The Mammuthus Moment

Are you a Neanderthal?

Creationists often state that the concept of “created kinds” is a clear organizational tool for biodiversity superior to the Linnaean classification system more commonly employed by scientists. Given the rather ambiguous nature of the “kind” classification, would Neanderthals be considered stout humans with bad haircuts and big foreheads or were they something else?

Morphologically, there is a large body of literature that deals with the differences in Neanderthal finds relative to modern human morphological features. I’m not going to deal with that but rather focus on the molecular work that has been done to approach the question of human/Neanderthal relationships.

In 1997, to great fanfare and public interest, Krings et al. of Svante Pääbo’s research group announced their DNA findings from the Neanderthal type specimen (Neandertal DNA sequences and the origin of modern humans). To summarize their findings, comparing the Neanderthal mitochondrial DNA (DNA that resides in an internal cell structure called the mitochondria, as opposed to DNA in chromosomes) sequence to those of a large sample of human and chimpanzee sequences revealed that 1) the pair wise differences between humans and Neanderthals barely overlap (i.e., each base of DNA in the sequence compared to each base in human sequences includes few matches) 2) chimpanzee pair wise differences did not overlap with either human or Neanderthal 3) the phylogenetic (evolutionary history) placement of the Neanderthal specimen was outside of the human mitochondrial gene pool but occurred long after the split of the lineage leading to humans from the chimpanzee lineage. The conclusion? Neanderthals were closely related to humans but not a direct ancestor, i.e., a different now extinct relative of the human species.

Since this first result was announced, more sequence from the type specimen has been obtained (DNA sequence of the mitochondrial hypervariable region II from the neandertal type specimen), and several additional Neanderthals have been sequenced from different localities (A view of Neandertal genetic diversity; No Evidence of Neandertal mtDNA Contribution to Early Modern Humans; Molecular analysis of Neanderthal DNA from the northern Caucasus). All have reconfirmed the results of the initial study.

A few caveats. Mitochondrial DNA is exclusively transmitted from mother to offspring and thus does not reflect any paternal contribution. It is still possible that Neanderthal nuclear genes have entered the human gene pool. In addition, as modern DNA contamination is a huge problem in ancient DNA (both dinosaur DNA and the studies of DNA from amber inclusions have not withstood scrutiny), Neanderthal sequences that look like modern human sequences would likely be regarded as contaminants or at the very least, would be greeted with extreme skepticism. This is a problem since only divergent sequences can be confirmed as authentic thus only allowing for the conclusion that Neanderthals were different. This also makes the hypothesis that modern humans and Neanderthals did not mix unfalsifiable. However, the data thus far, has produced only divergent sequences and all have been rigorously tested. They are apparently a different species if one uses a definition by which there is evidence of genetic distinction and no evidence (thus far) of mixing of the two populations.

Assuming that reports of human sequences from Neanderthals have not been retrieved, what “kind” are Neanderthals? How would a “created kind” classification benefit the molecular studies of Neanderthals? And the big question: were Neanderthals human?