(2021-08) Why Animals Play

88 Pages·2021·24.66 MB·english

by  Scientific American

A New
AUGUST 2021 SCIENTIFICAMERICAN.COM
Understanding
of Alzheimer’s
The Coolest Stars
in the Universe
The Hype about
Hypersonic Weapons
W HY
ANIMALS
PLAY
The rules of the game
for dogs, apes
and elephants
© 2021 Scientific American

August 2021
VOLUME 325, NUMBER 2
48
ASTRONOMY NEUROSCIENCE
30 Not Quite Stars 56 The Stuttering Mind
Brown dwarfs straddle the line Research on the genetic and neuro-
between stars and planets, and logical origins of this speech disor-
they might help solve mysteries der is pointing to new treatments.
about both. By Katelyn Allers By Lydia Denworth
NEUROLOGICAL DISEASE SECURITY
38 A New Understanding 64 Overhyped
of Alzheimer’s Physics dictates that hypersonic
Immune cells called microglia weapons cannot live up to the
have become a promising target grand promises made on their
for researchers studying the behalf. By David Wright and
neurodegenerative disease. Cameron Tracy
By Jason Ulrich and
EPIDEMIOLOGY
David M. Holtzman
72 The Year Flu
QUANTUM COMPUTING Disappeared
44 Chemistry’s Public health measures meant
Quantum Future to slow the spread of COVID-19
Quantum computers will bring essentially defeated influenza.
molecular modeling to a new level By Katie Peek
of accuracy, reducing researchers’
mages dependence on serendipity. 74 GTEhNeD WERo SrTlUdD’sI EFSirst AOnNim atl pHlaEy i sC noOt jVusEt Ra l eisurely pursuit.
and magesGetty I 48 F BAWryNo hI JliMecyakA niAnLn gnBe thEitmoHe nMAaeVs.l  IGspO ahPRryclsiaicayal fitness TIRifn eri Gsta eheanrarmsdc nhaC’ ntwl ybio,n etuheilnced Idbneess tatir tcuoeytnee tdfuo rbry yS oe lxdu a l Tssakuh micollhsue gatahnhse s efy uov nwaf dafilolilln orng wte hpeienrd egp td aoyaro sttuoiucnrcispgc,a esftnoeetrdrsg s,li a nitttog ei s rpa arilnlalisa clonitf iec ce—es and
Gallo I and cognition. By Caitlin O’Connell the Nazis. By Brandy Schillace Pcohmotpoegtirnagp fho rb my attoeds—d ign uas staaffes eonnv.ironment.
August 2021, ScientificAmerican.com 1
© 2021 scientific American
4 From the Editor
6 Letters
10 Science Agenda
Laws that forbid gender-affirming health care
for trans people are unscientific.
By the Editors
12 Forum
Pesticides are killing worms, beetles and
other organisms that keep our soils healthy.
By Nathan Donley and Tari Gunstone
14 Advances
10
Visualized letters pulled from the brain into text. Hidden
history in imperfect diamonds. Grass that can clean
a toxic explosive. The key to a potent mosquito repellent.
26 Meter
A naturalist marries for science.
By Jessy Randall
28 The Science of Health
Fewer days on antibiotics may be as good as more.
By Claudia Wallis
80 Recommended
Why humans cooperate. How animals perceive
the world. A novel of love and wolf research.
14 What if a pill could edit human consciousness?
By Amy Brady
82 Observatory
Why studies that can’t be confirmed often
get more citations than studies that can be.
By Naomi Oreskes
83 50, 100 & 150 Years Ago
By Mark Fischetti
84 Graphic Science
Bird counts reveal many rare species
and few common ones.
By Clara Moskowitz, Jen Christiansen
and Liz Wahid
80
Scientific American (ISSN 0036-8733), Volume 325, Number 2, August 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, August 2021
© 2021 scientific American

