The Two-Headed Goat
While there have been ancient myths about mysterious animals with multiple heads, these myths likely began from a real-life issue that can happen before an animal is born. Although, our “two-headed goat” friend has two faces and not two heads. Known as craniofacial duplication, one will be born with essentially two faces with one head. This can actually happen to humans as well as animals as the extremely rare birth defect is not species specific. The versions can differ where one might develop three or four eyes, some have just one nose or mouth, and others have complete facial features. Yet this is simply one creature, making it differ from something like conjoined twins where most do not share the same brain. This occurs due to the fusion or incomplete separation of two embryos.
In the case of the goat, it is believed that twin goats were going to be born until the eggs weren’t able to fully split. All of this is a result of abnormal activity of the SHH protein. Along with corresponding genes, SHH plays a critical role in signaling craniofacial patterning during the process of embryonic development. As widening becomes greater, the more structures end up duplicating. This will occur in a mirror image form, giving something like the two-headed goat identical facial features. Specialized neural tissues control the size and shape of brain structures, but cyclopia can occur too. This is what caused facial features not to develop completely, resulting in perhaps the loss of an eye, nose, etc. Sadly for our goat friend, his life was quite short.