scientificamerican--2020-12-16--Physicists Achieve Best-Ever Measurement of Fine-Structure Constant

Researchers at the Kastler Brossel Laboratory in Paris have made the most precise measurement of one of the fundamental constants , called the fine-structure constant , providing physicists with a vital tool to verify the consistency of their most cherished theoretical models .
The fine-structure constant determines the strength of the electromagnetic force , and is central in explaining a number of phenomena including the interactions between light and charged elementary particles such as electrons .
It is an important part of the equations of the Standard Model , a theory that predicts and describes all the known fundamental forces @ @ @ @ @ @ @ the weak and strong nuclear forces .
The team in Paris measured the value of the fine-structure constant as 1/137.035999206 , to an accuracy of 11 digits .
The result appears in a study published in Nature .
“ I am amazed by the level of precision achieved , ” says Massimo Passera of the Italy-based National Institute for Nuclear Physics , who was not a part of the experiment .
Using the fine-structure constant in the Standard Model equations , one can calculate the magnetic moment of the electron , a property @ @ @ @ @ @ @ the influence of a magnetic field .
The electron ’ s magnetic moment makes for an excellent candidate to test the Standard Model , as it has been repeatedly measured in the lab and theoretically predicted to a very high degree of precision .
“ With the new determination of the fine-structure constant , these predicted and experimental values agree at better than one part per billion , thereby providing an outstanding consistency check of the Standard Model of particle physics—in particular of its electromagnetic sector , ” Passera says .
“ Moreover @ @ @ @ @ @ @ sets a strong limit on the possible internal structure of the electron.
” Performed using rubidium atoms in a technique called atom interferometry , the new measurement is more accurate by a factor of three from the previous record-holding determination , which was achieved by a team from the University of California , Berkeley , in an experiment using cesium atoms .
According to Pierre Cladé , who co-authored the Nature paper , the improvement was the result of “ continuous work of small steps.
” In addition to a major upgrade in @ @ @ @ @ @ @ he says , the team ’ s success arose from efforts to reduce noise and systemic effects .
“ We did a lot of modeling to deeply understand the physics of our experiment .
Three years ago , we reached a better understanding of the interaction between a photon and the rubidium atom.
” That enhanced understanding allowed the team to determine a more precise value for a rubidium atom ’ s mass .
“ Once the mass of the rubidium atom is measured , we use it with the relative mass of @ @ @ @ @ @ @ .
The more precise the mass of the rubidium atom , the more accurate the value of the fine-structure constant , ” says Saïda Guellati-Khelifa , the paper ’ s lead author .
The experiment employed multiple standard approaches to reach its stunning precision , starting with the laser cooling of a cloud of rubidium atoms .
Six laser beams exert force on the atoms in such a way that they drastically reduce the atoms ’ velocities .
Because such atomic kinetic motions are the basis of macroscale manifestations of heat , the @ @ @ @ @ @ @ ’ velocities is to lower their temperature to a mind-bogglingly frigid four microkelvins—slightly above absolute zero , or –273.15 degrees Celsius .
“ At such temperatures , an atom behaves like a particle and a wave , ” Cladé says .
This wavelike behavior of atoms is quite different from the waves of water that we are more familiar with .
In this case , the wave in question concerns the probability of finding a rubidium atom in a certain position .
Using lasers , the team prepared the atoms in both the @ @ @ @ @ @ @ the latter the atom moves with a slightly greater velocity ) .
“ This produces two trajectories that are separated and later recombined to create an interference pattern , ” Cladé says .
“ The interference depends on the velocity acquired by the atoms after they absorb photons from a laser source .
Once this recoil velocity is measured from the interference , the rubidium atomic mass can be derived.
” As a first step , the team began an almost yearlong run of the experiment in December 2018 , collecting data to @ @ @ @ @ @ @ “ While performing such experiments , there are different physical processes that underlie what is being measured .
Each process can potentially affect the accuracy of the measurement by inducing errors .
We need to understand and evaluate errors in order to make corrections , ” says Guellati-Khelifa , who has been taking measurements of the fine-structure constant for more than 20 years .
After making the corrections , the team derived final measurements during a monthlong run , finally determining the fine-structure constant ’ s value to a precision of 81 parts @ @ @ @ @ @ @ efforts to find the precise values of fundamental constants are complementary to the particle accelerator–based experiments that exploit huge energies in order to create new , never-before-seen particles .
“ The ‘ tabletop ’ experiments such as the ones in the Kastler Brossel or Berkeley laboratories , are done at very low energies .
And yet , their extremely precise measurements can indirectly reveal the existence or even the nature of a particle that may not yet be directly seen at high energies .
Even the very last digits of a precise measurement @ @ @ @ @ @ @ Passera says .
Consider , for instance , the muon—a cousin of the electron that is two hundred times heavier .
Just like the electron , the muon also exhibits a magnetic moment when subjected to a magnetic field .
Moreover , similar to the electron , there is a difference between the theoretical and experimental values of the muon ’ s magnetic moment .
Discrepancies in this context are determined in terms of standard deviation , which is a combination of the difference in the two values and the uncertainties associated with @ @ @ @ @ @ @ each value .
In the case of the electron , the experimental measurement of the magnetic moment is 1.6 standard deviations above the theoretical prediction based on the fine-structure constant measured by the Paris group .
Whereas the muon ’ s experimental value , announced and refined in a trio of papers published between 2002 and 2006 , is 3.7 standard deviations above the figure predicted by the Standard Model theory .
Physicists are now eagerly awaiting the first results of the “ Muon g-2 ” experiment at Fermilab that is expected to @ @ @ @ @ @ @ the muon ’ s magnetic moment .
If this value goes beyond five standard deviations from the theory—the gold standard for discovery in particle physics—it would be convincing evidence of new physics beyond the Standard Model .
Generally , when it comes to the theoretical prediction of the magnetic moment using the Standard Model , the muon discrepancy is not as sensitive to the precise value of the fine-structure constant as the electron .
However , according to Alex Keshavarzi , who is managing operations and leading analysis efforts for the Muon g-2 @ @ @ @ @ @ @ measurement is interesting for the muon discrepancy.
” Keshavarzi , who is not part of the Paris research group , says if new physics emerges from the Muon g-2 results of the muon measurement , the positive discrepancies for both the electron and the muon would make it simpler to develop models and explanations than if the discrepancies were in the opposite directions .
However , he adds that even aside from its potential connection to the muon , the Paris group ’ s electron-based measurement of the fine-structure experiment has introduced other @ @ @ @ @ @ @ standard deviation of 1.6 whereas the 2018 experiment at Berkeley produced a negative deviation of 2.5 .
According to Cladé , both the Paris and Berkeley experiments are based on the same physics , making the divergence all the stranger .
“ I don ’ t think the discrepancy is due to the use of cesium or rubidium .
There is probably something in one of the two experiments that may not have been accounted for .
That is something we should now try to understand , ” he says .

Researchers at the Kastler Brossel Laboratory in Paris have made the most precise measurement of one of the fundamental constants, called the fine-structure constant, providing physicists with a vital tool to verify the consistency of their most cherished theoretical models.
The fine-structure constant determines the strength of the electromagnetic force, and is central in explaining a number of phenomena including the interactions between light and charged elementary particles such as electrons. It is an important part of the equations of the Standard Model, a theory that predicts and describes all the known fundamental forces other than gravity—namely electromagnetism as well as the weak and strong nuclear forces. The team in Paris measured the value of the fine-structure constant as 1/137.035999206, to an accuracy of 11 digits. The result appears in a study published in Nature.
“I am amazed by the level of precision achieved,” says Massimo Passera of the Italy-based National Institute for Nuclear Physics, who was not a part of the experiment.
Using the fine-structure constant in the Standard Model equations, one can calculate the magnetic moment of the electron, a property exhibited by the negatively charged particle under the influence of a magnetic field. The electron’s magnetic moment makes for an excellent candidate to test the Standard Model, as it has been repeatedly measured in the lab and theoretically predicted to a very high degree of precision.
“With the new determination of the fine-structure constant, these predicted and experimental values agree at better than one part per billion, thereby providing an outstanding consistency check of the Standard Model of particle physics—in particular of its electromagnetic sector,” Passera says. “Moreover, the closeness of the two values sets a strong limit on the possible internal structure of the electron.”
Performed using rubidium atoms in a technique called atom interferometry, the new measurement is more accurate by a factor of three from the previous record-holding determination, which was achieved by a team from the University of California, Berkeley, in an experiment using cesium atoms.
