Health & Science

Measuring a nation’s mood; New respect for the spleen; How humans first got malaria; Success beats failure

Measuring a nation’s mood

The national mood is a nebulous thing. How best to gauge it? Directly polling large populations with questions about feelings—“Are you feeling happy today?”—tends to prompt respondents to skew their answers positively. But two University of Vermont statisticians have found a unique, Internet-based approach to measuring the rise and fall of the public’s sense of well-being. First they downloaded 230,000 song lyrics from, to get a sense of what types of songs—melancholy, upbeat, angry—were popular at any given time. Then they sifted through hundreds of millions of sentences from, which scans 2.4 million blogs for the phrases “I feel” and “I am feeling.” Next they searched the texts for key words rated 1 to 9 on a happiness scale. (“Triumphant” and “love” garner an 8.7; “hostage” rates 2.2.) From these figures, the scientists calculated the average societal happiness each day, going back decades. Among the results: Vacations and holidays are consistently happy days. Two particularly bright days were President Obama’s election and inauguration, while Sept. 11, 2001, and its anniversaries caused a profound drop in the national mood, with 2003 marking a low point. “We argue that you can use this data as a kind of remote sensor of well-being,” co-author Peter Dodds tells The New York Times. This new form of analysis—which will focus on tweets next—“is really exciting,” says psychologist James Pennebaker, who was not involved in the study. “It’s going to change the social sciences. That is very clear.’’

New respect for the spleen

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Pity the spleen—small, unromantic, and typically lumped with the other vestigial organs that, technically, we could live without. In truth, scientists know the spleen as an important part of the immune system, where red blood cells are spruced up and antibodies synthesized. Now research with mice reveals another critical role. The spleen was found to store monocytes, white blood cells essential to repairing heart and other tissue, and to make them available en masse on short notice. “Timing is a really important issue when you want to fight pathogens or heal after an injury,” immunologist and co-author Mikael Pittet tells Science News. The researchers induced heart attacks in the mice; those without spleens had fewer monocytes in play and did not recover as well. The results echo a study from the 1970s, which found that war veterans who’d lost their spleens were twice as likely to later die from cardiovascular disease than vets with spleens. Perhaps “vestigial” just means we don’t understand it yet, says Matthias Nahrendorf, another co-author. “Evolution has an edge on us. I would be very careful about saying, ‘You don’t need this organ, get rid of it.’”

How humans first got malaria

Chimpanzees passed the virus that causes AIDS to humans, and now they are being blamed for transmitting another dread disease: malaria. The disease, caused by a blood parasite and carried by mosquitoes, kills more than a million people every year. Although chimps carry their own strain of malaria, it was thought to be unrelated to ours. But a new genetic study suggests that the most common and dangerous form affecting humans, caused by the parasite Plasmodium falciparum, mutated from the chimp strain and reached us in a single leap, perhaps as recently as 10,000 years ago. “Current wisdom that P. falciparum has been in humans for millions and millions of years is wrong,” study co-author Nathan Wolfe tells National Geographic News. The researchers speculate that early humans may have contracted it when they were settling into agrarian lives in Africa and encroaching on chimp territory. Wolfe warns that similar parasites, including another malaria strain, are poised to make the cross-species jump today; once in humans, “it could very well be the beginning of something that lasts for thousands of years.”

Success beats failure

We learn more from failure than from success, says the old aphorism. It sounds reasonable, but a new study says it’s simply not true. Researchers at the Massachusetts Institute of Technology showed monkeys a series of pictures and trained them to turn their heads left or right depending on which image was presented. When the monkeys chose correctly, they received a reward. The scientists found that when the monkeys made the right choices, the neurons involved in learning and discrimination were very active. The neurons “learn better when the animal had a recent success,” MIT researcher Earl Miller tells Success breeds success, because the rewards it produces raise attention levels. When the monkeys made mistakes and got nothing, their ability to respond correctly didn’t improve.

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