DINO STARScientists reveal - the real Dilophosaurus, a Jurassic Park icon - Literary Theory and Criticism
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JANUARY 2021 SCIENTIFICAMERICAN.COM How COVID-19
Wrecks the
Immune System
Ancient Galaxy
Clusters
Understanding
Mountain Ice
DINO
STAR
Scientists reveal
the real Dilophosaurus,
a Jurassic Park icon
© 2020 Scientific American
Ja n ua ry 2 0 2 1
VO LU M E 3 2 4 , N U M B E R 1
00
68
A S T R O N O MY PA L E O N TO LO G Y
26 Too Big for the Universe 46 The Real Dilophosaurus
Ancient galaxy clusters seem to The most comprehensive study
have grown so quickly that they of the iconic Jurassic Park d
inosaur
would have broken the laws reveals a very different animal
of the cosmos. By Arianna S. Long from the one the movie portrayed.
By Matthew A. Brown and
I M M U N O LO G Y
Adam D. Marsh
34 The Immune Havoc
of COVID-19 N AT U R A L R E S O U R C E S
The virus flourishes by under 54 Peak Water
mining the body’s chemical Data retrieved from Earth’s highest
defense system. mountains show that the water
By Akiko Iwasaki and supply to two billion people
Patrick Wong is changing. By Walter Immerzeel
P U B L I C H E A LT H MEDICINE
42 The Very Real Death Toll 62 Malignant Cheaters
of COVID-19 Cells coexist by cooperating.
President Trump and other When some break the rules,
NASA, JPL AND UNIVERSITY OF ARIZONA
cancers result. By Athena Aktipis O N THE C OVE R
conspiracy fantasists touted
J urassic Park m
ade D ilophosaurus famous before
the fake claim that COVID death S PAC E S C I E N C E scientists had a thorough understanding of
counts are exaggerated. But 68 Dynamic Planet this dinosaur. A new analysis of Dilophosaurus
three kinds of evidence point For 15 years the Mars Reconnais remains has provided the most detailed picture
yet of a dinosaur of its vintage and revealed the
to more than 250,000 deaths, sance Orbiter has transformed
creature as it truly was: a large-bodied, nimble
a toll that grows every day. our view of the Red Planet. predator that hunted other dinosaurs.
By Christie Aschwanden By Clara Moskowitz Illustration by Chase Stone.
January 2021, ScientificAmerican.com 1
© 2020 Scientific American
4 From the Editor
6 Letters
10 Science Agenda
Time to get Internet regulation right. By the Editors
11 Forum
Young people will pay the price if we ignore the fate of
nature while fighting the pandemic. By Jordan Salama
12 Advances
11 Little crabs’ ecosystem-shaping impact. Secrets of the Ice
Age locked in soil. A high-tech tracker for rhinoceros foot
prints. Ancient Peruvian farmers harnessing epic floods.
22 Meter
Restoring alewives to their rightful aquatic homes.
By Alison Hawthorne Deming
24 The Science of Health
Education makes a dramatic difference in how well
you age. By Claudia Wallis
76 Recommended
A celebration of all things bird. How our brains dream.
12
Probing the central messages of modern physics.
Pioneering sisters of medicine. B y Andrea Gawrylewski
77 Observatory
In moments of national disunity, we may be tempted
to imagine a reinvigorated program of space exploration
bringing us back together. By Naomi Oreskes
78 50, 100 & 150 Years Ago
By Dan Schlenoff
80 Graphic Science
The good and bad news about cholesterol.
77 By Mark Fischetti and Jen Christiansen
Scientific American (ISSN 0036-8733), Volume 324, Number 1, January 2021, published monthly by Scientific American, a division of Springer Nature America, Inc., 1 New York Plaza, Suite 4600, New York, N.Y. 10004-1562.
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2 Scientific American, January 2021
© 2020 Scientific American
FROM
THE EDITOR Laura Helmuth is editor in chief of Scientific American.
Follow her on Twitter @laurahelmuth
How Science the early universe and how any unusual discovery is first assumed
to be a software bug before it is accepted. Turn to page 26.
Works We’re in a great age of dinosaur discoveries. Starting on page
46, fossil experts Matthew A. Brown and Adam D. Marsh show
how much has been learned about Dilophosaurus, our cover Dino
The heroes o f the COVID-19 pandemic are legion: nurses, doctors Star, since it appeared in the film J urassic Park i n 1993. They point
and others who care for the sick; epidemiologists and public health out that paleontology is more tedious and less glamorous than
experts who track the disease and offer clear lifesaving guidance; how it’s depicted in movies, but understanding the bodies and
and everyone who masks up and avoids crowds and protects their habitats and behaviors of a 183-million-year-old dinosaur is the
own health and the health of their communities. And around the next best thing to bringing it back to life.
world many scientists are working practically nonstop to under- Some data are harder to gather than others. To understand
stand the virus, how it spreads and what it does to the body. the water cycle that sustains billions of people, mountain hydrol-
We learned more about the immune system in 2020 than in ogist Walter Immerzeel and his colleagues camp at 5,300 meters
any year in history. Akiko Iwasaki heads one of the labs leading elevation (about 17,400 feet) and go higher to set up monitoring
the global effort to save people from COVID-19. Starting on stations that have been twisted by winds and knocked over by
page 34, she and grad student Patrick Wong explain how the avalanches. As he reports on page 54, climate change is disrupt-
immune system reacts to the new virus and how that knowledge ing ice melt, monsoons and river flows, and the consequences
might lead to new treatments. They describe how their team took could be catastrophic.
on the urgent challenge and how the process of science changed Evolutionarily, we are all well-functioning cellular civili
in 2020 ( p
age 40). zations, according to psychologist and evolutionary biologist
Understanding the process of science can protect people Athena Aktipis (page 62). Multicellularity has a lot of advantag-
against misinformation—or at least we hope so. One of the out- es, and it has led to exquisite cooperation. But when some cells
rageous myths about the pandemic is that the death toll is exag- cheat, they can threaten the entire organism. Thinking of cancer
gerated. It’s not. More than a quarter of a million people in the cells as cheaters has led to new approaches to treatment.
