Born from the chocolate family at U-Wisconsin-Madison,

Rolo (born 12/12/96) and Yohoo, (born 7/8/97) male and brother to Rolo,were quite an excitable pair.

Rolo dominated his brother Yohoo, but both participated in studies well. They were the only monkeys who figured out how to bar press levers for treats.

Yohoo is on the left, Rolo, on the right.

Yohoo was returned to U-Wisconsin-Madison during the summer of 2004 to mate with an older female. Rolo had health problems in the Fall of 2004 and died then (at age 8), but lived with Ophelia for a short time before he died and was enjoying the large family cage. Yohoo also died recently at U-Wisconsin-Madison.