RDP451 was used to analyse the set of 12 ancient sequences plus a representative set of 15 modern human and non-human primate sequences (see Methods). The seven recombination programs used by RDP4 suggested that all genotype A sequences are recombinants, with the genotype D sequence HBV-DA51 as the minor parent and an unknown major parent. The obvious interpretation is that recombination formed an ancestor of the oldest sequences, evidence of which is still present in the less-ancient and the modern representatives. The figure shows the graphical evidence and predicted recombination break-point distribution for the two oldest genotype A sequences, HBV-RISE386 and HBV-RISE387, according to three of the RDP4 methods (MaxChi, Bootscan and RDP). In all subplots, the predicted location of the break points is shown as a dashed vertical line and the surrounding grey area shows the 99% confidence interval for the break point. Subplots on the same row share their y axis and those in the same column share their x axis. a, HBV-RISE386 analysed by MaxChi. b, HBV-RISE386 analysed by Bootscan. c, HBV-RISE386 analysed by RDP. d, HBV-RISE387 analysed by MaxChi. e, HBV-RISE387 analysed by Bootscan. f, HBV-RISE387 analysed by RDP.