U.S. have died of COVID-19 as of November. Beginning on page 42, When things get tumultuous on our planet, it’s a nice escape
journalist Christie Aschwanden details how we know the disease to look at another one. The Mars Reconnaissance Orbiter has
has become the third leading cause of death in the U.S. been photographing the Red Planet for 15 years now, and on page
One of the most intriguing stages in the process of science is 68 senior editor Clara Moskowitz shares some of the most gor-
noticing when something is ... weird. Astronomers using new tools geous views. They reveal that Mars has dust devils, landslides
to see parts of space that had been shrouded by dust have observed and asteroid impacts just like Earth does.
that galaxy clusters formed much faster than anyone expected and All of us at Scientific American w ish you a Happy New Year.
that they seem to be too big for our universe. Grad student Arian- We hope your 2021 is healthy and full of pleasant discoveries. And
na S. Long recounts the excitement of rethinking the time line of may science keep showing us more ways to save lives.
BOARD OF ADVISERS
Robin E. Bell Jonathan Foley John Maeda
Research Professor, Lamont-Doherty Earth Observatory, Executive Director, Project Drawdown Global Head, Computational Design + Inclusion, Automattic, Inc.
Columbia University Jennifer A. Francis Satyajit Mayor
Emery N. Brown Senior Scientist, Woods Hole Research Center Senior Professor, National Center for Biological Sciences,
Edward Hood Taplin Professor of Medical Engineering Tata Institute of Fundamental Research
Carlos Gershenson
and of Computational Neuroscience, M.I.T., John P. Moore
Research Professor, National Autonomous University of Mexico
and Warren M. Zapol Professor of Anesthesia, Harvard Medical School Professor of Microbiology and Immunology,
Alison Gopnik Weill Medical College of Cornell University
Vinton G. Cerf
Professor of Psychology and Affiliate Professor Priyamvada Natarajan
Chief Internet Evangelist, Google
of Philosophy, University of California, Berkeley Professor of Astronomy and Physics, Yale University
Emmanuelle Charpentier
Lene Vestergaard Hau Donna J. Nelson
Scientific Director, Max Planck Institute for Infection Biology,
Mallinckrodt Professor of Physics and of Applied Physics, Professor of Chemistry, University of Oklahoma
and Founding and Acting Director, Max Planck Unit for the
Harvard University Lisa Randall
Science of Pathogens
Hopi E. Hoekstra Professor of Physics, Harvard University
Rita Colwell
Alexander Agassiz Professor of Zoology, Harvard University Martin Rees
Distinguished University Professor, University of Maryland College Park Astronomer Royal and Professor of Cosmology and Astrophysics,
and Johns Hopkins Bloomberg School of Public Health Ayana Elizabeth Johnson
Institute of Astronomy, University of Cambridge
Founder and CEO, Ocean Collectiv
Kate Crawford Daniela Rus
Director of Research and Co-founder, AI Now Institute, Christof Koch Andrew (1956) and Erna Viterbi Professor of Electrical Engineering
and Distinguished Research Professor, New York University, Chief Scientist, MindScope Program, Allen Institute for Brain Science and Computer Science and Director, CSAIL, M.I.T.
and Principal Researcher, Microsoft Research New York City Meg Lowman Meg Urry
Nita A. Farahany Director and Founder, TREE Foundation, Rachel Carson Fellow, Israel Munson Professor of Physics and Astronomy, Yale University
Professor of Law and Philosophy, Director, Ludwig Maximilian University Munich, and Research Professor, Amie Wilkinson
Duke Initiative for Science & Society, Duke University University of Science Malaysia Professor of Mathematics, University of Chicago
4 Scientific American, January 2021 Illustration by Nick Higgins
© 2020 Scientific American
LETTERS
editors@sciam.com
“A great sadness legacies will continue to distort scientific
inquiry. Science is a social enterprise, and
has overtaken me it is shaped not only by theories and data
as I parse the odds but also by personal experience, common
sense and the social uses to which it is put.
of life on this planet Research may gain currency not from the
making it through. weight of evidence but because it serves
the political and economic interests of
Let’s keep our those with the power to promulgate it (for
fingers crossed.” example, by justifying economic and racial
inequality). When that happens, it has an
susan williams l akewood, colo.
enduring, distorting effect on science.
Once absorbed into received knowledge,
such research misinforms subsequent sci
clients were losing the abilities we had entific judgments.
helped them develop to integrate into the Thus, to foster accuracy in the field, we
larger community, to pursue lives of mean must do more than weigh the existing evi
ing and purpose. dence. We must evaluate how relevant
September 2020 Of course, we created a daily schedule evidence may have been shaped by sci
of Zoom classes, but not every client is ence’s social uses and actively investigate
able to participate or benefit from those. and correct resulting errors. That is, act
NATURAL HISTORY REPEATS And without our structure, some of our ing with integrity as scientists requires
“The Worst Times on Earth,” by Peter clients engaged in behaviors at home that applying sociopolitical theories about how
Brannen, describes past mass extinctions endangered them and sometimes their our political economy shapes scientific
and what they could mean for our future. family members. belief and organizing to overturn distort
Brannen has written one of the most beau I beg the authors and your readers not ing forces.
tiful and poignant pieces I’ve ever read to write off those whose opinions are dif Contrary to many scientists’ demands
here, all the more so because a great sad ferent from yours as oppressors or worse. for a “politics-free science,” merely using
ness has overtaken me as I parse the odds Schwartz and Schlenoff ask “how else sociopolitical theories to assess evidence
of life on this planet making it through. to explain” some people’s advocacy for is not “bias.” The reverse is true: failing
Let’s keep our fingers crossed. “going back to normal.” But there are other to consider how our political economy
Susan Williams L akewood, Colo. ways to explain it. Rather than assuming shapes scientific evidence heightens the
those advocates believe “some of us are risk of error.
