The Church taught it that way to make the case for original sin as they understood it.  The reality is that it came from three lines teaching and was an adaptation of the Sumeric story.  It was all the science they knew, because it was not separated from Theology and Philosophy.  The evidence places the first homo sapiens in the Kalahari Dessert, where the Bushmen until very recently did not seem to have knowledge of good and evil (see The Gods Must be Crazy).  Sadly, these people are now in the modern world, living in air conditioned apartments in Jo-Burg.  We are certain that people came out of Africa to the Middle East, not the other way around.  Africa has the highest genetic diversity in the planet, while outside of Africa there is less diversity and an unfortunate mix with the less than fully evolved Neanderthals.