Fossil evidence of 'hibernation-like' state in 250-million-year-old Antarctic animal

Date:

August 27, 2020

Source:

University of Washington

Summary:

Scientists report evidence of a hibernation-like state in Lystrosaurus, an animal that lived in Antarctica during the Early Triassic, some 250 million years ago. The fossils are the oldest evidence of a hibernation-like state in a vertebrate, and indicate that torpor -- a general term for hibernation and similar states in which animals temporarily lower their metabolic rate to get through a tough season -- arose in vertebrates even before mammals and dinosaurs evolved.

Hibernation is a familiar feature on Earth today. Many animals -- especially those that live close to or within polar regions -- hibernate to get through the tough winter months when food is scarce, temperatures drop and days are dark.

According to new research, this type of adaptation has a long history. In a paper published Aug. 27 in the journal Communications Biology, scientists at the University of Washington and its Burke Museum of Natural History and Culture report evidence of a hibernation-like state in an animal that lived in Antarctica during the Early Triassic, some 250 million years ago.

The creature, a member of the genus Lystrosaurus, was a distant relative of mammals. Antarctica during Lystrosaurus' time lay largely within the Antarctic Circle, like today, and experienced extended periods without sunlight each winter.

The fossils are the oldest evidence of a hibernation-like state in a vertebrate animal, and indicates that torpor -- a general term for hibernation and similar states in which animals temporarily lower their metabolic rate to get through a tough season -- arose in vertebrates even before mammals and dinosaurs evolved.

"Animals that live at or near the poles have always had to cope with the more extreme environments present there," said lead author Megan Whitney, a postdoctoral researcher at Harvard University who conducted this study as a UW doctoral student in biology. "These preliminary findings indicate that entering into a hibernation-like state is not a relatively new type of adaptation. It is an ancient one."

Lystrosaurus lived during a dynamic period of our planet's history, arising just before Earth's largest mass extinction at the end of the Permian Period -- which wiped out about 70% of vertebrate species on land -- and somehow surviving it. The stout, four-legged foragers lived another 5 million years into the subsequent Triassic Period and spread across swathes of Earth's then-single continent, Pangea, which included what is now Antarctica.

"The fact that Lystrosaurus survived the end-Permian mass extinction and had such a wide range in the early Triassic has made them a very well-studied group of animals for understanding survival and adaptation," said co-author Christian Sidor, a UW professor of biology and curator of vertebrate paleontology at the Burke Museum.

Paleontologists today find Lystrosaurus fossils in India, China, Russia, parts of Africa and Antarctica. These squat, stubby, creatures -- most were roughly pig-sized, but some grew 6 to 8 feet long -- had no teeth but bore a pair of tusks in the upper jaw, which they likely employed to forage among ground vegetation and dig for roots and tubers, according to Whitney.

Those tusks made Whitney and Sidor's study possible. Like elephants, Lystrosaurus tusks grew continuously throughout their lives. The cross-sections of fossilized tusks can harbor life-history information about metabolism, growth and stress or strain. Whitney and Sidor compared cross-sections of tusks from six Antarctic Lystrosaurus to cross-sections of four Lystrosaurus from South Africa.

Back in the Triassic, the collection sites in Antarctica were at about 72 degrees south latitude -- well within the Antarctic Circle, at 66.3 degrees south. The collection sites in South Africa were more than 550 miles north during the Triassic at 58-61 degrees south latitude, far outside the Antarctic Circle.

The tusks from the two regions showed similar growth patterns, with layers of dentine deposited in concentric circles like tree rings. But the Antarctic fossils harbored an additional feature that was rare or absent in tusks farther north: closely-spaced, thick rings, which likely indicate periods of less deposition due to prolonged stress, according to the researchers.

"The closest analog we can find to the 'stress marks' that we observed in Antarctic Lystrosaurus tusks are stress marks in teeth associated with hibernation in certain modern animals," said Whitney.

The researchers cannot definitively conclude that Lystrosaurus underwent true hibernation -- which is a specific, weeks-long reduction in metabolism, body temperature and activity. The stress could have been caused by another hibernation-like form of torpor, such as a more short-term reduction in metabolism, according to Sidor.

Lystrosaurus in Antarctica likely needed some form of hibernation-like adaptation to cope with life near the South Pole, said Whitney. Though Earth was much warmer during the Triassic than today -- and parts of Antarctica may have been forested -- plants and animals below the Antarctic Circle would still experience extreme annual variations in the amount of daylight, with the sun absent for long periods in winter.

Many other ancient vertebrates at high latitudes may also have used torpor, including hibernation, to cope with the strains of winter, Whitney said. But many famous extinct animals, including the dinosaurs that evolved and spread after Lystrosaurus died out, don't have teeth that grow continuously.

"To see the specific signs of stress and strain brought on by hibernation, you need to look at something that can fossilize and was growing continuously during the animal's life," said Sidor. "Many animals don't have that, but luckily Lystrosaurus did."

If analysis of additional Antarctic and South African Lystrosaurus fossils confirms this discovery, it may also settle another debate about these ancient, hearty animals.

"Cold-blooded animals often shut down their metabolism entirely during a tough season, but many endothermic or 'warm-blooded' animals that hibernate frequently reactivate their metabolism during the hibernation period," said Whitney. "What we observed in the Antarctic Lystrosaurus tusks fits a pattern of small metabolic 'reactivation events' during a period of stress, which is most similar to what we see in warm-blooded hibernators today."

