When watching Episode 22 of The Natural the female Akatsuki (Akatsukiko) looks pretty good. Then take a look at the second half of the episode, see Akatsuki's mom, and notice they share a good number of features!
Earth ("Manhome") is discussed quite often in comparison with Aqua. It has been described as an orderly place, impossible to get lost in, with no clear sky, no real seasons (with a constant, stable temperature all year-round), and no real nature. Combine this with Akari's frequent comments ("I've only seen simulated fireworks" and "I've only seen shinto shrines in old movies") and this implies that most of Earth's human settlements were rebuilt in a more orderly fashion, based only on comfort and necessity. One wonders exactly what happened to Earth and its culture, then, for all the cities to need to have been rebuilt and for such massive centerpieces of local culture to only be found now as centuries-old relics on Mars.
The fact that the original Venice has since become a drowned city, the ocean and soil can no longer be played in, and the sky is no longer clear heavily implies that Earth, while still inhabitable to humans, has gone extremely downhill from a naturalist perspective. Perhaps old cities were no longer inhabitable, and had to be abandoned in favor of newer cities that could handle the changes Earth was going through.