According to Pierre Cladé, who co-authored the Nature paper, the improvement was the result of “continuous work of small steps.” In addition to a major upgrade in the apparatus and new laser sources, he says, the team’s success arose from efforts to reduce noise and systemic effects. “We did a lot of modeling to deeply understand the physics of our experiment. Three years ago, we reached a better understanding of the interaction between a photon and the rubidium atom.” That enhanced understanding allowed the team to determine a more precise value for a rubidium atom’s mass.
“Once the mass of the rubidium atom is measured, we use it with the relative mass of an electron to calculate the fine-structure constant. The more precise the mass of the rubidium atom, the more accurate the value of the fine-structure constant,” says Saïda Guellati-Khelifa, the paper’s lead author.
The experiment employed multiple standard approaches to reach its stunning precision, starting with the laser cooling of a cloud of rubidium atoms. Six laser beams exert force on the atoms in such a way that they drastically reduce the atoms’ velocities. Because such atomic kinetic motions are the basis of macroscale manifestations of heat, the end result of reducing the rubidium atoms’ velocities is to lower their temperature to a mind-bogglingly frigid four microkelvins—slightly above absolute zero, or –273.15 degrees Celsius. “At such temperatures, an atom behaves like a particle and a wave,” Cladé says.
This wavelike behavior of atoms is quite different from the waves of water that we are more familiar with. In this case, the wave in question concerns the probability of finding a rubidium atom in a certain position. Using lasers, the team prepared the atoms in both the ground state and excited state (in the latter the atom moves with a slightly greater velocity). “This produces two trajectories that are separated and later recombined to create an interference pattern,” Cladé says. “The interference depends on the velocity acquired by the atoms after they absorb photons from a laser source. Once this recoil velocity is measured from the interference, the rubidium atomic mass can be derived.”
As a first step, the team began an almost yearlong run of the experiment in December 2018, collecting data to ensure their equipment was working properly.
“While performing such experiments, there are different physical processes that underlie what is being measured. Each process can potentially affect the accuracy of the measurement by inducing errors. We need to understand and evaluate errors in order to make corrections,” says Guellati-Khelifa, who has been taking measurements of the fine-structure constant for more than 20 years.
After making the corrections, the team derived final measurements during a monthlong run, finally determining the fine-structure constant’s value to a precision of 81 parts per trillion.
According to Passera, efforts to find the precise values of fundamental constants are complementary to the particle accelerator–based experiments that exploit huge energies in order to create new, never-before-seen particles.
“The ‘tabletop’ experiments such as the ones in the Kastler Brossel or Berkeley laboratories, are done at very low energies. And yet, their extremely precise measurements can indirectly reveal the existence or even the nature of a particle that may not yet be directly seen at high energies. Even the very last digits of a precise measurement have a story to tell,” Passera says.
Consider, for instance, the muon—a cousin of the electron that is two hundred times heavier. Just like the electron, the muon also exhibits a magnetic moment when subjected to a magnetic field. Moreover, similar to the electron, there is a difference between the theoretical and experimental values of the muon’s magnetic moment.
Discrepancies in this context are determined in terms of standard deviation, which is a combination of the difference in the two values and the uncertainties associated with the theoretical calculation and experimental measurement of each value.
In the case of the electron, the experimental measurement of the magnetic moment is 1.6 standard deviations above the theoretical prediction based on the fine-structure constant measured by the Paris group. Whereas the muon’s experimental value, announced and refined in a trio of papers published between 2002 and 2006, is 3.7 standard deviations above the figure predicted by the Standard Model theory.
Physicists are now eagerly awaiting the first results of the “Muon g-2” experiment at Fermilab that is expected to provide the most precise experimental measurement of the muon’s magnetic moment. If this value goes beyond five standard deviations from the theory—the gold standard for discovery in particle physics—it would be convincing evidence of new physics beyond the Standard Model.
Generally, when it comes to the theoretical prediction of the magnetic moment using the Standard Model, the muon discrepancy is not as sensitive to the precise value of the fine-structure constant as the electron. However, according to Alex Keshavarzi, who is managing operations and leading analysis efforts for the Muon g-2 experiment, “the new fine-structure constant measurement is interesting for the muon discrepancy.”
Keshavarzi, who is not part of the Paris research group, says if new physics emerges from the Muon g-2 results of the muon measurement, the positive discrepancies for both the electron and the muon would make it simpler to develop models and explanations than if the discrepancies were in the opposite directions.
However, he adds that even aside from its potential connection to the muon, the Paris group’s electron-based measurement of the fine-structure experiment has introduced other mysteries—namely, why it produced a positive standard deviation of 1.6 whereas the 2018 experiment at Berkeley produced a negative deviation of 2.5.
According to Cladé, both the Paris and Berkeley experiments are based on the same physics, making the divergence all the stranger. “I don’t think the discrepancy is due to the use of cesium or rubidium. There is probably something in one of the two experiments that may not have been accounted for. That is something we should now try to understand,” he says.


scientificamerican--2020-12-17--Brain Sides Both Busy In New Language Learning

Anyone who has tried to learn a new language as an adult knows how hard it can be .
And usually the ability to comprehend someone else comes before the capacity for speaking the new tongue .
“ When you 're listening , you can kind of gloss over the details .
So , you may not need to understand every single syllable , every single word perfectly.
” Cognitive neuroscientist Kshipra Gurunandan , of the Basque Center on Cognition , Brain and Language .
But actually speaking a new language fluently takes much more work .
“ Adults are @ @ @ @ @ @ @ hear foreign sounds.
” Gurunandan suspected that , as we learn , the relative ease of comprehension might be explained by changes in the area of the brain that processes language .
It 's been known since the 1800s that , for most people , the left hemisphere of the brain is essential for language .
“ However , in more recent times , we 've started to realize that it 's not quite that simple.
” For example , when people suffer brain injuries to the left hemisphere , the right hemisphere @ @ @ @ @ @ @ flexibility suggests that language is not the exclusive domain of the left hemisphere .
To find out if the two sides of the brain process comprehension and speech differently during language learning , Gurunandan and her team scanned the brains of Spanish-speaking volunteers who were learning either Basque or English .
“ They performed language tasks in the scanner involving reading , listening , and speaking in their native and their new language .
And then we looked at whether activation in the language regions was greater in the left hemisphere or the @ @ @ @ @ @ @ in each task.
” The researchers found that speaking primarily activated language regions in the left side of the brain no matter how advanced the language learner was .
But reading and listening comprehension were much more variable .
“ In the earliest stages of language learning the native and new languages tended to activate the same hemisphere , while in the more advanced learners they activated different hemispheres .
And the switch from the same to the opposite hemispheres was largest in reading , it was slightly smaller in listening and it @ @ @ @ @ @ @ reason that speech may be more constrained to the left hemisphere because it contains specialized circuits dedicated to the motor control of speech production .
“ While in comprehension , you have the auditory system and the visual system , which are more bilateral—and it 's possible that is why comprehension is more bilateral in the brain.
” The study is in the Journal of Neuroscience .
[ Kshipra Gurunandan , et al .
Converging evidence for differential specialisation and plasticity of language systems ] Learning a new language will always be challenging @ @ @ @ @ @ @ let that stop you .
“ Language learning is a hard skill .
It 's hard for everybody .
But it 's not because of your brain plasticity .
You can learn words , you can learn grammar rules , your language learning capacity is just fine.
” As long as you maintain your joie de vivre .

Full Transcript
Anyone who has tried to learn a new language as an adult knows how hard it can be. And usually the ability to comprehend someone else comes before the capacity for speaking the new tongue.
“When you're listening, you can kind of gloss over the details. So, you may not need to understand every single syllable, every single word perfectly.”
Cognitive neuroscientist Kshipra Gurunandan, of the Basque Center on Cognition, Brain and Language. But actually speaking a new language fluently takes much more work.
“Adults are not quite able to reproduce or really hear foreign sounds.”
Gurunandan suspected that, as we learn, the relative ease of comprehension might be explained by changes in the area of the brain that processes language. It's been known since the 1800s that, for most people, the left hemisphere of the brain is essential for language.
“However, in more recent times, we've started to realize that it's not quite that simple.”
For example, when people suffer brain injuries to the left hemisphere, the right hemisphere can take over language tasks. That flexibility suggests that language is not the exclusive domain of the left hemisphere.
