Traces of ancient rainforest in Antarctica point to a warmer prehistoric world

by Imperial College London

Map of the drill site and how to continents were arranged 90 million years ago. Credit: Alfred-Wegener-Institut

Researchers have found evidence of rainforests near the South Pole 90 million years ago, suggesting the climate was exceptionally warm at the time.

A team from the UK and Germany discovered forest soil from the Cretaceous period within 900 km of the South Pole. Their analysis of the preserved roots, pollen and spores shows that the world at that time was a lot warmer than previously thought.

The discovery and analysis were carried out by an international team of researchers led by geoscientists from the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research in Germany and including Imperial College London researchers. Their findings are published today in Nature.

Co-author Professor Tina van de Flierdt, from the Department of Earth Science & Engineering at Imperial, said: "The preservation of this 90-million-year-old forest is exceptional, but even more surprising is the world it reveals. Even during months of darkness, swampy temperate rainforests were able to grow close to the South Pole, revealing an even warmer climate than we expected."

The work also suggests that the carbon dioxide (CO2) levels in the atmosphere were higher than expected during the mid-Cretaceous period, 115-80 million years ago, challenging climate models of the period.

Professor Tina van de Flierdt and Dr Johann Klages work on the sample of ancient soil. Credit: T. Ronge, Alfred-Wegener-Institut

The mid-Cretaceous was the heyday of the dinosaurs but was also the warmest period in the past 140 million years, with temperatures in the tropics as high as 35 degrees Celsius and sea level 170 metres higher than today.

However, little was known about the environment south of the Antarctic Circle at this time. Now, researchers have discovered evidence of a temperate rainforest in the region, such as would be found in New Zealand today. This was despite a four-month polar night, meaning for a third of every year there was no life-giving sunlight at all.

The presence of the forest suggests average temperatures were around 12 degrees Celsius and that there was unlikely to be an ice cap at the South Pole at the time.

The evidence for the Antarctic forest comes from a core of sediment drilled into the seabed near the Pine Island and Thwaites glaciers in West Antarctica. One section of the core, that would have originally been deposited on land, caught the researchers' attention with its strange colour.

The team CT-scanned the section of the core and discovered a dense network of fossil roots, which was so well preserved that they could make out individual cell structures. The sample also contained countless traces of pollen and spores from plants, including the first remnants of flowering plants ever found at these high Antarctic latitudes.

Illustration of the Antarctic rainforest. Credit: Alfred-Wegener-Institut/James McKay

To reconstruct the environment of this preserved forest, the team assessed the climatic conditions under which the plants' modern descendants live, as well as analysing temperature and precipitation indicators within the sample.

They found that the annual mean air temperature was around 12 degrees Celsius; roughly two degrees warmer than the mean temperature in Germany today. Average summer temperatures were around 19 degrees Celsius; water temperatures in the rivers and swamps reached up to 20 degrees; and the amount and intensity of rainfall in West Antarctica were similar to those in today's Wales.

To get these conditions, the researchers conclude that 90 million years ago the Antarctic continent was covered with dense vegetation, there were no land-ice masses on the scale of an ice sheet in the South Pole region, and the carbon dioxide concentration in the atmosphere was far higher than previously assumed for the Cretaceous.

Lead author Dr. Johann Klages, from the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, said: "Before our study, the general assumption was that the global carbon dioxide concentration in the Cretaceous was roughly 1000 ppm. But in our model-based experiments, it took concentration levels of 1120 to 1680 ppm to reach the average temperatures back then in the Antarctic."UN: Antarctic high temp records will take months to verify

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More information: Temperate rainforests near the South Pole during peak Cretaceous warmth, Nature (2020). DOI: 10.1038/s41586-020-2148-5 , https://nature.com/articles/s41586-020-2148-5

Journal information: Nature 

Reflections on COVID-19 and our destruction of nature

by Radhika Iyengar, State of the Planet
 

Credit: Salazar Barnz on Unsplash

In 2015 I was helping to draft a UNESCO report, Education for People and Planet. To gather various opinions on the role of education in creating a sustainable planet, I met with a professor of ecology and biodiversity at Columbia University. In my interview with him, he said something that I have never forgotten: "Nature is not your friend—it does what it does."


I think about that now as I look at the last green pepper in my fridge. This is the last vegetable that I have after three weeks of being homebound due to the coronavirus pandemic. Two weeks back, I mustered up some courage, as if I was going out to war, and went to my local Trader Joe's. A place that I used to frequent once a week, always carrying my reusable grocery bags, and saying my usual hellos to the employees who all know my kids and me very well. My kids get stickers from the friendly cashier. However, my visit two weeks back was different. The customers made a line, six feet apart from each other, and the line spilled over the parking lot. After an hour of waiting outside, a Trader Joe's employee handed me a wet wipe to disinfect my cart and I was among the lucky 25 who got to go in. "Twenty-five at a time is the new rule." I wore my yellow kitchen gloves, didn't make any eye contact, and stayed away from people.

