A simulation to assess the conditions required for high level heterosexual transmission of HIV in Africa. 
We used a previously described simple compartment model to simulate the conditions required for heterosexual (penile-vaginal) contact to be responsible for 80% or more of transmission of HIV in Africa.  In general, the configurations required substantially exceed reported survey and other data for the number of sexual partners, the transmission probabilities, and the distribution of HIV prevalence in population segments.  Though the model does not capture nuances of transmission dynamics, it does offer an approximation of the gap between empirical data and current hypotheses.