To find out if the two sides of the brain process comprehension and speech differently during language learning, Gurunandan and her team scanned the brains of Spanish-speaking volunteers who were learning either Basque or English.
“They performed language tasks in the scanner involving reading, listening, and speaking in their native and their new language. And then we looked at whether activation in the language regions was greater in the left hemisphere or the right hemisphere for each of the languages in each task.”
The researchers found that speaking primarily activated language regions in the left side of the brain no matter how advanced the language learner was. But reading and listening comprehension were much more variable.
“In the earliest stages of language learning the native and new languages tended to activate the same hemisphere, while in the more advanced learners they activated different hemispheres. And the switch from the same to the opposite hemispheres was largest in reading, it was slightly smaller in listening and it was non-existent in speaking.”
The researchers reason that speech may be more constrained to the left hemisphere because it contains specialized circuits dedicated to the motor control of speech production.
“While in comprehension, you have the auditory system and the visual system, which are more bilateral—and it's possible that is why comprehension is more bilateral in the brain.”
The study is in the Journal of Neuroscience. [Kshipra Gurunandan, et al. Converging evidence for differential specialisation and plasticity of language systems]
Learning a new language will always be challenging, but Gurunandan says you shouldn't let that stop you.
“Language learning is a hard skill. It's hard for everybody. But it's not because of your brain plasticity. You can learn words, you can learn grammar rules, your language learning capacity is just fine.”
As long as you maintain your joie de vivre.
—Susanne Bard
(The above text is a transcript of this podcast)


scientificamerican--2020-12-16--Food Industry-Backed Research Gives Results Funders Want, New Analysis Shows

Did you know that eating soup could prevent obesity , and consuming grapes and blueberries may improve college students ’ cognitive function ?
These two findings come from some of the latest research on nutrition science .
But the results are also from a subset of studies backed by food manufacturers .
A paper published December 16 in PLOS ONE reports that more than 13 percent of peer-reviewed studies in 10 of the top nutrition science journals had connections to the food industry—and of those , more than half reported findings favorable to business interests .
Previous studies have linked @ @ @ @ @ @ @ but this is the first to analyze comprehensively the extent of that involvement in leading nutrition science journals , says lead author Gary Sacks , a public health scientist at Deakin University in Australia .
“ Unhealthy diets are the biggest cause of ill health globally , and given that , it ’ s too important an area for the science to be skewed by food industry involvement , ” Sacks says .
“ What this study shows is that when the food industry is involved , it ’ s skewing the research @ @ @ @ @ @ @ food industry , as opposed to you.
” Sacks and his colleagues analyzed 1,461 articles published in the 10 most-cited peer-reviewed journals on diet and nutrition for 2018 , and found food manufacturers funded or were connected to nearly 200 of them .
About 55 percent of industry-involved studies either concluded that a food product had health benefits or undermined evidence a product was harmful .
Less than 10 percent of articles without industry involvement did so .
The Journal of Nutrition , published by the American Society for Nutrition , had the @ @ @ @ @ @ @ manufacturers funded nearly 30 percent of the 223 articles it published in 2018 .
Teresa Davis , JN ’ s editor-in-chief , and a Baylor College of Medicine pediatric nutritionist , says the journal does not reject manuscripts based on their funding sources .
“ I think it ’ s not appropriate for us to discriminate based on the institution the manuscript is submitted from , or the funding source , or the country , ” she says .
“ We evaluate the science .
We look at the message , we don @ @ @ @ @ @ @ says that industry funding for nutrition research is necessary because government support has plateaued for decades in the U.S. Sacks agrees that more government and independent sources of funding are needed , and suggests one way to protect research integrity would be to pool industry funding and have it distributed by an independent body .
“ We could perhaps move in that direction , but at this time , that ’ s not readily available , ” Davis says .
“ I don ’ t disagree that that would be the ideal situation.
@ @ @ @ @ @ @ “ very rigorous process ” for evaluating the transparency and scientific reproducibility—key principles of the scientific method—of the studies it publishes .
But careful peer review may not be enough , says Lisa Bero , a pharmacologist at the University of Colorado who studies research bias .
Bero contends that industry may skew research in ways peer review can not catch .
She cites four key approaches industry uses to manipulate research : by influencing what research questions are asked , how studies are designed , how conclusions interpret data and whether unfavorable @ @ @ @ @ @ @ is more likely to fund research that is likely to show the benefits of their product or detract from [ its ] harms , ” she says .
“ The problem with that is that those might not be the most important health questions.
” Bero also criticizes some studies ’ emphasis on individual nutrients .
“ The food industry tends to focus on specific nutrients that can be manipulated in a processed product , [ and ] this allows them to make health claims , ” she says .
“ Are those @ @ @ @ @ @ @ ?
Many folks argue they are not.
” Marion Nestle , a molecular biologist and public health nutritionist at New York University , agrees .
“ What matters is the whole diet—everything you eat , plus your lifestyle , plus genetics , ” she says .
“ There ’ s only one reason for doing this kind of research , and that is to support the product , either by demonstrating it has health benefits or that it ’ s not harmful.
” Davis from the Journal of Nutrition concurs that it ’ @ @ @ @ @ @ @ patterns , but says that “ you need to know what the effect is of these individual nutrients on health outcomes as well.
” One overriding issue , Nestle says , is that researchers are often unconscious of just how much industry is influencing their work .
“ Bias comes in the research question , primarily , ” she says .
“ The way the research question is designed is so it will give the answer that the funder wants .
”

Did you know that eating soup could prevent obesity, and consuming grapes and blueberries may improve college students’ cognitive function? These two findings come from some of the latest research on nutrition science. But the results are also from a subset of studies backed by food manufacturers. A paper published December 16 in PLOS ONE reports that more than 13 percent of peer-reviewed studies in 10 of the top nutrition science journals had connections to the food industry—and of those, more than half reported findings favorable to business interests.
Previous studies have linked industry involvement to favorable study results, but this is the first to analyze comprehensively the extent of that involvement in leading nutrition science journals, says lead author Gary Sacks, a public health scientist at Deakin University in Australia. “Unhealthy diets are the biggest cause of ill health globally, and given that, it’s too important an area for the science to be skewed by food industry involvement,” Sacks says. “What this study shows is that when the food industry is involved, it’s skewing the research agenda to things that matter to the food industry, as opposed to you.”
Sacks and his colleagues analyzed 1,461 articles published in the 10 most-cited peer-reviewed journals on diet and nutrition for 2018, and found food manufacturers funded or were connected to nearly 200 of them. About 55 percent of industry-involved studies either concluded that a food product had health benefits or undermined evidence a product was harmful. Less than 10 percent of articles without industry involvement did so.
The Journal of Nutrition, published by the American Society for Nutrition, had the highest proportion of industry involvement; food manufacturers funded nearly 30 percent of the 223 articles it published in 2018. Teresa Davis, JN’s editor-in-chief, and a Baylor College of Medicine pediatric nutritionist, says the journal does not reject manuscripts based on their funding sources. “I think it’s not appropriate for us to discriminate based on the institution the manuscript is submitted from, or the funding source, or the country,” she says. “We evaluate the science. We look at the message, we don’t shoot the messenger.”
Davis says that industry funding for nutrition research is necessary because government support has plateaued for decades in the U.S. Sacks agrees that more government and independent sources of funding are needed, and suggests one way to protect research integrity would be to pool industry funding and have it distributed by an independent body. “We could perhaps move in that direction, but at this time, that’s not readily available,” Davis says. “I don’t disagree that that would be the ideal situation.” She adds that JN has a “very rigorous process” for evaluating the transparency and scientific reproducibility—key principles of the scientific method—of the studies it publishes.
But careful peer review may not be enough, says Lisa Bero, a pharmacologist at the University of Colorado who studies research bias. Bero contends that industry may skew research in ways peer review cannot catch. She cites four key approaches industry uses to manipulate research: by influencing what research questions are asked, how studies are designed, how conclusions interpret data and whether unfavorable findings ever get published. “Industry is more likely to fund research that is likely to show the benefits of their product or detract from [its] harms,” she says. “The problem with that is that those might not be the most important health questions.”
Bero also criticizes some studies’ emphasis on individual nutrients. “The food industry tends to focus on specific nutrients that can be manipulated in a processed product, [and] this allows them to make health claims,” she says. “Are those reductionist questions the important questions in nutrition? Many folks argue they are not.” Marion Nestle, a molecular biologist and public health nutritionist at New York University, agrees. “What matters is the whole diet—everything you eat, plus your lifestyle, plus genetics,” she says. “There’s only one reason for doing this kind of research, and that is to support the product, either by demonstrating it has health benefits or that it’s not harmful.” Davis from the Journal of Nutrition concurs that it’s important to look at overall dietary patterns, but says that “you need to know what the effect is of these individual nutrients on health outcomes as well.”