If so, this distant cousin of mammals isn't just an example of a hearty creature. It is also a reminder that many features of life today may have been around for hundreds of millions of years before humans evolved to observe them.

The research was funded by the National Science Foundation

Journal Reference:
Megan R. Whitney, Christian A. Sidor. Evidence of torpor in the tusks of Lystrosaurus from the Early Triassic of Antarctica. Communications Biology, 2020; 3 (1) DOI: 10.1038/s42003-020-01207-6

University of Washington. "Fossil evidence of 'hibernation-like' state in 250-million-year-old Antarctic animal." ScienceDaily. ScienceDaily, 27 August 2020. .

Newly discovered rare dinosaur embryos show sauropods had rhino-like horns

An incredibly rare dinosaur embryo discovered perfectly preserved inside its egg has shown scientists new details of the development and appearance of sauropods which lived 80 million years ago.

Date:August 27, 2020

Source:University of Manchester

An incredibly rare dinosaur embryo discovered perfectly preserved inside its egg has shown scientists new details of the development and appearance of sauropods which lived 80 million years ago.

Sauropods were the giant herbivores made famous as being 'veggie-saurs' in the 1993 film Jurassic Park. The incredible new find of an intact embryo has shown for the first time that these dinosaurs had stereoscopic vision and a horn on the front of the face which was then lost in adulthood.

The international research team say that this is the most complete and articulate skull known from any titanosaur, the last surviving group of long-necked sauropods and largest land animals known to have ever existed.

The sauropod egg was discovered in Patagonia, Argentina, in an area not previously known to provide evidence of dinosaur fossils. It was imperative the egg was repatriated to Argentina however as it is illegal to permanently remove fossils from the country.

Dr John Nudds from The University of Manchester said: "The preservation of embryonic dinosaurs preserved inside their eggs is extremely rare. Imagine the huge sauropods from Jurassic Park and consider that the tiny skulls of their babies, still inside their eggs, are just a couple of centimetres long.

"We were able to reconstruct the embryonic skull prior to hatching. The embryos possessed a specialised craniofacial anatomy that precedes the post-natal transformation of the skull in adult sauropods. Part of the skull of these embryonic sauropods was extended into an elongated snout or horn, so that they possessed a peculiarly shaped face."

The examination of the amazing specimen enabled the team to revise opinions of how babies of these giant dinosaurs may be hatched and to test previously held ideas about sauropodomorph reproduction. The elongated horn is now thought to have been used as an 'egg tooth' on hatching to allow babies to break through their shell.

The findings, published today in Current Biology, were the result of a novel technique to reveal embryonic dinosaurs in their shells. The embryo within the egg was revealed by carefully dissolving the egg around it using an acid preparation. The team were then able to perform a virtual dissection of the specimen at the European Synchrotron Radiation Facility (ESRF) in Grenoble.

Sauropod embryology remains one of the least explored areas of the life history of dinosaurs. The first definitive discovery of sauropod embryos came with the finding of an enormous nesting ground of titanosaurian dinosaurs discovered in Upper Cretaceous deposits of northern Patagonia, Argentina, 25 years ago. This new discovery however, is the first time a fully intact embryo has been able to be studied.

Other eggs were also found at the Argentinian site which the scientists now aim to examine in a similar fashion. It is thought that some of the eggs could contain well-preserved dinosaur skin which could help further piece together the mysteries of some of the most fascinating animals to ever walk the Earth.


Journal Reference:
Martin Kundrát, Rodolfo A. Coria, Terry W. Manning, Daniel Snitting, Luis M. Chiappe, John Nudds, Per E. Ahlberg. Specialized Craniofacial Anatomy of a Titanosaurian Embryo from Argentina. Current Biology, 2020; DOI: 10.1016/j.cub.2020.07.091

University of Manchester. "Newly discovered rare dinosaur embryos show sauropods had rhino-like horns." ScienceDaily. ScienceDaily, 27 August 2020.

Genetics of the tree of life
Scientists advance genetic understanding of African baobab tree

Summary:Baobab trees can live for more than a thousand years and provide food, livestock fodder, medicinal compounds, and raw materials. Scientists counted the significant tree's chromosomes -- information critical for conservation, agricultural improvement, and further genetic work

Date:August 27, 2020

Source:USDA Forest Service - Southern Research Station

The African baobab tree (Adansonia digitata) is called the tree of life. Baobab trees can live for more than a thousand years and provide food, livestock fodder, medicinal compounds, and raw materials. Baobab trees are incredibly significant. However, there are growing conservation concerns and until now, a lack of genetic information.


The African baobab tree has 168 chromosomes -- critical knowledge for further genetic studies, conservation, and improvement for agricultural purposes. The findings were published in the journal Scientific Reports. Previous studies estimated that the tree has between 96 and 166 chromosomes.

"We were able to unequivocally count the chromosomes," says Nurul Faridi, a USDA Forest Service research geneticist who co-led the study with Hamidou Sakhanokho, a USDA Agricultural Research Service research geneticist.

The researchers used fluorescent probes to see the genetic components of individual chromosomes within the cells -- which glow like jewels.

The analysis also revealed that the tree has a massive nucleolus organizer region (NOR). Relative to the main chromosome body, this region appears larger than that of any other plant species. During certain stages of the cell cycle, nucleoli form at the NORs. The nucleoli are essential for ribosome assembly and protein synthesis in eukaryotes and are an important feature that differentiates eukaryotes from prokaryotes.

