Cows and bulls have since ancient times a relationship with humans. It is believed that the access to the protein in milk was the reason for the human brain to grow larger relative to its body than in other species. Since then humans have domesticated the animal and used it as a source for food, clothing and material for tools and utensils. They have evolved over time and are bred for different purposes. Cows and bulls were and are revered as gods and holy animals in ancient times and today.