The FOXP2 gene supports Neandertals being fully human
Speech enables humans to communicate effectively and is probably the most prominent trait which distinguishes people from other creatures. However, some people are born with an impaired ability for language and speech development, a syndrome known as specific language impairment (SLI). Children with SLI lag behind their peers in language development and comprehension, which contributes to learning and reading disabilities in school. Recently, a defective gene in a three-generation family that had the SLI speech disorder was identified as the FOXP2 gene. The FOXP2 gene was also defective in a non-relative who suffered from the same disorder.1,2 Those with a defective FOXP2 are more prone to display SLI difficulties, but the same mutational variants do not always result in this disorder, reflecting the complexity of the genetics of speech.3
The entire DNA sequence of the human FOXP2 gene is known, and the genetic homologues in chimpanzee, gorilla, orangutan, rhesus monkey and mouse have recently become available. The FOXP2 proteins are identical in chimp, gorilla and rhesus monkey. Orangutan and mouse differ by only two amino acids outside the Q regions (The Q regions are not taken into account, since they are subject to rapid mutations (due to slippery DNA polymerases)). In contrast to these five sequences, the human version differs at two positions. Depicted in figure 1, amino acid residue 304 has ‘N’ for humans, ‘T’ for the other five organisms; amino acid residue 326 has ‘S’ for humans, ‘N’ for the other five organism.2 The two amino acid variations are present in all 226 examined human samples and typify the human FOXP2 gene sequence. The FOXP2 genes and proteins can thus be used as an indicator gene, a genetic tool to distinguish between humans, primates and other species (figure 1).
The recent DNA analysis of the Neandertaler, who according to evolutionary timescales evolved around 400 thousand years ago, showed they carried the exact same FOXP2 protein (deduced from the DNA sequence) as modern humans, including the N and S at position 304 and 326, respectively.4 In addition to morphological and physiological evidence for the vocal tract, including the modern hyoid bone,5 molecular biology is now providing support that Neandertals were fully equipped for speaking complex languages. The FOXP2 genes found in Neandertals therefore show that they were Homo sapiens. These findings are entirely in accord with the creationist’s stance that Neandertals were fully human (post-Flood) inhabitants of Europe and Asia.
- Lai, C.S., Fisher, S.E., Hurst, J.A., Vargha-Khadem, F. and Monaco, A.P., A forkhead-domain gene is mutated in a severe speech and language disorder, Nature 413:519–523, 2001. Return to text.
- Enard W., Przeworski, M., Fisher, S.E., Lai, C.S., Wiebe, V., Kitano, T., Monaco, A.P. and Pääbo, S., Molecular evolution of FOXP2, a gene involved in speech and language, Nature 418:869–872, 2002. Return to text.
- Newbury, D.F. et al. and the International Molecular Genetic Study of Autism Consortium, FOXP2 is not a major susceptibility gene for autism or Specific Language Impairment, Am. J. Hum. Genet. 70:1318–1327, 2002. Return to text.
- Krause, J. et al., The derived FOXP2 variant of modern humans was shared with Neandertals, Curr. Biol. 17:1908–1912, 2007. Return to text.
- References in: Mahathey, S.A., Neandertal speech capability and the limitations of osteological analysis, J. Creation 14(3):118–127, 2000. Return to text.