A scanning electron microscope image of an American house dust mite.
I found an interesting study that challanges evolutionary progress as being irreversible.
Dollo's Law[]
States that evolution goes one direction and cannot be reversed. This hypothesis was proposed in 1893 by paleontologist Louis Dollo.
New Research[]
In 2013, a study was published in Systematic Biology by two genetic biologists from the University of Michigan challenging Dollo's Law based on the evolution of the common house dust mite. Early evolution evidence might have been reversed as dust mites changed from parasites into free living organisms. In the spirit of inquiry, these scientists "asked a purely academic question that may result in broad practical applications," states the author of the study.
Reference
Klimov, P. and O'Conner, B. (2013). Is Permanent Paratism Reversible? - Critical evidence from early evolution of house dust mites. Systematic Biology, 62(6):?.