SCIENCE VS. ANTISCIENCE inherently more worthy of life than oth Jerzy Eisenberg-Guyot and
In their article, “Reckoning with Our Mis ers,” put yourselves in the shoes of our Nadja Eisenberg-Guyot New York City
takes,” Jen Schwartz and Dan Schlenoff clients and their families. They want the
state, “Americans who are willing to sac best for their loved ones, and that may Schwartz and Schlenoff note that only half
rifice the lives of people who are disabled, mean masks and social distancing rather of Americans responded to a poll that they
poor, elderly or from historically op than lockdowns. would get a coronavirus vaccine when it
pressed groups so that the U.S. economy Renee Kameah is available, which they called an “anti
can ‘go back to normal’ sound like mod Rockland County, New York State science” stance.
ern-day eugenicists.” The authors should be very careful of
I am supervisor of a day program for It is laudable that Scientific American ac the context of the poll and answers to it. I
adults with intellectual and physical dis knowledges, and endeavors not to repeat, am not in any way an anti-vaxxer. My wife
abilities. After we were required to close our its role in disseminating and legitimizing and I get flu shots annually and were dil
program in late March, I received continu scientific racism, sexism and imperialism. igent in keeping our children up-to-date
ous calls pleading for information about Human fallibility aside, Schlenoff and on their inoculations when they were
when we would reopen. These calls came Schwartz mention several sources of sci young. But if I were asked whether I would
from the individuals we serve, as well as entific error, but they do not mention the get the hypothetical coronavirus vaccine,
their families. Our clients missed their potential for systematic error de riving I’m not sure how I would answer.
friends and our structured program of voca from scientific methodology itself. After watching the Food and Drug
tional and social-skills classes, the volun Because we can only gauge the likely Administration’s and Centers for Disease
teer jobs we facilitate for them around the truth of new hypotheses by drawing on Control and Prevention’s responses to the
community daily, our healthy lifestyle activ existing beliefs, insofar as histories of rac pandemic, I fear that the basis for far too
ities, and more. ism, sexism and imperialism shape our many of their decisions concerns politics,
Parents’ constant concern was that our current corpus of scientific belief, these not science. These government agencies
6 Scientific American, January 2021
© 2020 Scientific American
LETTERS
editors@sciam.com
ESTABLISHED 1845
EDITOR IN CHIEF
Laura Helmuth
MANAGING EDITOR Curtis Brainard COPY DIRECTOR Maria-Christina Keller CREATIVE DIRECTOR Michael Mrak
seemed to have become a wing of the com
EDITORIAL
mittee to reelect President Donald Trump. CHIEF FEATURES EDITOR Seth Fletcher CHIEF NEWS EDITOR Dean Visser CHIEF OPINION EDITOR Michael D. Lemonick
John Melquist C aledonia, Ill. FEATURES
SENIOR EDITOR, SUSTAINABILITY Mark Fischetti SENIOR EDITOR, SCIENCE AND SOCIETY Madhusree Mukerjee
SENIOR EDITOR, CHEMISTRY / POLICY / BIOLOGY Josh Fischman SENIOR EDITOR, TECHNOLOGY / MIND Jen Schwartz
SENIOR EDITOR, SPACE / PHYSICS Clara Moskowitz SENIOR EDITOR, EVOLUTION / ECOLOGY Kate Wong
THE AUTHORS REPLY: Melquist’s point
NEWS
is well taken. In criticizing individuals’ SENIOR EDITOR, MIND / BRAIN Gary Stix ASSOCIATE EDITOR, SUSTAINABILITY Andrea Thompson
SENIOR EDITOR, SPACE / PHYSICS Lee Billings ASSOCIATE EDITOR, HEALTH AND MEDICINE Tanya Lewis
unwillingness to receive a potential vac- ASSOCIATE EDITOR, TECHNOLOGY Sophie Bushwick ASSISTANT NEWS EDITOR Sarah Lewin Frasier
cine against COVID-19 in our article, we MULTIMEDIA
SENIOR EDITOR, MULTIMEDIA Jeffery DelViscio
indeed meant one that would be well test- SENIOR EDITOR, AUDIENCE ENGAGEMENT Sunya Bhutta SENIOR EDITOR, COLLECTIONS Andrea Gawrylewski
ed, well studied, well prepared, and rec- ART
ART DIRECTOR Jason Mischka SENIOR GRAPHICS EDITOR Jen Christiansen
ommended on a sound scientific and sta- PHOTOGRAPHY EDITOR Monica Bradley ART DIRECTOR, ONLINE Ryan Reid
tistical basis. ASSOCIATE GRAPHICS EDITOR Amanda Montañez ASSISTANT PHOTO EDITOR Liz Tormes
COPY AND PRODUC TION
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MITIGATING LETHAL FORCE MANAGING PRODUCTION EDITOR Richard Hunt PREPRESS AND QUALITY MANAGER Silvia De Santis
In “How to Reinvent Policing” [Science CONTRIBUTOR S
EDITORS EMERITI Mariette DiChristina, John Rennie
Agenda], the editors make a number of
Gareth Cook, Katherine Harmon Courage, Lydia Denworth,
EDITORIAL
good points about bettering policing by Ferris Jabr, Anna Kuchment, Robin Lloyd, Steve Mirsky,
Melinda Wenner Moyer, George Musser, Ricki L. Rusting,
improving police accountability and com Dan Schlenoff, Dava Sobel, Claudia Wallis
munities’ perception of officers. They do ART Edward Bell, Zoë Christie, Lawrence R. Gendron, Nick Higgins, Katie Peek, Beatrix Mahd Soltani
not mention, however, that improvements EDITORIAL ADMINISTRATOR Ericka Skirpan EXECUTIVE ASSISTANT SUPERVISOR Maya Harty
can also be made to hiring practices.
