It took a team of engineers and some tricky math, but scientists say they now know how cats drink.
Jeffrey Aristoff and his team published a study on how cats lap water Thursday in Science. They did the study without any funding.
Almost everyone has watched cats lap milk from a bowl, Aristoff writes, but casual observation fails to capture the elegance of the act — the tongue moves too fast for us to see.
The team decided to study the physics of a cat’s lap after watching one of their cats, Cutta Cutta, drink milk, Aristoff says. They got nine cats plus Cutta Cutta to drink from bowls while filming them with a high-speed camera.
Previous high-speed films from the 1940s showed that cats extend their tongues in a J-shaped fashion so that its topside hits the liquid first, suggesting that, like dogs, they used their tongues like ladles.
But the team’s footage showed that only the topside of the tongue touched the liquid. Once it did, the cats snatched their tongues back at up to 78 centimetres per second. Inertia drew a column of liquid up with the tongue, one that gradually thinned at the top due to gravity. The cats then snapped their mouth shuts to catch the column before it broke and fell away.
It turns out that cats were using some tricky math. As the column of water moves up due to inertia, Aristoff says, gravity is pulling it back down. If the cat closes its mouth too late, the column breaks and falls away; too early, and most of the liquid is still in the puddle.
The cats timed their mouth movements so that they’d close at almost the exact moment when inertia and gravity balanced out, just before the column broke. This maximized the amount of drink they got per lap while keeping their whiskers dry.
That same interplay of forces also determined lap frequency — bigger tongues meant more time between pinch-offs, which means slower laps. Video footage of tigers and lions found that bigger cats did indeed take slower laps.
These results show that cats can take advantage of hydrodynamics to get the most out of each drink, Aristoff says. As for how the cats figured this out, he says, “I suppose they have had plenty of time to practice.”
The team hopes this research could lead to soft-bodied water-walking robots, Aristoff says, as water-walking uses the same principles as a cat’s lap.
Is your mind wandering? Then it’ll bring back sadness.
Researchers at Harvard University have discovered that people are more likely to be unhappy when their minds are not focused on the task at hand.
Previous studies suggest the human mind wanders most of the time, writes researcher Matthew Killingsworth in this week’s Science, which philosophers suggest is bad for the soul. Most philosophies emphasize living in the moment to attain true happiness. But it’s been tough to confirm this, as researchers haven’t had a cheap, convenient way to get people to track their thoughts, actions and feelings throughout the day.
Enter the iPhone. Killingsworth and his team created an iPhone app which quizzed people throughout the day, asking them three questions: how they were feeling, what they were doing, and whether they were thinking about something other than what they were doing. Their responses were sent to a website, trackyourhappiness.org, for analysis. About 2,250 people participated.
The study found respondents sent their minds wandering about 47 per cent of the time, and wandered at least 30 per cent of the time during every class of activity except for making love. Mind wanderers were more likely to be unhappy than those focused on their task, no matter what they were doing or thinking. Statistical analysis found mind wandering tended to precede unhappiness — and not vice-versa — which could mean that wandering causes unhappiness.
“A human mind is a wandering mind,” Killingsworth concludes, “and a wandering mind is an unhappy mind.” Mind wandering may let us learn, he writes, reason and plan, but it might not make us happy.
