For ‘Gender’, See ‘Turtles’: Experiments in Empathetic Biology

by Callum Angus

Callum Angus is the author of A Natural History of Transition (Metonymy Press), as well as managing editor of the journal smoke and mold. His work appears around the web and on calangus.com.

We hatchlings know how to escape the dark without a metaphor. In sand we trust the signs of the world. To be suspended in sand is to be in darkness, but not without knowledge; inside the egg, but still aware of the events of the outside world through the many-channeled receptors of a body that take in sound, vibration, hot and cold. A stiffness in our joints. A glitching in our chromosomes. Heat inside the beach means it’s time for sisters. No boys allowed. Sand seems dumb, we know, but it’s not; it’s capable of telling us everything we need to know.


An online company sells bracelets made from stone beads, each of which “comes with a real sea turtle to track,” with a number you can enter online and watch them move across the globe like a FedEx delivery. From GPS trackers to Pixar’s animated surfers of the East Australian Current, sea turtles have a special hold on the human imagination. But recent research indicates that there’s reason to worry about the viability of turtles in the future. That’s because most turtles, and some alligators and crocodiles, exhibit temperature-dependent sex determination, or TSD.

In most species, gender is determined during fertilization. However, the sex of most turtles, alligators, and crocodiles is determined after fertilization. The temperature of the developing eggs is what decides whether the offspring will be male or female.

Research shows that if a turtle’s eggs incubate below 81.86 Fahrenheit, the turtle hatchlings will be male. If the eggs incubate above 87.8° Fahrenheit, however, the hatchlings will be female. Temperatures that fluctuate between the two extremes will produce a mix of male and female baby turtles. Warmer temperatures, however, mean warmer sands, and scientists are concerned this could heavily skew turtle gender toward female, imperiling species of turtles worldwide.


The heady grumbling thunder felt deep in our shells signals potential flooding—time to hatch and be dragged into the impossible sea. Time for us to do the thing for which we’re named, a hatching that will make us hatchlings into something else—the hatched. The stupid! The ignorant! The begin-again, learn outside the egg where sound and light and temperature are unmediated by the many-particled softness of a suffocating sand; but first, we climb. We cast off rubbery remnants of shell, pieces stuck on our noses, and begin to flounder, to flail and scramble up the ladder of our squirming kin. All that matters is getting out. It’s a waterfall in reverse of hatchlings. Without the throng of us there’d be no leverage, no escape.


The heady grumbling thunder felt deep in our shells signals potential flooding—time to hatch and be dragged into the impossible sea.


In college I worked for two summers as a naturalist, giving public programs in the natural history museum where I talked about a pair of recovering ravens, or held my lapel mic up to Stickley the porcupine as she munched on sweet potato, or broke up fights between river otters with buckets of ice cubes. I’d stop my car to help a snapping turtle cross the road, and for a long time I thought I was going to do something with animals, which was why I decided to study abroad in Costa Rica at the Monteverde cloud forest my sophomore year of college. My Spanish couldn’t always keep up and I frequently wound up in the car not knowing where we were headed. One weekend my host-mother’s brother Carlos took us camping on the beach , a long and twisty drive from the cloud forests to the Pacific where we pitched tents on the sand and played soccer in the surf. We were all asleep one night when Carlos came running and shaking the tents’ thin nylon walls , telling us to wake up. We followed him and his flashlight out onto the pitch black beach where a lone sea turtle was laying her eggs in a hole in the sand. How did he find her? He must have been walking up and down the sand for a very long time, carefully scanning for a small lump of darkness within the bigger dark—in such gloom they blend right in. Gloom was important to her, Carlos said, and so lights and camera flashes had to remain off lest she confuse their brightness for the pull of the moon leading her back to the ocean, but no matter, we watched without shame as she scraped sand back over her eggs. Once she’d finished, Carlos whispered “okay,” and we rushed forward and touched her shell, sand papery and hard, as she heaved her bulk back to the ocean and the waves, nothing more appealing than her getting away from us now and so I could risk a little touch.


We emerge with little bits of the earth, sand and stone, tiny grains stuck in all our most hidden places, inside our ears, in the folds of our necks, between our legs. It’s impossible to see just what we look like, so begrimed are we. And we would keep it that way, yes, we would, but the sea beckons. We follow the light of the horizon. You can’t see it? A shame. To us it’s just a brighter line, but something new, something we never had in sand: a destination, a vanishing point glimpsed from afar. Somewhere to go. A journey.


Kdm6b is the gene responsible for the gender of turtles. At colder temperatures, Kdm6b becomes activated and it gets to work producing testes for male turtlings. When things heat up, the testicle production line goes dormant, Kdm6b turns off, and female turtles with ovaries crawl out of the eggs instead. Most articles reporting on the research behind Kdm6b start with some variation of the following:

Boy or girl? For those who want to influence their baby’s sex, superstition and folk wisdom offer no shortage of advice whose effectiveness is questionable at best—from what to eat to when to make love. But some animals have a technique backed by scientific proof: In turtles and other reptiles, whether an egg hatches male or female depends on the temperature of its nest.

Here turtles plan gender-balanced families, trying to exert control over their offspring’s gender. Other writers, however, may not go in for such anthropomorphizing, and we end up with an opening like this:

In most species, gender is determined during fertilization. However, the sex of most turtles, alligators, and crocodiles is determined after fertilization. The temperature of the developing eggs is what decides whether the offspring will be male or female.


We skip and walk and crawl. You could say some of us plod or flail, and they’re the first to be picked off by birds who wheel and eye our tiny black comma shells silhouetted against the beach. Our coming out en masse like this is carnage; we know most won’t make it, and we’re fine with that. We’ve forged no special bonds in the sand; we’ve even grown a faint dislike for one another. All those flipping switches underground, so little space, such darkness. By the time we’re making for the sea we just want to get away from each other, from the too-familiar faces.


Others likely claim greater allegiance to the world because they cry for it. There is a catharsis in crying, or so I’ve been told. I am a fool to care so much and cry so little. Blame it on the hormones, the antidepressants, that make tears slow to come, if at all. The sea turtle cries when laying its eggs, expelling excess salt from a gland that allows them to drink seawater without adverse effects on their bodies. What looks like tears in a turtle is actually an adaptation for survival. What looks like gender in a turtle is actually just temperature. What looks to us like temperature is actually air moving from one place to another at the bidding of the sun, except for when it’s modified by our own noxious fumes. Which is to say, by heating up the world we’re responsible for making more trans turtles.


You might think that once we reach the waves, we’re safe. But no. It’s still possible for a bird to swoop and pluck a wetted one of us, slightly briney from the damp sand, suddenly whisked away having tasted only the scum of one wave’s retreat. Our shells are still soft at this stage, tiny rubber shields that do little to protect us, easily pierced by strong beaks. And we know we said we escape the nest without a metaphor, and that’s true, we do, we wouldn’t lie to you. It’s the coming-home that begs comparison, when those of us who grow and harden will remember to return to the same square of beach that spawned us and start the cycle over, once more, only it’s a bit warmer now. We’re the better for it. Should the scales be tipped irrevocably, the rituals we’ve cultivated for millennia will become a dance of death with no leading partner. But that’s alright, an unpartnered dance is still a dance, we’ve still got rhythm to obey, and we can’t stop to mourn because if we did then it would be over sooner, without a single one to return to this beach by following the instinct to doggy paddle for the horizon. 

 


Callum Angus is the author of A Natural History of Transition (Metonymy Press), as well as managing editor of the journal smoke and mold. His work appears around the web and on calangus.com.

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