Johansson, Sverker, Constraining the Time When Language Evolved (PDF), in Evolution of Language: Sixth International Conference, Rome, aprile 2006, p. 152, DOI:10.1142/9789812774262_0020. URL consultato il 10 settembre 2007 (archiviato dall'url originale il 15 ottobre 2006).
«Hyoid bones are very rare as fossils, as they are not attached to the rest of the skeleton, but one Neanderthal hyoid has been found (Arensburg et al., 1989), very similar to the hyoid of modern Homo sapiens, leading to the conclusion that Neanderthals had a vocal tract similar to ours (Houghton, 1993; Bo¨e, Maeda, & Heim, 1999).»