Police departments should recruit can SCIENTIFIC A MERIC AN CUS TOM MEDIA
MANAGING EDITOR Cliff Ransom CREATIVE DIRECTOR Wojtek Urbanek
didates who have good problem-solving, MULTIMEDIA EDITOR Kris Fatsy MULTIMEDIA EDITOR Ben Gershman
ENGAGEMENT EDITOR Dharmesh Patel ACCOUNT MANAGER Samantha Lubey
negotiation, communication and interper
sonal skills, as well as empathy and sensi ACTING PRESIDENT
tivity. They can come close to achieving Stephen Pincock
that goal by expanding their pool to in EXECUTIVE VICE PRESIDENT Michael Florek VICE PRESIDENT, COMMERCIAL Andrew Douglas
PUBLISHER AND VICE PRESIDENT Jeremy A. Abbate
clude more women, minorities and college
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force that un derstands that all people DIRECTOR, INTEGRATED MEDIA Matt Bondlow
should be treated with dignity, respect BUSINESS DEVELOPMENT Stan Schmidt
HEAD, PUBLISHING STRATEGY Suzanne Fromm
and fairness.
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O PINI O N A N D A N A LYS I S FR OM
S C IENTIFIC A MERIC AN ’ S B OA R D O F E D ITO R S
Politicians and list allowed erotic listings, the o verall female homicide rate
dropped by 10 to 17 percent. Although other researchers have
Tech Billionaires
contested the link between online advertising and greater safe-
ty, consensual sex workers have reported negative effects as a
result of FOSTA-SESTA.
Can’t Fix Joe Biden and Donald Trump have both called for outright
repeal of Section 230. Others in Congress are proposing less rad-
Social Media
ical changes, offering bills such as the Platform Accountability
and Consumer Transparency (PACT) Act, which would require
social media companies to disclose their moderation practices to
show they are not arbitrary and to promptly take down content
Laws to stop malicious use that a court deems illegal. The stricter takedown standard would
can backfire without wider input favor wealthy companies such as Facebook, which can afford to
By the Editors employ armies of moderators and lawyers, and disfavor start-
ups—just the problem Section 230 was meant to prevent. In
If the New York Times or the L as Vegas Review-Journal or addition, as they did in response to the laws intended to curtail
Scientific American p ublishes a false statement that hurts some- sex trafficking, smaller platforms are likely to increase overly
one’s reputation, that person can sue the publication. If such def- broad censorship of users to avoid legal challenges.
amation appears on Facebook or Twitter, however, they can’t. The As digital-rights group the Electronic Frontier Foundation
reason: Section 230 of the federal Communications Decency Act. (EFF) points out, hobbling Section 230 could have a chilling
Signed into law in 1996, it states that online platforms—a cate- effect on free speech online and make it much more difficult
gory that includes enormously rich and powerful tech companies for new competitors to challenge the dominance of big tech.
such as Facebook and Google, as well as smaller and less influ- The EFF is not the only voice picking holes in legislation like
ential blog networks, forums and social media start-ups—are not the PACT Act: academics and other technology advocacy
considered “publishers.” You can sue the person who created the groups have offered measured critiques of the bill and pro-
video or post or tweet but not the company that hosted it.
The law was designed to protect Internet companies, many in
their infancy at the time, from legal actions that could have held
Hobbling [the law] could have
back their ability to innovate and grow. But today immunity from a chilling effect on free speech and
consequences has also allowed hate speech, harassment and mis-
information to flourish. In a belated effort to deal with those prob-
make it harder for competitors
lems, the biggest platforms now attempt to flag or ban what they to challenge big tech.
feel are objectionable content generated by users. This often infu-
riates those whose posts or tweets have been singled out, who posed their own solutions for strategically modifying Section
complain their freedom of speech is being suppressed. 230. One of their suggestions is to ensure the bill would apply
Last October the U.S. Senate Committee on Commerce, Sci- only to platforms that host users directly—not to the compa-
ence and Transportation held a hearing about how to modify nies providing background support for functions such as Inter-
the law. But high-handed changes often don’t consider all con- net access and payment processing—to protect the larger infra-
sequences—and that can lead to real danger. Prime examples structure of the Internet from legal liability. Another idea is to
are 2018’s Fight Online Sex Trafficking and Stop Enabling Sex improve users’ ability to flag problematic content by working
Traffickers Acts (FOSTA-SESTA). These laws removed Section with legal authorities to develop a standardized reporting pro-
230’s protections for content that advertises prostitution, in an cess that any platform could apply.
effort to stop victims of sex trafficking from being bought and Input from experts like these—not just from billionaire
sold online. The idea was to use potential legal liability to force CEOs such as Facebook’s Mark Zuckerberg and Twitter’s Jack
platforms to remove content that encouraged such crimes. In Dorsey, the usual suspects when hearings are convened on
practice, sites that lacked the resources to patrol users’ activity Capitol Hill—is crucial to craft nuanced legislation that will
ended up banning legitimate pages where illegal content had give online platforms incentives to protect users from harass-
appeared in the past, deleting large swaths of material or shut- ment and to suppress malicious content without unduly com-
ting down entirely. The purge kicked consensual sex workers promising free speech. If that happens, we might get Internet
out of online spaces they had used to find clients and assess regulation right.
any risk of harm before agreeing to in-person meetings. With-
out the ability to screen clients online, prostitution can be
J O I N T H E C O N V E R S AT I O N O N L I N E
extremely dangerous; one 2017 paper, updated in 2019, sug- Visit Scientific American on Facebook and Twitter
gests that in cities where the online classified ad service Craigs or send a letter to the editor: editors@sciam.com
10 Scientific American, January 2021
© 2020 Scientific AmericanFORUM
Jordan Salama is a writer and journalist. His first book, C OMM E N TA RY O N S C IE N C E IN
Every Day the River Changes, a book of travels along the greatest T H E N E W S FR OM T H E E X PE R T S
river in Colombia, will be published by Catapult in 2021.
Earth Is on Fire
COVID is no excuse to ignore
environmental flames
By Jordan Salama
I’ve never known a n Earth that wasn’t on fire.
