Vol 466|26 August 2010

RESEARCH HIGHLIGHTS
T. Hampel/Univ. CHiCago

EVOLUTIONARY BIOLOGY

Lice in hiding

Am. Nat. doi:10.1086/656269 (2010)

Bird lice reduce their chances of being picked off by
their hosts by evolving to match the colour of thebirds’ feathers.
Camouflage has been well documented in
predator–prey relationships. Sarah Bush and hercolleagues at the University of Utah in Salt Lake City
now report that the same evolutionary trend exists
between parasites and their hosts.
By comparing lice from species of dark- and lightcoloured birds (pictured), the researchers found that‘feather’ lice — which live on a bird’s body — matchthe colour of their host’s plumage (insets). However,‘head’ lice do not necessarily blend in. This suggeststhat bird preening drives lice-colour evolution: birds
cannot see or groom their heads, so there is no
selective pressure for head lice to be camouflaged.

Record data storage
Appl. Phys. Lett. doi:10.1063/1.3463470 (2010)

Data have been recorded on a tiny slice ofa metal oxide at a density eight times thatoffered by today’s most advanced magnetic
disk drives.
In magnetic data storage, data are written
to disk by a magnetic read-and-write headthat changes the magnetization of a region afew hundred nanometres across. One option
for boosting memory in ever-shrinking
electronics is to use ferroelectric materials,
in which data can be encoded in thepolarization of smaller regions.
Kenkou Tanaka and Yasuo Cho at Tohoku
University in Sendai, Japan, recorded
64 × 64 bits of real data at a spacing of 12.8
nanometres per bit on a crystalline slice oflithium tantalate. This amounts to a density of
0.6 trillion bits per square centimetre.
NEUROSCIENCE

Quick mood lift
Science 329, 959–964 (2010)

Patients taking traditional antidepressantshave to wait several weeks for the drugs tokick in. However, a few severely depressed
patients taking ketamine, an anaesthetic andrecreational drug, have shown improvement
within hours. How does it act so quickly?
Ronald Duman and his team at Yale
University in New Haven, Connecticut, showthat the ketamine affects a brain signalling
pathway called mTOR. Ketamine rapidly
activated this pathway in the prefrontalcortex of healthy rats, resulting in theformation of more connections between
1024

neurons. Treated rats also showed improved
performance in three behavioural tests thatmodel depression. These responses were alllost when the scientists blocked the mTOR
pathway biochemically.
ASTRONOMY

Exploding computer models
Astrophys. J. 720, 694–703 (2010)

When a star much more massive than theSun runs out of fuel, its core collapses andsparks an enormous explosion, or supernova.
Neutrinos in the core are believed to be key
to triggering the blast, but observations ofneutrinos from real explosions don’t match
up well with theoretical predictions.
Jason Nordhaus of Princeton University
in New Jersey and his colleagues think theproblem may be a dimensional one. Most
supernova computer models are one- or twodimensional, to expedite calculations. Whenthe team used supercomputers to run a threedimensional simulation of a supernova, theyfound that the extra degree of freedom led toa significantly more efficient and vigorous,
and earlier explosion (pictured) — a resultthat more closely matches observations.

ANIMAL BEHAVIOUR

Genetics and culture clashProc. R. Soc. B doi:10.1098/rspb.2010.1112 (2010)

Culture may not be the only factor underlying
differences in tool use and other behaviours
across groups of wild chimpanzees — genetic
variation may also play a part.
Primatologists have previously invoked
culture to explain why, for instance, one
chimpanzee community digs for termites andanother does not, even when their ecologicalenvironments are similar. Kevin Langergraberat the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany, and his
team analysed DNA from cell organelles
called mitochondria for 246 chimps spanning
nine groups in East and West Africa todetermine how the groups were related to
one another. They then compared these
relationships with existing data on whether
or not members from these sites display anyof 38 different behaviours — many involving
tool use. Genetically related communities
often had a similar suite of behaviours.
ASTRONOMY

Brown dwarf spotted
Astrophys. J. 720, L82–L87(2010)

Scientists have directly imaged a browndwarf — an object too big to be a planet yet
not massive enough to ignite into a star —travelling in a highly eccentric orbit around
its parent star. At its closest approach thecompanion is within 9 astronomical unitsof the star, a distance similar to that between
Saturn and the Sun, whereas its furthest reachis double that distance.
Beth Biller at the University of Hawaii in© 2010 Macmillan Publishers Limited. All rights reserved

am. asTron. soC.

APPLIED PHYSICS