On Feb. 28, 2023, a team from the University of Sydney reported that a flu virus found in a sturgeon hints that influenza viruses originated in fish around 600 million years ago and evolved with their hosts to infect a wide range of species today.

The team scoured a genetic database of fish for an influenza-related virus, uncovering one in the intestine of a Siberian sturgeon. In comparing the genetic sequence of the virus in the sturgeon with those of all known influenza viruses, the team found that it closely matches the predicted sequence of the ancestor of these viruses.