Friday, February 24, 2012

stop exploding your melanocytes

I really hate to see girls going to tanning beds. I even get nervous when I see people lay out in the sun without sunscreen on. Yes, yes, I know- the warmth feels so nice and you look like you belong in a Ralph Lauren magazine ad afterwards. That’s just a misleading coincidence, though. A tan is literally the observable result of directly damaging your skin via radiation. Won’t be so cute when you’re only 30 and your chin skin is already drooping, you have brown spots all over, and wrinkles you shouldn’t have until you’re 50.
Big brown blotch is a melanocyte releasing melanin
into the skin.
Melanin is the brown/black pigment in your skin, and is made and released by cells called melanocytes. Everyone has melanin (except albinos), although the amount of melanin people produce varies. Interestingly enough, it has been found that everyone, no matter ethnicity, has the about the same amount of melanocytes. What determines skin color is DNA, and whether it tells them to make melanin or not. Black and Indian people’s melanocytes tend to produce more than Viking-type folk, so they appear darker.

Melanin exists in your skin to help absorb the ultraviolet radiation you get from the sun. UV radiation literally bursts your melanocytes (sounds violent, doesn’t it? Yeah. It’s not good. Stop going to the tanning bed.) so that melanin is released into the skin to act as a sort of protective blanket for your dermal tissues. That tan and glowy girl working in American Eagle is really wearing one big skin Band-aid.

Back in 1986, there was an explosion and subsequent fire at a nuclear power plant in Ukraine. The fire caused a radioactive gas to float across an extensive landscape and into the atmosphere, sending civilians into a panic and mass exodus. The radiation wiped out life in the area. Birds, fish, mammals, bugs, you name it. And what didn’t receive lethal amounts of radiation and survived was still radioactive. Nothing thrived in this environment… until recently.

In 2006, Chernobyl research robots found a curious black fungus crawling on the walls of old reactor. Samples were taken and it was found that it had an enormous concentration of melanin. This fungus had adapted to the radioactive environment via high melanin production. While it does not “de-radioactivate” the radiation, it sort of stores it as a means of energy acquisition.

Researchers have conjectured that this may be a means of energy production in the future. Since the fungus is harnessing energy, maybe it could be eaten as an energy-rich food. Or maybe astronauts could use it to absorb the excess radiation they’re continually exposed to. I’m sure we’ll see something come of this in the future.

I, however, point out that if melanin is produced in a black crawling fungus in Chernobyl to absorb leftover radiation, it exists in us for similar reasons. The difference is, we cannot capture the energy in a beneficial way like the fungus. Instead, radiation causes the breakdown of skin elasticity and the increased likelihood of cancer. This being said, let me clarify that moderate sun-exposure is in no way comparable to the radiation at Chernobyl. But this little melanin story should get you thinking. Your skin reacts to the tanning bed in same way that this fungus has reacted to nuclear radiation… increased melanin production. 

Friday, February 17, 2012

happy major histocompatability complex day

I hope all of you had a nice Valentine’s Day- whether it consisted of celebrating it with your sweetheart, gorging on Ferrero Rochers and watching TV by yourself, eating appetizers and drinking wine with your friends, or ignoring the holiday altogether.

So in the spirit of romance, I want to talk about a study that specifically looked at female -> male attraction in humans, more scientifically known as “mate choice.” You may have heard of this particular experiment, as it was groundbreaking and applicable to everyone. Basically, they had 6 guys wear tee-shirts for a few nights without washing them, and then had a bunch of girls smell them and rate them on how good they smelled. Consistently, girls liked the smell of tee-shirts worn by guys with the most differing MHC (major histocompatability complex) from their own, and disliked those worn by guys with similar MHC’s. MHC-whaaaaat? I’ll explain.

In the most very basic sense, MHC a protein profile. All of your cells have a membrane, like the skin of a balloon. Except your cell membranes are not smooth; they have tons of proteins sticking out of the surface. A specific group of these surface proteins are involved in your immune system, and they are coded by a long sequence of genes called the major histocompatability complex. Complex is an appropriate word, since 128 genes determine the MHC. As you can imagine, everyone’s is intricate and different.