One overriding issue, Nestle says, is that researchers are often unconscious of just how much industry is influencing their work. “Bias comes in the research question, primarily,” she says. “The way the research question is designed is so it will give the answer that the funder wants.”


scientificamerican--2020-12-16--Defense Experts Call on Biden to Ready Military for Climate Change

The incoming Biden administration should press U.S. defense and intelligence agencies to do more about climate change , a panel of national security experts said yesterday .
And one way to do it is through the power of their massive federal budgets .
The talk , hosted by the Center for Climate and Security , was centered on the advocacy group ’ s Climate Security Plan for America , released in 2019 .
The plan calls on officials in the White House , the Department of Defense , the Department of Homeland Security and elsewhere to develop holistic strategies to @ @ @ @ @ @ @ mitigate the country ’ s contributions to its destabilizing effects .
Sherri Goodman , who from 1993 to 2001 was the first deputy undersecretary of Defense for environmental security , said the Center for Climate and Security plan is “ a road map for how to elevate climate as a core national security priority.
” “ This is an opportunity now to up our game and reenergize and get a lot of things done that we have been working on for many years , ” Goodman said .
“ At the end of @ @ @ @ @ @ @ strategy without a plan is hallucination.
” Climate hawks have been heartened by Biden ’ s win in the 2020 election , and many are hoping to see the incoming administration revive or surpass Obama-era environmental regulations that were rolled back during the Trump administration .
But some would like to see defense leaders go further by using the purchasing power of the U.S. military to fuel investments in clean energy and preventive technologies to mitigate the effects of climate change .
The U.S. military budget in fiscal year 2019 was $ 686.1 @ @ @ @ @ @ @ in operations and maintenance and $ 138.6 billion in personnel .
The panelists said at least part of the hundreds of billions of dollars Biden planned to invest in clean energy could go to security projects , including microgrid investments domestically or support for countries with unsustainable energy infrastructure abroad , if they had national security relevance .
“ We have to make climate change a key part of literally every part of government responsibilities we have , ” said retired Navy Vice Adm. Dennis McGinn .
One hurdle for the incoming administration @ @ @ @ @ @ @ leaders to treat climate change as a threat .
Alice Hill , a former senior counselor to Homeland Security Secretary Janet Napolitano and a National Security Council veteran , said she faced midlevel career officials in DHS who were climate skeptics .
She said Biden ’ s next appointees will have to highlight the danger that climate changes poses to the United States and the world , and encourage leaders to develop plans for worst-case scenarios .
“ We ’ re going to have to have strong leadership ... to really turn around @ @ @ @ @ @ @ ’ t a question of who you ’ re going to shoot or what hill you ’ re going to take , ” Hill said .
Hill joined fellow panelists in saying that required education on climate resilience in officer training could help spread awareness of the urgent threat of climate change .
And McGinn said the Biden administration could kick-start a culture change by having a list of “ concrete and measurable actions ” to pursue on day one in order to convince longtime leaders there is a path forward .
“ @ @ @ @ @ @ @ McGinn said .
“ We ’ ve got to walk the walk and talk the talk.
” The panel was optimistic about Biden ’ s early Cabinet appointments .
In particular , they praised the influence that former Secretary of State John Kerry could have on the National Security Council , saying his leadership on key environmental policies would be vital in a room filled with defense experts .
“ The opportunity in front of the incoming administration is to really hopefully ... allow for reality to be considered in our national security @ @ @ @ @ @ @ a fellow at the Center for Climate and Security .
“ I think Secretary Kerry ’ s appointment is a tremendous first step in that because the National Security Council is where we consider those challenges.
” Similarly , Goodman called for the “ climatization of security.
” She said she hopes the Biden administration will return to the “ three Ds ” of diplomacy , development and defense that were priorities in the Obama years .
The plan calls for a Climate Security Conflict Prevention Framework under the U.S. Agency for International @ @ @ @ @ @ @ dollars toward stabilizing countries deemed most at risk for climate change .
The idea , Hill said , is to prevent crises of migration from regions such as Central America due to climate catastrophe .
This year alone , Hurricanes Eta and Iota affected millions of Central Americans , according to the Red Cross .
Those disasters have the potential to spur migration north , the Associated Press reported .
“ We are somewhat behind in the U.S. compared to others in understanding how this could affect what we have traditionally understood as @ @ @ @ @ @ @ fresh water , food , shelter , ” Hill said .
One way the Pentagon can mitigate its contribution to climate change is through the purchase of cleaner energy and infrastructure on its military bases , several panelists said .
Currently , the military has a maintenance backlog on its bases with a price tag of more than $ 100 billion .
With Biden ’ s $ 2 trillion climate plan , some of that money could go toward building green infrastructure and investing in clean vehicles , Wu said .
That investment @ @ @ @ @ @ @ of advanced energy and infrastructure systems that we ’ re going to need for tomorrow ’ s military , ” Wu said .
Wu called for a new Office of Energy Innovation in the Department of Defense to compete with investments made internationally .
He pointed to Japanese investments in hydrogen technology as an area where the United States could join its allies in preparing for the future .
“ We haven ’ t played any role in the climate security mechanism in the U.S. to date , and now we can , @ @ @ @ @ @ @ is that enables us to build on the good work that ’ s already been done by the countries that have been active in it.
” Reprinted from Climatewire with permission from E & E News .
E & E provides daily coverage of essential energy and environmental news at www.eenews.net .

The incoming Biden administration should press U.S. defense and intelligence agencies to do more about climate change, a panel of national security experts said yesterday.
And one way to do it is through the power of their massive federal budgets.
The talk, hosted by the Center for Climate and Security, was centered on the advocacy group’s Climate Security Plan for America, released in 2019.
The plan calls on officials in the White House, the Department of Defense, the Department of Homeland Security and elsewhere to develop holistic strategies to meet the threat of climate change and mitigate the country’s contributions to its destabilizing effects.
Sherri Goodman, who from 1993 to 2001 was the first deputy undersecretary of Defense for environmental security, said the Center for Climate and Security plan is “a road map for how to elevate climate as a core national security priority.”
“This is an opportunity now to up our game and reenergize and get a lot of things done that we have been working on for many years,” Goodman said. “At the end of the day, as we say, strategy without a plan is hallucination.”
Climate hawks have been heartened by Biden’s win in the 2020 election, and many are hoping to see the incoming administration revive or surpass Obama-era environmental regulations that were rolled back during the Trump administration.
But some would like to see defense leaders go further by using the purchasing power of the U.S. military to fuel investments in clean energy and preventive technologies to mitigate the effects of climate change.
The U.S. military budget in fiscal year 2019 was $686.1 billion, which included $244.4 billion in operations and maintenance and $138.6 billion in personnel. The panelists said at least part of the hundreds of billions of dollars Biden planned to invest in clean energy could go to security projects, including microgrid investments domestically or support for countries with unsustainable energy infrastructure abroad, if they had national security relevance.
“We have to make climate change a key part of literally every part of government responsibilities we have,” said retired Navy Vice Adm. Dennis McGinn.
‘Culture eats strategy’
One hurdle for the incoming administration is the entrenched reluctance of some military leaders to treat climate change as a threat.
Alice Hill, a former senior counselor to Homeland Security Secretary Janet Napolitano and a National Security Council veteran, said she faced midlevel career officials in DHS who were climate skeptics.
She said Biden’s next appointees will have to highlight the danger that climate changes poses to the United States and the world, and encourage leaders to develop plans for worst-case scenarios.
“We’re going to have to have strong leadership ... to really turn around the mindset to understand that this isn’t a question of who you’re going to shoot or what hill you’re going to take,” Hill said.
Hill joined fellow panelists in saying that required education on climate resilience in officer training could help spread awareness of the urgent threat of climate change.
And McGinn said the Biden administration could kick-start a culture change by having a list of “concrete and measurable actions” to pursue on day one in order to convince longtime leaders there is a path forward.
“Culture eats strategy for breakfast,” McGinn said. “We’ve got to walk the walk and talk the talk.”
Leadership in the White House
The panel was optimistic about Biden’s early Cabinet appointments. In particular, they praised the influence that former Secretary of State John Kerry could have on the National Security Council, saying his leadership on key environmental policies would be vital in a room filled with defense experts.
