Revising the Rainbow

In this week’s episode of Science Teaching Tips, we look at my favorite thing — light.  Light, like, rulez.  Dude.  And so does my old mentor, Paul Doherty, who will tell you one of his best stories from the history of science about how the spectrum came to be the spectrum.  I mean, what the heck is indigo anyway?  The answer turns out to be, like all good history of science stories, steeped in mysticism and superstition.   Give it a listen, it’s a good story!

Episode 65:  Revising the Rainbow.

 

New study on synthesia

I got a lot of comments on my previous post on synthesia, so it seems there’s some interest there.  Check out this post on Cognitive Daily about a study of the rarest form of synthesia – tasting words.

For more common (or rather, less uncommon) forms of synesthesia, the most convincing evidence that it’s real comes from studies showing that synesthetic associations are stable. If “A” is associated with the color blue now, it will still be associated with blue six months from now. What’s more, sometimes the letter-color associations are the same for different people. With only one example to study, this type of evidence is harder to come by, but at least Gendel could test TD at different times and see if her associations were stable.

Gendel presented TD with 806 randomly selected words, and 222 nonsense words created from English-language sounds. She was asked to write down what taste (if any) she associated with each word, and rate the strength of the association. Then the test was repeated three months later. Almost 50 percent of the time, TD experienced a taste sensation accompanying the word. In those cases, 88 percent of the time that sensation was identical or nearly identical three months later. Stronger taste sensations were significantly more likely to be repeated at the end of the study.

 

Why do your fingers wrinkle?

Why is it that your fingers get all wrinkly when you’re in the bath too long?

It’s a pretty simple little answer.  You know how a spongue gets bigger when it gets wet.  The outer layer of our skin is like that too — it soaks up a bunch of water and gets swollen.  But it can’t just get big and puffy because it’s firmly fastened to the layer of skin underneath.  But that extra surface area has to go somewhere, so it buckles up into folds, and wrinkles.  This happens after a long time in the bath because the skin oils (sebum), which usually protect your skin, eventually washes away, letting the water in to your skin.

As a commenter on the Wonderquest site put it,

My high school biology teacher explained it as: you have a size 3 finger and size 3 skin. After you have been in water, you still have a size 3 finger but now you have size 7 skin.

This is all in the epidermis, the outermost layer of our skin.  The stratum corneum is the part that is on the outside, and it’s got a bunch of dead keratin cells.  Keratin’s the stuff found in our hair and fingernails.  The dead keratin cells absorb water.  It happens mostly on our hands and feet because those parts of our body go through a lot of wear and tear, so they’ve got more dead keratin cells on them than, say, the sensitive and soft underside of our arm.

Great physiology and physics!

More on the Library of Congress Everyday Mysteries Site, and Wonderquest.

 

Photos of ovulation!

Here are some fantastic photos from the New Scientist website — accidentally captured the clearest picture of a woman’s ovary in the process of ovulation.

Pictures and articles here

I guess it’s pretty hard to get pictures of an event that happens for just a few minutes at one poorly determined time each month. They just happened to have this woman already cut open at the time (she was getting a partial hysterectomy). What luck. Apparently the main scientific result of the images is that the process happened much slower than previously thought — it took about 15 minutes for the egg to emerge.

I was actually just as interested to see the ovary and the follicle themselves (the follicle is *huge*!) as the emergence of the egg.

Hmm, a funny post for Father’s Day, I realize!

And, congratulations to me, I turn 100 today!  This is my 100th post…

 

This so-called life…

Yesterday’s post in Engineering Life talks about the questions that are raised by genetic engineering, and whether we ought to be more worried than we are. I wanted to take the chance to point you to WNYC Radio Lab’s (So-called) Life episode, which talks about just this — what is life, what counts as natural? Brilliant radio. Listen to it!

Engineering Life’s blogger Carl Zimmer writes:

Imagine that mad scientists defied nature and violated the barriers between species. They injected human DNA into non-human creatures, altering their genomes into chimeras–unnatural fusions of man and beast. The goal of the scientists was to enslave these creatures, to exploit their cellular machinery for human gain. The creatures began to produce human proteins, so many of them that they become sick, in some cases even dying. The scientists harvest the proteins, and then, breaching the sacred barrier between species yet again, people injected the unnatural molecules into their own bodies.

This may sound like a futuristic nightmare, the kind that we will only experience if we neglect our moral compass and let science go berserk. But it is actually happening right now. Today millions of people with diabetes will inject themselves with insulin that was produced by E. coli.

The fact that no one is disturbed by this state of affairs says a lot.

But thirty years ago, the public rebelled against the same idea — of sticking genes into E. Coli so that it would produce human insulin. The project was condemned by many activitists. And yet…

We suffered no epidemic of diabetic comas, no cancer viruses spread by E. coli from host to host. None of the dire warnings about engineered E. coli, in fact, came to pass. It appears that the safeguards put in place were good enough, and that engineered E. coli could not compete with its wild cousins. Scientists continued to engineer E. coli, and today it can make all manner of substances, from blood-thinners to jet fuel

Today we’re capable of much more than this with genetic engineering, including the engineering of chimeras (beings created by mixing cells that originated from two different beings).

