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Scientist Says Our Oldest Ancestor May Have Been Only ‘Half Alive’

Home, sweet home in the heat and chemical chaos of a hydrothermal vent. Image credit: NOAA Vents Program via Wikimedia Commons // Public Domain

Here are some things we think we know about the first organism to ever appear on Earth: Its name was LUCA. It lived on the hot sea floor about 4 billion years ago. And although it eventually gave rise to every person, plant, and virus alive today, scientists now say LUCA itself might only have lived a sort of half-life. They published these controversial findings in Nature Microbiology.

LUCA (our Last Universal Common Ancestor) may have been cruder than a single-celled bacterium, but that doesn’t make it uninteresting. Quite the opposite, in fact: This older-than-old organism could teach us volumes about the appearance of life on Earth as we know it.

The tricky part of studying an ancient, formless organism is that it could leave no footprints, feathers, or bones behind. Fortunately, LUCA left something better: its genes, moving forward through time.

Researchers at Heinrich Heine University (HHU) in Dusseldorf, Germany set out to find LUCA’s genes in its single-celled descendants, bacteria and archaea. They combed the genomes of 1847 bacterial and 134 archaeal species, looking for shared genetic material. Any proteins that appeared in at least two groups of bacteria and two groups of archaea would likely signify a common parent.

The team found 355 overlapping protein clusters out of the 286,514 they examined. The shared proteins suggested that LUCA was even more primitive than scientists had previously imagined. The genetic lines drew a picture of an organism getting by in the dark of a boiling, oxygen-less hydrothermal vent, feeding on hydrogen gas and metals.

The life LUCA led was so very different from our own that study co-author William F. Martin told The New York Times it could be considered just “half alive.”

If you consider LUCA a biological bridge between a lifeless planet and the life forms that came after it, this framework makes sense. But that theory has its detractors.

Biochemist Steven Benner, a distinguished fellow at the Foundation for Applied Molecular Evolution, told the Times that if LUCA could synthesize proteins—and the genetic analysis suggests it could have—the organism could likely synthesize other, simpler things as well, even if the HHU team didn’t find them. “It’s like saying you can build a 747 but can’t refine iron,” he said.

Chemist John Sutherland of the University of Cambridge had his own objections. He says that LUCA’s dependence on its environment was not as extreme as Martin makes it out to be. “It’s like saying I’m half alive because I depend on my local supermarket.”

Sutherland and Benner don’t disagree with the HHU researchers’ conclusion that LUCA was, well, our LUCA, and they’re fine placing it on a hydrothermal vent. But they don’t think LUCA was the first life form, and they say a lot more research is needed before we can really pin down just what that ancient little weirdo was up to. 

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Animals
Watch the First-Ever Footage of a Baby Dumbo Octopus
NOAA, Wikimedia Commons // Public Domain
NOAA, Wikimedia Commons // Public Domain

Dumbo octopuses are named for the elephant-ear-like fins they use to navigate the deep sea, but until recently, when and how they developed those floppy appendages were a mystery. Now, for the first time, researchers have caught a newborn Dumbo octopus on tape. As reported in the journal Current Biology, they discovered that the creatures are equipped with the fins from the moment they hatch.

Study co-author Tim Shank, a researcher at the Woods Hole Oceanographic Institution in Massachusetts, spotted the octopus in 2005. During a research expedition in the North Atlantic, one of the remotely operated vehicles he was working with collected several coral branches with something strange attached to them. It looked like a bunch of sandy-colored golf balls at first, but then he realized it was an egg sac.

He and his fellow researchers eventually classified the hatchling that emerged as a member of the genus Grimpoteuthis. In other words, it was a Dumbo octopus, though they couldn't determine the exact species. But you wouldn't need a biology degree to spot its resemblance to Disney's famous elephant, as you can see in the video below.

The octopus hatched with a set of functional fins that allowed it to swim around and hunt right away, and an MRI scan revealed fully-developed internal organs and a complex nervous system. As the researchers wrote in their study, Dumbo octopuses enter the world as "competent juveniles" ready to jump straight into adult life.

Grimpoteuthis spends its life in the deep ocean, which makes it difficult to study. Scientists hope the newly-reported findings will make it easier to identify Grimpoteuthis eggs and hatchlings for future research.

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15 Confusing Plant and Animal Misnomers
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iStock

People have always given names to the plants and animals around us. But as our study of the natural world has developed, we've realized that many of these names are wildly inaccurate. In fact, they often have less to say about nature than about the people who did the naming. Here’s a batch of these befuddling names.

1. COMMON NIGHTHAWK

There are two problems with this bird’s name. First, the common nighthawk doesn’t fly at night—it’s active at dawn and dusk. Second, it’s not a hawk. Native to North and South America, it belongs to a group of birds with an even stranger name: Goatsuckers. People used to think that these birds flew into barns at night and drank from the teats of goats. (In fact, they eat insects.)

