David Berreby is the author of "Us and Them: The Science of Identity." He has written about human behavior and other science topics for The New Yorker, The New York Times Magazine, Slate, Smithsonian, The New Republic, Nature, Discover, Vogue and many other publications. He has been a Visiting Scholar at the University of Paris, a Science Writing Fellow at the Marine Biological Laboratory, a resident at Yaddo, and in 2006 was awarded the Erving Goffman Award for Outstanding Scholarship for the first edition of "Us and Them." David can be found on Twitter at @davidberreby and reached by email at david [at] davidberreby [dot] com.
Models of the mind are never ``just theories'' -- ideas about human nature shape the rules and habits that guide daily life.
A case in point: If people were purely rational in their decisions about risks and rewards, it would be a simple matter to explain to agricultural workers that all pesticides are harmful, be they powders or liquids, and so workers should wear protective gear and take showers at the end of the day.
But real decisions are shaped by conflicting motives, inbuilt mental biases and the distorting effects of supposedly irrelevant forces, like fatigue, love and tradition.
Case in point: Today the American Journal of Public Health is publishing the results of a study of 99 Mexican farmworkers who were working in Washington state in 2005 and 2006. (When it goes online, it should be here.) In the paper, Shedra Amy Snipes of the University of Texas and her colleagues report that the workers didn't think odorless powder pesticides were as dangerous as liquids (which smelled bad). Chemically, that's not true, but it's human nature to be more repelled by bad-smelling stuff than by something that gives no offense.
The workers also sometimes declined to wear protective clothes which would have reduced their pesticide exposure -- because that would have slowed them down, and they are paid according to the amount of fruit they harvested. They wanted to bring the most money home to their families. Some also avoided showers and decontamination at the workday's end, because they were tired and achey (an effect of when in the day they were asked to shower) and because they thought water was bad for an overheated body (an effect of a cultural belief).
These results suggest that farmworkers would be safer from the effects of pesticides if they were paid by the hour (those who are paid that way don't refuse to wear protection, as being slower doesn't reduce their wages). Regulators might also consider requiring that dry pesticides contain something to make them smell bad, and launching a campaign to inform people about the importance of decontamination. None of that would be required if people fit the ``Rational Economic Man'' model. But they don't, and it's not a purely academic point.
Here's the science of black holes, from supermassive monsters to ones the size of ping-pong balls.
- There's more than one way to make a black hole, says NASA's Michelle Thaller. They're not always formed from dead stars. For example, there are teeny tiny black holes all around us, the result of high-energy cosmic rays slamming into our atmosphere with enough force to cram matter together so densely that no light can escape.
- CERN is trying to create artificial black holes right now, but don't worry, it's not dangerous. Scientists there are attempting to smash two particles together with such intensity that it creates a black hole that would live for just a millionth of a second.
- Thaller uses a brilliant analogy involving a rubber sheet, a marble, and an elephant to explain why different black holes have varying densities. Watch and learn!
- Bonus fact: If the Earth became a black hole, it would be crushed to the size of a ping-pong ball.
Military recruits are supposed to be assessed to see whether they're fit for service. What happens when they're not?
- During the Vietnam War, Robert McNamara began a program called Project 100,000.
- The program brought over 300,000 men to Vietnam who failed to meet minimum criteria for military service, both physically and mentally.
- Project 100,000 recruits were killed in disproportionate numbers and fared worse after their military service than their civilian peers, making the program one of the biggest—and possibly cruelest—mistakes of the Vietnam War.
In a breakthrough for nuclear fusion research, scientists at China's Experimental Advanced Superconducting Tokamak (EAST) reactor have produced temperatures necessary for nuclear fusion on Earth.
- The EAST reactor was able to heat hydrogen to temperatures exceeding 100 million degrees Celsius.
- Nuclear fusion could someday provide the planet with a virtually limitless supply of clean energy.
- Still, scientists have many other obstacles to pass before fusion technology becomes a viable energy source.
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