evidence. He and his colleagues published an article in the Journal of Human Evolution which insisted Mrs Ples was "an adult female". The assertion was based in part on the apparently small size of the canine tooth sockets.

A rebuttal and new measurements

The research we've just published is a rebuttal to Grine and his colleagues' arguments. The heart of the issue is that they omitted to present all of the data that Broom had obtained about Mrs Ples before the teeth sockets were damaged by acid.

We compared Broom's measurements of Mrs Ples against those obtained for about 12 other specimens of Australopithecus africanus from Sterkfontein. These including specimens that have previously been clearly identified as males or females.

Using the measurements of canine sockets from all of these specimens, we were able to show that Mrs – or rather, Mr – Ples should clearly be grouped with small males rather than with large females.

Of course, science being what it is, the debate is probably not over. We are continuing our research on "Mr Ples", using state of the art CT scans to test our view that the skull is male. For now, and based on our careful comparative study, it seems that the human ancestor who roamed the Sterkfontein Caves so many millions of years ago and whose skull has become a scientific treasure was a male, not a female.

In the final analysis, whether Ples is a Mr or a Mrs doesn't detract from the significance of what the skull tells us about our human ancestry.

Author: Gaokgatlhe Mirriam Tawane & Francis Thackeray | Source: Wits University [February 01, 2018]

Researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, reveal how and when the typical globular brain shape of modern humans evolved. Their analyses based on changes in endocranial size and shape in Homo sapiens fossils show that brain organization, and possibly brain function, evolved gradually within our species and unexpectedly reached modern conditions only recently.

Brain shape evolution in Homo sapiens: brain shape of one of the earliest known members of our species, the 300,000 year-old cranium Jebel Irhoud 1 (left). Brain shape, and possibly brain function, evolved gradually. Brain morphology has reached the globularity typical for present day humans suprisingly recently (right) [Credit: MPI EVA/ S. Neubauer, Ph. Gunz]

The evolutionary history of our own species can be traced back to fossils from Jebel Irhoud (Morocco) dated to about 300,000 years ago. Last year's analysis of these fossils by researchers from the Department of Human Evolution at the Max Planck Institute for Evolutionary Anthropology in Leipzig was highlighted as one of the top science stories of 2017 by a diverse range of print and online media. Together with crania from Florisbad (South Africa, 260,000 years old), and Omo Kibish (Ethiopia) dated to 195,000 years ago, the Jebel Irhoud fossils document an early evolutionary phase of Homo sapiens on the African continent. Their face and teeth look modern, however their elongated braincase appears more archaic as in older human species and in Neanderthals. In contrast, it is a globular braincase, which characterizes the skull of present-day modern humans together with small and gracile faces.

In a new paper published in Science Advances, members of the same research team now reveal additional surprising findings about brain evolution in Homo sapiens. The paleoanthropologists Simon Neubauer, Jean-Jacques Hublin and Philipp Gunz used micro computed tomography scans to create virtual imprints of the internal bony braincase, so called endocasts that approximate brain size and shape. They used state-of-art statistics to analyze endocasts of various fossils and present-day humans.

Evolution of the parietal lobe and the cerebellum

Neubauer and colleagues document a gradual change within Homo sapiens, from an elongated endocranial shape towards a more globular one. Two features of this process stand out: parietal and cerebellar bulging. Parietal brain areas are involved in orientation, attention, perception of stimuli, sensorimotor transformations underlying planning, visuospatial integration, imagery, self-awareness, working and long-term memory, numerical processing, and tool use. The cerebellum is not only associated with motor-related functions like the coordination of movements and balance, but also with spatial processing, working memory, language, social cognition, and affective processing.

