Huh? Methinks you either misread the article or are making this up. Science has never said man evolved from chimps. Man and chimps evolved from a common ancestor and split somewhere between 5MYA and 7MYA.
Isn't that just a really dumb way to measure time? Next year we'll have to revise that statement to say,
"somewhere betweeen 5.000001 and 7.000001 MYA."