“The opportunity in front of the incoming administration is to really hopefully ... allow for reality to be considered in our national security decisionmaking,” said Michael Wu, a fellow at the Center for Climate and Security. “I think Secretary Kerry’s appointment is a tremendous first step in that because the National Security Council is where we consider those challenges.”
Similarly, Goodman called for the “climatization of security.” She said she hopes the Biden administration will return to the “three Ds” of diplomacy, development and defense that were priorities in the Obama years.
The plan calls for a Climate Security Conflict Prevention Framework under the U.S. Agency for International Development, which would direct international development dollars toward stabilizing countries deemed most at risk for climate change.
The idea, Hill said, is to prevent crises of migration from regions such as Central America due to climate catastrophe. This year alone, Hurricanes Eta and Iota affected millions of Central Americans, according to the Red Cross. Those disasters have the potential to spur migration north, the Associated Press reported.
“We are somewhat behind in the U.S. compared to others in understanding how this could affect what we have traditionally understood as national security when people lose access to fresh water, food, shelter,” Hill said.
Buying a cleaner future
One way the Pentagon can mitigate its contribution to climate change is through the purchase of cleaner energy and infrastructure on its military bases, several panelists said.
Currently, the military has a maintenance backlog on its bases with a price tag of more than $100 billion. With Biden’s $2 trillion climate plan, some of that money could go toward building green infrastructure and investing in clean vehicles, Wu said.
That investment “lays a foundation for the kinds of advanced energy and infrastructure systems that we’re going to need for tomorrow’s military,” Wu said.
Wu called for a new Office of Energy Innovation in the Department of Defense to compete with investments made internationally. He pointed to Japanese investments in hydrogen technology as an area where the United States could join its allies in preparing for the future.
“We haven’t played any role in the climate security mechanism in the U.S. to date, and now we can,” Wu said. “My hope is that enables us to build on the good work that’s already been done by the countries that have been active in it.”
Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.


scientificamerican--2020-12-16--How the First Life on Earth Survived Its Biggest Threat--Water

On 18 February next year , a NASA spacecraft will plummet through the Martian atmosphere , fire its retro-rockets to break its fall and then lower a six-wheeled rover named Perseverance to the surface .
If all goes according to plan , the mission will land in Jezero Crater , a 45-kilometre-wide gash near the planet ’ s equator that might once have held a lake of liquid water .
Among the throngs of earthlings cheering on Perseverance , John Sutherland will be paying particularly close attention .
Sutherland , a biochemist at the MRC Laboratory of Molecular Biology in @ @ @ @ @ @ @ the scientists who lobbied NASA to visit Jezero Crater , because it fits his ideas about where life might have originated—on Mars and on Earth .
The choice of landing site reflects a shift in thinking about the chemical steps that transformed a few molecules into the first biological cells .
Although many scientists have long speculated that those pioneering cells arose in the ocean , recent research suggests that the key molecules of life , and its core processes , can form only in places such as Jezero—a relatively shallow body of @ @ @ @ @ @ @ s because several studies suggest that the basic chemicals of life require ultraviolet radiation from sunlight to form , and that the watery environment had to become highly concentrated or even dry out completely at times .
In laboratory experiments , Sutherland and other scientists have produced DNA , proteins and other core components of cells by gently heating simple carbon-based chemicals , subjecting them to UV radiation and intermittently drying them out .
Chemists have not yet been able to synthesize such a wide range of biological molecules in conditions that mimic @ @ @ @ @ @ @ many researchers to abandon the idea that life emerged in the oceans and instead focus on land environments , in places that were alternately wet and dry .
The shift is hardly unanimous , but scientists who support the idea of a terrestrial beginning say it offers a solution to a long-recognized paradox : that although water is essential for life , it is also destructive to life ’ s core components .
Surface lakes and puddles are highly promising , says David Catling , a planetary scientist at the University of Washington @ @ @ @ @ @ @ a lot of work that ’ s been done in the last 15 years which would support that direction.
” Although there is no standardized definition of life , most researchers agree that it needs several components .
One is information-carrying molecules—DNA , RNA or something else .
There must have been a way to copy these molecular instructions , although the process would have been imperfect to allow for mistakes , the seeds of evolutionary change .
Furthermore , the first organisms must have had a way to feed and maintain themselves @ @ @ @ @ @ @ , something held these disparate parts together , keeping them separate from their environment .
When laboratory research into life ’ s origins started in earnest in the 1950s , many researchers assumed that life began in the sea , with a rich mix of carbon-based chemicals dubbed the primordial soup .
This idea was independently proposed in the 1920s by biochemist Alexander Oparin , in what was then the Soviet Union , and geneticist J .
B. S. Haldane in the United Kingdom .
Each imagined the young Earth as a huge @ @ @ @ @ @ @ chemicals dissolved in the waters of the early oceans .
Oparin reasoned that increasingly complicated particles were formed , culminating in carbohydrates and proteins : what he called “ the foundation of life ” .
In 1953 , a young researcher named Stanley Miller at the University of Chicago in Illinois described a now-famous experiment that was seen as confirming these ideas .
He used a glass flask holding water to mimic the ocean , and another flask containing methane , ammonia and hydrogen to simulate the early atmosphere .
Tubes connected the @ @ @ @ @ @ @ .
A few days of heating and electric shocks were enough to make glycine , the simplest amino acid and an essential component of proteins .
This suggested to many researchers that life arose near the surface of the ocean .
But many scientists today say there ’ s a fundamental problem with that idea : life ’ s cornerstone molecules break down in water .
This is because proteins , and nucleic acids such as DNA and RNA , are vulnerable at their joints .
Proteins are made of chains of amino @ @ @ @ @ @ @ of nucleotides .
If the chains are placed in water , it attacks the links and eventually breaks them .
In carbon chemistry , “ water is an enemy to be excluded as rigorously as possible ” , wrote the late biochemist Robert Shapiro in his totemic 1986 book Origins , which critiqued the primordial ocean hypothesis .
This is the water paradox .
Today , cells solve it by limiting the free movement of water in their interiors , says synthetic biologist Kate Adamala at the University of Minnesota in Minneapolis .
@ @ @ @ @ @ @ the cytoplasm—the substance inside the cell—are often wrong .
“ We are taught that cytoplasm is just a bag that holds everything , and everything is swimming around , ” she adds .
“ That ’ s not true , everything is incredibly scaffolded in cells , and it ’ s scaffolded in a gel , not a water bag.
” If living things keep water controlled , then the implication , say many researchers , is obvious .
Life probably formed on land , where water was only intermittently present .
Some @ @ @ @ @ @ @ this idea emerged in 2009 , when Sutherland announced that he and his team had successfully made two of the four nucleotides that comprise RNA .
They started with phosphate and four simple carbon-based chemicals , including a cyanide salt called cyanamide .
The chemicals were dissolved in water throughout , but they were highly concentrated , and crucial steps required UV radiation .
Such reactions could not take place deep in an ocean—only in a small pool or stream exposed to sunlight , where chemicals could be concentrated , he says .
@ @ @ @ @ @ @ that the same starter chemicals , if they are treated subtly differently , can also produce precursors to proteins and lipids .
The researchers suggest that these reactions might have taken place if water containing cyanide salts was dried out by the Sun , leaving a layer of dry , cyanide-related chemicals that was then heated by , say , geothermal activity .
In the past year , his team has produced the building blocks of DNA—something previously thought implausible—using energy from sunlight and some of the same chemicals at high concentrations .
@ @ @ @ @ @ @ Moran Frenkel-Pinter at the NSF–NASA Center for Chemical Evolution in Atlanta , Georgia , and her colleagues .
Last year , they showed that amino acids spontaneously linked up to form protein-like chains if they were dried out .
And those kinds of reaction were more likely to occur with the 20 amino acids found in proteins today , compared with other amino acids .
That means intermittent drying could help to explain why life uses only those amino acids , out of hundreds of possibilities .
“ We saw selection for today @ @ @ @ @ @ @ Frenkel-Pinter .
Intermittent drying out can also help to drive these molecular building blocks to assemble into more-complex , life-like structures .
A classic experiment along these lines was published in 1982 by researchers David Deamer and Gail Barchfeld , then at the University of California , Davis .
Their aim was to study how lipids , another class of long-chain molecule , self-organize to form the membranes that surround cells .
They first made vesicles : spherical blobs with a watery core surrounded by two lipid layers .