"These genetic findings are foundational and will make genetic conservation of the African baobab tree more efficient and effective," says Dana Nelson, a coauthor and project leader of the Southern Research Station's genetic unit. "This research is also a precursor for tree breeding programs seeking to improve baobab for silvicultural applications."

Journal Reference:
Nurul Islam-Faridi, Hamidou F. Sakhanokho, C. Dana Nelson. New chromosome number and cyto-molecular characterization of the African Baobab (Adansonia digitata L.) - 'The Tree of Life'. Scientific Reports, 2020; 10 (1) DOI: 10.1038/s41598-020-68697-6

USDA Forest Service - Southern Research Station. "Genetics of the tree of life: Scientists advance genetic understanding of African baobab tree." ScienceDaily. ScienceDaily, 27 August 2020. .

Antiviral used to treat cat coronavirus also works against SARS-CoV-2

Summary:Researchers are preparing to launch clinical trials of a drug used to cure a deadly disease caused by a coronavirus in cats that they expect will also be effective as a treatment for humans against COVID-19.

Fast-tracked research leads to Phase 1 clinical trials

Date:August 27, 2020

Source:University of Alberta Faculty of Medicine & Dentistry

Researchers at the University of Alberta are preparing to launch clinical trials of a drug used to cure a deadly disease caused by a coronavirus in cats that they expect will also be effective as a treatment for humans against COVID-19.

"In just two months, our results have shown that the drug is effective at inhibiting viral replication in cells with SARS-CoV-2," said Joanne Lemieux, a professor of biochemistry in the Faculty of Medicine & Dentistry.

"This drug is very likely to work in humans, so we're encouraged that it will be an effective antiviral treatment for COVID-19 patients."

The drug is a protease inhibitor that interferes with the virus's ability to replicate, thus ending an infection. Proteases are key to many body functions and are common targets for drugs to treat everything from high blood pressure to cancer and HIV.

First studied by U of A chemist John Vederas and biochemist Michael James following the 2003 outbreak of severe acute respiratory syndrome (SARS), the protease inhibitor was further developed by veterinary researchers who showed it cures a disease that is fatal in cats.

The work to test the drug against the coronavirus that causes COVID-19 was a co-operative effort between four U of A laboratories, run by Lemieux, Vederas, biochemistry professor Howard Young and the founding director of the Li Ka Shing Institute of Virology, Lorne Tyrrell. Some of the experiments were carried out by the Stanford Synchrotron Radiation Lightsource Structural Molecular Biology program.

Their findings were published today in the peer-reviewed journal Nature Communications after first being posted on BioRxIV, a research website.

"There's a rule with COVID research that all results need to be made public immediately," Lemieux said, which is why they were posted before being peer-reviewed.

She said interest in the work is high, with the paper being accessed thousands of times as soon as it was posted.

Lemieux explained that Vederas synthesized the compounds, and Tyrrell tested them against the SARS-CoV-2 virus in test tubes and in human cell lines. The Young and Lemieux groups then revealed the crystal structure of the drug as it binds with the protein.

"We determined the three-dimensional shape of the protease with the drug in the active site pocket, showing the mechanism of inhibition," she said. "This will allow us to develop even more effective drugs."

Lemieux said she will continue to test modifications of the inhibitor to make it an even better fit inside the virus.

But she said the current drug shows enough antiviral action against SARS-CoV-2 to proceed immediately to clinical trials.

"Typically for a drug to go into clinical trials, it has to be confirmed in the lab and then tested in animal models," Lemieux said. "Because this drug has already been used to treat cats with coronavirus, and it's effective with little to no toxicity, it's already passed those stages and this allows us to move forward."

"Because of the strong data that we and others have gathered we're pursuing clinical trials for this drug as an antiviral for COVID-19."

The researchers have established a collaboration with Anivive Life Sciences, a veterinary medicine company that is developing the drug for cats, to produce the quality and quantity of drug needed for human clinical trials. Lemieux said it will likely be tested in Alberta in combination with other promising antivirals such as remdesivir, the first treatment approved for conditional use in some countries including the United States and Canada.

The U of A researchers' work was funded by the Canadian Institutes of Health Research, the Natural Sciences and Engineering Research Council of Canada, Alberta Innovates, Li Ka Shing Institute of Virology and the GSK Chair in Virology.
make a difference: sponsored opportunity

Journal Reference:
Wayne Vuong, Muhammad Bashir Khan, Conrad Fischer, Elena Arutyunova, Tess Lamer, Justin Shields, Holly A. Saffran, Ryan T. McKay, Marco J. van Belkum, Michael A. Joyce, Howard S. Young, D. Lorne Tyrrell, John C. Vederas, M. Joanne Lemieux. 

Feline coronavirus drug inhibits the main protease of SARS-CoV-2 and blocks virus replication. Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-18096-2

University of Alberta Faculty of Medicine & Dentistry. "Antiviral used to treat cat coronavirus also works against SARS-CoV-2: Fast-tracked research leads to Phase 1 clinical trials." 

ScienceDaily. ScienceDaily, 27 August 2020. .

Our energy hunger is tethered to our economic past: study

by Paul Gabrielsen, University of Utah

Credit: CC0 Public Domain

Just as a living organism continually needs food to maintain itself, an economy consumes energy to do work and keep things going. That consumption comes with the cost of greenhouse gas emissions and climate change, though. So, how can we use energy to keep the economy alive without burning out the planet in the process?


