Of the many innate social forms of behavior, maternal instinct is the strongest. Studies have attempted to establish the developmental stages behind this instinct. A Belgian study on worms could be helpful. Worms lead a simple life and they live off bacteria that populate places where there is fermentation. When the worms produce larvae that will in turn become worms a conflict of interests arises because little worms and parent worms feed on the same sources. When there is a food shortage worms stop eating to the benefit of their little ones. The process is under the control of oxytocin, a hormone. Remove the hormone and mother worm continues eating without bothering about her young ones. Same thing happens if the daughter larvae are exchanged for other larvae. Maternal (and presumably paternal) instinct is under the control of a neural circuit which responds to oxytocin and the mechanism has distant origins.