The ancient Egyptians used sutures made from linen ribbons and animal tendons, and in South Africa and India the heads of large biting ants were used to hold the edges of wounds. Humans have used natural and artificial materials for centuries to repair all types of fabrics. More than 4,000 years later, American engineer Kristi Anseth is investigating how the most modern and sophisticated biomaterials help regenerate cartilage, help bones heal faster, and better understand some diseases.