The oldest animal fossils everyone agrees on are about 574 million years old. A new study argues the first animals are much older. A team including researchers at Oxford reran the molecular clock. That method dates branches of the tree of life from the pace of genetic change. The clock needs fossil checkpoints to set its limits. The authors swapped in older geological deposits as the ceiling instead of a younger one often used before. That one change pushed the estimated origin of animals back about 200 million years, to between 800 and 700 million years ago. That window overlaps Snowball Earth, when ice sheets spread across much of the planet. The lead author is careful to say this does not prove animals lived then. No body fossils from that age exist. It is a model estimate, and other scientists dispute it. Still, it widens the gap between when animals may have arisen and when they left a trace.
Source: Science Advances, 3 October 2026
