Scientists have unveiled the ultimate mystery of life: they've definitively determined what came first—the chicken or the egg.

Researchers from the University of Geneva have made a groundbreaking discovery, delving into one of life's greatest mysteries: which came first — the chicken or the egg? Their study focused on an ancient organism, Chromosphaera perkinsii, which demonstrates that the cellular processes responsible for egg formation occurred over a billion years ago, long before the emergence of animals, as reported by Study Finds.

Chromosphaera perkinsii, a unicellular marine organism, possesses a biological plan reminiscent of embryonic development, fundamentally changing scientists' understanding of the evolutionary period of life. Observations of C. perkinsii revealed a process called palintomy, where synchronized cell divisions occur without growth. This leads to the formation of multicellular colonies containing various types of cells — a level of complexity previously thought impossible for unicellular organisms.

This mechanism reflects early stages of embryonic development observed in more complex life forms. These findings allowed researchers to suggest that the genetic tools for egg formation and complex cellular coordination were established long before the first animals appeared.

As the organism transitions into multicellular colonies, it differentiates into three types of cells: flagellated, amoeboflagellates, and dividing cells. This behavior mimics early sequences of gene activation observed during embryogenesis in animals. "This behavior shows that processes of multicellular coordination and differentiation existed even before the first animals on Earth emerged," stated Omayya Dudin, the lead researcher.

This discovery has provided scientists with a glimpse into the history of evolution, illustrating how unicellular life forms served as precursors to the complex developmental mechanisms of modern animals. It also reinforces the idea that the complexity of life is deeply rooted in ancient cellular functions that have evolved over millennia.

The study's results, published in the journal Nature, indicate that the ability of life to specialize and organize arose before the "chicken" or any other animal, with this timeframe being incredibly vast. In addition to solving this age-old mystery, the research emphasizes the importance of studying ancient life forms for a better understanding of the origins of its diversity. It helps scientists rethink the process of evolving complexity, showing that even the simplest organisms hold secrets to the deepest mysteries of life.