The Homo sapiens fossils were found to have increasingly more modern endocranial shapes in accordance with their geological age. Only fossils younger than 35,000 years show the same globular shape as present-day humans, suggesting that modern brain organization evolved some time between 100,000 and 35,000 years ago. Importantly, these shape changes evolved independently of brain size -- with endocranial volumes of around 1,400 milliliters, even the oldest Homo sapiens fossils from Jebel Irhoud fell within present-day variation of brain size. "The brain is arguably the most important organ for the abilities that make us human," says Neubauer. But modern human brain shape was not established at the origin of our species together with other key features of craniodental morphology. Neubauer adds: "We already knew that brain shape must have evolved within our own species, but we were surprised to discover just how recent these changes to brain organization were."

Evolutionary changes in early brain development

In present-day humans, the characteristic globular shape of the braincase develops within a few months around the time of birth. Philipp Gunz explains, "The evolution of endocranial shape within Homo sapiens suggests evolutionary changes of early brain development -- a critical period for neural wiring and cognitive development." The researchers therefore argue that evolutionary changes to early brain development were key to the evolution of human cognition. Jean-Jacques Hublin, co-author and director of the Department of Human Evolution at the Max Planck Institute in Leipzig, says: "The gradual evolution of modern human brain shape seems to parallel the gradual emergence of behavioral modernity as seen from the archeological record."

The new findings are in agreement with recent genetic studies that show changes in genes related to brain development in our lineage since the population split between Homo sapiens and Neanderthals. They add to the accumulating archeological and paleoanthropological evidence demonstrating that Homo sapiens is an evolving species with deep African roots and long-lasting gradual changes in behavioral modernity, brain organization, and potentially brain function.

Source: Max Planck Society [January 25, 2018]

In the Earth's early history, several billion years ago, only traces of oxygen existed in the atmosphere and the oceans. Today's air-breathing organisms could not have existed under those conditions. The change was caused by photosynthesizing bacteria, which created oxygen as a by-product -- in vast amounts. 2.5-billion-year-old rock layers on several continents have yielded indications that the first big increase in the proportion of oxygen in the atmosphere took place then.

Rock layers in the Pongola Basin, South Africa [Credit: Axel Hofmann/University of Johannesburg]

Now, working with international colleagues, Dr. Benjamin Eickmann and Professor Ronny Schönberg, isotope geochemists from the University of Tübingen have discovered layers in South Africa's Pongola Basin which bear witness to oxygen production by bacteria as early as 2.97 billion years ago. That makes the Basin the earliest known home to oxygen-producing organisms -- known as an oxygen oasis. The study has been published in the latest Nature Geoscience.

Conditions on Earth some three billion years ago were inhospitible to say the least. The atmosphere contained only one-one hundred thousandth of the oxygen it has today. The primeval oceans contained hardly any sulfate; but they did contain large amounts of ferrous iron. When bacteria started producing oxygen, it could initially bond with other elements, but began to enrich the atmosphere in a massive oxygen emission event around 2.5 billion years ago.

"We can see that in the disappearance of reduced minerals in the sediments on the continents. Certain sulfur signatures which can only be formed in a low-oxygen atmosphere are no longer to be found," says Benjamin Eickmann, the study's lead author. This event, which could be described as global environmental pollution, went down in the Earth's history as the Great Oxygenation Event. It was a disaster for the early bacteria types which had evolved under low-oxygen conditions; the oxygen poisoned them. "However, after the first big rise, the atmosphere only contained 0.2 percent oxygen; today it's around 21 percent," Eickmann explains. Exposed to an atmosphere which contained increasing amounts of oxygen, the continents were subject to enhanced erosion. That led to more trace elements entering the oceans. The improved supply of nutrients in turn led to more life forms in the seas.

Sulfur signatures as an archive of Earth history

In their current study the researchers investigated the 2.97-bilion-year-old sediments deposited in the Pongola Basin in what is now South Africa. From the proportions of sulfur isotopes (particularly the of 34S/32S ratio), in the sediments, the researchers are able to conclude that the bacteria used the sulfate in the primeval seas as a source of energy, reducing it chemically.

