Breast feeding plays an important role in the growth and development of a baby. Researchers say that certain changes that occur during the later phases of pregnancy help in generation of milk producing cells.
Two nuclei are developed by the breast cells during the lactation phase. After many milk-producing cells are generated, the nuclei tends to disappear post lactation.
The whole process occurs only for the sake of lactation and to help the new born baby survive. Most of the mammals undergo certain processes to adapt to the conditions of pregnancy.
Current studies say that these biological processes evolved to enhance the production of milk in mothers.
And the reason behind the lactation could be the purpose of supporting the life of a new born. Nature could have designed the whole process in a way that supports the life of the baby in the initial phases until he or she starts getting adapted to the world and the food that is available.