We know the city where HIV first emerged
Simian AIDS was discovered after human AIDS. How do they know the jump didn't occur in reverse?Here is the first report of simian AIDS:
"Examination of the species-specific annual mortality rates of macaques at the center during the previous 4 yr showed a significant increase in deaths in 1980 and 1981"
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC393899/Also, it is convenient they do not share the mcmc traces. Based on these settings I bet they were ugly:>"For each data set, at least 3 MCMC chains of 250 million steps were computed. Parameters and trees were sampled every 50,000th step. Samples were combined with LogCombiner (77) and between 10 to 30% of each MCMC chain was discarded as burn-in. MCMC mixing was diagnosed using visual trace inspection and calculation of effective sample sizes in Tracer (77). We report the posterior mean and 95% Bayesian credible intervals for evolutionary parameters."http://dx.doi.org/10.1126/science.1256739Another thing, they write:"Our estimated location of pandemic origin explains the observation that Kinshasa exhibits more contemporary HIV-1 genetic diversity than anywhere else"This is totally circular. As shown in their figure S2, they used genetic diversity in a region as an indication of earlier presence.