Artificial organ almost always preceded by extensive experiments with animals. Initial testing in humans is frequently limited to those either already facing death or who have exhausted every other treatment possibility. Artificial arms and legs, or prosthetics, are intended to restore a degree of normal function to amputees. Mechanical devices that allow amputees to walk again or continue to use two hands have probably been in use since ancient times, the most notable one being the simple peg leg. Since then, the development of artificial limbs has progressed rapidly. New plastics and other materials, such as carbon fiber have allowed artificial limbs
The King of Limbs Up the Ghost" is an acoustic guitar ballad with layered vocal harmonies. The final track, "Separator", has guitar and piano, a "brittle" drum loop, and echoing vocals. Yorke said he felt "The King of Limbs" was a "visual" album, with lyrics and artwork about "wildness" and "mutating" inspired by his environmental concerns. The album title is thought to refer to the King of Limbs, an ancient oak tree in Wiltshire's Savernake Forest, near Tottenham House, where Radiohead recorded "In Rainbows". At eight tracks and 37 minutes in length, "The King of Limbs" is Radiohead's shortest album. O'Brien explained that Radiohead