Then the researchers dried @ @ @ @ @ @ @ into a multi-layered structure like a stack of pancakes .
Strands of DNA , previously floating in the water , became trapped between the layers .
When the researchers added water again , the vesicles reformed—with DNA inside them .
This was a step towards a simple cell .
“ These wet–dry cycles are everywhere , ” says Deamer , who is now at the University of California , Santa Cruz .
“ It ’ s as simple as rainwater evaporating on wet rocks.
” But when they are applied to biological chemicals @ @ @ @ @ @ @ remarkable things happen .
In a 2008 study , Deamer and his team mixed nucleotides and lipids with water , then put them through wet–dry cycles .
When the lipids formed layers , the nucleotides linked up into RNA-like chains—a reaction that would not happen in water unaided .
Other studies are pointing to a different factor that seems to be a key part of life ’ s origins : light .
That ’ s one of the conclusions coming from the team of synthetic biologist Jack Szostak at Massachusetts General Hospital in @ @ @ @ @ @ @ ’ —simple versions of cells that contain a handful of chemicals , but can grow , compete and replicate themselves .
The protocells display more-lifelike behaviours if they are exposed to conditions similar to those on land .
One study , on which Adamala was a co-author , found that the protocells could use energy from light to divide , in a simple form of reproduction .
Similarly , Claudia Bonfio , now also at the MRC Laboratory of Molecular Biology , and her colleagues showed in 2017 that UV radiation drives the @ @ @ @ @ @ @ crucial to many proteins .
These include those in the electron transport chain , which helps to power all living cells by driving the synthesis of the energy-storage molecule ATP .
The iron–sulfur clusters would break apart if they were exposed to water , but Bonfio ’ s team found they were more stable if the clusters were surrounded by simple peptides 3–12 amino acids long .
Water , but not too much Such studies have given momentum to the idea that life began on a well-lit surface with a limited amount of @ @ @ @ @ @ @ debate over how much water was involved , and what part it played in starting life .
Like Deamer , Frenkel-Pinter argues that wet–dry cycles were crucial .
Dry conditions , she says , provided an opportunity for chain molecules such as proteins and RNA to form .
But simply making RNA and other molecules is not life .
A self-sustaining , dynamic system has to form .
Frenkel-Pinter suggests that water ’ s destructiveness could have helped to drive that .
Just as prey animals evolved to run faster or secrete toxins @ @ @ @ @ @ @ molecules might have evolved to cope with water ’ s chemical attacks—and even to harness its reactivity for good .
This year , Frenkel-Pinter ’ s team followed up on its previous study showing that drying caused amino acids to link up spontaneously .
The team found that their proto-proteins could interact with RNA , and that both became more stable in water as a result .
In effect , water acted as a selection pressure : only those combinations of molecules that could survive in water would continue , because the others @ @ @ @ @ @ @ that , with each cycle of wetting , the weaker molecules , or those that could not protect themselves by binding to others , were destroyed .
Bonfio and her team demonstrated this in a study this year , in which they attempted to convert simple fatty acids into more-complex lipids resembling those found in modern cell membranes .
The researchers created mixtures of lipids , and found that the simple ones were destroyed by water , while the larger , more complex ones accumulated .
“ At some point , you would @ @ @ @ @ @ @ to form membranes , ” she says .
In other words , there might be a Goldilocks amount of water : not so much that biological molecules are destroyed too quickly , but not so little that nothing changes .
Where might all this have happened ?
On this point , there is a generational divide in the field .
Many senior researchers are committed to one scenario or another , whereas younger researchers often argue that the question is wide open .
The open ocean is unviable , says Frenkel-Pinter , because @ @ @ @ @ @ @ become concentrated .
“ That ’ s really a problem , ” agrees Bonfio .
An alternative marine idea has been championed since the 1980s by geologist Michael Russell , an independent researcher formerly at the Jet Propulsion Laboratory in Pasadena , California .
Russell argues that life began in vents on the seabed , where warm alkaline water seeps up from geological formations below .
Interactions between warm water and rocks would provide chemical energy that would first drive simple metabolic cycles , which would later start making and using chemicals such @ @ @ @ @ @ @ Sutherland ’ s approach .
“ He ’ s doing all these fantastic bits of chemistry , ” he says , but for Russell , none of it is relevant .
That ’ s because modern organisms use completely different chemical processes to make substances such as RNA .
He argues that these processes must have arisen first , not the substances themselves .
“ Life , it picks very particular molecules .
But you can ’ t pick them from the bench .
You ’ ve got to make them from scratch @ @ @ @ @ @ @ ” Sutherland counters that once RNA , proteins and so forth had formed , evolution would have taken over and enabled proto-organisms to find new ways to make these molecules and thus sustain themselves .
Meanwhile , many researchers have expressed scepticism about Russell ’ s alkaline-vent hypothesis , arguing that it lacks experimental support .
By contrast , chemical experiments that simulate surface conditions have made the building blocks of nucleic acids , proteins and lipids .
“ None of that synthesis exists in that deep-sea hydrothermal vent hypothesis .
It just @ @ @ @ @ @ @ and possibly because it can ’ t be done , ” says Catling .
Frenkel-Pinter is also critical of the vent idea , because the molecules she works with wouldn ’ t survive long in those conditions .
“ The formation of these protopeptides is not very compatible with hydrothermal vents , ” says Frenkel-Pinter .
A possible solution was proposed in May by geochemist Martina Preiner , a postdoc at the University of Düsseldorf in Germany , and her colleagues .
She argues that in the rocks beneath hydrothermal vents , heat @ @ @ @ @ @ @ or break them apart—creating dry spaces .
“ There are rock–water interactions getting rid of the water to a certain extent , ” she says .
Intermittently , more seawater would trickle in , giving “ something like a wet–dry cycling ” .
This ought to make the deep-sea rocks much more suitable for the formation of key molecules , argues Preiner , although she acknowledges this is still a hypothesis .
“ Of course , you still have to do the according experiments to prove that this could do certain reactions.
” @ @ @ @ @ @ @ doesn ’ t exist .
Meanwhile , experimental support is growing for the idea that life started in small bodies of water on land .
Sutherland favours a meteorite impact crater , heated by the Sun and by the residual energy of the impact , with multiple streams of water running down the sloping sides , and finally meeting in a pool at the bottom .
This would have been a complex , 3D environment with mineral surfaces to act as catalysts , where carbon-based chemicals could have been alternately dissolved in water @ @ @ @ @ @ @ “ You can say with some degree of confidence we need to be on the surface , we can ’ t be deep in the ocean or 10 kilometres down in the crust , ” says Sutherland .
“ Then we need phosphate , we need iron .
A lot of those things are very easily delivered by iron–nickel meteorites.
” The impact scenario has a further advantage : meteorite impacts shock the atmosphere , producing cyanide , says Sutherland .
Deamer has long championed a different suggestion : volcanic hot springs .
@ @ @ @ @ @ @ and his colleague Bruce Damer argued that lipids would have formed protocells in the hot waters , as his earlier experiments indicated .
The wet–dry cycles on the edges of the pools would have driven the formation and copying of nucleic acids such as RNA .
Deamer has conducted several experiments in modern volcanic hot springs to test his ideas .
In 2018 , his team showed that vesicles could form in hot spring water , and even enclose nucleic acids—but they would not form in seawater .
A follow-up study last year @ @ @ @ @ @ @ dried , nucleotides linked up to form RNA-like strands .
Narrowing down the location where life started will require understanding of the broader picture of prebiotic chemistry : how the many reactions fit together , and the ranges of conditions under which they occur .
That mammoth task has been attempted by a group led by chemist Sara Szymkuć , president of the start-up firm Allchemy in Highland , Indiana .
The team published a comprehensive study in September that used a computer algorithm to explore how a vast network of known prebiotic @ @ @ @ @ @ @ biological molecules used in life today .
The network was highly redundant , so key biological compounds could still form even if multiple reactions were blocked .
For this reason , Szymkuć argues that it is too early to rule out any of the scenarios for where life originated .
That will require systematically testing a range of different environments , to see which reactions occur where .
If experiments such as Sutherland ’ s do point the way to how life began on Earth , they can also help to explore where @ @ @ @ @ @ @ cosmos .
Mars has attracted the most attention , because there is clear evidence it once had liquid water on its surface .
The landing site for NASA ’ s Perseverance rover , the Jezero Crater , was chosen in part because it seems to have once been a lake—and could have hosted the chemistry Sutherland has studied .
