A new study proposes that animals could have first evolved as early as 800 to 700 million years ago. That would put their origin about 200 million years before some earlier estimates, reshaping the timeline of life on Earth.
If correct, the earliest animals would have appeared before or during Snowball Earth, a period of extreme glaciation. Because these creatures were probably soft-bodied, they would have left little fossil evidence, which may explain why the fossil record has not clearly shown them.
The research is based on a single analysis, and the authors acknowledge the uncertainty inherent in tracing soft-bodied ancestors. Still, the findings offer a new hypothesis for when complex life first emerged.