So, why would we prefer mates who had different MHC than our own? It all has to do with increasing genetic variation. For one, people with really different MHC’s are less likely to be related to you. So it decreases the chance of mating with a relative. Furthermore, if you are to mate with someone with dramatically different immunity proteins, then your kids are likely to get a wide variety of immunity. Ah lah, healthier offspring.

But the story doesn’t end there. Girls that were on the pill had reversed preferences. They preferred the scents of guys with more similar MHC, which is just completely screwy and in no way advantageous. Ladies, when it comes time to get serious and find yourself a husband, I would consider going au natural for a while so that you aren’t out at bars trying to pick up your second cousin.

I think the next step in this might be to look at gay people’s mate choice in relation to major histocompatability complex. This study only considered straight people. But if we remove the gender variable, I’m willing to bet the exact same thing is happening with gay peoples’ mate preference.

Here, one might be tempted to say that we’re all just bags of chemicals and love is just the result of hormones and pheromones. But I don’t buy that. I think it’s a large part of it, but certainly not all of it. I’m confident that there’s more going on than just chemical pathways.

So if you have a special someone, be sure to tell him or her that you care about them deeply… and that you find their MHC irresistibly different from your own. That’s sexy, right?


MHC is super complex, so if you want to know more, I encourage you to look into it. Better yet, find a molecular nerd to tell you about it.

The study is described in the paper MHC-dependent mate preferences in humans by Claus Wedekind, Thomas Seebeck, Florence Bettens, and Alexander J. Paepke. Published in The Royal Society’s Proceedings: Biological Sciences, Vol. 260, No. 1359, June 1995.

Friday, February 10, 2012

eye hope you like this

Lizards and frogs have three eyes. Say WHAAA?! Think real hard; picture them in your mind. Only remember two eyes, right? But I kid you not, there is another eye (lesser developed and often unnoticed) sitting right atop their heads. It is scientifically known as a parietal eye, or “third eye”.

When we think of the word “eye,” we think of the well-developed organs in our faces that are capable of sensing light in such detail that they can form real-time images of our surroundings. To say that the parietal eye falls in this category would be misleading. Really, a better descriptor would be “light sensing organ.” It is part of the epithalamus of the brain (hence its location atop the skull) and functions not in sight, but rather in circadian rhythm regulation.

Get your mind out of the gutter, it's the pineal gland.
The pineal gland is part of the epithalamaus and produces hormones. These hormones are specifically functional in what I can best describe as “body timing.” Wake/sleep and reproductive cycles, and other cycles that fall under the blanket of circadian rhythms. The parietal eye is connected to this gland and feeds it information on light surroundings. Basically, it senses day-length so that the brain can figure out what time of the year it is so it can regulate hormonal cycles.

We humans don’t really have seasonal hormonal cycles, unless you count the female ovulation cycle. And that is based off of the lunar cycle, not photoperiod (day length). So we don’t really need a season-sensing mechanism. But think of how frogs, for instance, have breeding seasons. How do they know what season it is? Frogs don’t keep datebooks or calendars (that we know of), and it would be embarrassing to go around humping your frog friends at the wrong time of year. This mechanism is a component of the evolutionary solution.
Can you spot the parietal eye on this anole?

The parietal eye exists in varying degrees across the herpetological fauna. Some salamanders have been found to have very poorly developed ones, while Tuataras (a distinct and pretty nifty lineage of lizards) have parietal eyes with structures comparable to a retina and lens! In frogs, it appears as just a little light-colored spot between the eyes. In lizards, it usually is a tiny light-colored spot on the parietal scale right on top of the skull. In all cases, it is covered by clearish skin so that light can penetrate.
File:Frog parietal eye.JPG
Bullfrog's parietal eye (wikicommons)

And might I mention that you too have a pineal gland. You do not have a light-sensing organ on the top of your head, but you certainly have the organ from which it emerged in other vertebrates. Or, you could look at it conversely. Is our pineal gland actually a remnant of a parietal eye? A question worth looking into…

If you have a reptile-loving friend who has a lizard, ask them if you can observe their pet’s parietal eye. If they look at you like you’re a crazy person, I hope that you will lay some serious parietal-eye facts down. Spread the knowledge.

