cut in half and slightly souped up

There are certain advantages to being a man. More upper body strength means you don’t have to find someone to help you lift the flat tire you just changed all by yourself into the trunk, even though you know how to do the whole thing by yourself but just aren’t strong enough to pick up the dang tire (what, I’m not bitter). Negotiators take men more seriously (not saying it’s fair, but it’s true). Men are statistically way less likely to be mugged or assaulted. But at the end of the day, men are inherently lacking in an area that women aren’t: genetic material.

Female allosomes on left, male on right. Notice the DINKY,
 LITTLE, Y. (http://www.brusselsgenetics.be)

You have 23 pairs of chromosomes- one of each pair coming from one parent. One pair represents your allosomes, aka “sex chromosomes.” If you’re a boy, you got a “y” chromosome from your dad and an “x” chromosome from your mom. If you’re a girl, you got an “x” from your dad AND an “x” from your mom. So, girls= xx and boys = xy.

That Y chromosome is really key in determining sex. It is way smaller than the X chromosome, and doesn’t really carry too much information on it aside from the most vital male-determining genes. It contains a gene, called the SRY gene, that “turns on” maleness/testosterone production. You see, being female is like the default condition. The presence of a y chromosome lays the groundwork for being male, but the activation of its SRY gene is what actually drops the ball(s). (Which, by the way, are really ovaries that were told to descend and produce sperm by the SRY gene). So, morphologically, all embryos start off as female and then are changed into male once the Y chromosome kicks into action.

The X chromosome carries way more DNA, including sequences that are not directly sex-relevant.  Yes, there’s DNA for instructions on building ovaries and eating Ben and Jerry’s once a month (don’t forget, men have this too on their X chromosome, but that Y turns on the maleness that covers up the female condition). But there’s also genes for more unfortunate things like the recessive male-patterned baldness and colorblindness.

Women carry these genes all the time. But since they’re recessive, the trait is not expressed unless a very unlucky lady happens to get them on BOTH her X’s. And that’s just not very likely. But if a female who has colorblindness in one of her X chromosomes gives that X to her son, he’s screwed. That scrawny little Y from dad doesn’t have enough punch to combat the trait like a girl’s extra X would. This is why color blindness and male-pattern baldness are almost exclusive to men. Since he got the X from his mother, he knows that one of her parents is responsible. If it was her dad, he will have expressed the trait. This kind of inheritance is called sex-linked inheritance.

So really, an XY is just a cut-in-half and then slightly souped-up version of an XX. Ladies, we may not have enough testosterone to lift a tire into the trunk, but we have enough DNA to keep colorblindness and pattern baldness at bay. We win… this one.

i need more sticky notes

I work at a small natural history museum where we receive lots of museum catalogues. Last week, a copy of the 2011 “Bone Clones” product catalog found its way into my hands. Let’s just say that I’ve spent way too much time flipping through it and putting sticky notes on pages that have cool stuff. They've got all different skulls from all different humanoid species. They've got bird skeletons. They've got eggs. They've got reptile and amphibian skeletons. They've got extinct animal bones. I can't even handle it.  I’m going to have to buy more sticky notes.

I love bones. They tell stories- yes, stories in the cheesy “NCIS” forensic way- but they tell more expansive stories too. Bones have been our clearest windows into our evolutionary past. With technology advances, DNA sequencing is becoming the front runner. But bones, I think, will always be the most tangible (and my personal favorite) way to unravel our past’s morphological secrets.

I would like to share with you a few of my favorite human bones- all of which are part of the spine. Our spine is important in that it fostered the major changes in our posture when we became tetrapedal land animals, and then eventually bipedal humans.

Atlas (wikicommons)

The top two vertebrae in your spinal column hold special significance. At the tippy top of the spinal column is your C1 vertebra (first cervical)- known as the atlas. Right below it is the C2 (second cervical) vertebra, called the axis. These two vertebrae are shaped in a way that allows for way more movement than other vertebrae. By articulating against the skull and each other, these two bones allow you to nod and turn your head. Notice how the Atlas has two contoured dips where the skull rests and may articulate, rather than a fused spinal-cerebral junction like you see in fish. (Poor fishies can't nod yes or no, can they?)

Axis (wikicommons)

Way back when we were fishies on our way out of the seas, emerging land animals like Tiktaalik would hide from predators in the shallows. But our fish predecessors were not well-built for air-breathing in the shallows. To make air breathing easier, nose holes migrated to the top of the head and the atlas began to form, allowing it to tip its head up and out of the water. And so, we left the water for drier prospects. As life diverged on land, predatory and prey niches were filled and binocular vision developed, moving eyes to the front of the head and limiting peripheral vision. The Axis stepped in to allow for more side-to-side head movement, allowing for more efficient predation AND predation evasion.