I’m 23 years old, and my entire generation has come of age in
a world so defined by climate change and other forms of environ-
mental degradation that it’s sometimes been hard to fathom what
an even more dismal future might look like. It has, that is, until
the pandemic reared its ugly head. The fate of nature, like so much
else, has temporarily become an agonizing side story to COVID—
and now the environment is a real-time plot followed mostly, I
think, by those of us young enough to one day see the worst of it.
At first, things seemed hopeful. Struggling to adjust to the
new normal of life in quarantine in March and April, we were
relieved to read that emissions levels had dipped, even if only
temporarily, and that the skies over New Delhi and Los Angeles
and Buenos Aires had cleared of smog. I smiled, as we all did, to
notice that animals were roaming free through quiet, traffic-free
cities. Nature seemed to be reclaiming spaces humans had aban- ecological price for the rest of our lives. I’m not just talking about
doned. In the midst of so much present grief, these story lines those of us living in developed nations. I’m talking about chil-
gave us faith in the planet’s resilience. Maybe, some optimists dren from impoverished families worldwide whose health and
speculated, it would even inspire us to be better stewards of our food security have plunged into even more uncertainty because
world when this was over. This “anthropause” was a once-in-a- of the devastating one-two punch of climate change and the
lifetime opportunity for humans to understand our impact on coronavirus—both of which have laid bare systemic racism and
wildlife in a crowded world that seemed, for a moment, a little socioeconomic inequities. I’m talking about young climate orga-
less crowded. nizers across the globe who have been calling out people’s igno-
But only for a moment. Pandemics like this happen and will rance of science for years and feel now more than ever that
keep happening because we humans have long encroached on they’re screaming into a void. And, perhaps most brutally, I’m
wild spaces, increasing the chances of spillovers of disease from talking about young Indigenous people in Latin America, whose
animals to people. In the temporary absence of international entire cultures (many of them predicated on harmony with
watchdogs and local enforcement, South America’s Pantanal, the nature) are being erased as their elders die of infection and as
world’s largest tropical wetland, has burned like never before. In ranchers and miners violently and illegally drive them from their
May there was a major oil spill in the Russian Arctic, followed by ancestral lands.
others in places such as Mauritius and Venezuela—terrible eco- In today’s pandemic moment, nature’s story line has reached
logical catastrophes that are buried underneath headlines of case a low point. It’s unfathomable to me that some people can still so
numbers and mortality rates. Poaching is on the rise in Africa. easily shrug it off—especially if they have kids or love anyone who
The list goes on. is younger than they are—while for so many in my generation, it
And in the U.S., we’ve somehow become l ess t houghtful in our is such a constant, excruciating worry. Apathy, let alone denial, is
daily choices—accepting that extra plastic bag at the supermar- no longer an acceptable option, because we know that if we stay
ket, ordering takeout despite all the single-use containers and, on this course, the destruction will inevitably come for us, too.
if we’re privileged enough, driving instead of taking public trans- But I like to think that the anthropause still gives some hope—
portation—because, well, “it’s a global pandemic.” Take a walk that perhaps if we all live a little lighter, if we listen to those who
outside, and you’ll find masks and latex gloves littering our are in harmony with the land and if we take solace in all that there
streets and beaches and parks that will eventually fill rivers, is to love in the world, nature might meet us halfway. The planet
lakes and seas. and our fates hang in the balance.
It’s as if the pandemic has suddenly given people everywhere
even more of a license to dirty the world—if that’s even possi-
J O I N T H E C O N V E R S AT I O N O N L I N E
ble—with carelessness, if not outright contempt. I fear that for Visit Scientific American on Facebook and Twitter
every day it continues, today’s young people will be paying the or send a letter to the editor: editors@sciam.com
Illustration by Brooke VanDevelder January 2021, ScientificAmerican.com 11
© 2020 Scientific AmericanADVANCES
1
Tidal creeks cross Sapelo Island’s
salt marshes (1) and are expanding
because of purple marsh crabs (2) .
12 Scientific American, January 2021
© 2020 Scientific AmericanD I S PATC H E S FR OM T H E FR O N TIE R S O F S C IE N C E , T E C H N O LO GY A N D M E D I C IN E IN S ID E
• A queen bee’s sperm-storing sac
holds clues to colony collapse
• Lasers reveal huge sequoias are
even bigger than thought
• Tiny crystals spur dangerous
volcanic eruptions
• Gruesome blood worms infected
an unfortunate dinosaur
E C O LO G Y
Losing Ground
Sea-level rise is letting a tiny crab
drastically alter marsh landscapes
Halfway down G eorgia’s coastline, Sapelo
Island is surrounded by more than 4,000
acres of salt marshes, with vast stretches
of lush grasses that blaze gold in the colder
months. But this beautiful barrier island is
experiencing some of the harshest effects
of climate change: seawater intrusion, intense
storms and flooding.
And scientists have noticed something
more subtle and unusual happening to the
island in the past several years. A once
inconspicuous burrowing crab is suddenly
wiping out swaths of marsh cordgrass, a
plant that holds much of the South’s coastal
marshland in place and protects vulnerable
species. The tiny purple marsh crab, S esar-
ma reticulatum, seems to be reshaping—
and fragmenting—the island’s marshes.
Sinead Crotty, an ecologist and project
director at Yale University’s carbon-con-
tainment laboratory, used aerial images to
document the crab’s impact on marshland
along the U.S.’s southeastern coast. To
investigate the cause of the changes, Crotty
and her colleagues combined analysis of
the aerial imagery with historical tide data
2 and numerical models of sea-level rise.
