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ADVANCES


14 Scientific American, April 2019


HEALTH TECH


Cervical


Cancer App


An AI algorithm diagnoses


the disease from images


One of the most common and cost-effec-
tive ways to detect cervical cancer is the
pap smear, in which cells are scraped from
a woman’s cervix and sent to a laboratory
for analysis. But this method requires
equipment and medical expertise that are
not always available in some low-income
countries. Now scientists are making an
app they hope could use artificial intelli-
gence to identify precancerous or cancer-
ous cells with just a photograph.
The app is being developed by research-
ers at the National Institutes of Health and


Global Good; the latter is a joint effort by Bill
Gates and invention firm Intellectual Ven-
tures. Their preliminary results, published
online in January in the Journal of the National
Cancer Institute, suggest that such an ap -
proach could significantly improve cervical
cancer diagnosis in low-resource settings.
Cervical cancer rates are higher in
countries or regions that lack the resourc-
es to conduct pap smears. Health care
providers in these areas often use a less
accurate diagnostic technique, in which
they swab the cervix with dilute acetic

acid and visually inspect it for any white
spots that might signal abnormal cells.
Over a seven-year period nih research-
ers routinely photographed the cervixes
of more than 9,400 women in Costa Rica.
They used these images to train an AI algo -
rithm to recognize characteristics of abnor-
mal tissue—and to predict later cancer
devel opment. When the algorithm analyzed
new images, it performed better than a clin-
ical expert did by visual inspection.
“We were surprised to see that comput-
ers could see much more sensitively and
clearly which cervixes are or are not pre-
cancerous,” says Mark Schiffman, a molec-
ular epidemiologist at the National Cancer
Institute and senior author of the paper. “I
really thought [the AI was] cheating.” The
scientists ultimately plan to implement their
algorithm on mobile phones and aim to
train future iterations of the program with
digital camera photos. — Wudan Yan STEVE GSCHMEISSNER

Science Source

ANIMAL FORENSICS

Catching


Paleo Killers


New technique identifies
predators of ancient animals

Nowadays detectives can use DNA analy-
sis to help catch a killer. But what happens
when a crime scene has been exposed to
the elements for thousands of years? DNA
does not always stay intact that long—so
for a paleontologist trying to figure out
what kind of predator killed a long-dead
fossil animal, the case often goes cold.
But a new method promises to help
researchers identify these ancient killers.
It relies on the fact that when a predator
gulps down the bones of its prey—say,
when a swooping owl snatches and
eats a small rodent in the night—the
diner’s stomach juices leave behind
microscopic etchings on the surface of
the victim’s bones.
These etchings occur in patterns that
are unique to the type of predator that
did the deed, making them a bit like finger-
prints that scientists can use to crack
un solved cases, explains Rebecca Terry,
a paleo ntologist at Oregon State Universi-

ty, who led the team that studied the
etchings. This technique, she adds,
will help researchers paint pic-
tures of what kinds of preda-
tors were active in long-van-
ished ecosystems, particu-
larly in areas where fossils
are scarce. “It’s really
powerful,” she says.
Terry and her team
used a scanning electron
microscope to examine
the leftover bones that
modern predatory birds
regurgitate as pellets after
a meal. They also looked at
the feces of carnivorous mam-
mals. “A bone that passes into
and out of a nocturnal owl is clearly
distinguishable from bones that have
been eaten by diurnal raptors” or mam-
mals, Terry says. Patterns etched on bones
inside an owl’s stomach tend to be relative-
ly short and close together; those from the
stomach of a hawk or mammal tend to be
longer and more widely spaced, according
to the study, which was published last
November in PALAIOS. And the patterns
left by the modern-day owls and mam-
mals, Terry adds, were “indistinguishable”
from those found on fossil bones digested
by similar predators long ago.

These findings will help answer one
of paleontologists’ most basic questions
about the fossils of animals they suspect
were killed and eaten: “Whodunit?” As
Joshua Miller, a paleobiologist at the Uni-
versity of Cincinnati, who was not involved
in the new research, says, “You can actual-
ly look at an individual bone and get some
perspective on why that bone is where you
found it. And that’s really neat.” — Lucas Joel

Cervical cancer cell

Illustration by Thomas Fuchs
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