Hyoid (wikicommons)

Not far from your atlas and axis hangs the hyoid bone. The hyoid bone is not the most well known, because it is often missing from skeletons and skeleton drawings. This is because it is unconnected to the rest of the skeleton. It essentially floats in the throat area, suspended only by muscles and ligaments. If you press on the underside of your chin and back a little, that’s about where it is buried. The hyoid bone itself is an evolutionary descendent of a gill arch- a cartilaginous support structure found in the gills of fish. In us, it serves as an anchor for the back of your tongue so you can say words. (On a cheesy NCIS note: the hyoid bone almost never gets broken unless someone tries to strangle you. So fractured hyoid = homicide by strangulation.)

Coccyx (wikicommons)

The coccyx, or the tailbone, is the very last bone in your spine. It’s more of a “bone unit,” actually consisting of several fused vertebrae. Way back in our primate histories, we had tails. As we climbed out of the trees and onto the plains, they disappeared in our current primate lineages. But they left the coccyx remnant- hence the name “tailbone.” Now they’re only good for bruising, breaking, and the occasional vestigial-tailed mutant baby.

If I could choose one art project to work on for the rest of my life, it would be cataloging and illustrating every single vertebra in every major vertebrate family. They themselves are strange little works of art, their contours and projections both beautiful and telling of their function.

But if I don't ever find a life-long job opening for "vertebrae drawer," I'll just name my kids Atlas, Axis, Hyoid, and Coccyx. They'll hate me forever, but man, what cool names they'll have.

lavender candles and toilet handles

Today was one of those wonderful days. It was sunny and gorgeous outside, I got a ton done at work, and I had one of those rare but oh-so-satisfying, single-girl, “I just fixed something that broke without having to ask for help” moments when I installed a new handle/lever arm in my broken toilet. Small victories, people.

I wish you could smell
through the internet.

The best part of my day was undoubtedly receiving a care package (from my soul-twin, of course) that was full of goodies like herbal tea, cozy socks, fancy office supplies, facial masks, and chocolate. Nestled in this little box of heaven was this lavender and eucalyptus aromatherapy candle (left).

Lavender has been used in a medicinal capacity for millennia.  It helps aid relaxation, can ease dermal irritations, alleviates pain, and acts as an antiseptic. It’s easy to grow at home, and smells absolutely divine.

Once upon a time, doctors noticed something fishy going on with young boys and lavender oil. Several pre-pubescent boys were experiencing gynocomastia, clinically known as “boob development.” The onset of this breast development coincided with all of the patients’ use of a topical ointment with a principal ingredient of lavender oil. Was lavender oil inducing estrogen production in these kids?

Lavender in bloom (sloatgardens.com)

Yes, come to find out. A study by Henley and Korach (2010) confirmed that several essential oils, the most common of which being lavender and tea tree oil, routinely cause “endocrine distrupting activity”- aka they mess with your hormones. Specifically, your sex hormone estrogen. They considered both estrogen production and the different estrogen receptors in mice to see at what level the lavender was acting. They found that lavender exposure actually enhances expression of estrogen-producing genes. This means that lavender actually causes your cells to read the DNA blueprint for estrogen at a greater rate, flooding the system with excess estrogen.

Men have estrogen too, just as women have testosterone. They just have them in different proportions. So, both genders are vulnerable to the estrogen-spike that lavender exposure can initiate. Naturally, it is more noticeable in the sex with lesser estrogen. Luckily for those poor kids in the study, the gynocomastia subsided with decreased lavender exposure. Phewph. So if you are a guy, don't go shooting up with lavender oil unless you want to start wearing a bra.

Here’s to fixing stuff on your own, having wonderful friends who take care of you from 3,000 miles away, and hoping that my new candle will induce gynocomastia to help a sista’ out if ya’ know what I mean.

Or at the very least, that it will induce some aromatherapeutic relaxation while I soak in my tub wearing a facemask and listen to Enya, all the while admiring my new toilet handle out of the corner of my eye.

Myer-Briggs voodoo magic

Have you ever taken the Myer-Briggs personality test? It’s the one that gives you four letters, each representing some part of your personality. We had to take one our senior year of high school as a way to help point us to potential career choices. The questions seemed completely arbitrary- i.e. Do you like to sit to the left, center, or right of a room? I remember thinking what a crock it must be as I finished it up and turned it in.