Their results, published in the Proceedings
of the National Academy of Sciences USA,
show the crabs are altering salt marshes’
response to sea-level rise by gorging on
JOHN SCHALLES (1 ) ; SINEAD CROTTY (2 )
cordgrass at the heads of tidal creeks. The
researchers say rising water levels caused
by climate change have softened marsh soil,
creating optimal burrowing conditions for
the crabs. The crabs’ increased activity then
results in longer and broader creeks that
drain the marshes into the ocean. Over years
J O I N T H E C O N V E R S AT I O N O N L I N E Visit Scientific American on Facebook and Twitter
© 2020 Scientific AmericanADVANCES
this process transforms marshes from con- crabs to gain a significant claw-hold, and ing and acidification make it easier for pred-
tiguous grasslands into patches fractured by Crotty and her colleagues wondered if sea- ators such as sea urchins to gnaw away at
crab-grazed creeks. level rise could be making them softer. coral. Native plants are losing ground to
This finding challenges the long-standing The team analyzed tidal data and found exotic varieties that can bloom earlier as
paradigm that only water flow, sediment, that southern marshes are now submerged weather warms. Higher temperatures in the
plants and human activity—not animals— up to an hour longer a day than they were in Caribbean could help invasive, reef-destroy-
shape how salt marshes respond to sea-level the 1990s. The researchers say this process ing lionfish expand their range there. But
rise. The researchers say this crab may be has indeed softened the soil, helping the scientists have not previously documented
the first identified organism to reach the sta- burrowing crabs thrive. Aerial photographs such organisms exerting the kind of influ-
tus of a keystone species, an organism that along the U.S.’s southeastern coast indicate ence purple marsh crabs do over the way an
has disproportionate importance and influ- the number of S esarma-grazed marsh ecosystem functions, from its actual shape
ence in its ecosystem, because of climate creeks increased by an average of two and to the interplay between predators and prey.
change. It is unlikely to be the last. a half times from the 1990s to late 2010s. In “I have no reason to doubt that climate
Crotty says it is mind-boggling that “this study areas, the team found that the rapid change will alter species’ interactions such
very small organism, an inch or two in diam- expansion of crab-grazed creeks increased that new keystone species emerge,” says
eter, can alter something as large as an drainage of the marsh by up to 35 percent. Linda Blum, an ecologist at the University
entire marsh landscape visible from Google By wiping out cordgrass, crabs also de of Virginia, who was not involved in the
Earth images.” stroy protective cover for ecologically critical study. But, she adds, the team’s conclusion
Scientists working on Georgia’s coast animals, including snails and other mollusks. that sea-level rise creates new crab habitat
already knew Sesarma crabs were enlarging The researchers checked predation levels on by softening marsh soil is built on “a lot of
tidal creeks by grazing cordgrass, says Mer- Sapelo Island by tethering snails and mussels circumstantial evidence.” She suggests it
ryl Alber, director of the University of Geor- to fishing line near grazed and ungrazed should be tested with field experiments to
gia Marine Institute on Sapelo Island. But this creeks. They found this loss of cover can determine whether the crabs’ own activi-
new work suggests the crabs’ actions may make small invertebrates—which provide ties could contribute to easier burrowing.
be accelerating the long-term loss of the food to commercially important species such Now the researchers are investigating
marsh to rising seas. “This shows that our as blue crab and redfish—more vulnerable how increased activity from Sapelo Island’s
marshes may be more vulnerable than we to predator feeding frenzies, Crotty says, Sesarma crabs might be exposing buried car-
thought,” she says. Alber was not directly potentially disrupting entire ecosystems. bon to the air, as well as if the crabs are rais-
involved in the study, but the institute provid- Human activities are resetting which ing concentrations of contaminants from a
ed logistical support to the research team. species hold the most sway over ecosys- nearby superfund site by accumulating these
Crotty first encountered S esarma as an tem behavior, says Christine Angelini, an chemicals in their bodies.
undergraduate in co-author Mark Bertness’s ecologist at the University of Florida and More work is also needed to understand
Brown University lab. In 2011 Bertness’s principal investigator for the study. Because whether the crabs are influencing how
team discovered that the crabs were behind of overfishing and climate change, she quickly seas move inland, Angelini says:
sudden marsh die-offs on Cape Cod, after observes, purple marsh crabs are “wreak- “We don’t know if it’s the first step toward,
overfishing had diminished predator popula- ing havoc everywhere” across their range. ultimately, the marsh drowning or if marsh-
tions such as striped bass. Marsh soils farther Climate change has given several spe- es will stay stable and persist for decades in
south had previously been too hard for the cies a dangerous advantage. Ocean warm- this fractured state.” —Stephenie Livingston
P S YC H O LO G Y
Applied
least one real-world situation, a single eth- 11-minute video on the topic and joined a
ics lesson may have had lasting effects. 50-minute discussion. The other half
Ethics
The researchers investigated one class focused on charitable giving instead. Then,
session’s impact on eating meat. They unbeknownst to the students, the research-
chose this particular behavior for three rea- ers studied their anonymized meal-card
One college class discussion sons, according to study co-author Eric purchases for that semester—nearly 14,000
had weeks-long effects on Schwitzgebel, a philosopher at the Univer- receipts for almost 500 students. “It’s an
meat consumption sity of California, Riverside: students’ atti- awesome data set,” says Nina Strohminger,
tudes on the topic are variable and unsta- a psychologist who teaches business ethics
Although ethics classes are common ble, behavior is easily measurable, and eth- at the University of Pennsylvania and was
around the world, scientists are unsure if ics literature largely agrees that eating less not involved in the study.
their lessons can actually change behavior; meat is good because it reduces environ- Schwitzgebel predicted the interven-
evidence either way is weak, relying on mental harm and animal suffering. Half of tion would have no effect; he had previ-
contrived laboratory tests or sometimes the students in four large philosophy class- ously found that ethics professors do not
unreliable self-reports. But a new study es read an article on the ethics of factory- differ from other professors on a range of
published in Cognition f ound that, in at farmed meat, optionally watched an behaviors, including voting rates, blood
14 Scientific American, January 2021
© 2020 Scientific AmericanIntelligent
BBIIO
OLO
LOG
GYY
mystery stories
Clues to for the
Collapse scientifically-inclined!
Analyzing fluid from queen
Honeybee
Honeybee colonies
colonies
bees’ specialized sperm sacs
depend
depend onon the
the queen’s
queen’s
can expose colony stressors store
store of
of sperm.
sperm.
