Shree Krishna explains that the destiny awaiting the souls is based upon the
guṇas
of their personalities. We get what we deserve is God’s law, the law of karma. Those who cultivated virtues, knowledge, and a service attitude toward others are born in families of pious people, scholars, social workers, etc. Or else, they go to the higher celestial abodes. Those who permitted themselves to be overcome by greed, avarice, and worldly ambitions are born in families focused on intense material activity, very often the business class. Those who were inclined to intoxication, violence, laziness, and dereliction of duty are born amongst families of drunks and illiterate people. Otherwise, they are made to descend down the evolutionary ladder and are born into the animal species.
Many people wonder whether having once attained the human form, it is possible to slip back into the lower species. This verse reveals that the human form does not remain permanently reserved for the soul. Those who do not put it to good use are subject to the terrible danger of moving downward into the animal forms again. Thus, all the paths are open at all times. The soul can climb upward in its spiritual evolution, remain at the same level, or even slide down, based upon the intensity and frequency of the
guṇas
it adopts.