UCR Researchers Discover the Oldest Evidence of Animal Life
The oldest clues of animal life were found by researchers at the University of California, Riverside. These traces date back to 660-635 million years ago, in the Neoproterozoic Era. That was at least 100 million years before the Cambrian explosion.
The lead author of the study is Gordon Love, a professor in UCR’s Department of Earth Sciences. The first author is a doctoral student from Love’s research group – Alex Zumberge.
Together, the team tracked down molecular traces of animal life – known as biomarkers. And they found them in the ancient rocks and oils in Oman, Siberia, and India. There was a steroid compound only sponges produced – making them the earliest animals that ever lived on this planet.
Demosponges That Lived 660-635 Million Years Old
“Molecular fossils are important for tracking early animals since the first sponges were probably very small, did not contain a skeleton, and did not leave a well-preserved or easily recognizable body fossil record,” Zumberge explained.
He added that the team was looking for certain stable biomarkers that showed sponges or early animals lived on earth billions of years before the Cambrian explosion.
They identified a steroid compound called 26-methylstigmastane (26-mes) which can only be synthesized by some modern sponges known as demosponges. Zumberge concluded the following:
“This steroid biomarker is the first evidence that demosponges, and hence multicellular animals, were thriving in ancient seas at least as far back as 635 million years ago.”
This finding shows that demosponges lived in the ancient seafloor, providing more information on the modern demosponges. The researchers found that the modern ones prefer to produce 26-mes steroids, while others produce 24-ipc steroids. Love explained that the demosponges have the “ability to make such unconventional steroids” and that it all “arose deep within the demosponge phylogenetic tree but now encompasses a wide coverage of modern demosponge groups.”
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