"Sulfate is a form of oxidized sulfur. A higher concentration of sulfate in the water indicates that sufficient free oxygen must have been present in the shallow sea of the Pongola Basin," Ronny Schönberg says. This free oxygen must have been produced by other, photosynthesizing bacteria. At the same time, another sulfur isotope signature (the 33S/32S ratio) in these sediments indicates a continued reduced, very low-oxygen atmosphere.

"That makes the Pongola Basin the oldest oxygen oasis known to date. The oxygen was building up in the water long before the Great Oxygenation Event, Schönberg explains. Several hundred million years later, the steadily rising levels of oxygen led to the oxidation of the atmosphere, and that is what made life on Earth -- in all its variety as we know it today -- even possible.

Source: Universitaet Tübingen [January 18, 2018]

The digital reconstruction of the skull of a 200-million-year-old South African dinosaur, Massospondylus, has made it possible for researchers to make 3D prints and in this way facilitate research on other dinosaurs all over the world.

The profile view of the Massospondylus skull [Credit: Kimberley Chapelle]

Kimi Chapelle, a PhD student at the Evolutionary Studies Institute at the University of the Witwatersrand in Johannesburg, South Africa (Wits), has used the Wits MicroFocus CT facility to peer inside the skull of the dinosaur Massospondylus.

Chapelle was able to use the CT facility to rebuild every bone of Massospondylus's cranium, and to even look at tiny features like nerves exiting the brain and the balance organs of the inner ear. Her research is published today in the open-access journal PeerJ.

Along with the paper, which is open for anybody to download and read, a 3D surface file of the skull is available to be downloaded.

"This means any researcher or member of the public can print their own Massospondylus skull at home," says Chapelle.

The profile view of the Massospondylus skull after being scanned [Credit: Kimberley Chapelle]

Massospondylus is one of the most famous dinosaurs from South Africa and was named in 1854 by the celebrated anatomist Sir Richard Owen. Fossils of Massospondylus have been found in many places in South Africa, including Golden Gate National Park, where James Kitching discovered fossil eggs and embryos in 1976. Surprisingly, the skull of Massospondylus has never been the focus of an in-depth anatomical investigation.

"I was amazed when I started digitally reconstructing Massospondylus' skull, and found all these features that had never been described," said Chapelle, "it just goes to show that researchers still have a lot to learn about South Africa's dinosaurs."

Some of the most interesting discoveries from the skull, which is described in Chapelle's paper include:

• details on how the inner ear and the middle ear contacted each other and what these looked like
• Where the nerves connecting different parts of the skull to the brain were and which bones they went through 
• that replacement teeth don't erupt in a specific pattern and are present on all teeth, and
• that the bones that surround the brain in this specific fossil were not fully fused.

"By comparing the inner ear to that of other dinosaurs, we can try and interpret things like how they held their heads and how they moved. You can actually see tiny replacement teeth in the bones of the jaws, showing us that Massospondylus continuously replaced its teeth, like crocodiles do, but unlike humans that can only do it once," says Chapelle.

PhD student Kimberley Chapelle at work in the field [Credit: Wits University]

"Also, the fact that the bones of the braincase aren't fully fused means that this particular fossil is that of an individual that is not fully grown yet. This allows us to understand how Massospondylus grew, how fast it grew and how big it could grow."

Hundreds of Massospondylus fossils have been found in South Africa, ranging in size from hatchlings to adult. Chapelle is using CT technology to study these additional fossils for her PhD. "I'll be using scans of other specimens to answer new questions," said Chapelle, "for example, how did Massospondylus babies weighing less than 100g grow up to be half-tonne adults?."

"Students like Kimi have been able to use our CT facility to produce cutting-edge research like this" said Prof. Jonah Choiniere, the supervisor and co-author of the study, "and it's changing the way we do dinosaur research."

Source: University of the Witwatersrand [January 12, 2018]

Scientists have found fossil evidence of deep-sea marine life burrowing up to eight metres below the seabed -- four times the previously observed depth for modern deep-sea life.