A few weeks later, our teacher hands us back our sealed envelopes with our results. I read mine, astounded that this test understood me better than anyone I’ve ever known. Well, better than anyone except my best friend Ashley- who coincidentally sat right behind me. (Ashley and I call each other “soul twins”; in a world where we feel quite different than most, we just get each other). I spun around to discuss the results of this voodoo magic with her. And would you believe it, she and I scored the exact same personality type. The rarest type at that- making up 1% of the population. If that doesn’t verify a friendship, I don’t know what does.

In previous posts, we’ve talked about how behaviors evolve. But personalities- where do they come from? Are they genetically linked? If so, did natural selection act on them during the development of our species? Did personality evolve?

I did some research into the evolution of personalities. There are a bunch of scientific papers on it. In general, most of them say that there is evidence that many personality traits are genetically linked, but there are so many variables involved that it is an abstract and a “poorly understood” mechanism. Translation: it's likely. But we can’t figure it out yet.

Somewhere in our history as tribal animals, social hierarchies emerged. Maybe, each tier in the social hierarchy can be thought of as a niche, and each individual as a particular species. Individuals had to divergently evolve to reduce competition for a singular niche, making it easier for each social role to be filled.

What if everybody in a tribe was super outgoing, or overly dominant? There would be fights and pissing contests all the time- that wouldn’t work very well. What if everyone kept to themselves and didn’t share ideas? That wouldn’t work very well either. Is it possible that this could have been the groundwork for the evolution of personalities? Populations of humans with wider ranges of temperaments and social roles were the most successful?

Who knows? Maybe. Even if it was, then a lot has happened to complicate and deepen the human personality since then.

This post answers zero questions, and raises a bunch. But I kind of love it when science hasn’t yet figured out something. Not knowing things allows us a sense of wonder that answers don’t. It’s amazing how different people can be, and thank goodness for it.  My sister and I, for instance, are as different as night and day. But I couldn’t have asked for a more complimentary sibling counterpart. And I know that I could never marry someone just like me. We’d read books on weekend nights and never be forthcoming with our thoughts or feelings. Regardless of how they came to be, personalities help make our world go ‘round.

If you haven’t taken the Myers-Briggs test, there are a few online. They’re not as thorough as the official one, but I at least scored the same on both. After getting your score, consider: if you had been Tuk-tuk in the early ages of human, what social role might you have filled?

Here are the links to a couple tests:

http://similarminds.com/jung.html

http://www.humanmetrics.com/cgi-win/jtypes2.asp

musical memories

Y’all- rarely do I blow my own mind. But tonight, I did just that.

I was typing the word “accept” and had to momentarily consider whether it or its homonym “except” was appropriate. The thought train took me to “accept is a verb” and “except is a …. what is it?…. ah yes, preposition.”

And then, I spontaneously busted out in a song that I have not heard nor sang in sixteen years. You see, my third grade language teacher made us memorize all of the prepositions by putting them to the tune of Yankee Doodle. Catchy little song. I aced my English test on prepositions and have not thought about that song since.

Yet sixteen years later, I am able to perfectly rattle off those forty-six arbitrary words in perfect alphabetical order. That song was in my brain all this time. Untapped, unused, but unchanged. How can this be?

Remember our chat about neurons? Well, their little fingers are called dendrites. These dendrites are what reach out and make connections to other neurons. The number of dendrites per cell is plastic- meaning your neurons can grow or lose dendrites- and therefore connections- according to how much the present ones are used (do a Sodoku puzzle tonight! Grow some dendrites!). These connections are what constitute your memories. Fire one chain of them off, boom: your fifth birthday party. Fire a different combination of connections off: that Halloween you lost your wallet and walked home in the rain, maybe sort of inebriated, dressed as Chewbacca. Your recollection of your life’s experiences is a complex network of chemo-electric signals. That’s insane, right?

A study in the mid-90’s looked at memory and music. And boy, are they correlated. Text recall was significantly better when set to the tune of a song than when simply spoken. However, it was significantly worse when just one verse was sung or when plural melodies were introduced in a single song (Wallace 1994). From this, we can conclude that it’s not just rhythm that enhances our dendritic connections- it’s actual music. Be it a stupid yet catchy tune (“Call Me Maybe,” I’m looking at you and your stupid lyrics), or soul-moving sounds like Mozart’s Requiem.

