Are there any sub-species of human beings?

No. All extant humans are of the species Homo sapiens. The variation in modern human DNA is very small (about 0.1%) compared to other species, which suggests that all modern humans descend from a small group that lived about 100,000 years ago. No modern human group has been classified as a sub-species. However, H. neanderthalensis is sometimes classified as a sub species of H. sapiens (H. sapiens neanderthalensis).

Several species of humans existed in the past. H. erectus spread out of Africa and into Europe and Asia almost 2 million years ago, long before modern humans evolved from a common ancestor in Africa around 200,000 years ago. H. erectus eventually evolved into other species, such as H. antecessor, H. heidelbergensisand H. neanderthalensis. Modern humans who migrated out of Africa around 70,000 years ago coexisted with H. neanderthalensis and other sister species and my have shared habitat with them for long periods of time. These sister species were extinct by about 33,000 years ago.