Since the FOXP2 gene is present in other, non-speaking creatures, it must have some difference beyond merely being in the genome. This is probably a difference in gene expression--the gene must be turned up or down, probably the former, much more in humans.
Work Step by Step
When looking at genes and genomes, if some important difference exists between organisms, first ask if there are differences in what genes are present. If there are not, then turn to differences in gene expression.