Humans still similar to first animals without heads, arms, or skeletons

555-million-year-old oceanic creatures share genes with today's humans, finds a new study.

Humans still similar to first animals without heads, arms, or skeletons

artist rendering of Ikaria wariootia

Credit: Sohail Wasif/UCR
  • A new study finds genetic links between early oceanic animals and humans.
  • The animals studied had no heads, skeletons, legs, or arms.
  • The creatures were from the Ediacaran era, living about 555 million years ago.

As complex as modern humans can get, they still retain some features of the earliest animals on Earth. According to new research, we are not as different as we might think from strange prehistoric organisms that didn't have any heads, arms, legs, or skeletons.

A study from UC Riverside identified 555-million-year-old oceanic creatures that share genes with humans and other contemporary animals.

The paper's co-author, UC Riverside geology professor Mary Droser, thinks the animals of the so-called Ediacaran era, which lasted from 571 million to 539 million years ago, were almost nothing like creatures of today.

"None of them had heads or skeletons. Many of them probably looked like three-dimensional bathmats on the sea floor, round discs that stuck up," said Droser in a press release. "These animals are so weird and so different, it's difficult to assign them to modern categories of living organisms just by looking at them, and it's not like we can extract their DNA — we can't."

Droser and her colleague Scott Evans of the National Museum of Natural History used fossil records to tie ancient ocean dwellers to the genetics of things alive now. They looked specifically at four animals as stand-ins for the 40+ Ediacaran era species scientists have been able to identify so far. Some of the creatures under discussion were as small as a few millimeters while others got almost a meter long. These included multicellular organisms like the sea-floor-scraping Kimberella, flat oval-shaped Dickinsonia, as well as the immobilized bottom-dweller Tribrachidium.

They also studied the Ikaria, animals that were recently discovered (by a team that also featured Evans and Droser). These jelly-bean-like creatures were no bigger than a grain of rice and represented the first bilaterians in the study. As the press release explains, bilaterians are symmetrical "organisms with a front, back, and openings at either end connected by a gut." If you're wondering, humans are bilateral. As are spiders and pigs. The scientists think the Ikaria might have had mouths, but those didn't get survive to be included in the fossil records.

Dickinsonia fossil, an animal from the Ediacaran era.

Credit: Mary Droser/UCR

How did the creatures get around without heads? They probably had the genetic parts that could govern heads as well as the requisite sensory organs. But their genes didn't yet work together in the complex way necessary for the heads and other sophisticated organs humans have to develop.

"The fact that we can say these genes were operating in something that's been extinct for half a billion years is fascinating to me," Evans pointed out.

The team plans to study the evolution of early animals further, investigating muscle development next.

Check out the study published in Proceedings of the Royal Society B.

Paleontologist Scott Evans looking for fossils in the Australian outback.

Credit: Droser Lab/UCR

Your body’s full of stuff you no longer need. Here's a list.

Evolution doesn't clean up after itself very well.

Image source: Decade3d-anatomy online via Shutterstock
Surprising Science
  • An evolutionary biologist got people swapping ideas about our lingering vestigia.
  • Basically, this is the stuff that served some evolutionary purpose at some point, but now is kind of, well, extra.
  • Here are the six traits that inaugurated the fun.
Keep reading Show less

Godzilla vs. Kong: A morphologist chooses the real winner

Ultimately, this is a fight between a giant reptile and a giant primate.

Surprising Science

The 2021 film “Godzilla vs. Kong" pits the two most iconic movie monsters of all time against each other. And fans are now picking sides.

Keep reading Show less

How do you tell reality from a deepfake?

The more you see them, the better you get at spotting the signs.

ROB LEVER/AFP via Getty Images
Technology & Innovation
  • The number of deepfake videos online has been increasing at an estimated annual rate of about 900%.
  • Technology advances have made it increasingly easy to produce them, which has raised questions about how best to prevent malicious misuse.
  • It's been suggested that the best way to inoculate people against the danger of deepfakes is through exposure and raising awareness.
  • Keep reading Show less
    Surprising Science

    Ancient cave artists were getting high on hypoxia

    A new study says the reason cave paintings are in such remote caverns was the artists' search for transcendence.