In a paper in PLOS ONE, University of Utah professor of atmospheric sciences Tim Garrett, with mathematician Matheus Grasselli of McMaster University and economist Stephen Keen of University College London, report that current world energy consumption is tied to unchangeable past economic production. And the way out of an ever-increasing rate of carbon emissions may not necessarily be ever-increasing energy efficiency—in fact it may be the opposite.

"How do we achieve a steady-state economy where economic production exists, but does not continually increase our size and add to our energy demands?" Garrett says. "Can we survive only by repairing decay, simultaneously switching existing fossil infrastructure to a non-fossil appetite? Can we forget the flame?"

Thermoeconomics

Garrett is an atmospheric scientist. But he recognizes that atmospheric phenomena, including rising carbon dioxide levels and climate change, are tied to human economic activity. "Since we model the earth system as a physical system," he says, "I wondered whether we could model economic systems in a similar way."

He's not alone in thinking of economic systems in terms of physical laws. There's a field of study, in fact, called thermoeconomics. Just as thermodynamics describe how heat and entropy (disorder) flow through physical systems, thermoeconomics explores how matter, energy, entropy and information flow through human systems.

Many of these studies looked at correlations between energy consumption and current production, or gross domestic product. Garrett took a different approach; his concept of an economic system begins with the centuries-old idea of a heat engine. A heat engine consumes energy at high temperatures to do work and emits waste heat. But it only consumes. It doesn't grow.
Now envision a heat engine that, like an organism, uses energy to do work not just to sustain itself but also to grow. Due to past growth, it requires an ever-increasing amount of energy to maintain itself. For humans, the energy comes from food. Most goes to sustenance and a little to growth. And from childhood to adulthood our appetite grows. We eat more and exhale an ever-increasing amount of carbon dioxide.

"We looked at the economy as a whole to see if similar ideas could apply to describe our collective maintenance and growth," Garrett says. While societies consume energy to maintain day to day living, a small fraction of consumed energy goes to producing more and growing our civilization.

"We've been around for a while," he adds. "So it is an accumulation of this past production that has led to our current size, and our extraordinary collective energy demands and CO2 emissions today."

Growth as a symptom

To test this hypothesis, Garrett and his colleagues used economic data from 1980 to 2017 to quantify the relationship between past cumulative economic production and the current rate at which we consume energy. Regardless of the year examined, they found that every trillion inflation-adjusted year 2010 U.S. dollars of economic worldwide production corresponded with an enlarged civilization that required an additional 5.9 gigawatts of power production to sustain itself . In a fossil economy, that's equivalent to around 10 coal-fired power plants, Garrett says, leading to about 1.5 million tons of CO2 emitted to the atmosphere each year. Our current energy usage, then, is the natural consequence of our cumulative previous economic production.

They came to two surprising conclusions. First, although improving efficiency through innovation is a hallmark of efforts to reduce energy use and greenhouse gas emissions, efficiency has the side effect of making it easier for civilization to grow and consume more.

Second, that the current rates of world population growth may not be the cause of rising rates of energy consumption, but a symptom of past efficiency gains.

"Advocates of energy efficiency for climate change mitigation may seem to have a reasonable point," Garrett says, "but their argument only works if civilization maintains a fixed size, which it doesn't. Instead, an efficient civilization is able to grow faster. It can more effectively use available energy resources to make more of everything, including people. Expansion of civilization accelerates rather than declines, and so do its energy demands and CO2 emissions."

A steady-state decarbonized future?

So what do those conclusions mean for the future, particularly in relation to climate change? We can't just stop consuming energy today any more than we can erase the past, Garrett says. "We have inertia. Pull the plug on energy consumption and civilization stops emitting but it also becomes worthless. I don't think we could accept such starvation."

But is it possible to undo the economic and technological progress that have brought civilization to this point? Can we, the species who harnessed the power of fire, now "forget the flame," in Garrett's words, and decrease efficient growth?

"It seems unlikely that we will forget our prior innovations, unless collapse is imposed upon us by resource depletion and environmental degradation," he says, "which, obviously, we hope to avoid."

So what kind of future, then, does Garrett's work envision? It's one in which the economy manages to hold at a steady state—where the energy we use is devoted to maintaining our civilization and not expanding it.

It's also one where the energy of the future can't be based on fossil fuels. Those have to stay in the ground, he says.

"At current rates of growth, just to maintain carbon dioxide emissions at their current level will require rapidly constructing renewable and nuclear facilities, about one large power plant a day. And somehow it will have to be done without inadvertently supporting economic production as well, in such a way that fossil fuel demands also increase."

It's a "peculiar dance," he says, between eliminating the prior fossil-based innovations that accelerated civilization expansion, while innovating new non-fossil fuel technologies. Even if this steady-state economy were to be implemented immediately, stabilizing CO2 emissions, the pace of global warming would be slowed—not eliminated. Atmospheric levels of CO2 would still reach double their pre-industrial level before equilibrating, the research found.

By looking at the global economy through a thermodynamic lens, Garrett acknowledges that there are unchangeable realities. Any form of an economy or civilization needs energy to do work and survive. The trick is balancing that with the climate consequences.

"Climate change and resource scarcity are defining challenges of this century," Garrett says. "We will not have a hope of surviving our predicament by ignoring physical laws."