While I look at the last vegetable in my fridge, my last pepper, I think about how, three weeks back I attended a course on food waste management in my local library. We exchanged tips on how to use the leftover half of an avocado, or the banana that we take to work that always gets wasted. We decided to purchase only what is required and to manage our fridge better. I had discussed how I need to better educate my kids to stop wasting food. Living in India, poverty and hunger is not invisible. But my kids, that is another story. I keep reinforcing that as per Hindu philosophy, it is a sin to waste food. Gopal Patel talks about sustainability and spirituality. In the COVID-19 days, I generate no waste. In the fear of attempting another war-like situation at the grocery store, I have been rationing food supplies at home and being very careful. It required nature to give me such a practical, mandatory lesson on food management.

I hear that New Jersey's air quality will drastically improve and the residents will breathe cleaner air than ever before. More cars stay at home and humankind will hold back on more destruction. April 18th was our town, Millburn's, Earth Day celebration, which is now postponed to September. My friends and I were planning ways to make our Earth greener, use less plastic, and "refuse, reuse, recycle" our waste. I have so many bins at home to manage my waste—trash, recycling, plastic bag recycling, compost bins. I was so busy trying to fit my waste into these bins to make this Earth greener. Now, I avoid buying, not because I want to, but because I can't. I produce much less waste, not by choice, but due to COVID-19. It took a pandemic to put me in my place.


My window tells me that spring is here. I look outside to admire the yellow blooming flowers. Open my window to get some spring air in my house. I go on my deck to get some sun. I cannot go outside, because there is nowhere to go. Probably starting my fossil fuel-filled car is already enough damage. Carlos Manuel Rodriguez, the minister of environment for Costa Rica, has called on leaders to put climate and biodiversity at the top of the agenda as they respond to the COVID-19 crisis. Probably one of those tree-hugging hippies who will soon be ignored. Greta has gone online, too. Will she be a victim of "out-of-sight, out-of-mind"? Maybe we will go back to our convenient status quo—but will it be easy this time?

For the time being, our new "normal" is here to stay. At the Earth Institute's COVID-19 briefing last week, epidemiologists asked us to prepare for the long haul. COVID-19 will not go away; the effects might get dissipated over many years to come. Many millions will be physically impacted, but Irwin Redlener noted that the impact on mental health will be as rampant as COVID-19 itself. Our communities are not prepared for disaster management, as per Jeffrey Schlegelmilch. Professor Jeffrey Sachs in his public briefing reminded us that this is not just an health issue, but will cost 10-20% of the GDP for many countries. Therefore, it is imperative that the world has an economic plan not just for the current crisis, but also post-crisis as well.

In a recent Mongabay India Series commentary, Gopikrishna Warrier notes that with the changing climate and rainfall, new diseases are emerging. The changing climate causes more stress to wild animals who are already confronted with shrinking habitats, thus making it easier for diseases to jump from animals to humans. A recent article in the Guardian seems to suggest that human destruction of biodiversity has brought us to a tipping point, and therefore it is time to face nature's wrath.

Normally, I am so busy in my life—going to and from the office, and getting the children to school—that there is just no time to think about biodiversity. Now, I am confined to my house. Boundaries have been made. I now imagine the life of a fish, who has limited places to go to because of the plastic we threw at her. Tall trees in Taylor Park that can't move, but inhale all the bad air we give them. I imagine the lives of animals in Disney World, the cute dolphin who jumps out and kisses you and goes back to jail. We have created a new world for them, and nature now creates a new world for us. "Social distancing" is not just for people; we need to maintain a safe distance between animals and ourselves.

I will cook the last pepper with a lot of care. Maybe throw in some potatoes and some curry powder. The core goes into the compost again. The only difference is, this time there will be no food wasted on my table.


Explore furtherCoronavirus is a wake-up call: our war with the environment is leading to pandemics
Provided by State of the Planet

This story is republished courtesy of Earth Institute, Columbia University http://blogs.ei.columbia.edu.

Golden age of Hollywood was not so golden for women

by Northwestern University

Casablanca (1942) had a male director, male producer, three male screenwriters, and seven featured male actors. Credit: Bill Gold

The Golden Age of Hollywood is known for its glitz, glamour and classic movies. Northwestern University researchers have peeled back the gilded sheen to reveal an industry tarnished by severe gender inequity.

