What is the SPF of your beard?

Have I told you guys lately that you should be reading the Scicurious blog, especially for Weird Science Fridays? Because, seriously, you guys. You guys, seriously.

Today, Scicurious tackles "DOSIMETRIC INVESTIGATION OF THE SOLAR ERYTHEMAL UV RADIATION PROTECTION PROVIDED BY BEARDS AND MOUSTACHES", a paper published in the journal Radiation Protection Dosimetry. Basically, it's about whether beards protect their owners' skin from sun damage. You need to go to Scicurious' site just to see the photo of the apparatus the researchers built to study this question. Suffice to say, it involves a lot of disembodied heads, in various stages of beardedness, hanging out on what looks like an old-fashioned merry-go-round.

Bearded gentlemen will be pleased to note that the beard is, actually, an effective means of sun protection. At least for the skin it covers.

Read more at Scicurious

Image: beard: the end, a Creative Commons Attribution (2.0) image from soundfromwayout's photostream

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Is responding to food as a reward the same thing as food addiction?

We've had a couple of posts recently about a hypothesis that links the current increase in obesity with an increase in easy access to foods that are designed to trigger reward systems in the human brain. Basically: Maybe we're getting fatter because our brains are seeking out the recurrent reward of food that makes us fat. Scientist Stephan Guyenet explained it all in more detail in a recent guest post.

It's an interesting—and increasingly popular—idea, though not without flaws. To give you some context on how scientists are talking about this, I linked you to a blog post by Scicurious, another scientist who wrote about some of the critiques of food reward and related ideas. In particular, Scicurious questioned some of the implicit connections being made here between body size and health, and eating patterns and body size.

She also talked about another critique, one which came up in a recent article in the journal Nature Reviews Neuroscience. If people are gaining weight because they're addicted to eating unhealthy foods, we ought to see some evidence of that in the way their brains respond to those foods. After all, brains respond to many physically addictive substances in special ways. But we don't see that with junk food. So does that invalidate the hypothesis?

Stephan Guyenet doesn't think it does. In a recent email to me, he explained that he thinks the food reward hypothesis is a bit more nuanced, and can't really be described as "food addiction". At least, not the same way that cigarettes or heroin are addictive. Read the rest