What the scientists are saying…
The secret of the Leaning Tower
The Leaning Tower of Pisa leans for the same reason that it has remained upright for 800 years: it sits in a soft, pliable stratum of clay and sand. This caused the subsidence that gave the monument its 5.5-degree tilt (closer to 4 degrees now, thanks to conservation work): it also absorbed the energy from the many earthquakes that have struck the region since 1173, when construction began. International researchers found that the 183ft height of the marble tower, and its stiffness and weight, in conjunction with the flexibility of the ground in which its shallow foundations sit, has “dampened” its “vibrational characteristics”, so that it doesn’t much resonate with ground motion – a phenomenon known as dynamic soil-structure interaction. “Ironically, the very soil that caused the leaning instability and brought the tower to the verge of collapse can be credited with helping it to survive,” said civil engineer Professor George Mylonakis, who worked on the study.
A mollusc’s memory “transplant”
It’s not clear how many memories California sea hare snails form as they feed on algae in the tide pools of the Pacific coast – but they do seem to remember pain events. And now, scientists claim to have transferred one of these simple memories from one snail to another, by way of a quick injection. The study was devised by neurobiologist Dr David Glanzman of UCLA, to test his controversial theory that some memories are stored not in the synapses between the brain’s neurons, but in the ribonucleic acid (RNA), the cellular “messenger” that transmits genetic instructions to cells. His team gave electric shocks to some marine snails in order to “sensitise” them: the result was that when they were touched, they exhibited a far stronger defensive reaction than snails who had not been shocked (like people who survive explosions being jumpy around loud noises). They then extracted RNA from the nervous systems of the snails and injected it into other snails. Snails that received RNA from unshocked snails showed no change in their reaction to being prodded, but those injected with RNA from the shocked snails suddenly became “sensitised” too – suggesting they had “received” the pain memory. However, critics were not convinced that the results proved Dr Glanzman’s theory.
Why wasps plague your picnic
If you’re having a picnic, keep an eye out for a lone wasp buzzing about: it may be a scout, preparing to fly back to the nest to bang the gong for dinner – almost literally. That wasps alert their nest-mates to the presence of food has long been suspected: it couldn’t be a coincidence that one wasp hovering over the jam is always followed by a horde. Now, scientists have worked out how they do this. When they find food, the “scout” wasps return to their colonies, and beat their abdomens against different parts of the nest, creating a distinctive drumming noise. Previously, this behaviour was assumed to signal hunger, said Professor Benjamin Taylor, of Laguardia Community College in New York, who conducted the study. “But what my team found was that the wasps are somehow informing each other that there’s good food near by, and other workers should be activated to go out and search for it.” Complex communication of this type is known as “recruitment”, and has often been seen in other insects (for instance, in ants, which leave pheromone trails for other ants to follow), but foraging wasps were thought to be simpler creatures.
Exercise does not slow dementia
Exercise does not appear to slow the advance of dementia in people in the early stages of the condition, a new study has found. There is evidence that people who keep fit in middle age are less likely to develop dementia, leading to the idea that it may also be slowed down in those already diagnosed. But when 329 patients with mild or moderate dementia were asked to go on a four-month-long programme to improve their strength and aerobic fitness, it did not seem to lead to any cognitive benefits (though their overall health did benefit). Twelve months later, their score in tests of relative cognitive impairment had increased to 25.2, on average, whereas in a control group of patients, the figure was 23.8. “This indicates greater impairment in the exercise group,” the study notes in the BMJ.