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Contents
- Sweet Confusion: Does high fructose corn syrup deserve such a bad rap?
- Closed Thinking: Without scientific competition and open debate, much psychology research goes nowhere
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Contents
- Better chow yields more milk: A more nutritious form of corn for dairy cows boosts farm profits, teen investigator finds
- Fuzzy future: Kids may suffer impaired vision from spending too little time outdoors, studies suggest
- Building with moon rocks: Working on the moon with lunar soil and grit could prove easier, more efficient and less costly than using earthly materials
Web edition: November 2, 2012
Print edition: November 17, 2012; Vol.182 #10 (p. 30)
Quick facial thinking
I have always found it remarkable that the average person can identify probably thousands of individuals by face “Face Smarts,” (SN: 10/6/12, p. 20) and perhaps hundreds by voice, as well as some just by their gait. Clearly such identification at a distance must have been a crucial survival advantage during our evolution; this unfortunately suggests to me that the larger threat to earlier humans was not lions or tigers and the like, but rather other members of our own species.
Peter Benson, North Oaks, Minn.
Timing human history
“No home for Homo sapiens” (SN: 10/20/12, p. 9) says that the Khoisan separated from the rest of humanity “at least 100,000 years ago.” For much (if not all) of that time, the Khoisan have had contact with other humans, and we can assume there has often been some interbreeding. If the Khoisan genome has incorporated sufficient DNA from other branches of the human family, the date of the split would look more recent than it actually was. Do the researchers have an earliest plausible date for the split? Is that date early enough that the split could have happened when Homo sapiens was first emerging, rather than after our species was well-established? And finally, if the split might be that ancient, could the Khoisan and the rest of us have been on the way to becoming separate species had it not been for adventurous sex?
Tim Cliffe, Emmitsburg, Md.
The researchers do not offer an earliest possible date for the Khoisan’s split from other populations, although 100,000 years is in line with other estimates. They do acknowledge that Khoisan mating with other populations could cause underestimates of when the Khoisan actually diverged. The estimated sizes of past populations also affect divergence dates. —Erin Wayman
Test for Alzheimer’s idea
“Alzheimer’s protein could help MS” (SN: 9/22/12, p. 14) is very interesting, but it would be difficult to do experiments in people — at least before we have some indication that it might work. One approach would be to compare the prevalence of MS in people with and without Alzheimer’s. If it’s lower in people with Alzheimer’s, that might be an indication that the idea is worth pursuing in people.
Ted Grinthal, Berkeley Heights, N.J.
Don’t try at home
“Dip your finger in water and then quickly dip it in molten lead...” This opening sentence in “Bubble-free boiling” (SN: 10/6/12, p. 16) makes me cringe. It’s scary to think of inexperienced people doing this on their own.
Bob Eramia, via e-mail
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It said that when you put something on your skin that is hot with a temperature in the 1,000's of degrees, the heat vaporizes the moisture on the skin, and it forms a colloidal state, a kind of foam/bubbles of steam. The colloidal gas insulates the skin from the heat, and you can walk across the coals.
When the temperature cools down into the 100's of degrees, the colloidal gas collapses, and it no longer insulates. Therefore, in order to do firewalking the fire has to be in the 1000's of degrees. You can tell the difference by the color. When something is in the 1000's of degrees, it glows. In the 100's of degrees it doesn't give off visible light. That is why they use coals, not hot metal or rocks.
I was curious about this, so I decided to test the explanation. I heated up a penny on a bunsen burner in the chemistry lab. When it glowed red hot, I dropped it onto my hand. Very slowly I shifted it back and forth from hand to hand, just like slow walking. This was really slow, maybe 5 or 6 seconds in each hand at a time. It didn't burn me. When the penny cooled down so it wasn't glowing, it burned my hand, and I got a blister.
One thing no one notices about the firewalkers is the approach to the fire pit. It is always something containing moisture, like wet grass, to make their feet damp. This guarantees enough moisture to form the colloidal gas.
The same explanation applies to plunging a wet/sweaty arm into molten lead.
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