It’s can be unsettling that memories of things like your first kiss or precious time with loved ones that have since died are nothing more than very specific paths of action potentials traveling from neuron to neuron in that hunk of meat we call a brain. But the fact that they are solidified by music makes it easier to stomach- at least for me. “Party in the USA” takes me right back to margaritas in my college apartment, laughing with my girlfriends so hard I couldn’t breathe. “Leave” by JoJo puts me right back in my sister’s Jetta, making late-night summer trips into Bossier City to get soft serve ice cream from the McDonald’s drive-through. I can put on Rachmoninov’s second concerto, about halfway through the first movement, and be transported back to my father’s strong hands on the steering wheel as he drove me home from my first year in college- and actually feeling the sense of content safety I felt then.

And that, to me, is simply beautiful- dendrites and action potentials included.


Wallace, Wanda T. Memory for music: Effect of melody on recall of text. Journal of Experimental Psychology: Learning, Memory, and Cognition, Vol. 20 (6). Nov. 1994, 1471-1485

walker texas ranger tears

As I sat and ate my grilled cheese sandwich on my lunch break not long ago, Walker Texas Ranger played on the TV. Walker’s girlfriend, Alex, has survived being kidnapped and almost killed, and is now lying in a hospital bed while he lovingly comforts her in all his ginger glory. He tells her how much she means to him, and then pulls a ring out of his pocket. And there it is… “Alex, will you marry me?”  It pans to the highlights of their relationship. In typical cheesy 90’s slow-mo style, Alex and Walker stroll through fields hand in hand, laugh together, cry together, and share loving looks into each other’s eyes as their perfectly teased Texas hair blows in the breeze.

And suddenly, I am bawling.

The credits begin to roll and I brush my tears off of my grilled cheese and wipe my eyes. Something isn’t right- I should be laughing hysterically, not crying hysterically. I look at my calendar on my phone and then it makes sense.

Let me tell you folks, hormones are very real. They don’t only control your mood- they control things like sleep, friskiness, stress response, fight or flight response, puberty, hunger, parenting, and in-utero develepment. Pretty much every process or event your body undergoes is driven by hormones in one way or another

But how do they work? Having to direct things from slow-paced things like ovulation to fast-acting processes like adrenaline rushes, how do they make things happen? Where do they come from? Where do they go? How do they get there?

Hormones are little molecules that are manufactured by your body. They can come from individual cells, organs, or more frequently from glands (think thyroid, testes, ovaries, adrenal, etc.). Different glands manufacture different hormones.

Major glands  (wikicommons)

To name a few: Testes and ovaries manufacture sexy hormones that influence puberty, ovulation, parenting, menopause, and male machoism. Your adrenal glands sit on top of your kidneys and produces adrenaline- key in stress response, fight or flight, and cell metabolism. Your thyroid gland in your neck manufactures a variety of hormones, mainly affecting metabolism. The big daddy gland- the pituitary- is buried at the base of your brain and is perhaps our most primitive gland. It regulates just about everything from sleep to sex drive. The pineal gland, also of primitive origin, plays a role in light detection and internal calendar regulation.

From their respective glands, hormones are released into the bloodstream in order to travel to their target tissues. Let’s take adrenaline, for example. Say you’re walking down a dark alley and all the sudden a man steps out in front of you with a knife and says “give me your money!” Time for fight or flight response. Your brain immediately sends signals down to your adrenal glands, which then flood your whole body with adrenaline. But you only need certain tissues to respond, right? Your cardiac muscles need to quicken, your pupils need to widen, your blood vessels need to dilate so you can haul ass. Well, nature has it so that only these target tissues have receptors to recognize these hormones. So while your pinky toe is getting the same dose of adrenaline, it don’t give a $h*t. But the cells of your heart and blood vessels certainly do- and respond to help you get out of this hairy situation. This is how the whole hormone system can be so refined- receptors only exist where their hormones are meant to act.

The guy with a knife is still standing in front of you. You kick him in the balls and run. You make it safely away and stop to catch your breath. That jittery feeling that makes you ready to punch somebody in the face is the adrenaline coursing through your body. Within the next few minutes, you’ll start to feel more normal. This is because the adrenaline is being cycled out of your cells and metabolized to the point of no longer being hormones.

The system is pretty much the same for slow-release events like ovulation and puberty. Your pituitary regulates your internal calendar, activating the right tissues at the right time.

