How can one distinguish between the genus Homo versus Australopithecus?

[AlannaR]

When did the genus Homo first depart Africa? Which species made the move?

[Eternal]

Homo ergaster/erectus was the earliest hominin found outside of Africa, and was dated to 1.75mya, in the modern day Republic of Georgia, at appx. 40 Degrees North Latitude...

By then, "we" were nearly six feet tall. Australopithecus was about 3' tall, and had less than half of the brain capacity that we do today!

[bravozulu]

That is debatable if georgicus is actually the same species as ergaster. It certainly wasn't the first Homo. That would be a habilis or rudolfensis. Floresiensis is likely descended from early Homo and not eerectus. That would mean that most likely an unknown lineage existed or some erectus wasn't the first to leave Africa.

"Homo georgicus is a species of hominin that was suggested in 2002 to describe fossil skulls and jaws found in Dmanisi, Georgia in 1999 and 2001, which seem intermediate between Homo habilis and H. erectus."
http://en.wikipedia.org/wiki/Homo_georgicus

That would mean that erectus waan't the first hominid to leave Africa.

The changed the standards for what is included in the genus Homo when they named floresiensis. It used to be a brain over 600 CC. Hobbits are much smaller.