By analyzing a century of data (1910 to 2010) in the American Film Institute Archive and the Internet Movie Database (IMDb), the researchers found that female representation in the film industry hit an all-time low during the so-called Golden Age. Women representation in the industry still is struggling to recover today.

"A lot of people view this era through rose-colored glasses because Hollywood was producing so many great movies," said Northwestern's Luís Amaral, who led the study. "They argue that types of movies being made—such as Westerns, action and crime—caused the decrease in female representation. But we found the decrease occurred across all genres, including musicals, comedy, fantasy and romance."

The study will be published on April 1 in the journal PLOS ONE.

Amaral is the Erastus Otis Haven Professor of Chemical and Biological Engineering in Northwestern's McCormick School of Engineering.

Historical trends of gender imbalance in the U.S. movie industry. Credit: Amaral et al, PLOS ONE 2020 (CC BY)

Consistent findings across all genres and jobs

To conduct the study, Amaral and his team analyzed 26,000 movies produced between 1910 and 2010.

The team looked across all genres—action, adventure, biography, comedy, crime, drama, documentary family, fantasy, film-noir, history, horror, music, musical, mystery, romance, sci-fi, sport, thriller, war, Western and short—to measure how many women worked as actors, screenwriters, directors and producers.

Across all genres and all four job types, the resulting graphs form the exact same "U-shape" pattern. Roles for women increased from 1910 to 1920 and then sharply dropped. Around 1950, the roles steadily increase until 2010.

"In general, we found that the percentage of women compared to men in any role was consistently below 50% for all years from 1912 until now," said study coauthor Murielle Dunand, a former intern in Amaral's laboratory and current student at Massachusetts Institute of Technology.

'Men hire men'

Amaral said his findings reflect what was happening in the film industry.

Before Hollywood's Golden Age, the industry was fueled by independent filmmakers, and women participation was steadily increasing. From 1910 to 1920, according to Amaral's data, women actors comprised roughly 40% of casts. Women wrote 20% of movies, produced 12% and directed 5%. By 1930, acting roles for women were cut in half; producing and directing roles hit close to zero.

Amaral and Dunand said the data suggest that the studio system, which emerged between 1915 and 1920, is most likely responsible for the shift. The industry condensed from a somewhat diverse collection of independent filmmakers scattered across the country to just five studios (Warner Bros., Paramount, MGM, Fox and RKO Pictures), which controlled everything.

"As the studio system falls under the control of a small group of men, women are receiving fewer and fewer jobs," Amaral said. "It looks like male producers hire male directors and male writers. This is association, not causation, but the data is very suggestive."

Women improve conditions for other women

Then, two groundbreaking lawsuits caused the studio system to break apart. First, Oscar-nominated actor Olivia de Havilland, who had an exclusive contract with Warner Bros., sued the studio in 1943 to be freed from her contract and won. In 1948, the U.S. federal government sued Paramount Pictures in an antitrust case. At the time, movie studios owned their own theaters and distributed their own movies. When Paramount lost, studios could no longer exclusively produce, distribute and exhibit their films.

"These legal changes took the power away from a handful of men and gave more people the power to start changing the industry," Amaral said. "There is a connection between increased concentration of power and decreased participation of women."

Among the insights hidden in the data, Amaral found that women producers tend to hire greater proportions of women to work in their films.

"Producers affect the gender of the director," he said. "Women with power in Hollywood are making conditions better for other women.

Celluloid Ceiling study finds women still largely underrepresented in Hollywood

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More information: Amaral LAN, Moreira JAG, Dunand ML, Tejedor Navarro H, Lee HA (2020) Long-term patterns of gender imbalance in an industry without ability or level of interest differences. PLoS ONE 15(4): e0229662. doi.org/10.1371/journal.pone.0229662

Journal information: PLoS ONE 

Provided by Northwestern University 

American robins now migrate 12 days earlier than in 1994

by Columbia University

A robin wearing a GPS tracker on its back. Credit: Brian Weeks

Every spring, American robins migrate north from all over the U.S. and Mexico, flying up to 250 miles a day to reach their breeding grounds in Canada and Alaska. There, they spend the short summer in a mad rush to find a mate, build a nest, raise a family, and fatten up before the long haul back south.

Now climate change is making seasonal rhythms less predictable, and springtime is arriving earlier in many parts of the Arctic. Are robins changing the timing of their migration to keep pace, and if so, how do they know when to migrate? Although many animals are adjusting the timing of their migration, the factors driving these changes in migratory behavior have remained poorly understood.

A new study, published in Environmental Research Letters, concludes that robin migration is kicking off earlier by about five days each decade. The study is also the first to reveal the environmental conditions along the migration route that help the birds keep up with the changing seasons. Lead author Ruth Oliver completed the work while earning her doctorate at Columbia University's Lamont-Doherty Earth Observatory.

