Determining diet of ancients from dental chips

[raw-al]

http://www.physorg.com/news203854387.html

[michaelwh]

The teeth in that photo look horrible. If I were shown that photo without knowing where it's from, I would have thought that it's from someone who drinks too much soda and eats too much candy, rather than a prehistoric human.

Did our ancestors generically have such bad teeth? Or perhaps this photo was selectively chosen to illustrate tooth damage, and such bad teeth are the exception, rather than the norm?