“When you get extraordinary results, you need to look for
extraordinary ideas to explain them.” — NICHOLAS HUMPHRE Y
Case for cold-blooded dinos dims
By Meghan Rosen
Life stories written in mammal bones
are being used to debunk a key argument
for cold-bloodedness in dinosaurs.
Annual growth lines etched in the
leg bones of 115 wild warm-blooded
mammals such as giraffes, reindeer and
gazelles are similar to those previously
seen in the remains of dinosaurs and
other reptiles, researchers report online
June 27 in Nature.
“People always said that mammals do
not show these lines,” says study lead au-
thor Meike Köhler, a paleontologist at the
University of Barcelona. This assumption
is “like a myth that’s going around; you
read it everywhere,” she says. “But people
haven’t really studied mammals.”
In reptiles, including dinosaurs, yearly
cycles of growth are stamped in the bones
like the rings of a tree. In fat months,
animals pack on blood vessel–rich bone
tissue. In lean months they lay down
only thin sheets. Under a microscope,
the slender sheets of bone look like dark
lines. Because these “lines of arrested
growth” or “rest lines” stripe bones, some
scientists assumed that dinosaurs, like
surviving reptiles, were cold-blooded. But
the new work shows that warm-blooded
mammals have banded bones, too.
Köhler’s team analyzed bone slices
from 41 species of ruminants — mammals with multichambered stomachs —
native to 23 different climate zones,
from the polar tundra of Norway to
the humid subtropics of South Africa.
Every mammal the researchers examined showed cyclical growth: fast and
furious when food was plentiful, slow
and sluggish when resources were scant.
What’s more, the rest lines from the
specimens looked just like those seen in
dinosaur fossils.
“It’s probably not going to close the
debate whether dinosaurs were warm-blooded or not,” says paleontologist
Martin Sander of the University of Bonn
in Germany, “but the argument that [rest
lines] mean cold-blooded is certainly not
valid any longer.” s
floats an alternative explanation for
Ayumu’s performance: Ayumu might
have synesthesia, a brain condition that
makes him see numbers in colors. If
Humphrey is right, Ayumu’s feat isn’t
such a monumental accomplishment.
“When you get extraordinary results,
you need to look for extraordinary ideas
to explain them,” says Humphrey.
Because synesthesia usually applies to
strings of symbols like letters or numbers, there would be no reason to think
that animals other than humans would
experience it. No reason, that is, until
Ayumu and his chimp colleagues learned
numbers, Humphrey says.
Chimp recall feat
may be mirage
Psychologist suggests ape
sees numbers as colors
By Laura Sanders
In what seems like a blow for humankind, a very smart chimpanzee in
Japan crushes any human challenger at
a number memory game.
After the numbers 1 through 9
make a split-second appearance on a
computer screen, the chimp, Ayumu,
gets to work. His bulky index finger flies
gracefully across the screen, tapping
white squares where the numbers had
flashed, in order. So far, no human has
topped him.
Ayumu’s talent has grown legendary
since Tetsuro Matsuzawa of the Primate
Research Institute at Kyoto University
and colleagues first reported it in 2007.
But psychologist Nicholas Humphrey
of Cambridge University in England says
the hype may be overblown. In the July
Trends in Cognitive Sciences, Humphrey
If Ayumu does perceive the num-
bers on the screen in colors, then when
the digits disappear each white square
that replaces them would, in his mind,
have a distinct aftereffect color. Ayumu
could simply be ordering these colors in
a learned sequence without having to
remember the original numbers.
After seeing numbers 1 through 9 for only a fraction of a second (left), Ayumu
touches them in order while they are obscured by white squares (right). His ability
could stem from synesthesia, a recent proposal suggests.
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July 28, 2012 | SCIENCE NEWS | 9