A clan is a group of people united by kinship and descent, which is defined by perceived descent from a common ancestor. Even if actual lineage patterns are unknown, clan members nonetheless recognize a founding member or apical ancestor. As kinship based bonds can be merely symbolical in nature some clans share a "stipulated" common ancestor, which is a symbol of the clan's unity. When this ancestor is not human, this is referred to as animallian totem. Generally speaking, kinship differs from biological relation, as it also involves adoption, marriage, and fictive genealogical ties. Clans can be most easily described as sub-groups of tribes and usually constitute groups of 7000 to 10 000 people.