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