Current research has established that human beings are genetically rather homogenous (similar). The DNA of individuals is more alike than usual for most species. This may have resulted from their relatively recent evolution or from the Toba catastrophe. Distinctive genetic have arisen as a result of small groups of people moving into new environmental circumstances. These adapted traits are a very small component of the "Homo sapiens" genome and include such outward 'racial' characteristics as skin color and nose shape, and internal characteristics such as the ability to breathe more efficiently at high altitudes.