Cross-cutting burrows on the margins of a sandstone injectite [Credit: Sarah Cobain,  University of Leeds]

A team of scientists from the University of Leeds and the National Oceanography Centre examined remains of deep-sea burrows in rocky outcrops that were part of the ocean floor roughly 250 million years ago.

These outcrops are made up of sand-sheets that are widespread on modern ocean floors, suggesting that deep-sea burrowing marine life may be much more abundant than previously considered.

Study author Professor David Hodgson, from the School of Earth and Environment at Leeds, said: "Ocean ecology shows us that deep-sea burrowers have only become more prevalent and diverse through time.

"Their adaptability to new environments strengthens the idea that if their pre-historic ancestors were burrowing to these depths, then it's likely we'd find them there today."

The team's findings, published in Scientific Reports, highlights the need for new future sampling strategies to better capture the depth range of animals living in modern deep-sea sands.

Sandstone outcrops from the Karoo Basin, South Africa [Credit: David Hodgson,  University of Leeds]

Collecting intact samples from the deep-ocean floor is technologically challenging. The distance to the ocean seabed and the difficulties of extracting samples makes it problematic to determine how deeply modern animals burrow. Modern deep-sea biological studies target muds as these are simpler to sample than the shifting sands of the deep seabed.

Lead author Dr Sarah Cobain conducted this research while a PhD student at the School of Earth and Environment, she is now based at Petrotechnical Data Systems in London. She said: "These outcrops give us a snapshot of ancient deep-sea life. We know that modern marine burrowing animals are living in the same material that has been fossilised in these rocks.

"The burrowers use the networks that are already present in the deep ocean sediment below the seabed and leave behind living traces. These networks -- what we call injectites after they've been fossilised -- are caused by sand-rich water being forcibly injected into mud. They provide the animals easy pathways to burrow and find nutrients and oxygen.

"Our understanding of the process by which these injectites form allows us to not only assess how these creatures lived but also how deeply they burrowed into the sediment below the seabed."

Burrows on the margins of a sandstone dyke [Credit: Sarah Cobain,  University of Leeds]

The branching structures that make up the trace fossils are believed to have been made by organisms that were previously thought to live mainly in the top 20 centimetres of sediment, rarely reaching further than 1.5 metres, due to the decline of oxygen and food in deeper levels of the sediment.

The team documented the creatures' living traces -- known as bioturbation -- on the margins of clastic injectites from at least eight metres below the seabed.

In order to produce living traces, organisms would need to survive long enough to burrow for hours or even days. The size of the burrows suggests macro-infaunal invertebrates (tiny shrimps and worms).

Study author, Jeffrey Peakall, Professor of Process Sedimentology at Leeds, said: "This discovery gives us a window into a widespread yet barely explored environment on our planet. Little is known about modern deep seabed environments, and less about the ancient.

"These trace fossils can give us new insight into the possibility that the deepest organisms may be present in sandy sediments, rather than the clays and silts typically targeted in modern seabed investigations."

Source: University of Leeds [January 10, 2018]

var addthis_config = {"data_track_clickback":true};

At approximately 21h30, on Monday night, the National Sea Rescue Institute (NSRI) in Port Elizabeth was requested by Air Traffic Control to investigate the sighting of an unidentified flying object - commonly called UFO.

"A Boeing 737 cargo aircraft Captain and Co-Pilot, flying from Cape Town International Airport to Port Elizabeth International Airport, reported seeing what appeared to be a green object increasing in altitude past the cockpit of their aeroplane reaching to about a thousand feet into clouds above them and then returning towards earth at high speed past the cockpit of the aeroplane," said NSRI spokesperson, Craig Lambinon. "The sighting was reported to Air Traffic Control at Port Elizabeth International Airport, who requested NSRI's assistance to investigate the possibility that an aircraft or craft may be in difficulty.

By www.rnews.co.za 12-13-16

Read more »