A new study from CIGENE’s Marie Saitou, published in Genome Biology and Evolution this month, suggests that the genes active within human breast tissue, and thereby the genes controlling mammary gland function, are not unique to mammals. Instead, many genes active in breast tissue are also found in secretory epithelial tissues of other vertebrates.
The mammary gland is a defining feature of mammals. It produces milk and supports offspring after birth. However, the evolutionary origin of the genes active within breast tissue has not been fully understood.
In this study, Dr Saitou examined gene activity in human breast tissue and compared it with other organs that produce and secrete substances. The results suggest that breast tissue uses many genes that are also active in other secretory tissues, including the salivary gland, pancreas, stomach, and skin.
The study also found that many of these genes are not limited to mammals. They are conserved across vertebrates, suggesting that breast tissue may have evolved partly by using genes that already existed before the origin of mammals.
These findings support the idea that the mammalian breast evolved through changes in how existing genes are used in a specific tissue, rather than through the appearance of entirely new mammal-specific genes.
You can read the study in full on the Genome Biology and Evolution journal website.