What Really Happens To Parents’ Breasts When They’re Done Nursing

Here's your daily dose of creepy yet fascinating facts about the human body: Breast cells actually eat one another. A new study in Developmental Cell identified a gene that plays a role in breast tissue's ability to consume dead cells after nursing. The researchers deleted the gene that produces the protein Rac1 in mice. The mice without the gene were unable to physically recover after breastfeeding the way mammals normally do. Leftover milk and dead cells caused inflammation in their breasts, and they couldn't nurse again. This happened because the alveoli, the sacs in the breast that produce milk, die when mammals are done breastfeeding. Then, normally, the epithelial cells in the ducts feed off them. But if they can't, they just stay there. Our bodies have evolved to do away with the dead alveoli cells quickly because otherwise, a potentially dangerous immune response could occur, study author Charles Streuli told Yahoo. Since the presence of dead cells can increase the risk of breast cancer, the researchers are examining whether they can manipulate the gene to prevent it, though the exact relationship is still unknown. For now, what we do know is that parents can probably thank the Rac1 protein for their ability to nurse more than one kid.