At Canada's Slave Lake, a pit stop for migrating birds, researchers have been recording spring migration timing for a quarter century. Their visual surveys and netting censuses revealed that robins have been migrating about five days earlier per decade since 1994.

In order to understand what factors are driving the earlier migration, Oliver and Lamont associate research professor Natalie Boelman, a coauthor on the paper, knew they needed to take a look at the flight paths of individual robins.

Small GPS 'backpacks' allowed researchers to track the environmental factors that influence American robin migratory behavior. Credit: Ruth Oliver

Their solution was to attach tiny GPS "backpacks" to the birds, after netting them at Slave Lake in mid-migration. "We made these little harnesses out of nylon string," Oliver explained. "It basically goes around their neck, down their chest and through their legs, then back around to the backpack." The unit weighs less than a nickel—light enough for the robins to fly unhindered. The researchers expect that the thin nylon string eventually degrades, allowing the backpacks to fall off.

The researchers slipped these backpacks onto a total of 55 robins, tracking their movements for the months of April through June. With the precise location from the GPS, the team was able to link the birds' movements with weather data on air temperature, snow depth, wind speed, precipitation, and other conditions that might help or hinder migration.

The results showed that the robins start heading north earlier when winters are warm and dry, and suggest that local environmental conditions along the way help to fine-tune their flight schedules.

"The one factor that seemed the most consistent was snow conditions and when things melt. That's very new," said Oliver. "We've generally felt like birds must be responding to when food is available—when snow melts and there are insects to get at—but we've never had data like this before."

Boelman added that "with this sort of quantitative understanding of what matters to the birds as they are migrating, we can develop predictive models" that forecast the birds' responses as the climate continues to warm. "Because the timing of migration can indirectly influence the reproductive success of an individual, understanding controls over the timing of migratory events is important."

GPS data revealed spring migration routes for 55 American robins. Analyzing the weather at locations along the flight paths revealed some of the environmental conditions that influence early migration. Credit: Oliver et al, 2020

For now, it seems as though the environmental cues are helping the robins to keep pace with the shifting seasons. "The missing piece is, to what extent are they already pushing their behavioral flexibility, or how much more do they have to go?" said Oliver.

Because the study caught the birds in mid-migration, the tracking data doesn't reflect the birds' full migration path. To overcome this limitation, the researchers plan to analyze tissue from the robins' feathers and claws, which they collected while attaching the GPS harnesses, to estimate where each bird spent the previous winter and summer.

Over the long term, Oliver says, she hopes to use the GPS trackers to sort out other mysteries as well, such as how much of the change in migration timing is due to the behavioral responses found in the study versus natural selection to changing environments, or other factors.

"This type of work will be really cool once we can track individuals throughout the course of their life, and that's on the near-term horizon, in terms of technological capabilities," she said. "I think that will really help us unpack some of the intricacies of these questions."Fifty years of data show new changes in bird migration

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More information: Ruth Y Oliver et al, Behavioral responses to spring snow conditions contribute to long-term shift in migration phenology in American robins, Environmental Research Letters (2020). DOI: 10.1088/1748-9326/ab71a0

Journal information: Environmental Research Letters 

Provided by Columbia University 

Modern humans, Neanderthals share a tangled genetic history, study affirms

by Charlotte Hsu, University at Buffalo

Comparison of Modern Human and Neanderthal skulls from the Cleveland Museum of Natural History. Credit: DrMikeBaxter/Wikipedia

In recent years, scientists have uncovered evidence that modern humans and Neanderthals share a tangled past. In the course of human history, these two species of hominins interbred not just once, but at multiple times, the thinking goes.

A new study supports this notion, finding that people in Eurasia today have genetic material linked to Neanderthals from the Altai mountains in modern-day Siberia. This is noteworthy because past research has shown that Neanderthals connected to a different, distant location—the Vindija Cave in modern-day Croatia—have also contributed DNA to modern-day Eurasian populations.

The results reinforce the concept that Neanderthal DNA has been woven into the modern human genome on multiple occasions as our ancestors met Neanderthals time and again in different parts of the world.

The study was published on March 31 in the journal Genetics.

"It's not a single introgression of genetic material from Neanderthals," says lead researcher Omer Gokcumen, a University at Buffalo biologist. "It's just this spider web of interactions that happen over and over again, where different ancient hominins are interacting with each other, and our paper is adding to this picture. This project will now add to an emerging chorus — we've been looking into this phenomenon for a couple of years, and there are a couple of papers that came out recently that deal with similar concepts."

