John Legend and Chrissy Teigen are basically the perfect couple.
He’s an incredible musician and she’s an actress, producer, and bestselling author. And they’re both ridiculously hot.
I mean, look at those smiles. Who better to make luxury fun, indeed?
In case you didn’t know, the two met when Chrissy was cast as the romantic interest in a music video John was filming. They started seeing each other casually, and then seriously, a transition marked by their first vacation to Lake Como, Italy. Classic first date spot. While there, Chrissy says that they went on a romantic boat tour to a little spot on the lake and were told to make a wish. “I asked for this to be the man I marry and have children with. I think John asked for the most perfect bite of cacio e pepe. Both came true, and here we are.”
Name a better love story, I’ll wait.
But even uber-successful, famous, beautiful people can’t be cool all the time. And luckily for their adoring fans, these two aren’t shy about admitting it. Several years ago, Chrissy Teigen posted this endearingly clueless tweet:
Oh Chrissy.
As it turned out, back in early 2017, a lot of people didn’t know what a headass was. It’s strange to think that a word that’s become ubiquitous in our modern vernacular once prompted this much confusion. But equally strange is the fact that no one seems to know how the insult originated. It just sprang into the public consciousness, fully formed, like Athena emerging from the head of Zeus. Except, well, a bit less dignified.
If you, like early 2017 Chrissy Teigen, are still wondering what a headass is, here’s the definition according to urban dictionary:
- A term used when one says something either obscured, unbelievable, or stupid (when trying to be funny)
2. A term used at the end of an insult when talking about someone
But what does “headass” mean in the most literal sense? Someone with their head up their ass? Someone whose head is an ass? That isn’t even possible, right?
Wrong.
I can’t speak to the physical feasibility of sticking one’s head up one’s ass (although it seems highly unlikely), but I can say with certainty that it is possible for living organisms to have an ass where their head should be.
Meet Drosophila melanogaster, the original headass.
If you’ve taken a biology class, you’re probably encountered D. melanogaster, otherwise known as the common fruit fly. It’s a classic model organism – an organism that scientists study in the laboratory to learn about biological processes. What you might not know is that D. melanogaster’s development can be severely altered by a single gene: bicoid.
Bicoid is an egg-polarity gene, which means that it determines which part of the developing larvae becomes the anterior (front) end and which becomes the posterior (back) end. But how, you ask? By using a morphogen gradient. Now, this sounds complicated, but it’s actually quite simple. Think of bicoid as a dye. The end of the larvae that is most saturated with dye – the part with the darkest hue – is the end that has the greatest concentration of bicoid. It becomes the anterior, or front, end, and eventually develops a head. Bicoid slowly diffuses from the anterior end to the opposite end. Because that end is the lightest hue (aka the least saturated in bicoid), it becomes the posterior end, and eventually develops an ass.
Here’s where it gets fun.
Larvae with normal copies of bicoid develop normal anterior-posterior axes and develop into fruit flies like the one pictured above. But larvae with mutated bicoid genes turn out very differently. A bicoid mutation means that, for some reason, the fruit fly cannot produce a functional bicoid protein. If there is no functional protein, there is no anterior side, which means– the fly in question cannot produce a head at either end.
The mutated D. melanogaster therefore develops a posterior end where the head should have been and becomes – you guessed it – a literal headass.
Fortunately (or unfortunately, depending on your perspective), scientists have not attempted to see whether this phenomenon extends to humans. We are much more complex than this lovely model organism, so even if we could develop asses where our heads should be, it would take significantly more than mutating a single gene to do it. But it is fun – albeit gross – to contemplate.
Now, do I think the creators of the word “headass” had D. melanogaster and bicoid in mind? Probably not. But it does show that biology is a lot more closely intertwined with popular culture and language than you might have thought.
And as for Chrissy Teigen and John Legend, here’s how their conversation ended:
Like I said: the perfect (if occasionally headass) couple.
Biology and Me 