16 | NewScientist | 21/28 December 2013

Island culture used binary in AD 1500

POLYNESIAN islanders spoke the language of computers centuries before the first programmer was born. It seems that speakers on Mangareva island used a hybrid of decimal and binary counting.

The binary system used by computers can represent any number via a string of 1s and 0s. First you create a series of columns, each one devoted to a different power of 2, starting with 1 (which is 20), followed by 2, 4, 8 and so on. You then put 1s in the columns needed to make up the target number and 0s in the rest.

Andrea Bender and Sieghard Beller of the University of Bergen, Norway studied the Mangarevan language, which dates back to AD 1500, or even earlier. As in the normal, decimal system, there are words for the numbers 1 through 9. After that, Mangarevans only had words for 10, 20, 40 and 80 – the binary powers multiplied by 10. So they used the binary system to count in 10s, but added 1 to 9 in the normal way (PNAS, DOI: 10.1073/pnas.1309160110).

Bender says the system may have come about because the islanders tallied items such as coconuts and octopuses, in groups of 1, 2, 4 and 8.

Europa report: first plume seen firing from Jovian moonAN ICY moon of Jupiter has been caught spitting into space.

For the first time, a towering plume of water vapour has been seen coming from Europa. The discovery strengthens the case that the moon has a liquid ocean beneath its icy crust, and may even offer a way to taste its seas and search for signs of life.

Images from the Galileo spacecraft, which orbited Jupiter from 1995 to 2003, hinted that Europa has a relatively thin crust in which fissures sometimes open up and let water escape from a

subsurface ocean. But the probe did not spot any active plumes, and nor did later search efforts.

That may have been in part because the plumes are intermittent, but also because previous scans were done in visible light, says Lorenz Roth of the Southwest Research Institute in San Antonio, Texas. Water vapour without any large particles of ice or dust to scatter sunlight might have been invisible. So Roth and his colleagues examined recent ultraviolet images taken by the Hubble Space Telescope.

YOU’VE heard of crocodile tears. Now it seems alligators have their own cunning trick.

American alligators have been spotted with twigs on their snouts, apparently to tempt birds looking for building materials.

In the first study of reptile tool use, Vladimir Dinets of the University of Tennessee in Knoxville, spent a year observing American alligators at two lakes in Louisiana. At each lake he also monitored a bird rookery.

The local alligators only balanced sticks on their heads when they were close to the rookeries, not elsewhere.

And they only did this during the birds’ breeding season, when the birds were looking for nest-building materials (Ethology Ecology & Evolution, doi.org/qf8).

Dinets also thinks mugger crocodiles in India try a similar trick, so the technique may be used by several crocodilian species. It is unclear whether the behaviour is innate or learned by watching others.

Either way, it seems to work. John Brueggen of Florida’s St Augustine Alligator Farm Zoological Park has often seen American alligators successfully catching birds this way.

Alligators use twig accessory as a lure

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They found a large cloud of hydrogen and oxygen extending from the moon’s south pole. A model suggests that it is a plume 200 kilometres high (Science, doi.org/qgv).

It’s possible that Europa’s ocean sustains life, making it a tempting target for future space missions. If a probe could catch some material from the plume, that would allow us to sample the seas without the difficult task of landing and drilling into the ice, says Cynthia Phillips at the SETI Institute in Mountain View, California.

Youngest child a baby in mum’s eye

EVER noticed how a youngest child is often babied? Well, don’t blame the parents, they could be under the “baby illusion”, where the youngest child is perceived as shorter than they really are.

Jordy Kaufman and colleagues from Swinburne University in Melbourne, Australia, asked 77 mothers to mark on a wall how tall their children were. The mums underestimated the height of their youngest child by 7.5 centimetres on average, but were almost spot on for the height of any older children (Current Biology, DOI: 10.1016/j.cub.2013.10.072).

Birth order is thought to affect many things, including how dominant or risk-averse you are. If mothers, and potentially fathers, see their youngest as shorter than they really are, they may treat them differently to elder siblings, which may be one reason we see birth order differences, says Kaufman. “One of the great mysteries of child development is birth order effects,” says Andrew Whitehouse at the University of Western Australian in Perth. “Perhaps we tend to see our youngest child as the baby and that never changes.”

It’s a striking example of a much broader phenomenon too, Whitehouse says: “How we perceive the world is different to the way the world really is.”

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