"The picture in my mind now is we have all these archaic hominin populations in Europe, in Asia, in Siberia, in Africa. For one reason or another, the ancestors of modern humans in Africa start expanding in population, and as they expand their range, they meet with these other hominins and absorb their DNA, if you will," Gokcumen says. "We probably met different Neanderthal populations at different times in our expansion into other parts of the globe."

Gokcumen, associate professor of biological sciences in the UB College of Arts and Sciences, led the study with first author Recep Ozgur Taskent, a recent UB Ph.D. graduate in the department. Co-authors include UB Ph.D. graduate Yen Lung Lin, now a postdoctoral scholar at the University of Chicago; and Ioannis Patramanis and Pavlos Pavlidis, Ph.D., of the Foundation for Research and Technology in Greece.

The research was funded by the U.S. National Science Foundation.

To complete the project, scientists analyzed the DNA of hundreds of people of Eurasian ancestry. The goal was to hunt for fragments of genetic material that may have been inherited from Neanderthals.

This research found that the Eurasian populations studied could trace some genetic material back to two different Neanderthal lineages: one represented by a Neanderthal whose remains were discovered in the Vindija cave in Croatia, and another represented by a Neanderthal whose remains were discovered in the Altai mountains in Russia.

Scientists also discovered that the modern-day populations they studied also share genetic deletions — areas of DNA that are missing — with both the Vindija and Altai Neanderthal lineages.

The DNA of the Vindija and Altai Neanderthals, along with the modern human populations studied, were previously sequenced by different research teams.

"It seems like the story of human evolution is not so much like at tree with branches that just grow in different directions. It turns out that the branches have all these connections between them," Gokcumen says. "We are figuring out these connections, which is really exciting. The story is not as neat as it was before. Every single ancient genome that is sequenced seems to create a completely new perspective in our understanding of human evolution, and every new genome that's sequenced in the future may completely change the story again."

Earliest interbreeding event between ancient human populations discovered

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More information: Ozgur Taskent et al, Analysis of Haplotypic Variation and Deletion Polymorphisms Point to Multiple Archaic Introgression Events, Including from Altai Neanderthal Lineage, Genetics (2020). DOI: 10.1534/genetics.120.303167

Evolutionary adaptation helped cave bears hibernate, but may have caused extinction

by Ellen Goldbaum-Kolin, University at Buffalo

The well-developed sinus system in the now extinct cave bear (top left) is associated with uneven mechanical stress distributions in biting simulations (bottom left) conducted at UB. The much less developed sinus system in living bears, for example the sun or honey bear, (top right) allows mechanical stress to distribute evenly over the forehead region, as seen in the biting simulation (bottom right). Credit: Alejandro Pérez-Ramos

A study published in Science Advances on April 1 reveals a new hypothesis that may explain why European cave bears went extinct during past climate change periods. The research was motivated by controversy in the scientific literature as to what the animal (Ursus spelaeus) ate and how that affected their demise.

The new hypothesis emerged, in part, from computational analysis and computer biting simulations conducted in the laboratory of Jack Tseng, Ph.D., assistant professor of pathology and anatomical sciences in the Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo.

Tseng is a co-author on the paper with corresponding authors Borja Figueirido, Ph.D., and Alejandro Pérez-Ramos, Ph.D., his doctoral student and first author, both of the Departamento de Ecologia y Geologia of the Universidad de Malaga, Spain.

Dietary dilemma

Cave bears were a species of bear (Ursus spelaeus) that lived in Europe and Asia that went extinct about 24,000 years ago. According to Figueirido, researchers have proposed different diets for cave bears, ranging from pure herbivory to carnivory or even scavenging.

"Knowing the feeding behaviour of the cave bear is not a trivial aspect," he said. "Feeding behaviour is intimately related to its decline and extinction."

He noted that two main hypotheses, not necessarily exclusive, have been proposed to explain cave bear extinction: a human-driven decline, either by competition for resources or by direct hunting; or a substantial demise in population sizes as a result of the climatic cooling that occurred during the late Pleistocene which caused vegetation to wane.

Previous research shows that cave bears were primarily herbivorous at least from 100,000 to 20,000 years ago. But even during the cooling periods, when vegetation productivity waned, these bears didn't change their diets. The researchers propose that this dietary inflexibility, combined with competition for cave shelters by humans, is what led to their extinction.

To find out if there were biomechanical explanations behind their inflexible diets, meaning that the bears weren't physically capable of adjusting their diets effectively during times of limited vegetation resources, the researchers analyzed three-dimensional computer simulations of different feeding scenarios.

Critical sinuses

They were especially interested in the sinuses of the bears because large paranasal sinuses allow for greater metabolic control, critical to survival during hibernation.

