Last Updated: Thursday, 22 February 2007, 17:13 GMT Chimpanzees in Senegal have been observed making and using wooden spears to hunt other primates, according to a study in the journal Current Biology. Researchers documented 22 cases of chimps fashioning tools to jab at smaller primates sheltering in cavities of hollow branches or tree trunks. The report's authors, Jill Pruetz and Paco Bertolani,