27 OCTOBER 2017 • VOL 358 ISSUE 6362 431 SCIENCE sciencemag.org
transmission continued,” Bertherat says. At
least 39 health workers have been infected.
Pasteur has distributed thousands of rapid
diagnostic tests. The institute confirms each
case with the polymerase chain reaction,
which takes about 8 hours, and its plague lab
is seriously backed up, Pasteur scientists say.
All Y. pestis strains isolated so far are susceptible to antibiotics.
International partners have helped set
up nine plague treatment centers and isolation wards, but WHO says more are urgently
needed as symptomatic people crowd into
clinics and hospitals, risking further spread.
“You want to make sure a suspected plague
case does not walk through the clinic,” says
Nyka Alexander, WHO’s communications
chief in Madagascar. WHO and its partners,
among them the U.S. Centers for Disease
Control and Prevention, UNICEF, and the
European Centre for Disease Prevention and
Control, are positioning supplies around the
country, including more than 1.2 million
doses of antibiotics and 150,000 sets of personal protective gear for health workers.
Disinfection and rat and flea control are
key to curbing bubonic plague. But for pneumonic plague, health workers need to find
and prophylactically treat everyone who has
come into contact with an infected person.
WHO has already trained almost 2000 community health workers in Antananarivo in
contact tracing, which began 12 October. Of
some 2500 contacts identified to date, 66%
have been given oral antibiotics. (For confirmed cases, treatment is far more harrowing—40 antibiotic shots given over 7 days.)
Contact with the dead can be risky. But as
in the Ebola epidemic, efforts to reduce risk
during burials conflict with deep cultural beliefs and traditions such as washing the body
and returning it to the person’s birthplace,
Bertherat says. “If we don’t respect [those tra-ditions], we risk that people will hide deaths.”
WHO is also worried that the outbreak
will spread beyond Madagascar; it considers
nine neighboring countries and territories at
very high risk (see map, p. 430). Departing
passengers are closely screened at Madagascar’s international airport. And technical
advisers are helping at-risk countries set up
systems for surveillance and contact tracing,
and are positioning medical supplies.
To infectious disease experts, the outbreak underscores the lesson of the Ebola
epidemic. As cities burgeon and populations
become more mobile, once-isolated diseases
are increasingly likely to reach cities, where
they can race out of control. “Next time,”
Bertherat says, “we need to be ready to manage [plague] in an urban setting.” j
Neandertals gave ‘lost’
African DNA back to moderns
Eurasians acquired genes linked to smoking and waist size
When Neandertalsmated withmod- ern humans, they shared more than an intimate moment and their own DNA. They also gave back thousands of ancient Afri- can gene variants that Eurasians
had lost when their ancestors swept out
of Africa in small bands, perhaps 60,000
to 80,000 years ago. Restored to their lineage, this diversity may have been a genetic
gift to Eurasian ancestors as they spread
around the world. Today, however, some of
these ancient variants are a burden: They
seem to boost the risk of becoming addicted
to nicotine and having wider waistlines.
In talks last week at the annual meeting
of The American Society of Human Genetics
here, researchers announced
that some “Neandertal” genetic variants inherited by
modern humans outside of
Africa are not peculiarly Neandertal genes, but represent
the ancestral human condition. The work highlights just
how much diversity was lost
when people passed through
a genetic bottleneck as they
moved out of Africa.
“They left many beneficial
variants behind in Africa,” says
evolutionary genomicist Tony
Capra of Vanderbilt University
in Nashville, who reported the results. “In-
terbreeding with Neandertals provided an
opportunity to get back some of those vari-
ants, albeit with many potentially weakly
deleterious Neandertal alleles as well.”
His team found the ancient African vari-
ants when they scrutinized the genomes of
more than 20,000 people in the 1000 Ge-
nomes Project and Vanderbilt’s BioVU data
bank of electronic health records. They
soon noticed a strange pattern: Stretches of
chromosomes inherited from Neandertals
also carried ancient alleles, or mutations,
found in all the Africans they studied, in-
cluding the Yoruba, Esan, and Mende peo-
ples. The researchers found 47,261 of these
single-base changes across the genomes of
Europeans and 56, 497 in Asians, Capra says.
In Eurasians these alleles are only found
next to Neandertal genes, suggesting all this
DNA was acquired at the same time, when
the ancestors of today’s Eurasians mated
with Neandertals roughly 50,000 years ago.
The most parsimonious explanation is that
these alleles represent the ancestral human
condition, inherited by both Neandertals and
modern humans in Africa from their common
ancestor, Capra says. When people migrated
out of Africa, their small numbers resulted in
a bottleneck, in which they lost many alleles
that remained in larger populations in Africa.
Later, the Neandertals reintroduced these alleles—along with distinct Neandertal genes—
to the ancestors of Eurasians, Capra says.
Some of these ancient alleles were beneficial,
such as one that boosted immune responses.
But today’s humans might prefer to shed
others. So far, Capra’s team has found three
functional variants, which are
associated with addiction to
nicotine, a wider waistline,
and skin pigmentation.
The data are “very compelling that Neandertals bring
back some of the lost ancestral
variance,” of modern humans,
said geneticist Mait Metspalu
of the Estonian Biocentre in
Tartu, who heard the talks.
Geneticists at the meeting
also zeroed in on archaic DNA
Using software that evaluates gene expression, Vanderbilt graduate student
Laura Colbran found that Neandertal versions of FOXP2 would have pumped out
much less of its protein than is expressed in
modern brains. A rare mutation that causes
members of a family to produce half the
usual amount of FOXP2 protein also triggered severe speech defects, notes Simon
Fisher, director of the Max Planck Institute
for Psycholinguistics in Nijmegen, the Netherlands, who discovered the gene. Boosting
FOXP2 expression may have been key to
modern human language, he says. j
By Ann Gibbons, in Orlando, Florida
Children in Madagascar’s capital city wear masks to
protect themselves from pneumonic plague.
“ … Neandertals
some of the