Are chimps closer to humans or gorillas?

This question occurred to me recently. Which species do chimps share a more recent ancestor, humans or gorillas? So I looked it up. According to the paper

Rannala, B. and Yang, Z, "Probability distribution of molecular evolutionary trees: A new method of phylogenetic inference", Journal of Molecular Evolution, 43(3): 304-311, 1996.

the most likely phylogenetic tree (based on genetic nucleotide sequencing data) looks like this,

Hominidae is the family of great apes, containing us (genus Homo), chimpanzees (Pan), gorillas (Gorilla), and orangutans (Pongo). As you can see, the chimps share a more recent ancestor with us than with the gorillas. In other words, chimpanzees are more closely related to humans than they are to gorillas.