<P> The underlying mutation rate used by the geneticists is more questionable . They often use different mutation rates and studies frequently arrive at vastly different conclusions . NRY and mtDNA may be so susceptible to drift that some ancient patterns may have become obscured . Another assumption is that population genealogies are approximated by allele genealogies . Guido Barbujani points out that this only holds if population groups develop from a genetically monomorphic set of founders . Barbujani argues that there is no reason to believe that Europe was colonised by monomorphic populations . This would result in an overestimation of haplogroup age, thus falsely extending the demographic history of Europe into the Late Paleolithic rather than the Neolithic era . Greater certainty about chronology may be obtained from studies of ancient DNA (see below), but so far these have been comparatively few . </P> <P> Whereas Y - DNA and mtDNA haplogroups represent but a small component of a person's DNA pool, autosomal DNA has the advantage of containing hundreds of thousands of examinable genetic loci, thus giving a more complete picture of genetic composition . Descent relationships can only be determined on a statistical basis, because autosomal DNA undergoes recombination . A single chromosome can record a history for each gene . Autosomal studies are much more reliable for showing the relationships between existing populations, but do not offer the possibilities for unravelling their histories in the same way as mtDNA and NRY DNA studies promise, despite their many complications . </P> <P> Genetic studies operate on numerous assumptions and suffer from methodological limitations, such as selection bias and confounding phenomena like genetic drift, foundation and bottleneck effects cause large errors, particularly in haplogroup studies . No matter how accurate the methodology, conclusions derived from such studies are compiled on the basis of how the author envisages their data fits with established archaeological or linguistic theories . </P> <Table> Percentage genetic distances among major continents based on 120 classical polymorphisms <Tr> <Th> </Th> <Th> Europe </Th> <Th> America </Th> <Th> East Asia </Th> <Th> Oceania </Th> </Tr> <Tr> <Td> America </Td> <Td> 9.5 </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> East Asia </Td> <Td> 9.7 </Td> <Td> 8.9 </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Oceania </Td> <Td> 13.5 </Td> <Td> 14.6 </Td> <Td> 10 </Td> <Td> </Td> </Tr> <Tr> <Td> Africa </Td> <Td> 16.6 </Td> <Td> 22.6 </Td> <Td> 20.6 </Td> <Td> 24.7 </Td> </Tr> </Table>

Which of these is not a homogeneous trait of western europe