Tuesday, February 7, 2012

your FACE

The human mind is prone to identifying recognizable shapes in whatever we are looking at. I’m always reminded of this when I watch those ghost shows and they show the picture someone took of a mirror in which there is supposedly the face of a man who killed himself in the house and continues to haunt it. They will draw a little red circle around the figure and zoom in on it. “Can you see the apparition?” the host will ask.

“NO,” I reply sassily through a mouthful of barbeque chips from my couch. I see a blob of discoloration in the photo in which there are two darker areas that could be mistaken for eyes, in the very loosest sense. A human face I see not. But I remind myself it is only natural to recognize the familiar. And the arrangement of eyes, a mouth, and a nose on a head on top of a body is certainly familiar. We see it all throughout Animalia. Have you ever stopped to think why it is that so many animals are built so similarly? There has to be a reason…

Eyes and a mouth on a head, followed by the rest of the body containing vital organs, off of which there may or may not be limbs. Fish, mammals, reptiles, amphibians, and birds share this blueprint. They are all distinct and sometimes dramatically different lineages, making this similarity worth investigating. As with many evolutionary inquiries, let’s start where they all originate…. a common ancestor.

Way back when the ocean was still the simmering pot of animal origins, sponges emerged as the first critters. They did not really have any body plan- they are haphazard and could grow to be really any shape.
Sponges have no body symmetry (Wikicommons)
Next came jellies- which certainly have a body plan. They have radial symmetry- meaning that they are organized in a circle.
File:Jelly cc11.jpg
Jellies have radial body symmetry (Wikicommons)
The next step up in body planning came bilateral symmetry. And what a coincidence, the rest of the animal kingdom should be dubbed Bilateria. Here is where we start seeing critters like early worms… which were unique in that they were the first to have “ends”- a front end and a back end with which to process food unidirectionally.

Imagine you are an early worm, really more like a living tube, swimming around. You don’t have eyes or any other sensory mechanisms but the most very basic sense of touch. This makes you an easy target, as well as an inefficient hunter. So let’s add some sensory organs. You name the place that they would be most beneficial…

Did you say head? If yes, you would be right. The most advantageous sensory placement would be at your front end so that you can tell what you’re headed towards, or into, before the rest of your body proceeds and is eaten or injured. Here, I flashback to how many times I’ve swum into the end of the pool because my primary sense, sight, was compromised by my overwhelming fear to open my eyes underwater…

The accumulation of sensory perception on an organism’s “front end” is one of the most profound evolutionary steps taken in the path to modern-day vertebrates (fish, amphibians, reptiles, birds, and mammals). It is called cephalization, which is Latin for “head development." Cephalization continued over the next couple hundred million years making increasingly complex animals that all share the same basic blueprint.

Where an animal has the most sensory perception would be an ideal spot for a feeding structure, oh say, like jaws. So, jaws were the next step. Well in that case, teeth would make it easier to capture prey, so teeth emerged. This produced an increased ability to hunt, which necessitated more mobility and agility. Enter rudimentary limbs. Then when life began to emerge from the water, air-breathing became necessary. So nasal openings (nares) appeared near the other respiratory structure- the mouth- so they could both stick out of the water at the same time. We’re getting pretty darn close to the thing we might refer to as a face…

When you’re brushing your teeth tonight and looking in the mirror, look at your face. I mean, really look at it. We’ve come a long way since being worms.

This faced worm is SO. WRONG. (

Wednesday, February 1, 2012

$50,000 worth of what?

