Chalk up another achievement for parrots.
Anastasia Krasheninnikova and colleagues at the Max Planck Institute for Ornithology in Germany tested four species of parrots in an experiment that required trading tokens for food and recently reported their findings in the journal Scientific Reports.
Chimpanzees, monkeys and cockatoos, among other species, can defer gratification, but what about the birds?
The birds, great green macaws, blue-throated macaws, blue-headed macaws and African grey parrots, learned that a metal hoop could be traded for a piece of dry corn, the lowest value food, a metal bracket for a medium-value sunflower seed and a plastic ring for the highest-value food, a piece of shelled walnut.
The green macaws were consistently the best. The African greys, who have a reputation as very intelligent, did reasonably well on the obvious choices, but instead of immediately taking a walnut, they would get the ring and then trade it for a walnut. Why take the extra step? Krasheninnikova said African greys enjoy manipulating objects. "We know they're very playful," she said.
Plants sense predators – and fight back
Plants have no eyes, no ears, no mouth and no hands. They do not have a brain or a nervous system. Muscles? Forget them. Yet, when something comes around to eat them, they sense it. And they fight back. How is this possible?
To reveal the secret workings of a plant's threat communication system, Masatsugu Toyota (now a professor at Saitama University) and other researchers in Simon Gilroy's lab at the University of Wisconsin, Madison, sent in caterpillars and slashed leaves. They applied glutamate, a neurotransmitter, and a glowing protein to trace calcium and accompanying chemical and electrical messages in the plant. Under a microscope, they saw that plants aren't as passive as they seem. The messages start at the point of attack, where glutamate initiates a wave of calcium that propagates through the plant's veins. The deluge turns on stress hormones and genetic switches that open plant arsenals. The plant reacted within a few seconds and transferred information from leaf to leaf in a couple of minutes. This is slower than your nervous system, but "for a plant biologist, that is booking it," Gilroy said.
Water droplets don't just hover on hot pan
Drip water on a hot pan, and the droplets will skitter around the pan, speeding like tiny mad hovercraft on cushions of steam.
This is the Leidenfrost effect, after Johann Gottlob Leidenfrost, a German doctor and theologian who described it in 1756. But French scientists have figured out something new about those drops. When they are small enough — about a millimeter — the roiling of heat in the liquid will cause the droplet to tilt and rotate. That propels the droplet to roll. It was known that the droplets, levitating on top of a layer of vapor, move easily, but the presumption was that they were sliding down a slope or pushed by air currents. The new research shows that they can move all by themselves.
"It's embarrassingly simple," said David Quéré, a scientist at the French National Center for Scientific Research and École Polytechnique. "The drop is running away. It has a little motor inside, which is surprising. From this view, it's amazingly different from usual drops, which, of course, stay where you place them."
Quéré calls it a Leidenfrost wheel.
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