Shrieking, hooting, and cooing gave way to consciously controlled speech, long on content, short on emotion. This story is repeated today by every infant. And their speech was something like human language as we know it . He bases his answer on the theory that a Neanderthal's prefrontal cortex was not very different from that of anatomically modem humans. The latter argue that to produce human speech requires a larynx placed low in the throat and an arched or flexed skull base.
Neanderthal fossils show that they possessed a high larynx and a straight skull base.
Deacon insists that language ability stems from the organization of the brain, not the position of the larynx or shape of the skull base. Humans whose larynx has been damaged or destroyed by disease or trauma retain the ability to speak with the help of mechanical devices. But there are modern languages in which vowels are subordinate to consonants. Also, vowel changes are essentially neutral to word meaning, whereas consonant changes have serious consequences for intelligibility. These researchers contend that existence of the bone supports the idea that Neanderthals could talk in much the same way as we do today.