Evolutionary theory has long held that the process can only go one way, a rule known as “Dollo’s Law.” But the new study in Systematic Biology shows that dust mites evolved from free-roaming creatures to specialized parasites before regressing back to their current form.
"All our analyses conclusively demonstrated that house dust mites have abandoned a parasitic lifestyle, secondarily becoming free-living, and then speciated in several habitats, including human habitations," researchers Pavel Klimov and Barry O’Connor said according to a Univeristy of Michigan press release.
The study is surprising because most parasites quickly lose their ability to survive on their own once they’re away from their natural host.
“They often experience degradation or loss of many genes because their functions are no longer required in a rich environment where hosts provide both living space and nutrients,” Klimov said. “Many researchers in the field perceive such specialization as evolutionarily irreversible."
Researchers hope that the study can give them a better look at how to fight the parasites, which are the most common cause of allergic reactions in humans, affecting more than a billion people worldwide. Dust mites typically live in mattresses, carpets and upholstered furniture in people’s homes.