Future work

This study marks the beginning of the collaboration between Garrett, Grasselli and Keen. They're now working to connect the results of this study with a full model for the economy, including a systematic investigation of the role of matter and energy in production.

"Tim made us focus on a pretty remarkable empirical relationship between energy consumption and cumulative economic output," Grasselli says. "We are now busy trying to understand what this means for models that include notions that are more familiar to economists, such as capital, investment and the always important question of monetary value and inflation."

Explore further   

How energy-intensive economies can survive and thrive as the globe ramps up climate action
More information: PLOS ONE (2020). DOI: 10.1371/journal.pone.0237672
Journal information: PLoS ONE
Provided by University of Utah

Civilization may need to 'forget the flame' to reduce CO2 emissions  

   

Date:August 27, 2020

Source:University of Utah

Summary:Current world energy consumption is tied to unchangeable past economic production. And the way out of an ever-increasing rate of carbon emissions may not necessarily be ever-increasing energy efficiency -- in fact it may be the opposite.Share:

Just as a living organism continually needs food to maintain itself, an economy consumes energy to do work and keep things going. That consumption comes with the cost of greenhouse gas emissions and climate change, though. So, how can we use energy to keep the economy alive without burning out the planet in the process?


In a paper in PLOS ONE, University of Utah professor of atmospheric sciences Tim Garrett, with mathematician Matheus Grasselli of McMaster University and economist Stephen Keen of University College London, report that current world energy consumption is tied to unchangeable past economic production. And the way out of an ever-increasing rate of carbon emissions may not necessarily be ever-increasing energy efficiency -- in fact it may be the opposite.
"How do we achieve a steady-state economy where economic production exists, but does not continually increase our size and add to our energy demands?" Garrett says. "Can we survive only by repairing decay, simultaneously switching existing fossil infrastructure to a non-fossil appetite? Can we forget the flame?"

Thermoeconomics

Garrett is an atmospheric scientist. But he recognizes that atmospheric phenomena, including rising carbon dioxide levels and climate change, are tied to human economic activity. "Since we model the earth system as a physical system," he says, "I wondered whether we could model economic systems in a similar way."

He's not alone in thinking of economic systems in terms of physical laws. There's a field of study, in fact, called thermoeconomics. Just as thermodynamics describe how heat and entropy (disorder) flow through physical systems, thermoeconomics explores how matter, energy, entropy and information flow through human systems.

Many of these studies looked at correlations between energy consumption and current production, or gross domestic product. Garrett took a different approach; his concept of an economic system begins with the centuries-old idea of a heat engine. A heat engine consumes energy at high temperatures to do work and emits waste heat. But it only consumes. It doesn't grow.

Now envision a heat engine that, like an organism, uses energy to do work not just to sustain itself but also to grow. Due to past growth, it requires an ever-increasing amount of energy to maintain itself. For humans, the energy comes from food. Most goes to sustenance and a little to growth. And from childhood to adulthood our appetite grows. We eat more and exhale an ever-increasing amount of carbon dioxide.

"We looked at the economy as a whole to see if similar ideas could apply to describe our collective maintenance and growth," Garrett says. While societies consume energy to maintain day to day living, a small fraction of consumed energy goes to producing more and growing our civilization.

"We've been around for a while," he adds. "So it is an accumulation of this past production that has led to our current size, and our extraordinary collective energy demands and CO2 emissions today."

Growth as a symptom

To test this hypothesis, Garrett and his colleagues used economic data from 1980 to 2017 to quantify the relationship between past cumulative economic production and the current rate at which we consume energy. Regardless of the year examined, they found that every trillion inflation-adjusted year 2010 U.S. dollars of economic worldwide production corresponded with an enlarged civilization that required an additional 5.9 gigawatts of power production to sustain itself . In a fossil economy, that's equivalent to around 10 coal-fired power plants, Garrett says, leading to about 1.5 million tons of CO2 emitted to the atmosphere each year. Our current energy usage, then, is the natural consequence of our cumulative previous economic production.

They came to two surprising conclusions. First, although improving efficiency through innovation is a hallmark of efforts to reduce energy use and greenhouse gas emissions, efficiency has the side effect of making it easier for civilization to grow and consume more.

Second, that the current rates of world population growth may not be the cause of rising rates of energy consumption, but a symptom of past efficiency gains.

"Advocates of energy efficiency for climate change mitigation may seem to have a reasonable point," Garrett says, "but their argument only works if civilization maintains a fixed size, which it doesn't. Instead, an efficient civilization is able to grow faster. It can more effectively use available energy resources to make more of everything, including people. Expansion of civilization accelerates rather than declines, and so do its energy demands and CO2 emissions."

A steady-state decarbonized future?

So what do those conclusions mean for the future, particularly in relation to climate change? We can't just stop consuming energy today any more than we can erase the past, Garrett says. "We have inertia. Pull the plug on energy consumption and civilization stops emitting but it also becomes worthless. I don't think we could accept such starvation."

But is it possible to undo the economic and technological progress that have brought civilization to this point? Can we, the species who harnessed the power of fire, now "forget the flame," in Garrett's words, and decrease efficient growth?

"It seems unlikely that we will forget our prior innovations, unless collapse is imposed upon us by resource depletion and environmental degradation," he says, "which, obviously, we hope to avoid."

So what kind of future, then, does Garrett's work envision? It's one in which the economy manages to hold at a steady state -- where the energy we use is devoted to maintaining our civilization and not expanding it.

