The primitive South American Piraha tribe doesn't have words for numbers greater than "one". How do they count? Not very well:

In one typical test, the researcher set out a group of one to 10 nuts and asked each participant to place an equal number of batteries--used because of their availability and size--on the table. The participants performed perfectly when matching sets of up to three batteries, but at four batteries the accuracy rate dropped to about 75 percent, and by nine none of the Piraha got the right answer.

Lead research Peter Gordon concludes,

...[T]he example of the Piraha tribe shows that language may have more sway over numerical concepts than many previously imagined.

"The lack of number-words seems to preclude the ability to entertain concepts of exact number," Gordon says. "There may be other ways to learn and represent exact numbers, but in the normal course of human learning, language is the route we take."

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