Scientists: Jellies Are the Oldest Animals on Earth

Bastique via Wikimedia Commons // CC BY-SA 3.0
Bastique via Wikimedia Commons // CC BY-SA 3.0

One of the hottest debates in science today concerns two very, very chill animals. Some scientists argue that sea sponges were the first-ever animals to evolve; others say jellies came first. There’s evidence to support both sides, but the latest research, published in the new journal Nature Ecology and Evolution, lands hard in favor of Team Jelly.

Sponges and comb jellies like the one shown above are certainly uncomplicated animals. Both have bodies that are essentially modified tubes, with no eyes, no brains, and no hearts. It might not be an exciting setup, but it’s been working out for these animals for millions and millions of years.

Determining the exact age of a boneless animal is much harder than dating, say, a dinosaur. After death, soft bodies essentially melt away, leaving almost no clues behind—except for the genes they’ve passed down to the next generation. Each animal’s genes is like a map of its evolutionary history. The trick is figuring out how to read it accurately.

Paper co-author Antonis Rokas is an evolutionary biologist at Vanderbilt University. He and his team had grown dissatisfied with existing phylogenomic (genetic map-reading) techniques, which can yield incomplete or ambiguous results.

“The current method that scientists use in phylogenomic studies is to collect large amounts of genetic data, analyze the data, build a set of relationships and then argue that their conclusions are correct because of various improvements they have made in their analysis,” Rokas said in a statement. “This has worked extremely well in 95 percent of the cases, but it has led to apparently irreconcilable differences in the remaining 5 percent."

What was needed, the researchers decided, was a more precise instrument, one that used only the most pertinent information instead of huge piles of data. In this case, that meant looking only at the relationships between different animals’ genetic maps.

“When you look at a particular gene in an organism, let's call it A,” Rokas said, “we ask if it is most closely related to its counterpart in organism B? Or to its counterpart in organism C? And by how much?"

The researchers say the results of this new tactic are clearer and more decisive than any research on the subject to date. And those results say comb jellies, not sponges, were the first animals to evolve.

"We believe that our approach can help resolve many of these long-standing controversies and raise the game of phylogenetic reconstruction to a new level," Rokas said.

Science Finds a Better Way to Calculate 'Dog Years'

thegoodphoto/iStock via Getty Images
thegoodphoto/iStock via Getty Images

Anyone who has ever owned a pet is likely familiar with the concept of “dog years,” which suggests that one year for a dog is like seven years for a human. Using this conversion metric, a 2-year-old dog is akin to a high school freshman, while a 10-year-old dog is ready for an assisted living facility.

If that seems rather arbitrary, that’s because it is. But now, researchers at the University of California, San Diego have come to a more data-based measurement on dog aging through DNA.

The paper, published on the preprint server bioRxiv, based the finding on DNA methylation, a process in which molecules called methyl groups attach themselves to DNA and serve as an indicator of aging. Generally speaking, the older living beings get, the faster the rate of methylation. In the study, 104 Labrador retrievers were examined, with subjects ranging from 1 month to 16 years old. The results of their DNA methylation were compared to human profiles. While the rate of methylation tracked closely between the two—young and old dogs had similar rates to young and old people—adolescent and mature dogs experienced more accelerated aging.

Their recommended formula for comparing dog and human aging? Multiply the natural logarithm of a dog’s age by 16, then add 31. Or, just use this calculator. Users will see that a 2-year-old dog, for example, wouldn’t be the canine equivalent of a 14-year-old. It would be equivalent to 42 human years old and should probably start putting money into a 401(k). But because methylation slows considerably in mid-life, a 5-year-old dog is approximately a 57-year-old human, while a 6-year-old dog is nearing 60 in human years—a minor difference. Things level out as the dog gets much older, with a 10-year-old dog nearing a 70-year-old human.

Different breeds age at different rates, so the formula might not necessarily apply to other dog breeds—only Labs were studied. The work is awaiting peer review, but it does offer a promising glimpse into how our furry companions grow older.

[h/t Live Science]

Sssspectacular: Tree Snakes in Australia Can Actually Jump

sirichai_raksue/iStock via Getty Images
sirichai_raksue/iStock via Getty Images

Ophidiophobia, or fear of snakes, is common among humans. We avoid snakes in the wild, have nightmares about snakes at night, and recoil at snakes on television. We might even be born with the aversion. When researchers showed babies photos of snakes and spiders, their tiny pupils dilated, indicating an arousal response to these ancestral threats.

If you really want to scare a baby, show them footage of an Australian tree snake. Thanks to researchers at Virginia Tech, we now know these non-venomous snakes of the genus Dendrelaphis can become airborne, propelling themselves around treetops like sentient Silly String.

That’s Dendrelaphis pictus, which was caught zipping through the air in 2010. After looking at footage previously filmed by her advisor Jake Socha, Virginia Tech Ph.D. candidate Michelle Graham headed for Australia and built a kind of American Ninja Warrior course for snakes out of PVC piping and tree branches. Graham observed that the snakes tend to spot their landing target, then spring upward. The momentum gets them across gaps that would otherwise not be practical to cross.

Graham next plans to investigate why snakes feel compelled to jump. They might feel a need to escape, or continue moving, or do it because they can. Two scientific papers due in 2020 could provide answers.

Dendrelaphis isn’t the only kind of snake with propulsive capabilities. The Chrysopelea genus includes five species found in Southeast Asia and China, among other places, that can glide through the air.

[h/t National Geographic]

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