http://www.grandin.com/inc/animals.in.translation.ch7.html
It's also worth considering that young humans can learn some things, like languages, far more easily than adults. The article in the OP tested young chimps against adult humans.
Thanks!
Animals in Translation:
Using the
Mysteries of Autism
to Decode Animal Behavior
by Temple Grandin
and Catherine Johnson
paperback
Google books
Google search
her other website