This should come as no surprise to readers of this blog. Reuters has the scoop:
Chimps performed about as well as college students at mental addition, U.S. researchers said on Monday in a finding that suggests non-verbal math skills are not unique to humans.
Essentially the difference is language. Humans need to verbalize with each other to become more than helpless infants. Chimps can do math.
Chimp thumb sucking picture goodness included in the link.
