Speciation is usually the result of some kind of severe population stress such as isolation from the main population. read more
It’s all pretty random. Also, it is totally possible or even probable that Homo sapiens sapiens will evolve even more slowly because of all the socio-cultural artificial means that we as a species have created to avoid being fully subject to the whims of nature. read more
From there Homo sapiens spread out across the globe. By 10,000 years ago modern humans had successfully colonized each of the continents save Antarctica, and adaptations to these many locales (among other evolutionary forces) led to what we loosely call races. read more