AA honeybee
honeybee queen queen mates ates only
m only during
during one one To examine
To examine queen queen failure,
failure, McAfee
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her life,
life, storing
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sperm in in aa her colleagues
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performed aa “molecular
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sac inside
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body for for later
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which they
they analyzed
analyzed the the fluid
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keep that
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sperm viable,
viable, her
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colony inside sperm-storing
inside sperm-storing sacs sacs after
after exposing
exposing
may collapse.
may collapse. This
This “queen
“queen failure”
failure” is is aa main
main queens to
queens to extreme
extreme heat,
heat, extreme
extreme cold cold oror
factor in
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the U.S.
U.S. drop-off
drop-off in in bee
bee numbers.
numbers. pesticides. They
pesticides. They found
found that that each
each stressor
stressor
Identifying reasons
Identifying reasons for for queen
queen failure
failure has has was associated
was associated with with elevated
elevated levels levels ofof dif-
dif-
proved difficult;
proved difficult; queens
queens show show no no clear
clear ferent proteins
ferent proteins in in the
the fluid.
fluid.
symptoms when
symptoms when itit happens.
happens. But But aa new
new The researchers
The researchers identified
identified the the two
two most
most
study offers
study offers aa way
way to to zero
zero in in on
on causes,
causes, elevated proteins
elevated proteins as as indicators
indicators for for each
each
which could
which could lead
lead to to aa valuable
valuable diagnostic
diagnostic stressor. When
stressor. When they they looked
looked for for these
these inin
tool for
tool for beekeepers.
beekeepers. failed queens
failed queens donated
donated by by British
British Columbia
Columbia
The queen
The queen is is the
the only
only female
female in in her
her colo-
colo- beekeepers, they
beekeepers, they found
found proteins
proteins indicating
indicating Expanded second edition in 2020!
ny who
ny who can
can reproduce.
reproduce. Without Without viableviable exposure to
exposure to pesticides
pesticides and and extreme
extreme heat heat Fourteen stories, six essays.
sperm she
sperm she cannot
cannot lay lay eggs,
eggs, and and the
the colony’s
colony’s but not
but not extreme
extreme cold.cold. TheThe results
results were were pub-
pub- Find treasures!
population plummets,
population plummets, says says Alison
Alison McAfee,
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lished BMC Genomics.
in BMC Genomics. Several stories based on actual events.
first author
first author of of the
the study
study and and aa bee
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McAfee and her
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using One of the nine best collections of
er at
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North Carolina
Carolina State State University.
University. This This is
is these results
these results to to develop
develop aa diagnostic
diagnostic test test short stories published in 2019 in
aa significant
significant concern
concern for for humans;
humans; as as pollina-
pollina- that distinguishes
that distinguishes between between different
different causes
causes the USA… — American Book Fest
tors of
tors of crops
crops such
such as as blueberries
blueberries and and apples,
apples, of queen
of queen failure.
failure. This
This tool
tool isis in
in its
its early
early stag-
stag-
“honeybees are
“honeybees are responsible
responsible for for around
around es, but
es, but Susan
Susan Cobey,
Cobey, aa bee bee researcher
researcher at at “If your reading tastes bend toward
between $16
between $16 billion
billion and
and $20 $20 billion
billion worth
worth of of Washington State
Washington State University,
University, who who was was not
not intellectual challenge, you will
economic contribution
economic contribution to to agriculture,”
agriculture,” says says involved in
involved in the
the study
study andand runs
runs aa bee-insemi-
bee-insemi- revel in Magner’s mastery.”
McAfee, who
McAfee, who also
also works
works for for the
the University
University nation business,
nation business, isis excited
excited by by its
its potential:
potential: — Prof. Leonard Engel,
of British
of British Columbia.
Columbia. ClimateClimate changechange further
further “If you
“If you can can determine
determine what’swhat’s going
going on on with
with Quinnipiac University
threatens honeybees’
threatens honeybees’ survival,
survival, with with previ-
previ- [the queens]
[the queens] and and take
take some
some preventive
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ous research
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showing that that high
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GETTY
tures are
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also associated
associated with with colony
colony loss.loss. would be
would be awesome.”
awesome.” Karen Kwon
—Karen
— Kwon relaxed…” — Kirkus Reviews
Very clever! The perfect gift!
donation and
donation and returning
returning library
library books.
books. But But Schwitzgebel suspects
Schwitzgebel suspects the
the greatest
greatest Solve clues to buried gold
among student
among student subjects
subjects who who discussed
discussed impact came
impact came from
from social
social influence—class-
influence—class- using a math trick // Thrill to
meat ethics,
meat ethics, meal
meal purchases
purchases containing
containing mates or
mates or teaching
teaching assistants
assistants leading
leading the
the a chemist’s escape from Nazi-
meat decreased
meat decreased from from 5252 toto 45
45 percent—
percent— discussions may
discussions may have
have shared
shared their
their own
own occupied Vienna using one of the
and this
and this effect
effect held
held steady
steady forfor the
the study’s
study’s vegetarianism, showing
vegetarianism, showing itit as
as achievable
achievable most ingenious smuggling
duration of
duration of several
several weeks.
weeks. Purchases
Purchases from from or more
or more common.
common. Second,
Second, thethe video
video may
may schemes in history // Win big
the other
the other group
group remained
remained at at 52
52 percent.
percent. have had
have had anan emotional
emotional impact.
impact. Least
Least rous-
rous- money playing poker // Secure loot
“That’s actually
“That’s actually aa pretty
pretty large
large effect
effect for
for aa ing, he
ing, he thinks,
thinks, was
was rational
rational argument,
argument, from a Spanish shipwreck // Search
pretty small
pretty small intervention,”
intervention,” Schwitzgebel
Schwitzgebel although his
although his co-authors
co-authors (University
(University ofof Kan-
Kan- an aunt’s house for hidden cash //
says. Strohminger
says. Strohminger agrees:
agrees: “The
“The thing
thing that
that sas’s Bradford
sas’s Bradford Cokelet
Cokelet and
and Princeton
Princeton Uni-
Uni- Escape from kidnappers using a
still blows
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mind isis that
that the
the only
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versity’s Peter Singer)
Singer) say
say reason
reason might
might sly ruse // Break a code that
that’s different
that’s different between
between thesethese two
two cases
cases isis play aa bigger
play bigger role.
