3 November 2018 | NewScientist | 17A WOMAN’S risk of breast cancer
is affected by how many children
she has and the age when she has
them – although exactly why is a
mystery. Now it seems pregnancy
duration may be key.
Mads Melbye at the Statens
Serum Institute in Denmark and
his colleagues examined Danish
and Norwegian registries on
childbirth and cancer. They
looked at long-term effects,tracking breast cancer cases at
least 10 years after pregnancy.
Women whose pregnancies
lasted 33 weeks or less saw their
breast cancer risk drop by 2.4 per
cent on average. If the pregnancies
reached 34 weeks or more, this
risk fell by 13.6 per cent (Nature
Communications, doi.org/cwbn).
The numbers did not change
when Melbye and his team
adjusted for socio-economicstatus. They also found that the
link between lower cancer risk
and a pregnancy of 34 weeks or
more occurred whether or not
the pregnancy resulted in a live
birth. Although breastfeeding
has been shown to cut cancer
risk after pregnancy, this finding
suggests other factors are at work.
Susan Gapstur at the American
Cancer Society says genetics,
alcohol consumption and
diabetes may also play a part,
alongside length of pregnancy.IN BRIEF
NATURE PICTURE LIBRARY/ALAMY STOCK PHOTO
Bird breaths may show how
dinosaurs ruled the planetMANY dinosaurs were swift and active animals, which
is puzzling given that Earth’s atmosphere held less
oxygen back then. But they may have thrived in the
challenging conditions due to efficient, bird-like lungs.
Robert Brocklehurst at the University of Manchester,
UK, and his colleagues compared dinosaur lungs both
with those of living crocodilians, which share a common
ancestor with dinosaurs, and with those of birds, which
descended from them.
First, they compared the lung of an alligator and an
ostrich. They found that the alligator’s lung cavity issmooth, which Brocklehurst says may allow the lungs
to slide as they move to pump air in and out while the
animal swims. In contrast, rows of vertebrae and ribs jut
into the ostrich lung cavity, leaving deep grooves in the
lung surface. With that much support, the lung walls can
be thinner, says Brocklehurst, allowing birds to transfer
more of the oxygen they breathe in into their blood.
When Brocklehurst and his colleagues used CT scans
to compare the lung cavities of modern birds and
crocodilians with those of 16 dinosaur species, they
found that all the dinosaurs had vertebrae more similar
in shape to those of birds than those of reptiles. This
suggests dinosaur vertebrae jutted into the lung cavity
as they do in living birds (Royal Society Open Science,
doi. org/cv99).Pregnancy length linked to breast cancer
AI can find people
from descriptionsFINDING someone in a
surveillance video could soon
be as easy as googling them.
Descriptions of a suspect or a
missing person are usually given
in terms of height, gender and
clothing. But trying to find a short
woman wearing a red jacket in a
video, say, often requires scanning
hours of footage manually. A new
tool can do it automatically.
The system, created by Hiren
Galiyawala at Ahmedabad
University in India and his
colleagues, uses machine learning
to match individuals in videos to
their descriptions.
It was trained on 110 videos.
Given a video it has not seen and
a physical description, it looks for
people in each frame and works
out their height. If several people
are the same height, it uses gender
and colour of clothing to narrow
down the selection. In tests, the
system found 28 out of 41 people
(arxiv.org/abs/1810.05080).Shipping puts a halt
to whale songsWHALES stop singing when
ships are nearby. Male humpback
whales living around the
Ogasawara Islands in Japan
stopped or reduced their singing
in response to low-frequency
shipping noise.
Koki Tsujii at the Ogasawara
Whale Watching Association and
colleagues used two underwater
recorders to capture the animals’
song in a remote area where a
passenger-cargo liner was the
only large ship running. They
found that fewer whales sang
within 500 metres of the ship’s
route than sang elsewhere.
Whales within 1200 metres of
the ship when it passed tended to
temporarily reduce or stop their
singing. There were 26 singers in
total (PLoS One, doi.org/cv98).