The term 'cello ancestor' refers to the VIOL, a four-letter stringed instrument that is considered to be the predecessor of the modern cello. The VIOL was popular in Europe during the Renaissance and Baroque periods, and it is believed to have been developed from the lira da braccio, an Italian bowed instrument. The VIOL is characterized by its deep, mellow tone and its sloping shoulders. It is typically tuned in fourths, with a low G string.