2. IRISH MOSS

It’s not a moss—it’s a red alga that lives along the rocky shores of the northern Atlantic Ocean. Irish moss and other red algae give us carrageenan, a cheap food thickener that you may have eaten in gummy candies, soy milk, ice cream, veggie hot dogs, and more.

3. FISHER-CAT

Native to North America, the fisher-cat isn’t a cat at all: It’s a cousin of the weasel. It also doesn’t fish. Nobody’s sure where the fisher cat’s name came from. One possibility is that early naturalists confused it with the sea mink, a similar-looking creature that was an expert fisher. But the fisher-cat prefers to eat land animals. In fact, it’s one of the few creatures that can tackle a porcupine.

4. AMERICAN BLUE-EYED GRASS

American blue-eyed grass doesn’t have eyes (which is good, because that would be super creepy). Its blue “eyes” are flowers that peek up at you from a meadow. It’s also not a grass—it’s a member of the iris family.

5. MUDPUPPY

The mudpuppy isn’t a cute, fluffy puppy that scampered into some mud. It’s a big, mucus-covered salamander that spends all of its life underwater. (It’s still adorable, though.) The mudpuppy isn’t the only aquatic salamander with a weird name—there are many more, including the greater siren, the Alabama waterdog, and the world’s most metal amphibian, the hellbender.

6. WINGED DRAGONFISH

This weird creature has other fantastic and inaccurate names: brick seamoth, long-tailed dragonfish, and more. It’s really just a cool-looking fish. Found in the waters off of Asia, it has wing-like fins, and spends its time on the muddy seafloor.

7. NAVAL SHIPWORM

The naval shipworm is not a worm. It’s something much, much weirder: a kind of clam with a long, wormlike body that doesn’t fit in its tiny shell. It uses this modified shell to dig into wood, which it eats. The naval shipworm, and other shipworms, burrow through all sorts of submerged wood—including wooden ships.

8. WHIP SPIDERS

These leggy creatures are not spiders; they’re in a separate scientific family. They also don’t whip anything. Whip spiders have two long legs that look whip-like, but that are used as sense organs—sort of like an insect’s antennae. Despite their intimidating appearance, whip spiders are harmless to humans.

9. VELVET ANTS

A photograph of a velvet ant
Craig Pemberton, Wikimedia Commons // CC BY-SA 3.0

There are thousands of species of velvet ants … and all are wasps, not ants. These insects have a fuzzy, velvety look. Don’t pat them, though—velvet ants aren’t aggressive, but the females pack a powerful sting.

10. SLOW WORM

The slow worm is not a worm. It’s a legless reptile that lives in parts of Europe and Asia. Though it looks like a snake, it became legless through a totally separate evolutionary path from the one snakes took. It has many traits in common with lizards, such as eyelids and external ear holes.

11. TRAVELER'S PALM

This beautiful tree from Madagascar has been planted in tropical gardens all around the world. It’s not actually a palm, but belongs to a family that includes the bird of paradise flower. In its native home, the traveler’s palm reproduces with the help of lemurs that guzzle its nectar and spread pollen from tree to tree.

12. VAMPIRE SQUID

Drawing of a vampire squid
Carl Chun, Wikimedia Commons // Public Domain

This deep-sea critter isn’t a squid. It’s the only surviving member of a scientific order that has characteristics of both octopuses and squids. And don’t let the word “vampire” scare you; it only eats bits of falling marine debris (dead stuff, poop, and so on), and it’s only about 11 inches long.

13. MALE FERN & LADY FERN

Early botanists thought that these two ferns belonged to the same species. They figured that the male fern was the male of the species because of its coarse appearance. The lady fern, on the other hand, has lacy fronds and seemed more ladylike. Gender stereotypes aside, male and lady Ferns belong to entirely separate species, and almost all ferns can make both male and female reproductive cells. If ferns start looking manly or womanly to you, maybe you should take a break from botany.

14. TENNESSEE WARBLER

You will never find a single Tennessee warbler nest in Tennessee. This bird breeds mostly in Canada, and spends the winter in Mexico and more southern places. But early ornithologist Alexander Wilson shot one in 1811 in Tennessee during its migration, and the name stuck.

15. CANADA THISTLE

Though it’s found across much of Canada, this spiky plant comes from Europe and Asia. Early European settlers brought Canada thistle seeds to the New World, possibly as accidental hitchhikers in grain shipments. A tough weed, the plant soon spread across the continent, taking root in fields and pushing aside crops. So why does it have this inaccurate name? Americans may have been looking for someone to blame for this plant—so they blamed Canada.

A version of this story originally ran in 2015.

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