"Our study proposes that climate cooling probably forced the selection of highly developed sinuses," which in turn led to the appearance of the characteristic domed skull of the cave bear lineage," said Alejandro Pérez-Ramos.

Tseng explained that when the sinus system expands, the act of chewing may cause more or less strain on the skull. In both humans and bears, the sinus system lightens the weight of the face, reducing the amount of bone tissue needed to grow the skull.

"Mechanically speaking, being 'thickheaded' may not be a bad thing because more bone means more structural strength," he said. "However, our findings support the interpretation that requirements for sinus system function in cave bears necessitated a trade-off between sinus development and skull strength."

Tseng and Pérez-Ramos, who spent three months at UB to learn the procedure, used a biomechanical simulation methodology to estimate the biting stresses and strains in different bear species and different models of them. The bear skull specimens used were from several European institutions, where CT scans had been done on them, as well as the scientific CT repository, also known as the digital morphology library, at the University of Texas at Austin.

They found that the development of paranasal sinuses in cave bears caused the cranial dome to expand upward and backward from the forehead, changing the geometry of the bear's skull.

"This geometrical change generated a mechanically suboptimal cranial shape, with a very low efficiency to dissipate the stress along the skull, particularly when biting with the canines or carnassials, the teeth most often used by predatory mammals," said Pérez-Ramos.

When the sinus system expands, Tseng explained, it results in bone reduction relative to the size of the skull and therefore less structural support to resist the physical forces that chewing generates. Although other mammals with expanded sinuses, such as hyenas, appear to have evolutionarily modified their skull shape to effectively deal with decreased structural support, cave bear skulls showed compromised biomechanical capability compared to living bear species.

"Through the use of new techniques and virtual methods, such as biomechanical simulations across each tooth and the comparative internal anatomical study of the paranasal sinuses, we propose that large sinuses were probably selected in cave bears in order to be able to hibernate for longer periods with very low metabolic costs," said Pérez-Ramos.

Ultimately, though, that trade-off may have resulted in the extinction of the species, a finding that also has relevance to humans, Tseng said.

"Being able to stay alive during the coldest periods would have been equally important to human and bear alike," he said. "The success or demise of prehistoric megafauna, such as cave bears, provide crucial clues as to how humans may have out-competed and out-survived other large mammals during a critical time for the evolution of our own species.

Ancient extinct cave bear DNA found in modern bears

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More information: A. Pérez-Ramos el al., "Biomechanical simulations reveal a trade-off between adaptation to glacial climate and dietary niche versatility in European cave bears," Science Advances (2020). advances.sciencemag.org/content/6/14/eaay9462

Skull scans reveal evolutionary secrets of fossil brains

by William Kimbel, Arizona State University

Brain imprints in fossil skulls of the species Australopithecus afarensis (famous for "Lucy" and the "Dikika child" from Ethiopia pictured here) shed new light on the evolution of brain growth and organization. The exceptionally preserved endocranial imprint of the Dikika child reveals an ape-like brain organization, and no features derived towards humans. Credit: Philipp Gunz, MPI EVA Leipzig.

Scientists have long been able to measure and analyze the fossil skulls of our ancient ancestors to estimate brain volume and growth. The question of how these ancient brains compare to modern human brains and the brains of our closest primate cousin, the chimpanzee, continues to be a major target of investigation.

A new study published in Science Advances used CT-scanning technology to view three-million-year old brain imprints inside fossil skulls of the species Australopithecus afarensis (famous for "Lucy" and "Selam" from Ethiopia's Afar region) to shed new light on the evolution of brain organization and growth. The research reveals that while Lucy's species had an ape-like brain structure, the brain took longer to reach adult size, suggesting that infants may have had a longer dependence on caregivers, a human-like trait.

The CT-scanning enabled the researchers to get at two long-standing questions that could not be answered by visual observation and measurement alone: Is there evidence for human-like brain reorganization in Australopithecus afarensis, and was the pattern of brain growth in this species more similar to that of chimpanzees or that of humans?

To study brain growth and organization in A. afarensis, the researchers, including ASU paleoanthropologist William Kimbel, scanned eight fossil crania from the Ethiopian sites of Dikika and Hadar using high-resolution conventional and synchrotron-computed tomography. Kimbel, leader of the field work at Hadar, is director of the Institute of Human Origins and Virginia M. Ullman Professor of Natural History and the Environment in the School of Human Evolution and Social Change.

