And That's The Origin Of Sex On Earth!

Canadian deep-sea fossils push the origin of animal sex and movement back 567 million years, rewriting early evolutionary timelines.

While humans like to think of sexual reproduction as a relatively modern biological mainstay, a groundbreaking discovery reveals its roots extend significantly further back in Earth's history than anyone realised.

A newly uncovered treasure trove of fossils indicates that complex animal behaviour -- including locomotion and sexual reproduction -- were occurring 567 million years ago, pushing our evolutionary timeline back by roughly five to 10 million years.

The discovery was made by an international team of scientists working in the remote Mackenzie mountains of Canada's Northwest Territories.

Conducting their research on the ancestral lands of the Sahtu Dene and Metis peoples, who granted access and vital guidance, the palaeontologists unearthed an exceptionally diverse ecosystem from the Ediacaran period.

This era, which predates the famous Cambrian Explosion by tens of millions of years, represents the absolute dawn of complex multicellular animal life.

The findings, published in the journal Science Advances, detail a collection of more than 100 soft-bodied fossils.

Among these are six distinct biological groups never before documented in North America, signalling that these ancient communities were far more widespread than previously recognised.

What happened 567 million years ago

Prior to this study, the planet had been a playground exclusively for single-celled microbes for nearly three billion years.

Then, a dramatic shift occurred.

Strange, macro-sized marine creatures emerged, displaying the foundational behaviour we still see in nature even today.

Researchers note that this particular Canadian site holds staggering potential for anyone trying to map out exactly how life transitioned from microscopic sludge into large, complex, undeniably animal forms.

How the first animal sex happened

Among the standout residents of this ancient ecosystem was Funisia, a stationary, tubular creature that anchored itself to the seafloor in dense clusters of similarly sized individuals.

Funisia provides the earliest definitive evidence of sexual reproduction in the animal kingdom.

Since these organisms grew in tightly packed groups of uniform size, scientists deduce they reproduced en masse. Much like modern-day corals, they likely synchronised the release of eggs and sperm into the ocean currents simultaneously.

The living 'bathmats' that mastered movement

The site also provided a glimpse into the beginnings of animal movement.

Researchers uncovered specimens of Dickinsonia, a flat, ribbed organism famously described as resembling a living 'bathmat' or 'pancake.'

Lacking a mouth, this creature crawled across the primordial slime, absorbing nutrients and bacteria through its underbelly. It stands as the oldest known example of an animal capable of active locomotion to forage for food.

Additionally, the team identified fossils of Kimberella, a creature equipped with a muscular foot used to scrape food off the ocean floor, much like an early relative of modern molluscs.

Kimberella is widely considered a primitive bilaterian -- a classification of animals boasting a distinct front, back, top, bottom and symmetrical sides.

Remarkably, this structural blueprint is shared by more than 99 per cent of all animal species alive today.

The deep sea: Evolution's original safe space

Beyond shifting the evolutionary clock, the discovery upends long-held theories about where complex life actually began.

It was traditionally assumed that early animals evolved in shallow coastal environments before eventually migrating to the abyss.

However, because these 567-million-year-old specimens were preserved in deep-marine sediment, the data implies that evolutionary breakthroughs actually originated in the deep ocean before spreading toward the coast.

While the modern deep sea is often viewed as a cold, inhospitable desert, it provides a uniquely stable environment.

Crucial factors like oxygen levels and water temperature fluctuate far less in the depths than they do in unpredictable shallow waters.

Scientists believe this ancient deep-sea stability provided the perfect, protective nursery for early animal life to experiment with complex survival strategies -- forever altering the biological trajectory of our planet.