It's also one where the energy of the future can't be based on fossil fuels. Those have to stay in the ground, he says.

"At current rates of growth, just to maintain carbon dioxide emissions at their current level will require rapidly constructing renewable and nuclear facilities, about one large power plant a day. And somehow it will have to be done without inadvertently supporting economic production as well, in such a way that fossil fuel demands also increase."

It's a "peculiar dance," he says, between eliminating the prior fossil-based innovations that accelerated civilization expansion, while innovating new non-fossil fuel technologies. Even if this steady-state economy were to be implemented immediately, stabilizing CO2 emissions, the pace of global warming would be slowed -- not eliminated. Atmospheric levels of CO2 would still reach double their pre-industrial level before equilibrating, the research found.

By looking at the global economy through a thermodynamic lens, Garrett acknowledges that there are unchangeable realities. Any form of an economy or civilization needs energy to do work and survive. The trick is balancing that with the climate consequences.

"Climate change and resource scarcity are defining challenges of this century," Garrett says. "We will not have a hope of surviving our predicament by ignoring physical laws."

Future work

This study marks the beginning of the collaboration between Garrett, Grasselli and Keen. They're now working to connect the results of this study with a full model for the economy, including a systematic investigation of the role of matter and energy in production.

"Tim made us focus on a pretty remarkable empirical relationship between energy consumption and cumulative economic output," Grasselli says. "We are now busy trying to understand what this means for models that include notions that are more familiar to economists, such as capital, investment and the always important question of monetary value and inflation."


Journal Reference:
Timothy J. Garrett, Matheus Grasselli, Stephen Keen. Past world economic production constrains current energy demands: Persistent scaling with implications for economic growth and climate change mitigation. PLOS ONE, 2020; 15 (8): e0237672 DOI: 10.1371/journal.pone.0237672

University of Utah. "Civilization may need to 'forget the flame' to reduce CO2 emissions." ScienceDaily. ScienceDaily, 27 August 2020. 

Arctic sea ice under attack, and ancient records that can predict the future effects of climate change

By Sarah Crespi, Paul Voosen, Kiki Sanford

Aug. 27, 2020 , 2:00 PM
Science Podcast


Staff Writer Paul Voosen talks with host Sarah Crespi about how Arctic sea ice is under attack from above and below—not only from warming air, but also dangerous hot blobs of ocean water.

Next, Damien Fordham, a professor and global change ecologist at the University of Adelaide, talks about how new tools for digging into the past are helping catalog what happened to biodiversity and ecosystems during different climate change scenarios in the past. These findings can help predict the fate of modern ecosystems under today’s human-induced climate change.

And in our books segment, Kiki Sanford talks with author Carl Bergstrom about his new book: Calling Bullshit: The Art of Skepticism in a Data-Driven World.

This week’s episode was produced with help from Podigy

Download a transcript (PDF).

Zena Werb (1945–2020)

Nancy Boudreau1,
Mina Bissell2

See all authors and affiliations
Science 28 Aug 2020:
Vol. 369, Issue 6507, pp. 1059
DOI: 10.1126/science.abe0952\

Zena Werb, renowned cancer biologist, passed away on 16 June. She was 75 years old. Zena was recognized internationally in the fields of proteolysis, development, and inflammation in breast cancer. Her studies of the development of the mammary gland and its neoplastic conversion during the initiation and progression of breast cancer revolutionized the fields of development and tumor biology and metastasis. Zena also served as a mentor and role model for myriad scientists.

Zena was born in the Bergen-Belsen concentration camp in Germany in March 1945. Her parents had been forced to separate during World War II, but after a fortunate reunion, they moved to Canada in 1948. Zena earned a bachelor's degree in biochemistry and physiology from the University of Toronto in 1966 and a Ph.D. in cell biology from the Rockefeller University in New York City in 1971. She conducted postdoctoral research at the Strangeways Research Laboratory in Cambridge, United Kingdom, where she studied matrix metalloproteinases (MMPs)—a type of enzyme that breaks down proteins—and then she taught briefly at Dartmouth College in New Hampshire. In 1976, she launched her own laboratory at the University of California, San Francisco (UCSF), where she would spend the rest of her career, most recently as professor and vice-chair in the department of anatomy and the associate director for basic science at the UCSF Helen Diller Family Comprehensive Cancer Center.

Through her pioneering work, Zena demonstrated the critical roles of MMPs in tissue functions during development and in disease. In the late 1970s and early 1980s, emerging evidence suggested that the extracellular proteins, which were targets of the lytic activity of MMPs, were providing not just structural support for cells but also cues that directly influence cellular signaling and behavior. These interactions between cells and extracellular proteins were suspected to be both dynamic and reciprocal. Zena elegantly showed that when cells bind to the extracellular protein fibronectin through a specific cell-surface receptor, intracellular signaling changes and the cell's production of MMPs increases. This critical piece of data demonstrated the bidirectional nature of interactions between cells and their extracellular environment (i.e., dynamic reciprocity).