This summer, I was fortunate enough to be sent to the National Conservation Training Center in West Virginia. It is a beautiful facility that belongs to the U.S. Fish and Wildlife Service where federal employees (and lucky Student Conservation Association interns like me) are sent for training. It is pretty much like summer camp for federally employed grown-ups. There are dorms that are named after prolific conservationists scattered in the woods, connected by little trails that meander through stands of huge Sycamores, paw-paws, and the other natural flora. And the cafeteria. OH, the cafeteria. It is like a North American nature-themed version of Hogwart’s Great Hall. At the head of the room, framed by the beautiful hand-hewn beams of the ceiling, is a woodpecker painted on the wall.

Ivory-billed Woodpeckers (
I was surprised to learn that out of the 20 or so interns that were there with me, I was the only one who knew the significance of this woodpecker. At first glance, you might think it is a rendering of the Woody the Woodpecker bird, formally known as a Pileated Woodpecker. And you wouldn’t be the only one. The two birds are very similar. But it is not Woody the Woodpecker that gazes out over the people eating in this dining hall. It’s an Ivory-billed Woodpecker.

Ivory-bills are a sort of national symbol for human-induced extinction. Once upon a time, these behemoths of woodpeckers flourished in the untouched forests of the Southeastern United States. People hunted them for a variety of reasons, a primary reason being for their skins (they are quite beautiful birds, and really pretty big). But, as in most cases, what really drove the nail in the coffin was habitat destruction. Trees were cut down in large numbers, usually by corporations who bought these large tracts of land for this purpose. Numbers dwindled until the bird was officially listed as endangered in the 1960’s.

Around the 1970’s, reports of sightings from here and there began to catch ornithologists’ attention. Two photos surfaced from a man in Louisiana that appeared to show a male Ivory-bill on a dead tree. However, it was taken from a distance and did not show enough detail to be clearly distinguishable from the similar Pileated Woodpecker. Some people even accused the man of attaching a dead stuffed Ivory-billed to the tree and then taking the photos. The Ivory-bill issue remained simmering for several decades, until a video surfaced in 2004.

The video was taken by people who were kayaking in a marshy swamp area in Arkansas. In the grainy background, a woodpecker flutters off of a tree. Scientists and bird enthusiasts alike (after likely peeing themselves out of excitement) fueled the idea that this was indeed a video of the Ivory-billed Woodpecker. This was a big deal. It made headlines and news programs around the country. The Cornell Lab of Ornithology (the premier bird authority in the country) offered $10,000 to anyone who could lead one of their biologists to the bird. After 2 years passed and no one was successful, they upped it to $50,000. A $50,000 reward for finding a bird…

Here, I can’t help but take a step back and think. The bird sighting itself is not worth this money, but rather the money must be representative of some other value that the Ivory-bill’s existence would hold. Perhaps it’s $50,000 worth of absolved guilt we carry for recklessly and needlessly wiping such a beautiful animal out of existence. Maybe it’s $50,000 worth of satisfaction that we as guardians of the natural world have managed to do something right in the midst of environmental enlightenment. Maybe it’s $50,000 worth of hope. Or maybe it’s simply $50,000 worth of the good ole “never give up” spirit.

I think it is probably a mixture of all of them. The video from 2004 was further analyzed and everyone eventually agreed that it was actually footage of a Pileated. The underside coloration of the wings proved to be the determining factor.

Ivory-bill on the left, Pileated on the right (Cornell Lab of Ornithology)
Reported sightings have continued to surface here and there, but concrete evidence has never been provided of the Ivory-billed Woodpecker’s survival. Who knows, maybe there are a few elusive birds out there, the living incarnations of the twilight of their own species. We will never be able to know for sure. At any rate, it is sad. Sad in the sort of way that can’t be fixed or eased. We can’t undo this mistake, or even apologize for it. 

If this saga catches your heart or imagination, explore further. I recommend the documentary “Ghost Bird,” available on Netflix or sometimes plays on the documentary channel if you have Direct TV. “Ivorybill Hunters: The Search for Proof in a Flooded Wilderness” by Geoff Hill is also worth checking out.