Peter - I would expect your bird aji (C. baccatum) was not brought over by birds from South America. If that was something that happens, it would already have happened centuries ago, and you would by now have evolved endemic African species of Capsicum. Also, it seems a little unlikely that someone brought over a tiny bird aji pepper from Bolivia to Africa, and started them growing there (not impossible!). Most likely is that your plant is a descendent of the domestic ajis grown there (e.g., see the Kenyan aji page 50 "Peppers of the World"), that has since been selected by chile-headed African birds for smaller, upright fruits. Not so unlikely, since there is also the Zimbabwe bird pepper, and apparently others, that are bird-dispersed over there. It would take quite a few generations, I would expect, to select out a tiny bird pepper from a pendulous aji. Imagine a big field of domestic ajis, the birds picking up a few of the smallest ones, replanting them in nearby areas, and repeating the process..... Of course, I'm just hypothesizing......