Knowing that a complete understanding of MMPs would require the study of the complex biology of a variety of organs and conditions, Zena immersed herself in the biology of bone, mammary and salivary glands, embryonic development, wound healing, and then cancer. When the cancer field was coalescing around the notion that MMP inhibitors might prevent tumor metastasis, Zena was one step ahead. She knew that this strategy would wreak havoc on normal tissue function and potentially exacerbate the disease and also that metastasis was much more involved than simple protease-assisted breaching of basement membranes



Zena's research provided a molecular and mechanistic framework for understanding how the extracellular matrix contributed to tissue morphogenesis and remodeling and the tumor microenvironment. Her ground-breaking proposals required both courage and insight. In recognition of her pioneering work, she received the Excellence in Science Award from the Federation of American Societies for Experimental Biology, the E. B. Wilson Medal awarded by the American Society for Cell Biology (ASCB) “for far-reaching contributions to cell biology over a lifetime in science,” and the ASCB Sandra K. Masur Senior Leadership Award. In 2010, Zena was elected to the National Academy of Sciences.

I (M.B.) became a close friend and collaborator of Zena's in 1987. I (N.B.) met Zena when I was a postdoctoral fellow in M.B.'s lab; Zena was a co-mentor for our work on cell death and the extracellular matrix. We both remember how excited Zena was about every experiment, regardless of success or failure. She had a passion for exploration and an ability to distill highly complex biological questions into manageable and testable hypotheses.

Sharing knowledge with students was a thrill for Zena. When she taught, her mesmerizing encyclopedic knowledge was on full display. Those who did not know Zena personally were sometimes intimidated by her direct style, which was evident in her keynote lectures and her questions to other presenters. However, her eagerness to ask the difficult questions and her expectation of thoughtful answers were rooted in her passion for good science.

Those of us who were fortunate to know Zena personally found her to be kind-hearted and generous. She was never too busy to provide advice to the many who sought her input. She was sincerely interested in her mentees and loved to engage in lively discussions with colleagues, always showing an interest that extended beyond their ideas to their personal well-being. Her support for students and colleagues was well recognized: The American Association for Cancer Research and its Women in Cancer Research member group gave her the Charlotte Friend Memorial Lectureship for her meritorious contributions to the field of cancer research and her work advancing women in science. UCSF also honored her with a Lifetime Achievement in Mentoring Award.

Zena's extraordinary career and research were complemented by her humility and humanity. She will be remembered for her original, creative, and fearless thinking, which led to her seminal work demonstrating how the extracellular environment influences the function of normal and malignant cells. Her rich legacy supporting the careers of others will live on in the scientists she mentored.

• Obituary
• Published: 03 August 2020

Zena Werb 1945–2020

• Mikala Egeblad, 
• Lisa M. Coussens & 
• Valerie M. Weaver 

Nature Cancer volume 1, pages753–754(2020)

• details

Unlike 30 years ago, when the notion of tumor cells being regulated by cell-extrinsic mechanisms was akin to heresy, the tumor microenvironment (TME) is now recognized as a hallmark of cancer, with a broad community of researchers focusing on how it regulates malignant transformation, metastasis and therapy response. We owe this evolution in thinking to several scientific giants, but perhaps none more impactful in changing the storyline than Zena Werb, our intellectually fearless colleague, beloved mentor and generous friend, who died suddenly on 16 June 2020 at the age of 75.

Zena Werb as a graduate student at Rockefeller University, circa 1971. Credit: Rockefeller Grad – News and Notes. June 1971 Vol 2. No 10.

Zena was a professor and vice chair in the Department of Anatomy at the University of California San Francisco (UCSF) for over 40 years and was the associate director for basic science at the UCSF Helen Diller Family Comprehensive Cancer Center. Her foundational work on macrophage physiology, the extracellular matrix (ECM), mammary gland development, breast cancer and tumor-associated inflammation made her one of the most respected researchers in the world. Zena’s contributions led to numerous awards and honors, including election to the National Academy of Sciences and the American Association for Cancer Research, presidency of the American Society of Cell Biology, the E.B. Wilson Medal from the American Society of Cell Biology and the Paget-Ewing Award from the Metastasis Research Society. However, Zena, as a devoted mentor and a fierce advocate for junior faculty and particularly women, took special pride in the UCSF Lifetime Achievement in Mentoring Award, which she received in 2015. Thus, the story of Zena Werb and the TME is also the story of her dedicated mentoring.

Zena was born in 1945 in the Bergen-Belsen Nazi concentration camp in Germany. After the war, her family emigrated to Canada, and she grew up in a rural community, where she attended a one-room schoolhouse. Following her undergraduate studies, Zena conducted her graduate research with Zanvil A. Cohn at Rockefeller University, focusing on lipid metabolism in macrophages. Despite being biochemically inclined, Zena was enthralled when she first observed macrophages moving in real time under the microscope — an experience that laid the foundation for her later love of cell biology, innate immunity and intravital microscopy. During her postdoctoral training with John T. Dingle at the Strangeways Research Laboratory, in Cambridge, England, she began investigating a new (at the time) family of proteolytic enzymes secreted by fibroblasts, called matrix metalloproteinases (MMPs). This class of ECM-remodeling enzymes would comprise another cornerstone of her life’s work. After starting her own lab at Dartmouth Medical School, Zena relocated to UCSF in 1976, where she quickly established her reputation as a rigorous and prolific scientist. Much of her early independent research focused on fibroblast and macrophage MMPs, and she and her first postdoctoral fellow, Michael J. Banda, were the first to purify and characterize MMP12.