FROM
THE EDITOR
Laura Helmuth i s editor in chief of S cientific American.
Follow her on Twitter @laurahelmuth
Serious Play
der there are so many ways it can go wrong. Stuttering is one of
the most common neurodevelopmental disorders, as Scientific
American c ontributing editor Lydia Denworth writes, starting
We hope our cover story t his month brings you as much joy read­ on page 56. It affects about 5 percent of children and 1 percent
ing it as we have had producing it. The author, behavioral ecolo­ of adults. In the past few years scientists have identified many of
gist Caitlin O’Connell, has what sounds like one of the best jobs on the brain regions and some of the genes involved, and they are
Earth: observing elephants in the wild and making sense of their rolling out new treatments.
behaviors. Some of the silliest behaviors turn out to be surprising­ It’s refreshing when people who have had a lot of success in
ly meaningful. Young elephants play in their water holes much like their careers recognize the importance of luck. Chemist Jeannette
human children play in swimming pools during summer break. M. Garcia was mixing ingredients in a lab when a reaction went
They have toys and games and battles, with older relatives ready in an unexpected direction and she discovered a new family of
to intervene if the play turns dangerous (p age 48) . Many social spe­ polymers. That’s a surprisingly common origin story for many
cies, from meerkats to dogs to great apes, engage in ritualized play scientific advances, but now Garcia ( page 44) wants to reduce the
to hone skills they’ll need as adults—and, from everything we can need for serendipity by using quantum computing to predict
tell, for the joy of it. the chemically unpredictable.
Stars and planets are just different ends of a size spectrum, with In our Science Agenda editorial this month (p age 10) , we show
brown dwarfs in between, astronomer Katelyn Allers explains on that anti­transgender laws are contrary to science as well as
page 30. They can’t quite sustain fusion like a star does, so they’re cruel. The subject is in the news more than ever these days, but
harder to see, but they emit enough light from heat that astrono­ transgender experience is not a fad or an invention. As author
mers have recently realized they’re as abundant as stars in the uni­ Brandy Schillace writes on page 74, the first known transgender
verse, and they’re bizarre. Depending on its age and size, a brown health clinic was established in 1919 in Berlin. It thrived until it
dwarf might have an atmosphere containing titanium oxide or was destroyed by the Nazis and its library consumed by one of
quartz. And Allers has figured out how to measure wind speed on the first Nazi book burnings.
a brown dwarf (2,300 kilometers per hour). In our November 2020 issue, we ran a Graphic Science column
Many of us have lost loved ones to Alzheimer’s and desperate­ revealing that the Southern Hemisphere’s flu season was the mild­
ly hope for a meaningful treatment. Recent research on immune est ever recorded, an early sign that the 2020–2021 flu season in the
cells called microglia in the brain is leading to some new ap ­ North might not be so bad. On page 72, data­visualization design­
proaches. Neurologists Jason Ulrich and David M. Holtzman er and S cientific American c ontributing artist Katie Peek follows
( page 38) describe how genetics, mouse models and patient stud­ up with a remarkable series of graphics depicting how flu basical­
ies point to a two­phase progression of the disease. The story goes ly disappeared around the world during the C OVID pandemic. The
into great detail to show exactly where this research stands, with coronavirus is more elusive than flu, in part because it can be spread
hope but without hype. by those who have no symptoms and don’t know they’re infected.
As neuroscientist Soo­Eun Chang points out, “speech is one But if people wash their hands, wear masks in crowded indoor
of the most complex motor behaviors we perform.” It’s no won­ areas and stay home if they’re sick, that can stop the flu cold.
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 Carlos Gershenson Tata Institute of Fundamental Research
and of Computational Neuro science, M.I.T., Research Professor, National Autonomous University of Mexico John P. Moore
and Warren M. Zapol Prof essor 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
Kate Crawford Founder and CEO, Ocean Collectiv 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, August 2021 Illustration by Nick Higgins
© 2021 Scientific American

