16 | NewScientist | 12 April 2014

CHILDREN growing up severely disadvantaged can experience dramatic ageing in their chromosomes. By age 9, their telomeres – the caps on the ends of chromosomes that shrink each time cells divide – can be as short as those of someone decades older.

Daniel Notterman from Penn State University in University Park and colleagues found the effect in a group of 40 9-year-old

boys, half of whom were from extremely deprived backgrounds and half from privileged ones.

Telomeres protect chromosomes from damage, so their shortening over time is thought to be responsible for some of the negative effects of ageing. Children whose mothers changed partners more than once by the time they were 9 had telomeres 40 per cent shorter

than those with no changes. And those whose mothers attended college had 35 per cent longer telomeres than those who didn’t, on average (PNAS, DOI: 10.1073/pnas.1404293111).

“The social environment really conditions the way that these children are living, and their health,” says Notterman, who warns the link between shorter telomeres and health outcomes is not fully established. “But it’s a very profound change,” he says.

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Flimsy rocks allowed Earth’s plates to start moving

FRAGILE things can be useful. It seems that the shifting

plates of rock that make up Earth’s crust can only move

because the crust is partly made of damaged rocks.

Uniquely in the solar system, Earth’s crust is divided

into several tectonic plates that move over the aeons.

Often, one plate gets subducted under another and sinks

into the mantle beneath, while elsewhere, new rocks rise

to the surface. If the plates did not recycle like this, the

surface might not be so rich in the chemicals vital for life.

But it was unclear how the plates started moving. The

first subduction was probably about 4 billion years ago,

but it took another billion years for all the plates to move.

To explain this delay, David Bercovici of Yale University

and Yanick Ricard of the University of Lyon in France

modelled rocks in the highly viscous mantle. There,

strong currents create weak zones in the rocks.

Over time, more of these damaged rocks were thrust

back up to form new sections of plate. Because these

new plates were partly made of fragile rocks, their edges

were more breakable, making it easier for one to slide

under another (Nature, doi.org/r7m).

Bercovici says that may explain the delay: it took a

billion years to make the plates fragile enough that

subduction could get going in earnest.

“Their model makes intuitive sense,” says Catherine

McCammon of the University of Bayreuth in Germany.

Harsh world ages kids’ chromosomes

Blind cavefish sucks it and ‘sees’

IT HAS no eyes, but the Mexican blind cavefish never crashes. Now we know its secret: a navigation system based on sucking.

Astyanax mexicanus’s trick is to suck water into its mouth. The resulting currents bounce off objects, and the fish detects that with sense organs on its flanks. All fish suck and have these organs, but the cavefish is the first one we know of that uses them in tandem.

Roi Holzman of Tel Aviv University in Israel and colleagues recorded how often captive cavefish sucked in water. When Holzman rearranged the objects in their tank, the fish sucked four times as often and swam more slowly, as if lost. When the fish approached an object, they sucked at up to six times the normal rate (The Journal of Experimental Biology, doi.org/r6x).

Holzman says the fish use the system for navigation, not for hunting. “They eat bat guano.”

Dark energy hunt bags dwarf planets

OUR solar system just got a little more crowded, thanks to a camera designed to study dark energy.

Last week astronomers announced the discovery of 2012 VP113, a potential dwarf planet in the far outer fringes of the solar system. Days later, the same team reported two more potential dwarfs, known as 2013 FY27 and 2013 FZ27. These two objects are in the Kuiper belt, a closer grouping of small bodies beyond Neptune.

The haul came via the Dark Energy Camera at the Cerro Tololo Inter-American Observatory in Chile, designed to collect faint light from distant galaxies and hunt for clues about dark energy. It is so sensitive it can detect far-flung bodies in our solar system that until now have been invisible.

IN BRIEF