The setting is fifty-five million years in the future on Earth, with multiple humanoid species that have different ancestors, but share similar characteristics. Their ancestors would be animals that live today, such as alligators, cats, crows, octopuses... but their descendants would evolve human like traits that would make them very similar to each other to the point where some of these new species could be able talk or live in peace with each other. Something like relations or very similar characteristic despite vastly diverse ancestors between humans, vulcans and klingons in Star Trek.
My current theory is that around the year 2100, a mass extinction event would occur. It would be serious enough to wipe out a great amount of fauna and flora and make the human race leave the planet before the unstoppable event. It would also destroy many buildings, including factories and GMO research stations (which would be very popular at the time). Could it be possible for the chemicals to help the rNA which escaped from the facilities to get inside embryos of surviving organisms to trigger the evolution of human like traits?