Polygamy may be polygyny (one man having more than one wife at the same time) or polyandry (one woman having more than one husband at the same time) and it has been practiced sparsely throughout history in almost all cultures and sanctioned by various religions where necessary to meet population or economic needs. For example, when disease, war or famine has reduced populations, the taking of several wives has been the solution to restoring population. In some economically poor areas where infant mortality is high but children are a vital source of labor to maintain the earning capacity of the family, polygamy provides more children. Some states have defined marriage as the union of one man to one woman "to the exclusion of all others" and, in some cases, have criminalized bigamy or, as in Canada, have made polygamy an offense under the Criminal Code. Under section 293(a) of the Canadian Criminal Code, everyone who enters into any form of polygamy or any "conjugal union with more than one person at a time" is guilty of an offense, and under s. 293(b), there is a separate offense for any person who "celebrates, assists or is a party to a rite that sanctions a polygamous marriage".