The human body contains a multitude of evolutionary throwbacks. Image Credit: sxc.hu
A new study has identified new types of transient muscles in unborn babies that disappear before birth.
These remarkable extra muscles, which grow in our hands and feet while we are still in the womb, are thought to either fuse into other muscles or shrink away to nothing before we are born.
The muscles, which can be found in the digits of limbed animals with far more dexterous digits than ours, are thought to be evolutionary throwbacks dating back 250 million years to a time when our ancestors had started to evolve from reptiles.
As things stand however, it is unclear if these muscles can be found in all human embryos.
"Interestingly, some of the atavistic muscles are found on rare occasions in adults, either as anatomical variations without any noticeable effect for the healthy individual, or as the result of congenital malformations," said study co-author Rui Diogo from Howard University.
"This reinforces the idea that both muscle variations and pathologies can be related to delayed or arrested embryonic development, in this case perhaps a delay or decrease of muscle apoptosis, and helps to explain why these muscles are occasionally found in adult people."
"It provides a fascinating, powerful example of evolution at play."
Source: Live Science | Comments (3)