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Scientists just solved the chicken-and-egg debate, so what will we argue about now?

A billion-year-old discovery has officially cracked the ultimate evolutionary mystery.

Richard Symonds

This handsome gent just got some bad news.

In the ultimate mic-drop for chicken-or-egg debaters, Chromosphaera perkinsii, a billion-year-old unicellular organism, reveals that nature had "eggs" on the menu way before chickens (or any animals) arrived. But, though the mystery has been unscrambled, the discovery has cracked open an entirely new chapter in the story of life's origins.

Meet Chromosphaera perkinsii, a single-celled organism found in marine sediments off Hawaii that threw evolutionary biologists a curveball. This tiny protist, dating back more than a billion years, does something remarkable: it organizes itself into multicellular structures that look exactly like the earliest stages of animal embryos.

A sequence of images showing Chromosphaera perkinsii forming a colony. It looks like images you may have seen of early cell division, but this is of individual Chromosphaera perkinsii forming a colony. © UNIGE Omaya Dudin

Nature’s OG egg

Researchers from the University of Geneva (UNIGE), led by Omaya Dudin, have spent years studying this humble organism, and the findings are nothing short of stunning. Unlike most single-celled creatures, C. perkinsii can coordinate cell division without growing larger. Instead, it creates colonies that resemble the first steps of animal embryonic development.

"Although C. perkinsii is a unicellular species, this behaviour shows that multicellular coordination and differentiation processes are already present in the species, well before the first animals appeared on Earth."

— Omaya Dudin

Even more mind-blowing? When scientists analyzed the genetic activity within these colonies, they found it eerily similar to what happens in the embryos of modern animals. The processes that allow embryos to grow from a single cell into a multicellular organism—a hallmark of animal life—were apparently hanging out in the evolutionary toolbox long before animals even existed.

A billion years of practice

The study, published in Nature, even raises the possibility that multicellularity evolved multiple times in different lineages, meaning the transition from single-celled life to complex organisms could be less linear (and more chaotic) than previously believed.

"It’s fascinating, a species discovered very recently allows us to go back in time more than a billion years."

— Marine Olivetta

The research could also reignite debates about mysterious 600-million-year-old fossils that look like embryos. Are they early animals or ancient organisms like C. perkinsii? Either way, this tiny protist suggests that nature was testing out egg-like developmental strategies long before anything resembling a chicken—or even a jellyfish—arrived on the scene.

The egg’s ultimate win

For anyone still clinging to the chicken in this debate, it’s time to throw in the towel. The egg wins by a landslide. And while these ancient “eggs” might not have shells or yolks, they set the stage for the evolutionary leaps that eventually gave us the breakfast staple we know today.

Still not convinced? Neil deGrasse Tyson shares the evolutionary approach to the puzzle. He bluntly points out that the egg came first; it was just laid by a bird that was not a chicken.

@neildegrassetyson we've cracked the case over which came first, chicken or egg! 🐣 #scienceflex
♬ original sound - StarTalk

Discoveries like this remind us how much we still don’t know about the origins of life. If a billion-year-old protist can hold the key to one of our oldest questions, imagine what else nature has waiting for us in its archives. But one thing’s certain: we finally have our answer. The egg was here first, and it’s been waiting for us to catch up for over a billion years.

So, with that settled, we are now tasked with finding something else to argue about. Science has yet to weigh in on the tree in the woods. Perhaps that puzzle will be the next to fall.