He helped to write a 2018 presentation to NASA led by Catling , which summarized the prebiotic chemistry findings and advised on where Perseverance should look .
“ We presented this chemistry and said @ @ @ @ @ @ @ one they eventually chose , is the one where there was the highest likelihood of this chemistry playing out , ” says Sutherland .
It will be two months before Perseverance reaches Mars—and years before the samples it collects are returned to Earth by an as-yet-unnamed future mission .
So , there is still a long wait before we find out whether Mars harbours life , or if it did so billions of years ago .
But even if it did not , it might reveal traces of prebiotic chemistry .
The best @ @ @ @ @ @ @ Perseverance finds complicated carbon-based molecules in the layers of Martian sediment , such as lipids or proteins , or their degraded remains .
He also hopes for evidence of wet–dry cycles .
This might come in the form of carbonate layers that formed when a lake dried and refilled many times .
He suspects that “ life didn ’ t get particularly far on Mars ” , because we haven ’ t seen any obvious signs of it , such as clear fossils or carbon-rich black shales .
“ What we ’ re @ @ @ @ @ @ @ even to the point of being prebiotic rather than the actual cells themselves.
” It could be that Mars took only the first few chemical steps towards life , and did not go all the way .
In that case , we might find fossils—not of life , but of pre-life .
This article is reproduced with permission and was first published on December 9 2020 .

On 18 February next year, a NASA spacecraft will plummet through the Martian atmosphere, fire its retro-rockets to break its fall and then lower a six-wheeled rover named Perseverance to the surface. If all goes according to plan, the mission will land in Jezero Crater, a 45-kilometre-wide gash near the planet’s equator that might once have held a lake of liquid water.
Among the throngs of earthlings cheering on Perseverance, John Sutherland will be paying particularly close attention. Sutherland, a biochemist at the MRC Laboratory of Molecular Biology in Cambridge, UK, was one of the scientists who lobbied NASA to visit Jezero Crater, because it fits his ideas about where life might have originated—on Mars and on Earth.
The choice of landing site reflects a shift in thinking about the chemical steps that transformed a few molecules into the first biological cells. Although many scientists have long speculated that those pioneering cells arose in the ocean, recent research suggests that the key molecules of life, and its core processes, can form only in places such as Jezero—a relatively shallow body of water fed by streams.
That’s because several studies suggest that the basic chemicals of life require ultraviolet radiation from sunlight to form, and that the watery environment had to become highly concentrated or even dry out completely at times. In laboratory experiments, Sutherland and other scientists have produced DNA, proteins and other core components of cells by gently heating simple carbon-based chemicals, subjecting them to UV radiation and intermittently drying them out. Chemists have not yet been able to synthesize such a wide range of biological molecules in conditions that mimic seawater.
The emerging evidence has caused many researchers to abandon the idea that life emerged in the oceans and instead focus on land environments, in places that were alternately wet and dry. The shift is hardly unanimous, but scientists who support the idea of a terrestrial beginning say it offers a solution to a long-recognized paradox: that although water is essential for life, it is also destructive to life’s core components.
Surface lakes and puddles are highly promising, says David Catling, a planetary scientist at the University of Washington in Seattle. “There’s a lot of work that’s been done in the last 15 years which would support that direction.”
Primordial soup
Although there is no standardized definition of life, most researchers agree that it needs several components. One is information-carrying molecules—DNA, RNA or something else. There must have been a way to copy these molecular instructions, although the process would have been imperfect to allow for mistakes, the seeds of evolutionary change. Furthermore, the first organisms must have had a way to feed and maintain themselves, perhaps using protein-based enzymes. Finally, something held these disparate parts together, keeping them separate from their environment.
When laboratory research into life’s origins started in earnest in the 1950s, many researchers assumed that life began in the sea, with a rich mix of carbon-based chemicals dubbed the primordial soup.
This idea was independently proposed in the 1920s by biochemist Alexander Oparin, in what was then the Soviet Union, and geneticist J. B. S. Haldane in the United Kingdom. Each imagined the young Earth as a huge chemical factory, with multitudes of carbon-based chemicals dissolved in the waters of the early oceans. Oparin reasoned that increasingly complicated particles were formed, culminating in carbohydrates and proteins: what he called “the foundation of life”.
In 1953, a young researcher named Stanley Miller at the University of Chicago in Illinois described a now-famous experiment that was seen as confirming these ideas. He used a glass flask holding water to mimic the ocean, and another flask containing methane, ammonia and hydrogen to simulate the early atmosphere. Tubes connected the flasks, and an electrode simulated lightning. A few days of heating and electric shocks were enough to make glycine, the simplest amino acid and an essential component of proteins. This suggested to many researchers that life arose near the surface of the ocean.
But many scientists today say there’s a fundamental problem with that idea: life’s cornerstone molecules break down in water. This is because proteins, and nucleic acids such as DNA and RNA, are vulnerable at their joints. Proteins are made of chains of amino acids, and nucleic acids are chains of nucleotides. If the chains are placed in water, it attacks the links and eventually breaks them. In carbon chemistry, “water is an enemy to be excluded as rigorously as possible”, wrote the late biochemist Robert Shapiro in his totemic 1986 book Origins, which critiqued the primordial ocean hypothesis.
This is the water paradox. Today, cells solve it by limiting the free movement of water in their interiors, says synthetic biologist Kate Adamala at the University of Minnesota in Minneapolis. For this reason, popular images of the cytoplasm—the substance inside the cell—are often wrong. “We are taught that cytoplasm is just a bag that holds everything, and everything is swimming around,” she adds. “That’s not true, everything is incredibly scaffolded in cells, and it’s scaffolded in a gel, not a water bag.”
If living things keep water controlled, then the implication, say many researchers, is obvious. Life probably formed on land, where water was only intermittently present.
Land start
Some of the key evidence in favour of this idea emerged in 2009, when Sutherland announced that he and his team had successfully made two of the four nucleotides that comprise RNA. They started with phosphate and four simple carbon-based chemicals, including a cyanide salt called cyanamide. The chemicals were dissolved in water throughout, but they were highly concentrated, and crucial steps required UV radiation. Such reactions could not take place deep in an ocean—only in a small pool or stream exposed to sunlight, where chemicals could be concentrated, he says.
Sutherland’s team has since shown that the same starter chemicals, if they are treated subtly differently, can also produce precursors to proteins and lipids. The researchers suggest that these reactions might have taken place if water containing cyanide salts was dried out by the Sun, leaving a layer of dry, cyanide-related chemicals that was then heated by, say, geothermal activity. In the past year, his team has produced the building blocks of DNA—something previously thought implausible—using energy from sunlight and some of the same chemicals at high concentrations.
This approach has been extended by biochemist Moran Frenkel-Pinter at the NSF–NASA Center for Chemical Evolution in Atlanta, Georgia, and her colleagues. Last year, they showed that amino acids spontaneously linked up to form protein-like chains if they were dried out. And those kinds of reaction were more likely to occur with the 20 amino acids found in proteins today, compared with other amino acids. That means intermittent drying could help to explain why life uses only those amino acids, out of hundreds of possibilities. “We saw selection for today’s amino acids,” says Frenkel-Pinter.
Wet and dry
Intermittent drying out can also help to drive these molecular building blocks to assemble into more-complex, life-like structures.
A classic experiment along these lines was published in 1982 by researchers David Deamer and Gail Barchfeld, then at the University of California, Davis. Their aim was to study how lipids, another class of long-chain molecule, self-organize to form the membranes that surround cells. They first made vesicles: spherical blobs with a watery core surrounded by two lipid layers. Then the researchers dried the vesicles, and the lipids reorganized into a multi-layered structure like a stack of pancakes. Strands of DNA, previously floating in the water, became trapped between the layers. When the researchers added water again, the vesicles reformed—with DNA inside them. This was a step towards a simple cell.
“These wet–dry cycles are everywhere,” says Deamer, who is now at the University of California, Santa Cruz. “It’s as simple as rainwater evaporating on wet rocks.” But when they are applied to biological chemicals such as lipids, he says, remarkable things happen.
In a 2008 study, Deamer and his team mixed nucleotides and lipids with water, then put them through wet–dry cycles. When the lipids formed layers, the nucleotides linked up into RNA-like chains—a reaction that would not happen in water unaided.