When you break it down like this, it all sounds so scientific and straightforward. But when you’re sitting next to a lady with a baby on an airplane and are desperately hoping she’ll ask you to hold it, or crying at Walker Texas Ranger, it doesn’t feel so scientific or straightforward. Makes you wonder how much of the human experience is just molecules binding to receptors. But then again, maybe that makes it that much more extraordinary.

have you SEEN a dik-dik?

A recent and actual G-chat transcript, between my sister and me.

Alix: Have you SEEN a Dik-dik?

Me: No. What is a Dik-dik?

Alix: A tiny tiny antelope.
             They are monogamous.

They can run 26 mph.

Can you imagine if a Dik-dik ran past you at 26 mph?

It would be amazing.

I wish lap giraffes were real.

Okay got to go. Love you bye.

Of course, I immediately Wikipedia’ed Dik-dik, and was faced with the cutest ungulate I’ve ever seen.

OH MY GOD. (wikicommons)

They are little antelopes that live in Africa. They eat small plants and shrubs, throw it back up, chew it some more, and eat it again. This would be gross, but they’re so tiny that it’s more funny than it is gross.

What really caught my eye in the Wikipedia article was the blurb referring to their monogamy. It reads:

“Monogamy in dik-diks may be an evolutionary response to predation; surrounded by predators, it is dangerous to explore, looking for new partners.”

Monogamy exists all throughout the animal kingdom. Selective pressures vary in each instance of it, but it is safe to make the sweeping statement that monogamy usually evolves as a means to protect highly vulnerable young. Take us, for example. The survival rate of babies (before the present-day civilization) must have been waaaaay higher if Dad stuck around to protect mom and child from saber-toothed tigers and to help provide food. On the other end of the spectrum, consider a housefly. Baby houseflies are ready to buzz off and start life as soon as they hatch. Mom and dad aren’t even around- they’re already off having irresponsible sex with new partners. Monogamy wouldn’t make sense for them.

Dik-dik being sassy. (pbase.com)

Never before had I seen monogamy explained as a response to predatory danger for the parents. No way this could be true, I thought to myself. I researched further, and lo and behold: a whole paper has been published on Dik-dik monogamy. And they found something pretty interesting.

It had been previously assumed that Dik-diks were facultatively monogamous. Facultative monogamy is monogamy that is the result of restrictions on resources. In other words, male Dik-diks could only defend enough territory to accommodate one female, and that’s why they only mated one female. If more resources were available, then the male Dik-diks could afford to pimp two or more females.

Researchers found evidence to the contrary of this model. Male Dik-diks routinely defend territory (and therefore resources) to accommodate several females! Why do they date just one lady, then?

Obviously, because they have the capacity to love. (Alix, you stop reading here. Life will be better if you do.)

No, that’s not true. Rather, it’s because the males are jealous little suckers and don’t want any other guys picking up their girlfriends. It’s formally called mate guarding- and is an evolved behavior that increases the likelihood that their genetic material is passed on to the next generation. If Dik-diks had the equivalent to “The Maury Show,” the audience would be sorely disappointed that Dik-diks rarely question the paternity of their fawns. Daddy Dik-diks keep close enough eyes on their ladies that they’re not too worried about it.

This being said, monogamy rarely occurs in nature without extra-pair copulation, aka “getting some on the side.” In Dik-diks, only males will engage in extra-pair copulation. Mated females are noted to rarely, almost never, engage in extra-pair copulation (go figure).

So, several components contribute to Dik-dik monogamy. It is safer for the tiny, herbivorous animals to stick to their territory instead of going down to the local drinking hole to try to meet new Dik-diks. Also, mated pairs spending almost all of their time together increases paternal fidelity. And even though males have the capacity to mate more females, they don’t- the lingering urge to mate guard has been passed down from earlier times when perhaps the Dik-dik male could only defend territory for one female.

My initial balking reaction to the explanation of Dik-dik monogamy was short-sited. It wouldn’t make sense for the natural world to be as diverse and multifarious if evolution followed a blueprint. Regardless of how many notes I took or outlines I made about monogamy as an evolved reproductive strategy while I was in college, I don’t know diddly squat.

When asking questions about the evolution of life, always remember to keep an open mind. If researchers hadn’t kept open minds about Dik-dik monogamy, we’d still be without the knowledge that males mate one female, even though they can mate more. And I prefer to live in a world where Dik-diks stick by each other's sides in a non-obligatory capacity. Don’t you?

Here's the paper:

Female dispersion and the evolution of monogamy in the dik-dik. Brotherton, PNM, and Manser, MB. Animal Behavior, 1997. Volume 54 (6), 1413-1424.