The Measurement

The jar had a crack in the lid and a label in faded marker that said RHINELLA MARINA, and under that, in different handwriting, BUFO M., and under that, a date: 1987.

Soren had found it on the third shelf from the bottom, behind a box of rubber gloves and two broken pH meters. He was supposed to be cataloguing the supply room while Ranger Devereux finished her report. She had said it would take twenty minutes. That was two hours ago.

He held the jar up to the light from the small window.

The toad inside was preserved in something yellowish, legs folded in, expression unchanged from whatever expression it had held in 1987. A cane toad. He had seen live ones every night since he arrived, calling from the drainage ditch at the edge of the station, their voices like heartbeats in the dark.

He set the jar on the desk and wrote its measurements in his notebook. Snout to vent: sixty-one millimeters. Leg length, roughly: twenty-two millimeters. He measured twice. Wrote it both times.

Then he went back to the shelf.

There were eleven jars total, all cane toads, all dated. Nineteen eighty-seven. Nineteen ninety-three. Two thousand and one. Two thousand and eight. Two thousand and nineteen.

He measured all of them.

Soren was the kind of person who, if he started measuring, finished measuring. He knew this about himself. Other people would have stopped at three jars. He did not stop at three jars.

At the end he had a column of numbers going down one page and a second column beside it. Body length. Leg length. Ratio.

The ratio was not the same across all the jars.

He looked at it. Checked his arithmetic, which he had already done correctly the first time. Checked the measurements, going back to three of the jars with the ruler again.

The toads from 1987 had short legs relative to their bodies.

The toads from 2019 had longer legs. Not enormously longer. Measurably longer.

He stared at this for a while.

Ranger Devereux came in without knocking, which was her habit, and looked at the jars arranged in a line on the desk with a flicker of something behind her eyes that might have been surprise, or might have been the beginning of an explanation she was already tired of giving.

"You reorganized," she said.

"I measured," Soren said. He showed her the notebook.

She glanced at the numbers the way people glance at things they are about to dismiss, and then she didn't dismiss it. She pulled the notebook closer.

"You measured every one."

"There were only eleven."

She looked at his ratio column for a long moment. Then she said, "There are papers on this. It's a documented thing."

"I know," Soren said. "I looked it up on my phone after I noticed. But I didn't know it when I was measuring."

She handed the notebook back and leaned against the doorframe. "Toads with longer legs move faster. They reach new territory first. The ones at the invasion front -- the furthest out -- they've been selecting for speed for eighty years. Legs get longer. They were introduced in 1935. The front has been moving ever since."

"Like a race," Soren said.

"Like a race where the winners are the ones who go the furthest, and then their children do the same, and then their children." She folded her arms. "I have a meeting in four minutes."

Soren nodded. She left.

He looked at his numbers again.

Eighty years. His grandparents weren't born yet in 1935. And in eighty years, something had changed -- not because anything tried to change it, not because anything wanted to, but because the ones who moved fastest were the ones who kept going, and the ones who kept going were the ones who made more toads.

He thought about the snakes. He had read about the snakes. It was in the same papers he'd found on his phone, the ones that had felt electric because he'd already seen what they were describing, in a line of yellowing jars on a shelf nobody had bothered with since 2019.

The snakes ate the toads. The toads were poisonous. The snakes with wider mouths ate more toad and died. Over and over, for eighty years, in every wetland the toads reached, the wider-mouthed snakes died and the narrower-mouthed snakes survived. And now, across the whole invaded range, the snakes had smaller mouths.

The toads were changing the snakes. The snakes -- by dying -- were changing back.

Neither one was trying. Neither one knew. It was just: faster, and: survive, and: faster, and: survive, and eighty years later a boy with a ruler could measure the consequence.

Soren didn't move for a while.

They just moved forward, and had children, and the children moved forward.

He thought about the snakes at the very front of the toad invasion right now -- this season -- finding a toad they had no instructions about yet. He thought about which snakes would be there next season.

He thought about what eighty more years would measure.

He capped his pen and set it down on the desk, parallel to the notebook.

Then he picked up the 1987 jar and the 2019 jar and held one in each hand, even with each other, so their legs were at the same height, and looked at the distance between what one thing was and what the same thing had become, in the time it takes a species to forget it was ever different.