Equally definite and elaborate are the manifold restrictions on marriage, commensality, occupation, food, ceremonial observances and personal conduct which affect the mutual relations not only between the different castes but also between the innumerable sub-castes into which the higher castes especially have in turns split up.

The laws which govern marriage, descent, and inheritance amongst the more important castes throw a peculiarly interesting light on the archaic type of society which has survived in Southern India.

Under the matriarchal system of _Manumakkathayam_, which on the Malabar coast obtains to the present day, descent is traced only through the female line.

The male member of the family inherits, but he does so only as the son of a female member of the family through whom he may justly claim kinship, or, to put it in another form, a man's natural heir is not his son, or his brother's son, or the descendant of a common male ancestor, but his sister's, or his sister's daughter's son, or the descendant of a common female ancestress.

In the event of failure of heirs through the female line, adoption is permissible, but the adoption must be of females, through whose subsequent offspring the line of natural descent may be carried on.