Humans may be susceptible to ear infections because of the way the mammalian ear develops, report researchers from Kings College in London (Thompson H, Tucker AS. Science. 2013;339:1453-1456).
Studies in transgenic mice revealed that as the ear forms, the inner endodermal layer of cells breaks down and a new layer, neural crest tissue, is added to the middle ear cavity. This addition of neural crest tissue in mammals may be linked to the evolution of the middle ear sound-conducting bones, or ossicles: mammals have 3 ossicles, while nonmammals have only 1.
Hampton T. New Clues to Ear Infection. JAMA. 2013;309(17):1765. doi:10.1001/jama.2013.4801