Her research on MMPs and their targets led her to study ECM remodeling and resultant cellular behavior, including cell proliferation and survival. Some of her seminal work laid the framework for new fields of research investigating the microenvironmental regulation of developmental processes, tissue homeostasis and disease pathogenesis, including cancer. Establishing these new areas was interwoven with launching the careers of some of her other early trainees, including James McKerrow, Steven Frisch and Caroline Alexander. It was also during this time frame that Zena forged an enduring collaboration with Mina J. Bissell, who introduced her to mammary gland development and cancer. Together they published innovative research that changed the fields of cell biology and cancer, including studies on how ECM remodeling regulates mammary gland branching morphogenesis and involution, stem cell behavior, and cancer cell invasion and metastatic dissemination. This pivotal collaboration also launched the careers of numerous trainees, including Nancy Boudreau, Leif Lund, Andre Lochter, Farrah Kheradmand, Derek Radisky, Bryan Welm, Mark Sternlicht, Laurie Littlepage and Valerie M. Weaver, many of whom are recognized as leaders in their fields. Zena and Mina loved to challenge prevailing dogma. Among their notable work from this period was demonstrating that collagenolytic enzymes lead to the generation of oxygen radicals, and that ECM remodeling regulates growth factor receptor and integrin signaling and controls cell polarity, differentiation, proliferation and death. Among their more groundbreaking discoveries were the findings that MMP overexpression causes epithelial mesenchymal transition and genomic instability in non-transformed mammary epithelial cells, and that MMP overexpression is sufficient to induce tumors in the normal mouse mammary gland.

Another critical collaboration was with Douglas Hanahan. Together with their trainees Thiennu Vu, Gabriele Bergers and Lisa Coussens, they published a series of highly influential papers showing that when MMP9 is secreted by macrophages, mast cells or osteoclasts, it promotes angiogenesis during normal development and cancer. These reports coincided with the development of MMP inhibitors for cancer therapy. Nevertheless, Zena recognized early that some functions of MMPs also paradoxically protect against malignancy, and that the same is true for many TME-derived factors that both promote and inhibit neoplastic progression by context-dependent mechanisms. When MMP-inhibitor efficacy was not realized in the clinic, Zena turned to using MMPs as tools for understanding biology rather than as therapeutic targets. This strategy served as the foundation for mechanistic studies addressing the role of chronic inflammation in cancer, as discussed in a highly cited Nature article coauthored by Lisa Coussens and Zena in 2002.

Zena was scientifically fearless, routinely reinventing herself, while basing her research decisions on rigorous scientific facts. She was excited when findings were contrary to accepted dogma and especially when they went against her own expectations. She often said “the data are the data, and you follow the data.” Beyond steadfastly urging her mentees to follow their data wherever they led, she encouraged them to adopt or develop new technological approaches as needed. One such example was her early adoption of intravital imaging, which she used with Bryan Welm, Andrew Ewald and Mikala Egeblad to study cell invasion during mammary gland branching morphogenesis and cancer. This work yielded new insights into underlying mechanisms and striking similarities between the invasive programs of normal mammary epithelial cells and those of breast cancer cells, as she predicted. When intravital imaging of tumors revealed that non-tumor cells were far more motile than neoplastic cells were, Zena realized that the highly motile cells were monocytes and neutrophils. With Mikala Egeblad and another instrumental collaborator, Matthew Krummel, she refocused her work toward understanding the contributions of innate immune cells to the resistance of tumors to therapy.

In the past several years, Zena was increasingly determined to understand the mechanisms that regulate metastasis. With postdoctoral fellows Devon Lawson and Kai Kessenbrock, she embraced single-cell sequencing to reveal that breast cancer metastases are initiated by stem-like cells, while also using the technique to compare cancer cells with normal breast epithelial cells — an ever-present theme in her research. Until the end, Zena remained highly focused not only on understanding metastasis but also on identifying new biomarkers and therapies, using her encyclopedic knowledge of the ECM and inflammation, and her understanding of normal development.

Zena’s quirky personality endeared her to mentees, whether they were lab members, junior faculty or senior colleagues. Many were treated as family and were nurtured with scientific wisdom and witty remarks (“stressed is desserts spelled backwards” was a favorite line to worried senior trainees), as well as tickets to local museums, the symphony or opera, and Zena’s exceptional cooking. She maintained contact with her mentees as they transitioned into independent positions, and in many instances the mentoring relationships blossomed into deep kinships and productive collaborations — such as those we three experienced with her. With her passing, we grieve the loss of our cherished mentor and collaborator, and our loyal and unfailingly honest friend. Science has lost an original, indefatigable cell biologist and TME researcher. But we remind ourselves that although Zena was big-hearted, she was not sentimental. We can picture her telling us “Now, get on with it! Science needs you, and there’s a whole new generation of trainees who need mentoring.” So we will listen to our dear mentor, roll up our sleeves, nurture our mentees (sadly with our more pedestrian cooking) and follow the data. We — and so many others — carry some of her within us, ensuring that her wisdom, fearlessness and kindness remain, to become part of the fabric within which we pursue the scientific questions we seek to answer.

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Affiliations

1. Cancer Center, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
   Mikala Egeblad
2. Department of Cell, Developmental and Cancer Biology, Oregon Health Sciences University, Portland, OR, USA
   Lisa M. Coussens
3. Department of Surgery, University of California, San Francisco, San Francisco, CA, USA
   Valerie M. Weaver

Corresponding author

Correspondence to Valerie M. Weaver.

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Egeblad, M., Coussens, L.M. & Weaver, V.M. Zena Werb 1945–2020. Nat Cancer 1, 753–754 (2020). https://doi.org/10.1038/s43018-020-0101-z