How Old Are Cockroaches?

Way older than we had previously thought! Fossil records previously estimated that cockroaches had appeared about 140 million years ago, after the supercontinent Pangaea split. Now, a team led by Thomas Bourguignon, an assistant professor at OIST, has uncovered evidence that indicates that cockroaches appeared much earlier.

Through software designed to analyze molecular sequencing, the team has estimated the age of the common ancestor of modern cockroaches to be around 235 million years old. “We estimate that the group is 95 million years older than the earliest known fossil of modern cockroach,” Bourguignon said. This finding means that cockroaches have been around since before the split of Pangaea.

The team first build a foundation for their research by analyzing the nodes present in cockroach fossil records in reference to the cockroaches’ mitochondrial genomes. “We used whole mitochondrial genomes from over 100 cockroaches and termites in combination with 15 cockroach and termite fossils to estimate our ‘time tree’,” research scientist Nathan Lo said [1].

The team then analyzed the genomes in more detail in order to narrow down previous estimates.

This kind of analysis makes it easy to calibrate dates for the cockroach genomes, marking where the common ancestor evolved into subspecies. “The dates are not strict calibrations but distributions, which allows us to account for the uncertainty of the fossil record,” Bourguignon said. By using multiple research methods instead of relying solely on fossil records, Bourguignon’s team has uncovered a new approach to analyzing the histories of the organisms around us.