It’s not quite clear to me where the Engineering Life blogger (Carl Zimmer) stands on the issue, as he finishes with a less cautionary, more relativistic stance:

But it’s also important to bear in mind how easy it is to be terrified by a science-fiction caricature of what’s really going on in synthetic biology labs. We have a profound distrust of what seems unnatural, such as crossing species boundaries. Yet a casual glance at E. coli’s genome demonstrates that nature has been inserting foreign genes into it by the hundreds for millions of years. Our own genome is not immune from these violations. We carry the remains of thousands of viruses in our DNA, and most people on Earth may even carry genes inherited from another species of human–Neanderthals. We may be disgusted by the thought of violating species boundaries because of deeply ingrained instincts. But that disgust is an unreliable guide to the realities of biology, whether that biology is in E. coli or in ourselves.

I’m not really sure where I stand on the issue, to be honest. I don’t have an emotional reaction to mixing species — the “disgust” response outlined above. But I am cautious about introducing new creatures to our world, as the law of unintended consequences often seems to hold. But I feel somewhat powerless to make a stand one way or the other. I was not in favor of putting GMO corn out in the cornfields, and now look where we are — GMO corn has spread all over North America on the wind. Did we used to have more control over these new innovations, or has the public always felt unable to enter the debate about what is done in their world?

[Crossposted on Engineering Life]

[Picture: "The Young Family," by Patrician Piccini (2002-3). Wikipedia]

 

We’ve got 10X more bacteria than cells

check out this item from Science Daily…

Humans have Ten Times More Bacterial Than Human Cells: How do Microbial Communities Affect Human Health?

ScienceDaily -Jun. 5, 2008 — The number of bacteria living within the body of the average healthy adult human are estimated to outnumber human cells 10 to 1. Changes in these microbial communities may be responsible for digestive disorders, skin diseases, gum disease and even obesity. Despite their vital imporance in human health and disease, these communities residing within us remain largely unstudied and a concerted research effort needs to be made to better understand them, say researchers June 3 at the 108th General Meeting of the American Society for Microbiology in Boston.

This is interesting in its own right, but also gives me a chance to point you to my favorite Krulwich on Science episode. Don’t know Krulwich on Science? Check it out. They’re only about 5-10 minutes long and some of the best-produced and entertaining science stories on radio (aside from RadioLab).

So, one of my favorite Krulwich episodes (just 4 minutes of your time!) asks, so, who are we if we’re just microbe hotels? What constitutes you?

Bacteria Outnumber Cells in Human Body

July 1, 2006 · The human body contains 20 times more microbes than it does cells. In fact, a visitor from outer space might think the human race is just one big chain of microbe hotels.

 

Synthesia

I’ve always been sort of fascinated by synthesia. A brain with a predilection to mix colors and letters and days and feelings and smells sounds kinda trippy. I’ve always thought (and I think I may have read somewhere) that it seems like a very rich way to experience life. I mean, confusion is orange? I don’t even have a way to relate to what that means, except through certain experiences from my college days. A recent web article writes about synthesia and some current theories (they still don’t really know what causes it). One interesting theory

All of us are able to perceive the world as a unified whole because there is a complex interaction between the senses in the brain, the thinking goes. Ordinarily, these interconnections are not explicitly experienced, but in the brains of synesthetes, “those connections are ‘unmasked’ and can enter conscious awareness,” said Megan Steven, a neuroscientist at Beth Israel Deaconess Medical Center.

Because this unmasking theory relies on neural connections everyone has, it may explain why certain drugs, like LSD or mescaline, can induce synesthesia in some individuals.

One thing I’m curious about is how different (and how similar) the experiences of different “synthetes” is. The article mentions this a little bit. For example, a lot of synthetes associate colors with letters. But for some, they see the color in their minds’ eye. Others see the color sort of painted onto the physical letter. One synthete responded via a comment to the article above that the colors he sees associated with letters are completely different from those for others.

One synthete writes:

Not only do the colors vary from person to person, but the associations too. I see not only colors for letters and numbers, but gender too, which isn’t something I’ve seen discussed in articles like these. The letter “A” is not only red for me, but also very strongly female. Also, I see the year as a kind of pie chart around me (its orientation is synchronous), and numbers, especially the first 10 integers, have a very particular spacial position.

And another replies:

For me the colour is only the start – there’s a whole complex series of moods and associations that follow on from the first ‘hit’ of colour. This is particularly strong with peoples names.
An additional observation – often the colour of the word id bizarrely out of whack with the real colour of the object. So, for me, ‘tree’ has no trace of green or brown or any other ‘tree’ colour – it’s a soft grey, fading to creamy yellow at the end.

Interesting stuff, but hard (though not impossible) to study, being based on subjective experience.

 

Mystery 1: Is polar bear fur transparent?

The answer seems to be yes! Even though polar bears are white, their hair is actually colorless. I found this out by looking at a great site, Everyday Mysteries, run by the Library of Congress. You can browse tons of questions, and their interesting science answers, compiled by the expert reference librarians at the Library of Congress. Aren’t librarians great?

Here’s a link to the polar bear posting itself. The reason we can’t see through the “transparent” hair directly to the polar bear’s skin (eek! naked polar bear!) is that the hairs are hollow. The air inside the hollow space in the hair bounces the white light from the air back to our eye, sort of like millions of tiny mirrors tilted at tons of different angles. The result is that we see a white bear.

In that same LOC posting is an interesting tidbit — bears at some zoos were turning green! Why? There was algae growing inside the hairs… so those hollow spaces weren’t reflecting white light anymore, but green light. How embarrassing for the poor polar bear.

Note that polar bear hair is NOT a fiber optic. You can see my earlier posting about that.