A clan is a group of people unite by kinship and descent, which is defined by perceived descent from a common ancestor. Even if actual lineage patterns are unknown, clan members may nonetheless recognize a founding member or apical ancestor. As kinship based bonds 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 7,000 to 10,000 people.