"Scientists today announced the discovery of the oldest fossil skeleton of a human ancestor. The find reveals that our forebears underwent a previously unknown stage of evolution more than a million years before Lucy, the iconic early human ancestor specimen that walked the Earth 3.2 million years ago."

[link to news.nationalgeographic.com]


No one really know this answer, or at least do not release the information.

I personally believe we are not from this solar system but arrived millions of years ago bringing our domesticated animals with us. But how can we ever be sure if we do not run the world and have not lived that long to witness it?