This is an essay that explains the origins and what the "LAws of Manu" are all about

The Laws of Manu The Laws of Manu have drawn the attention of Western minds to Hindu ideals and how those principles influenced the day-to-day life of the four different classes within Hindu society. The rules and regulations that are contained in the law are considered to be universal to all and everlasting. The laws of Manu were a collection of writings that were legal and ethical in nature, dealing with the following problems. Beginning …

…Out of Manu's hands came the Kshatriyas, the rulers and warriors. The craftsmen came from his thighs and are called Vaisyas. The remainder of the people came from Manu's feet and are known as Sudras. The rebirth may be to a higher form, i.e., a member of a higher caste or god, or down the social ladder to a lower caste or animal, since the wheel of karma applies to both man and animals.