The Eurasian brown bear (Ursus arctos arctos) is one of the most common subspecies of the brown bear, and is found in much of Eurasia. It is also called the European brown bear, common brown bear, common bear, and colloquially by many other names. The genetic diversity of present-day brown bears (Ursus arctos) has been extensively studied over the years and appears to be geographically structured into five main clades based upon analysis of the mtDNA. Description The Eurasian brown bear has brown fur, which ranges from yellowish-brown to dark brown, red-brown, and almost black in some cases; albinism has also been recorded. The fur is dense to varying degrees and the hair can grow up to in length. The head normally is quite round in shape and has relatively small rounded ears, a wide skull and a mouth equipped with 42 teeth, including predatory teeth. It has a powerful bone structure and large paws equipped with claws that can grow up to in length. The weight varies depending on habitat and the time of the year. A full-grown male weighs on average between , and reaches a maximum weight of and length of nearly . Females typically range between 150 and . They have a lifespan of 20 to 30 years in the wild. History Eurasian brown bears were used in Ancient Rome for fighting in arenas. The strongest bears apparently came from Caledonia and Dalmatia. In antiquity, the Eurasian brown bear was largely carnivorous, with 80% of its diet consisting of animal matter. However, as its habitat increasingly diminished, the portion of meat in its diet decreased with it until by the late Middle Ages, meat consisted of only 40% of its dietary intake. Today, meat makes up little more than 10–15% of its diet. Whenever possible, the brown bear will consume sheep. Unlike in North America, where an average of two people a year are killed by bears, Scandinavia only has records of three fatal bear attacks within the last century. However, in late 2019, brown bears killed three men in Romania in just over a month. Species origin The oldest fossils are from the Choukoutien, China, and date back about 500,000 years. It is known from mtDNA studies that during the Pleistocene ice age it was too cold for the brown bear to survive in Europe except in three places: Russia, Spain, and the Balkans. Modern