The longstanding issue of how animals had anus seems to have been resolved. A new study suggests that the anal hole has evolved from a hole, which was originally used to release sperm.
The anus gives it a lot. It is undeniable that it is a great biophysiological innovation. However, no one knows very well how he evolved.
New genetic analysis in the BIORHIVIVE presents a theory never before written, suggesting that this hole began as a opening used to release sperm and later merged with the intestine.
This is described as an example of evolution that reuses structures.
Primitive animals are thought to developed the mouth and intestine before the anus. Some simple creatures still have this body plane. For example, the Meduses continue to “coconio” through the mouth.
In 2008, it was found that key genes that control the development of the mouth region are quite different from the large intestine genes, suggesting a independent origin for the anus “And now you think you found her.”
The new study investigated animals such as Xenoturbella bockian organism found at the bottom of the sea with mouth and intestines, but without anus – which can be a representative alive of an old group that was intermediate between the ancestors of the meduses and the first animals with anus.
Scientists found that the X. Bock has a separate opening to release sperm, called male gonoporo. This hole does not exist, however, in females, which frees eggs are released through the mouth.
The team also found that several of the genes-chave that control the development of posterior intestine in animals with anus also control the development of gloss in animals like the X. Bock – Which suggests an evolutionary connection.
“What happened is that, probably, the hole [gonóporo] It already existed and the digestive system was around. After merged. They called each other and made a common opening, ”explained the investigation leader, Andreas Hejnol from the University of Bergen, Norway, to New Scientist.
“Theory is very convincing”said to the same magazine Max Telfordfrom University College London, which was not part of the study.