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“ I haven’t lost my love of the sciences and
mathematics. Your magazine provides
me with the joy I used to feel but without
the heartache.”
tracie s. johnson v ia e-mail
HOUSTON-EDWARDS REPLIES: In re- ical feedstocks, shipping and aviation.
sponse to Rosenblatt: In percolation theory, Keeping warming within the 1.5 de-
a “dial” controls the local connectivity of a grees Celsius limit necessary to avoid cat-
network. When its needle lands on a critical astrophic climate destabilization requires
point, a phase transition occurs, and the us to reach net-zero emissions, meaning
global connectivity of the network changes we must leave the majority of the world’s
dramatically. To apply the theory to LQG, existing gas reserves unburned. And
one needs to describe how and why this dial whether methane is synthetic, biogenic or
April 2021 moves to the critical point. But as theoreti- fracked, if it’s pumped through the exist-
cal physicist Lee Smolin explained in an e- ing distribution network, it will face leak-
mail to S cientific American, n ature exhib- age, adding to atmospheric warming.
PERCOLATION INSPIRATION its several instances of “self-organized crit- Perhaps the most important omission
It was an absolute delight to read about ical phenomena,” in which the dial tunes is that decarbonizing gas does not solve
percolation theory in “The Math of Making itself toward the critical threshold. Smolin the health impacts of combustion. With
Connections,” by Kelsey Houston-Edwards. hypothesizes that such a self-organized low-carbon gases, we only get more ex-
Please feature more articles by this author phase transition might explain “the emer- pensive ways of polluting our homes.
and about mathematics as applied to sci- gence of classical spacetime in a quantum Sasan Saadat
ence. I’m not a mathematician, yet I enjoy theory of gravity,” including loop quantum Research and policy analyst, Earthjustice
learning about theory and application. I gravity. He and physicist Mohammad An-
love the expanse of disciplines you cover. sari explored these ideas in the 2008 paper WEBBER REPLIES: I t seems that we agree
I am an African-American woman with “Self-Organized Criticality in Quantum that addressing climate change is the most
a biology degree. I used to work as a re- Gravity.” It is unclear how extensively a urgent and important challenge of the 21st
search assistant in cancer research. That “self-tuning” version of percolation could be century. That realization led me to the con-
was until the racism that I consistently en- used for understanding a self-organized clusion that we need every solution possi-
countered wore me down, and I just phase transition in the case of LQG. ble to get us to carbon neutrality (and car-
didn’t want to ever work with scientists bon negativity!) as quickly, safely and
again. Although I am in another line of CLIMATE PRIORITY affordably as possible. As I write in the ar-
work, I haven’t lost my love of the sciences I was troubled by “What to Do about Nat- ticle, I think the first two priorities for de-
and mathematics. Your magazine pro- ural Gas,” Michael E. Webber’s article carbonizing the economy are (1) conserva-
vides me with the joy I used to feel but about ways to decarbonize the natural gas tion and efficiency and (2) electrification.
without the heartache. system. Pointing out that the primary al- Because low-carbon fuels play an impor-
Tracie S. Johnson via e-mail ternative, electrification, will be challeng- tant role for sectors that are difficult to elec-
ing is fair enough. But electrification does trify, we need to make progress on decar-
One approach to developing a theory of not have barriers that are greater than, or bonizing gases as the third step.
quantum gravity is called loop quantum even equal to, a zero-carbon gas system, As someone who invented sensors to
gravity (LQG). It treats space as a discrete which faces structural limitations. To his measure the emissions from combustion,
substance composed of individual spatial credit, Webber names some of these limi- I’m well aware of its pollution. And as
atoms, or nodes, at the Planck distance tations. But his presentation of them someone who quantitatively analyzes dif-
scale of 10−35 meter. They are connected to as solvable with some tweaks is disingenu- ferent forms of energy, I’m also aware of
one another in a way that would seem to ous. Even by the gas industry’s own esti- the significant ecosystem impacts of some
lend itself very well to percolation theory, mates, two decades of scaling up all low- utility-scale renewables. The energy sys-
which is precisely geared toward modeling carbon gases would displace only about 13 tem is all about trade-offs, and there is no
the connections among discrete nodes. Has percent of the U.S.’s existing gas demand. one fuel or technology option that is pure-
percolation been applied to advancing LQG Also, it would squander any genuinely sus- ly villainous or virtuous. Rather we must
and quantum gravity? tainable gases that could be used where we design a suite of solutions that meets soci-
Edward Rosenblatt v ia e-mail might actually need them, such as chem - ety’s complex needs.
6 Scientific American, August 2021
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EDITORIAL
MEMORY LOSS
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In “Prediction Predicament” [Advances], FEATURES
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impairs people’s ability to remember pre- SENIOR EDITOR, SPACE / PHYSICS Clara Moskowitz SENIOR EDITOR, EVOLUTION / ECOLOGY Kate Wong
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tial arts. Often when an instructor demon- SENIOR EDITOR, SPACE / PHYSICS Lee Billings ASSOCIATE EDITOR, SUSTAINABILITY Andrea Thompson
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