Because the biological mother is alive. And when I gave birth I also take care of the extension. With the pure love of this mother ultimately the cause of human existence to this day.
Because it is the mother gave birth to life and when she gave birth, and then to wait until he was fed with pure love grow this template itself that caused the mankind existence until today.
because she is the source of life, and when he was born, and his mother had grown with care to keep the love of holy mother. This is a national cause, human existence until today.