VIDEO 3-million-year old brain imprints in fossil skulls of the species Australopithecus afarensis (famous for “Lucy” and the “Dikika child” from Ethiopia shown here) shed new light on the evolution of brain growth and organization. Credit: Paul Tafforeau, ESRF Grenoble

Lucy's species inhabited eastern Africa more than three million years ago—"Lucy" herself is estimated to be 3.2 million years old—and occupies a key position in the hominin family tree, as it is widely accepted to be ancestral to all later hominins, including the lineage leading to modern humans.

"Lucy and her kin provide important evidence about early hominin behavior—they walked upright, had brains that were around 20 percent larger than those of chimpanzees, and may have used sharp stone tools," explains coauthor Zeresenay Alemseged (University of Chicago), who directs the Dikika field project in Ethiopia and is an International Research Affiliate with the Institute of Human Origins.

Brains do not fossilize, but as the brain grows and expands before and after birth, the tissues surrounding its outer layer leave an imprint on the inside of the bony braincase. The brains of modern humans are not only much larger than those of our closest living ape relatives but are also organized differently and take longer to grow and mature. Compared with chimpanzees, modern human infants learn longer and are entirely dependent on parental care for longer periods of time. Together, these characteristics are important for human cognition and social behavior, but their evolutionary origins remain unclear.

Brains do not fossilize, but as the brain grows, the tissues surrounding its outer layer leave an imprint in the bony braincase. The Dikika child's endocranial imprint reveals an ape-like brain organization, and no features derived towards humans. Credit: Philipp Gunz, CC BY-NC-ND 4.0

The CT scans resulted in high-resolution digital "endocasts" of the interior of the skulls, where the anatomical structure of the brains could be visualized and analyzed. Based on these endocasts, the researchers could measure brain volume and infer key aspects of cerebral organization from impressions of the brain's structure.

A key difference between apes and humans involves the organization of the brain's parietal lobe—important in the integration and processing of sensory information—and occipital lobe in the visual center at the rear of the brain. The exceptionally preserved endocast of "Selam," a skull and associated skeleton of an Australopithecus afarensis infant found at Dikika in 2000, has an unambiguous impression of the lunate sulcus—a fissure in the occipital lobe marking the boundary of the visual area that is more prominent and located more forward in apes than in humans—in an ape-like position. The scan of the endocranial imprint of an adult A. afarensis fossil from Hadar (A.L. 162-28) reveals a previously undetected impression of the lunate sulcus, which is also in an ape-like position.

Some scientists had conjectured that human-like brain reorganization in australopiths was linked to behaviors that were more complex than those of their great ape relatives (e.g., stone-tool manufacture, mentalizing, and vocal communication). Unfortunately, the lunate sulcus typically does not reproduce well on endocasts, so there was unresolved controversy about its position in Australopithecus.
Brain imprints (shown in white) in fossil skulls of the species Australopithecus afarensis shed new light on the evolution of brain growth and organization. Several years of painstaking fossil reconstruction, and counting of dental growth lines, yielded an exceptionally preserved brain imprint of the Dikika child, and a precise age at death. Credit: Philipp Gunz, CC BY-NC-ND 4.0

"A highlight of our work is how cutting-edge technology can clear up long-standing debates about these three million-year-old fossils," notes coauthor Kimbel. "Our ability to 'peer' into the hidden details of bone and tooth structure with CT scans has truly revolutionized the science of our origins."

A comparison of infant and adult endocranial volumes also indicates more human-like protracted brain growth in Australopithecus afarensis, likely critical for the evolution of a long period of childhood learning in hominins.

In infants, CT scans of the dentition make it possible to determine an individual's age at death by counting dental growth lines. Similar to the growth rings of a tree, virtual sections of a tooth reveal incremental growth lines reflecting the body's internal rhythm. Studying the fossilized teeth of the Dikika infant, the team's dental experts calculated an age at death of 2.4 years.


VIDEO Brain imprints in fossil skulls of the species Australopithecus afarensis (famous for “Lucy”, and the “Dikika child” from Ethiopia shown here) shed new light on the evolution of brain growth and organization. Several years of painstaking fossil reconstruction, and counting of dental growth lines, yielded an exceptionally preserved brain imprint of the Dikika child, and a precise age at death. These data suggest that Australopithecus afarensis had an ape-like brain and prolonged brain growth. Credit: Philipp Gunz, MPI EVA Leipzig

The pace of dental development of the Dikika infant was broadly comparable to that of chimpanzees and therefore faster than in modern humans. But given that the brains of Australopithecus afarensis adults were roughly 20 percent larger than those of chimpanzees, the Dikika child's small endocranial volume suggests a prolonged period of brain development relative to chimpanzees.

"The combination of apelike brain structure and humanlike protracted brain growth in Lucy's species was unexpected," says Kimbel. "That finding supports the idea that human brain evolution was very much a piecemeal affair, with extended brain growth appearing before the origin of our own genus, Homo."

