RT Journal
A1 Romualdi, Chiara
A1 Balding, David
A1 Nasidze, Ivane S.
A1 Risch, Gregory
A1 Robichaux, Myles
A1 Sherry, Stephen T.
A1 Stoneking, Mark
A1 Batzer, Mark A.
A1 Barbujani, Guido
T1 Patterns of Human Diversity, within and among Continents, Inferred from Biallelic DNA Polymorphisms
JF Genome Research 
JO Genome Research 
YR 2002 
FD April 01 
VO 12 
IS 4 
SP 602 
OP 612 
DO 10.1101/gr.214902 
UL http://genome.cshlp.org/content/12/4/602.abstract 
AB Previous studies have reported that about 85% of human diversity at Short Tandem Repeat (STR) and Restriction Fragment Length Polymorphism (RFLP) autosomal loci is due to differences between individuals of the same population, whereas differences among continental groups account for only 10% of the overall genetic variance. These findings conflict with popular notions of distinct and relatively homogeneous human races, and may also call into question the apparent usefulness of ethnic classification in, for example, medical diagnostics. Here, we present new data on 21 Alu insertions in 32 populations. We analyze these data along with three other large, globally dispersed data sets consisting of apparently neutral biallelic nuclear markers, as well as with a β-globin data set possibly subject to selection. We confirm the previous results for the autosomal data, and find a higher diversity among continents for Y-chromosome loci. We also extend the analyses to address two questions: (1) whether differences between continental groups, although small, are nevertheless large enough to confidently assign individuals to their continent on the basis of their genotypes; (2) whether the observed genotypes naturally cluster into continental or population groups when the sample source location is ignored. Using a range of statistical methods, we show that classification errors are at best around 30% for autosomal biallelic polymorphisms and 27% for the Y chromosome. Two data sets suggest the existence of three and four major groups of genotypes worldwide, respectively, and the two groupings are inconsistent. These results suggest that, at random biallelic loci, there is little evidence, if any, of a clear subdivision of humans into biologically defined groups.