Other studies are pointing to a different factor that seems to be a key part of life’s origins: light. That’s one of the conclusions coming from the team of synthetic biologist Jack Szostak at Massachusetts General Hospital in Boston, which works with ‘protocells’—simple versions of cells that contain a handful of chemicals, but can grow, compete and replicate themselves. The protocells display more-lifelike behaviours if they are exposed to conditions similar to those on land. One study, on which Adamala was a co-author, found that the protocells could use energy from light to divide, in a simple form of reproduction. Similarly, Claudia Bonfio, now also at the MRC Laboratory of Molecular Biology, and her colleagues showed in 2017 that UV radiation drives the synthesis of iron-sulfur clusters, which are crucial to many proteins. These include those in the electron transport chain, which helps to power all living cells by driving the synthesis of the energy-storage molecule ATP. The iron–sulfur clusters would break apart if they were exposed to water, but Bonfio’s team found they were more stable if the clusters were surrounded by simple peptides 3–12 amino acids long.
Water, but not too much
Such studies have given momentum to the idea that life began on a well-lit surface with a limited amount of water. However, there is still debate over how much water was involved, and what part it played in starting life.
Like Deamer, Frenkel-Pinter argues that wet–dry cycles were crucial. Dry conditions, she says, provided an opportunity for chain molecules such as proteins and RNA to form.
But simply making RNA and other molecules is not life. A self-sustaining, dynamic system has to form. Frenkel-Pinter suggests that water’s destructiveness could have helped to drive that. Just as prey animals evolved to run faster or secrete toxins to survive predators, the first biological molecules might have evolved to cope with water’s chemical attacks—and even to harness its reactivity for good.
This year, Frenkel-Pinter’s team followed up on its previous study showing that drying caused amino acids to link up spontaneously. The team found that their proto-proteins could interact with RNA, and that both became more stable in water as a result. In effect, water acted as a selection pressure: only those combinations of molecules that could survive in water would continue, because the others would be destroyed.
The idea is that, with each cycle of wetting, the weaker molecules, or those that could not protect themselves by binding to others, were destroyed. Bonfio and her team demonstrated this in a study this year, in which they attempted to convert simple fatty acids into more-complex lipids resembling those found in modern cell membranes. The researchers created mixtures of lipids, and found that the simple ones were destroyed by water, while the larger, more complex ones accumulated. “At some point, you would have enough of these lipids for them to form membranes,” she says. In other words, there might be a Goldilocks amount of water: not so much that biological molecules are destroyed too quickly, but not so little that nothing changes.
Warm little ponds
Where might all this have happened? On this point, there is a generational divide in the field. Many senior researchers are committed to one scenario or another, whereas younger researchers often argue that the question is wide open.
The open ocean is unviable, says Frenkel-Pinter, because there is no way for chemicals to become concentrated. “That’s really a problem,” agrees Bonfio.
An alternative marine idea has been championed since the 1980s by geologist Michael Russell, an independent researcher formerly at the Jet Propulsion Laboratory in Pasadena, California. Russell argues that life began in vents on the seabed, where warm alkaline water seeps up from geological formations below. Interactions between warm water and rocks would provide chemical energy that would first drive simple metabolic cycles, which would later start making and using chemicals such as RNA.
Russell is critical of Sutherland’s approach. “He’s doing all these fantastic bits of chemistry,” he says, but for Russell, none of it is relevant. That’s because modern organisms use completely different chemical processes to make substances such as RNA. He argues that these processes must have arisen first, not the substances themselves. “Life, it picks very particular molecules. But you can’t pick them from the bench. You’ve got to make them from scratch and that’s what life does.”
Sutherland counters that once RNA, proteins and so forth had formed, evolution would have taken over and enabled proto-organisms to find new ways to make these molecules and thus sustain themselves.
Meanwhile, many researchers have expressed scepticism about Russell’s alkaline-vent hypothesis, arguing that it lacks experimental support.
By contrast, chemical experiments that simulate surface conditions have made the building blocks of nucleic acids, proteins and lipids. “None of that synthesis exists in that deep-sea hydrothermal vent hypothesis. It just simply hasn’t been done, and possibly because it can’t be done,” says Catling.
Frenkel-Pinter is also critical of the vent idea, because the molecules she works with wouldn’t survive long in those conditions. “The formation of these protopeptides is not very compatible with hydrothermal vents,” says Frenkel-Pinter.
A possible solution was proposed in May by geochemist Martina Preiner, a postdoc at the University of Düsseldorf in Germany, and her colleagues. She argues that in the rocks beneath hydrothermal vents, heat and chemical reactions bind up water molecules or break them apart—creating dry spaces. “There are rock–water interactions getting rid of the water to a certain extent,” she says. Intermittently, more seawater would trickle in, giving “something like a wet–dry cycling”. This ought to make the deep-sea rocks much more suitable for the formation of key molecules, argues Preiner, although she acknowledges this is still a hypothesis. “Of course, you still have to do the according experiments to prove that this could do certain reactions.”
At present, however, that evidence doesn’t exist. Meanwhile, experimental support is growing for the idea that life started in small bodies of water on land.
Sutherland favours a meteorite impact crater, heated by the Sun and by the residual energy of the impact, with multiple streams of water running down the sloping sides, and finally meeting in a pool at the bottom. This would have been a complex, 3D environment with mineral surfaces to act as catalysts, where carbon-based chemicals could have been alternately dissolved in water and dried out in the Sun. “You can say with some degree of confidence we need to be on the surface, we can’t be deep in the ocean or 10 kilometres down in the crust,” says Sutherland. “Then we need phosphate, we need iron. A lot of those things are very easily delivered by iron–nickel meteorites.” The impact scenario has a further advantage: meteorite impacts shock the atmosphere, producing cyanide, says Sutherland.
Deamer has long championed a different suggestion: volcanic hot springs. In a study this year, he and his colleague Bruce Damer argued that lipids would have formed protocells in the hot waters, as his earlier experiments indicated. The wet–dry cycles on the edges of the pools would have driven the formation and copying of nucleic acids such as RNA.
Deamer has conducted several experiments in modern volcanic hot springs to test his ideas. In 2018, his team showed that vesicles could form in hot spring water, and even enclose nucleic acids—but they would not form in seawater. A follow-up study last year found that when the resulting vesicles were dried, nucleotides linked up to form RNA-like strands.
Narrowing down the location where life started will require understanding of the broader picture of prebiotic chemistry: how the many reactions fit together, and the ranges of conditions under which they occur. That mammoth task has been attempted by a group led by chemist Sara Szymkuć, president of the start-up firm Allchemy in Highland, Indiana. The team published a comprehensive study in September that used a computer algorithm to explore how a vast network of known prebiotic reactions could have produced many of the biological molecules used in life today.
The network was highly redundant, so key biological compounds could still form even if multiple reactions were blocked. For this reason, Szymkuć argues that it is too early to rule out any of the scenarios for where life originated. That will require systematically testing a range of different environments, to see which reactions occur where.
Beyond Earth
If experiments such as Sutherland’s do point the way to how life began on Earth, they can also help to explore where life might have started elsewhere in the cosmos.
Mars has attracted the most attention, because there is clear evidence it once had liquid water on its surface. The landing site for NASA’s Perseverance rover, the Jezero Crater, was chosen in part because it seems to have once been a lake—and could have hosted the chemistry Sutherland has studied. He helped to write a 2018 presentation to NASA led by Catling, which summarized the prebiotic chemistry findings and advised on where Perseverance should look. “We presented this chemistry and said this Jezero Crater, which is the one they eventually chose, is the one where there was the highest likelihood of this chemistry playing out,” says Sutherland.
It will be two months before Perseverance reaches Mars—and years before the samples it collects are returned to Earth by an as-yet-unnamed future mission. So, there is still a long wait before we find out whether Mars harbours life, or if it did so billions of years ago. But even if it did not, it might reveal traces of prebiotic chemistry.
The best case, says Catling, is that Perseverance finds complicated carbon-based molecules in the layers of Martian sediment, such as lipids or proteins, or their degraded remains. He also hopes for evidence of wet–dry cycles. This might come in the form of carbonate layers that formed when a lake dried and refilled many times. He suspects that “life didn’t get particularly far on Mars”, because we haven’t seen any obvious signs of it, such as clear fossils or carbon-rich black shales. “What we’re looking for is pretty simple, maybe even to the point of being prebiotic rather than the actual cells themselves.”
It could be that Mars took only the first few chemical steps towards life, and did not go all the way. In that case, we might find fossils—not of life, but of pre-life.
This article is reproduced with permission and was first published on December 9 2020.