18 | New Scientist | 16 November 2019Population biologyMonthly skin patch
to replace daily pill?A PATCH full of tiny needles can
inject up to 60 days’ worth of
hormonal contraceptives. Women
could apply it at home, possibly as
a hassle and pain-free alternative
to injections or implants.
Mark Prausnitz at the Georgia
Institute of Technology and his
team created the patch, which
contains 100 microneedles, each
around half a millimetre long and
0.01 millimetres wide. When theSense of smell that
seems impossibleTHE olfactory bulb, a structure at
the front of the brain, plays a vital
role in our ability to smell. Or, at
least, so we thought. Researchers
have now discovered a handful
of women who have a perfectly
normal sense of smell but who
seem to lack olfactory bulbs.
The team, including Tali Weiss
and Noam Sobel at the Weizmann
Institute of Science in Israel, say a
lack of olfactory bulbs is unusual
but not remarkable: one in 10,
people don’t have them, but we
had believed none could smell.
However, in the course of a
study into possible links between
ability to smell and reproduction,
the team happened across a
29-year-old woman who was
different: she lacked olfactory
bulbs but was adamant her sense
of smell remained very good.
Every test the researchers
threw at her suggested she didNeuroscience^ ContraceptionCLIMATE change, if left unchecked,
could drive emperor penguins
to extinction by the end of the
century as sea ice vanishes.
Stephanie Jenouvrier at the
Woods Hole Oceanographic
Institution in Massachusetts found
that the future of emperor penguins
hinges on international climate
efforts rather than on their ability
to adapt and move to new homes.
Disappearing sea ice affects
these penguins directly because
they rely on it for their nine-month
breeding season, as well as a place
to moult and escape from predators.
The ice is also crucial for the species
because it influences the food they
need, including krill.
Sea ice changes are already
affecting emperor penguins, with
breeding failures for three years in
a row at their second biggest colonyin the Antarctic pinned on early
break-up of ice used for breeding.
To examine the fate of the world’s
estimated 595,000 emperors,
Jenouvrier and her team modelled
colonies and populations under
three warming scenarios: hitting
the Paris agreement’s ideal 1.5°C
target, its alternative 2°C goal, and
what would happen if emissions
keep rising as they are today.
The result was an 81 to 86 per
cent fall in population by 2100
under a business-as-usual scenario.
By contrast, warming of 1.5°C
would see a 31 per cent dip, and
2°C a 44 per cent fall (Global
Change Biology, doi.org/ddwb).
The biggest of those declines
would leave so few individuals that
in ecological terms it would be
considered an extinction, says
Jenouvrier. Adam VaughanPenguins may be doomed if
global warming isn’t slowed
patch is applied, the needles come
off, break the skin and sit under
the surface. Each contains a dose
of levonorgestrel, a hormonal
contraceptive. This is slowly
released as the needles degrade
over a period of up to 60 days.
Long-acting contraceptives
usually need to be administered
by professionals, but this could be
self-administered, says Prausnitz.
The patch could be used once a
month, rather than the oral
contraceptive pill, taken every day.
The team tested the patch on
rats, finding that more than 90 per
cent of microneedles detached
after 50 seconds on average. To see
how well it would work on people,
the team trialled it with 10 women
but without any levonorgestrel.
The needles detached to enter the
body just as well as they did in rats
(Science Advances, doi.org/ddtb).
All the women involved said
they would opt for the patch over
a monthly injection of hormones,
while only one would stick with a
daily pill. Gege Liindeed have a good ability to
distinguish odours, despite
lacking the neurons typically
believed necessary to do so. The
team widened its investigation,
and found more women like this,
but no men at all.
The researchers were able to
estimate the odds of being a
woman who can smell normally
without these brain structures to
be about 0.6 per cent. Strangely,
the odds are raised dramatically
in left-handed women. Among
people who are left-handed,
women who lack olfactory bulbs
have a roughly 4 per cent chance
of still being able to smell
normally (Neuron, doi.org/dds9).
Sobel says this may be further
proof as to how plastic, or
adaptable, the brain is: if it lacks
olfactory bulbs, it can reorganise
itself so other brain regions take
on the task of odour perception.
Alternatively, the discoveries
might hint that we know less
about our ability to smell than we
thought. Jason Arunn MurugesuST
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INSTITUTE^ OF^ TECHNews In brief