Popular Science - USA (2020 - Winter)

22 WINTER 2020 / POPSCI.COM

BIG QS

our bodies

our guts?

by K AT ESCHNER

forecast

EVERY PERSON HOSTS
as many microbial cells as
human ones— bacteria,
viruses, fungi, and other
organisms that help keep
us healthy. “It’s like another
organ system,” says Lita
Proctor, former director
of the National Institutes
of Health’s Human Micro­
biome Project, which
identified many of the tiny
critters. Cultivating an ideal
mix might be key to feelin’
good. But there’s a lot to
learn before we can pop
probiotics for all our woes.
The first step is know­
ing exactly what’s inside
us. Since the ’90s, genomic
sequencing has helped
pinpoint species in our
guts—the most complex col­
onies. We’ve learned some
play an outsize role in health.
Excess Clostridium difficile,
for example, can trigger
gastrointestinal distress.
For now, the best way to
restore balance is with fe­
cal microbiota transplants
(FMT), which introduce
microbes via a donor’s en­
capsulated poop. FMT can
cure up to 90 percent of re­
current C. diff infections.

But the potential uses of

similar therapies aren’t yet

clear, because we don’t really

know what all the microbes

in healthy bellies actually do.

The next phase is seeing

what else FMT can treat.

Crohn’s and other bowel dis­

eases will likely be targets

in as little as five years. For

now, though, finding applica­

tions is imprecise: Without

a clear picture of which

species do what, the best

clinicians can do is try to re­

place ones that seem to hurt

with ones that seem to help.

By studying the guts of

people with certain condi­

tions, experts anticipate

we’ll pinpoint more con­

nections between microbes

and health within the next

10 years. Research building

off the Human Microbiome

Project hints that cancer,

acne, and Alzheimer’s could

all have something to do

with our inner settlers.

Still, turning that info

into medicine could take de­

cades. Any magic pill will

need to maintain the deli­

cate balance of our microbial

worlds—ecosystems we’re

still working to understand.

EXTREMOPHILES ARE WEE ORGANISMS THAT PERSIST IN

conditions so harsh—so hot, so cold, so alkaline—that the

creatures redefine our notion of what it takes to eke out a living.

Biologist Thomas Brock first discovered these beings when

he encountered the bacteria Thermus aquaticus in the boiling

hot springs of Yellowstone Park in the 1960s. Ever since, micro-

biologists have been searching the world’s driest, hottest,

deepest, and darkest spots to find creatures that flourish in con-

ditions once thought uninhabitable. We’ve identified classes

of microbes that thrive in incredibly high and low temperatures

(thermophiles and psychrophiles), in shockingly acidic and basic

pHs (acidophiles and alkaliphiles), and in crippling levels of pres-

sure (barophiles) and salt (halophiles). There are even some that

withstand two or more factors at once (polyextremophiles).

These critters help explain how our first ancestors got their

start 3.5 billion years ago, when our planet was remarkably hot.

But they may also help us spot life beyond Earth: Astrobiolo-

gists now know, for example, that organisms could theoretically

exist below the surface of Titan, Saturn’s largest moon. The

orb’s temperatures dip below –150 degrees Fahrenheit, and its

underground ocean is as salty as the Dead Sea. But Earthly halo-

psychrophiles (microbes tolerant of both cold and salt) prove

that such conditions aren’t necessarily as deadly as they seem.

explsinextremophiles

like i’m 5 by SANDRA^ GUTIERREZ^ G.

WHAT IF WE COULD

biologically weed out all of society’s

ills? At the turn of the 20th century,

mainstream academics believed that

if certain people didn’t reproduce

in the United States, the genetic

“stock” of the population could re­

main pure, thus leading to a perfect

civilization. Sociologist Herbert

Adolphus Miller wrote about the

field, dubbed eugenics, in the April

1914 issue of Popular Science: “The ra­

pidity with which it has spread is little

short of wonderful, and its value can­

not be overestimated.” These ideals

led to immigration and sterilization

policies that targeted poor, disabled,

and dark­skinned individuals— all

pinned to very scant science.

Eugenics leaders used rank and

power to push their movement,

but their methods weren’t backed

by any lab­ or field­ based evi dence,

says Miriam Rich, a lecturer in the

history of medicine at Yale. “It’s of­

fering this very reductive biological

solution to complex social, political,

and economic problems.”

DNA research has since shown

all that breeding can—and cannot—

influence. We know that diversity

creates resilience, and that the nar­

rowing of a gene pool can flood a

population with mutations and

result in disorders like the protrud­

ing Habsburg jaw in incestuous

Spanish royals. We also know that

biological building blocks make up

only a fraction of the human condi­

tion, a fact Miller conceded in 1914:

“If a perfect eugenic system were in

vogue,” he wrote, “practically every

social problem which we are now

trying to solve would still remain.”

No amount of reproductive cherry­

picking can change that.

CAN HUMANS BREED THEMSELVES

TO PERFECTION?

where we wentwrong

by sara kiley watson

When you’ve been publishing for

a century and a half, some off-

base ideas are going to creep into

your pages. We’re diving into the

archives to give you a fresher take

on “popular science.”

could we fix

by fixing