NASA

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THE last thing a seasoned

gardener would expect from

global warming is for leaves to

appear later in spring, but exactly

that is happening across the

southern US.

“It’s really surprising,”

says Xiaoyang Zhang of Earth

Resources Technology in Camp

Springs, Maryland, because studies

usually show plants greening

earlier. “Nobody had noticed

how warming temperatures can

delay the green-up.”

Zhang spotted the anomaly

when he examined satellite

images showing seasonal changes

in vegetation colour across the

US from 1982 to 2005. In latitudes

above 40° north, plants came into

spring bloom an average of

0.32 days per year earlier over the

period. But below 31° north, plants

bloomed an average of 0.15 days

later. The tipping point, where

climate change had no effect,

was at 35° north (Geophysical Research Letters, DOI:

10.1029/2007GL031447). A similar

pattern emerged when Zhang

examined records of when lilacs

flower each year.

Zhang thinks that some plants

need to be exposed to a short cold

snap to sprout. Plants at northern

latitudes still get this, but those

below 35° north do not, he says,

causing them to sprout later as

the climate warms.

Spring arrives later in a warm world

CURVIER women may have

smart children because hip fat

contains polyunsaturated fatty

acids critical for the development

of the fetus’s brain.

Using data from the US National

Center for Health Statistics,

William Lassek at the University of

Pittsburgh in Pennsylvania and

Steven Gaulin of the University of

California, Santa Barbara, found a

child’s performance in cognition

tests was linked to their mother’s

waist-hip ratio, a proxy for how

much fat she stores on her hips.

Children whose mothers had

wide hips and a low waist-hip

ratio scored highest, leading

Lassek and Gaulin to suggest that

fetuses benefit from a rich supply

of useful fatty acids (Evolution and Human Behavior, DOI: 10.1016/

j.evolhumbehav.2007.07.005).

Plump mums have brainy kids

THEY say that fasting purifies the

mind. Now it seems it may help

keep the heart healthy too.

About three-quarters of the

people of Utah are Mormons,

and many of them fast for a day

every month. Benjamin Horne

from the Intermountain Medical

Center in Salt Lake City, Utah,

asked 515 elderly people

undergoing X-ray examinations

for suspected heart disease about

their lifestyle. Those who fasted

were 39 per cent more likely than

non-fasters to have a healthy

heart. The results were presented

at the American Heart

Association’s Scientific Sessions

in Orlando, Florida, on Tuesday .

Horne thinks that fasting

might slow the development

of diabetes, which narrows the

blood vessels and increases the

risk of heart disesase. Periodic

withdrawal of food might

resensitise the insulin-producing

beta cells, a theory that is backed

by animal studies.

Don’t eat today

IT SEEMS super-Earths would be a pretty super place to live

compared with our puny planet. These big rocky planets in

other solar systems could stay warm enough for life up to

35 per cent longer than Earth.

Christine Bounama and colleagues at the Potsdam

Institute for Climate Impact Research in Germany

modelled various factors that make a planet habitable,

including volcanism, the atmosphere and the size of the

star it orbits. They found that super-Earths could host

life for up to 11.9 billion years, beating the estimated

8.8 billion years for Earth.

Super-Earths, which are up to 10 times the mass of

Earth, stay hot for longer than planets like ours, meaning

volcanism keeps the atmosphere topped up with carbon

dioxide, says Bounama. This helps warm the planet and

supports photosynthetic life.

Bounama says a hotter sun than ours would cut

short a super-Earth’s habitability by baking any life as it

brightens with age. The ideal would be a dim red star

0.9 times the mass of our sun. The team presented the

work at the 7th European Workshop on Astrobiology in

Turku, Finland, last month.

Life could survive longer on a super-Earth

In brief– Research news and discovery

www.newscientist.com 10 November 2007 | NewScientist | 21

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