The grey wolf (Canis lupus), also known as the timber wolf or western wolf, is a canine native to the wilderness and remote areas of Eurasia and North America. The Eurasian wolf (Canis lupus lupus), also known as the common wolf or Middle Russian forest wolf, is a subspecies of grey wolf native to Europe and the forest and steppe zones of the former Soviet Union. It was once widespread throughout Eurasia prior to the Middle Ages. It develops close relationships and strong social bonds, and demonstrates deep affection for its family. The pack is established according to a strict hierarchy, with the dominant male at the top of the pack, followed by the dominant female.