A clan is a group of people united by actual or perceived kinship and descent. Even if lineage details are unknown, clan members may be organized around a founding member or apical ancestor. The kinship-based bonds may be symbolical, whereby the clan shares a "stipulated" common ancestor that is a symbol of the clan's unity. When this "ancestor" is non-human, it is referred to as a totem, which is frequently an animal. Clans can be most easily described as tribes or sub-groups of tribes. The word clan is derived from clann meaning children or progeny but not family in the Irish language and Scottish Gaelic languages. According to the Oxford English Dictionary, the word was introduced into English around the year 1425 as a label for the tribal nature of the Scottish Highlands society. Clans in indigenous societies are likely to be exogamous, meaning that their members cannot marry one another. Clans preceded more centralized forms of community organization and government; they are located in every country. Members may identify with a coat of arms or other symbol to show they are an independent clan.