role. Now
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the researchers
researchers reveals a sinister plot
just that
just that one
one dayday in
in class.”
class.” She
She says
says she
she wants
wants are probing
are probing the the specific
specific effects
effects ofof teaching
teaching
the effect
the effect toto be
be real
real but
but cannot
cannot rule
rule out
out some
some style, T.A.s’
style, T.A.s’ eating
eating habits
habits and
and students’
students’ Order at Amazon, other sellers, or
unknown confounding
unknown confounding variable.
variable. And
And ifif real,
real, video exposure.
video exposure. Meanwhile
Meanwhile Schwitzgeb-
Schwitzgeb- www.seekinghiddentreasures.com
Strohminger notes,
Strohminger notes, itit might
might be be reversible
reversible by by el—who had
el—who had predicted
predicted no
no effect—will
effect—will bebe E-book $4.99 / Paperback / Hard cover
another nudge:
another nudge: “Easy
“Easy come,
come, easyeasy go.”
go.” eating his
eating his words.
words. — Matthew Hutson
—Matthew Hutson
January
January 2021, ScientificAmerican.com 15
2021, ScientificAmerican.com 15
© 2020 Scientific AmericanADVANCES
GENETIC S This big picture comes from smaller sam-
Getting Dirt
ples, Murchie explains: “With a combination
of our novel extraction and enrichment tech-
niques, we can pull out entire genomes of
Ancient DNA preserved in soil multiple extinct organisms simultaneously
may rewrite Ice Age knowledge we’re interested in,” says McMaster Uni- from less than a gram of sediment.”
versity geneticist Tyler Murchie. “We can’t The methodology is limited because
Based on bone a nd tooth records, the afford to lose whatever we can get.” In researchers using it need to know what DNA
Yukon’s last mammoths were thought to Quaternary Reports, M urchie and his col- to look for. If a saber-toothed cat species is
have gone extinct about 12,000 years ago. leagues describe gentler techniques that not already in the genetic library, for exam-
But a new genetic sampling technique sug- recover up to 59 times as much genetic ple, the analysis cannot detect that animal.
gests the great beasts may have stuck material as other methods do. For known species, however, the process
around a lot longer, plodding through the In the new approach, soil samples are may yield exciting information. In their study,
Arctic tundra with bison and elk for thou- extracted with a sterilized chisel and then the researchers detected about 2,100 kinds
sands of years more. The story is in the soil. broken into smaller portions, stirred and of plants and 180 animals—including
Bones are rich sources of prehistoric run through a “cold spin method” to sepa- American horses and woolly mammoths,
genetic information, but not the only ones; rate as much DNA as possible. The DNA is in samples from soil dated to thousands
items ranging from shed Ice Age skin cells to then compared against an existing genetic of years after their supposed extinction.
pine needles can contribute to the genetic library to detect species matches. Not yet published results from other
record stored in dirt. Paleogeneticists have “Not only do these techniques get more field sites are yielding similar results,
been extracting and analyzing “environ- DNA, but they get more diverse DNA,” Murchie says, and future fossil discoveries
mental DNA” from soil for a long time, but says East Tennessee State University pale- could strengthen the case. “We can use
getting rid of non-DNA material without ontologist Chris Widga, who was not this approach to identify species in places
destroying these fragile clues is daunting. involved in the new study. “It’s becoming and times we never knew they existed,”
“Environmental samples contain a huge more nuanced, and it looks like there is he adds, “helping our efforts to find their
range of other chemical substances that actually the potential to document larger fossils in places we wouldn’t have thought
ALAMY
are challenging to separate from the DNA slices of the ecosystem.” to look.” —Riley Black
70
Meters
0
TECH
Sequoia
30 stories off the ground. Now, for the The researchers found that coastal red-
first time, researchers have surveyed woods tended to be about 30 percent larg-
Secrets FROM “NEW 3D MEASUREMENTS OF LARGE REDWOOD TREES FOR BIOMASS AND STRUCTURE,”
S . sempervirens u sing laser scanning, er by volume than published scaling rela-
an automated technique that yields accu- tions predicted. The authors suggest this
rate measurements of a tree’s structure discrepancy might be because some
Lasers illuminate carbon-storing and volume. S. sempervirens s prout additional trunks BY MATHIAS DISNEY ET AL., IN S CIENTIFIC REPORTS, VOL. 10; OCTOBER 15, 2020
capacity of world’s tallest trees Mathias Disney, an environmental sci- as they age, a process called reiteration.
entist at University College London, and Based on their observations, Disney and
California’s coastal redwoods, Sequoia his colleagues assessed 145 redwoods for a his colleagues have established new scal-
sempervirens, a re the tallest trees on earth. study published in Scientific Reports. T
hey ing relations between tree diameter and
But measuring their precise dimensions— fired billions of near-infrared laser pulses at volume for the species.
which is key to determining how much the trees from multiple directions, record- Laser scanning can increase knowledge
climate-altering carbon they store as ing the time it took the pulses to bounce of old-growth forests that is important in
biomass—is fraught with uncertainty. back. This process let them assemble a conservation efforts, says Anil Raj Kizha,
Widely used scaling equations between detailed map of each tree, showing burrs, a forest operations scientist at the Univer-
trunk diameter and volume are based on twigs and other features as small as a few sity of Maine, who was not involved in
limited sampling of much smaller trees, centimeters. “This is giving us a new per- the research. “In the coming five to 10
given that few people are willing to don a spective on the three-dimensional struc- years,” he says, “this is going to be more
climbing harness and take measurements ture of trees,” Disney says. widespread.” —Katherine Kornei
16 Scientific American, January 2021
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