VIDEO  Brain imprints in fossil skulls of the species Australopithecus afarensis (famous for “Lucy”, and the “Dikika child” from Ethiopia pictured here) shed new light on the evolution of brain growth and organization. Several years of painstaking fossil reconstruction, and counting of dental growth lines, yielded an exceptionally preserved brain imprint of the Dikika child, and a precise age at death. These data suggest that Australopithecus afarensis had an ape-like brain and prolonged brain growth. Credit: Philipp Gunz, MPI EVA Leipzig

Among primates, different rates of growth and maturation are associated with different infant-care strategies, suggesting that the extended period of brain growth in Australopithecus afarensis may have been linked to a long dependence on caregivers. Alternatively, slow brain growth could also primarily represent a way to spread the energetic requirements of dependent offspring over many years in environments where food is not always abundant. In either case, protracted brain growth in Australopithecus afarensis provided the basis for subsequent evolution of the brain and social behavior in hominins and was likely critical for the evolution of a long period of childhood learning.

Peering into Little Foot's 3.67 million-year-old brain
More information: "Australopithecus afarensis endocasts suggest ape-like brain organization and prolonged brain growth," Science Advances (2020). DOI: 10.1126/sciadv.aaz4729 , https://advances.sciencemag.org/content/6/14/eaaz4729

Journal information: Science Advances

Ocean data portal maps show significant shifts by mid-Atlantic fish species

by Karl Vilacoba, Urban Coast Institute

A series of interactive maps published on the Mid-Atlantic Ocean Data Portal illustrates the shifts that have taken place over the last five decades by several commercially and recreationally important fish species living along the East Coast.

Users of the free and publicly accessible portal can automatically animate or toggle through hundreds of maps representing fish distributions during the spring or fall seasons in the 1970s, 1980s, 1990s, 2000s or 2010s. These maps can be activated in combination with any of the portal's 5,000 map layers showing data for commercial fishing hot spots, marine life habitats, zones being examined for offshore wind development and much more.

The Fish Species Through Time map collection was made possible by a grant from the Virginia Coastal Zone Management Program (CZM) to The Nature Conservancy. It was created based on an analysis of federal Northeast Fisheries Science Center (NEFSC) bottom trawl survey data collected between 1972 and 2017.

Many of the maps show a trend in fish moving to waters further north and further offshore from the 1970s to the present day. Some fish species that showed little presence off the New England coast decades earlier have since migrated past Cape Cod and established themselves in the Gulf of Maine.

"Our analysis and the maps make no assumptions as to the factors causing these shifts," said Chris Bruce, GIS manager at The Nature Conservancy in Virginia and a member of the portal's technical team. "However, there is no shortage of scientific research to refer to on how factors like climate change and increasing water temperatures are impacting marine habitats."

The fish species analyzed were alewife, American shad, Atlantic mackerel, black sea bass, blueback herring, bluefish, butterfish, longfin squid, monkfish, northern shortfin squid, red hake, sand lance, scup, spiny dogfish, spot, summer flounder, winter flounder and yellowtail. In addition to individual species, a pair of summary maps was created to illustrate shifts by demersal fish and forage fish. Overlap area maps were also created for each species showing the places where fish were consistently present each decade.

The portal also added a collection of maps projecting future shifts by the fish species through the year 2100. Users can animate these maps, which are based on data previously released by OceanAdapt (https://oceanadapt.rutgers.edu/), a collaboration between the Pinsky Lab of Rutgers University, NMFS, and Fisheries and Oceans Canada.

Users can access these maps in the portal's Marine Planner application by clicking on the Marine Life theme and then clicking on the dropdowns for Fish Species Through Time (for the data showing the 1970s-present) or Fish Species Future Projections.

"These maps tell an important story about the challenges our region's economies and communities face due to the rapid changes taking place in our ocean," said Laura McKay, program manager with Virginia CZM and the chair of MARCO's mapping and data team that manages the portal. "We hope that they help the region's ocean stakeholders and decision-makers understand the trends so they can plan and adapt accordingly."

The portal is an online toolkit and resource center that consolidates available data and enables state, federal and local users to visualize and analyze ocean resources and human use information such as fishing grounds, recreational areas, shipping lanes, habitat areas, and energy sites, among others.

"Regional coordination on ocean use planning is essential to ensure the long-term health of our invaluable ocean resources, and an important piece of this coordination is data accessibility," said Kisha Santiago-Martinez, chair of MARCO and deputy secretary of state at New York's Department of State. "Information on the portal is available to anyone who wishes to view data for any reason, such as ocean planning, education, or decision-making."Climate change threatens commercial fishers from Maine to North Carolina