Modern humans & the "out of Africa" theory.
The ability to use imagery and language best defines us as "modern humans". Symbolism, art and self consciousness can be traced back to our ancestors 100 000 years ago. Due to modern human skull bones found in Southern Africa, archeologist point to Africa as the beginning of the developed modern human brain. These skulls found were slightly enlarged, with a different structure to homo erectus or homo ergaster, which had spread from Africa to other parts of the world around 2million years ago. Counter to the believe that 'civilization' began in Europe (40 000 years ago), these homo sapiens skulls together with some sophisticated tools found (from c.100 000 years ago), point to Africa as the time when the "light to consciousness switched on".
The time & place when our ancestors started to make images is likely to be when and where we became "fully human" i.e the last step in the evolutionary process.
DNA ancestory testing confirms that all living humans have a common maternal & partenal ancestor found in Africa around 150 000 years ago, which supports the 'out of Africa' theory. This theory suggests that modern humans spread to the rest of the world from Africa, replacing their homo erectus ancestors who spread some 2 million years before.
To learn more about the origins history, visit the www.orgins.org.za, you can also visit the Origins Museum at the University of the Witwatersrand.
You can also find some good resources online on the out of africa/single origin theory: