After conducting genetic analysis of a newly found fossil of an early modern homo sapien, you find that several nucleotide sequences are the same as those documented in neanderthals. you know that this:

We know that is evidence that supports assimilation and multiregional evolution models for modern human evolution. This multiregional evolution is an hypothesis based on a scientific model that is in itself an alternative explanation o human evolution. Part of this claims that the neandertals can be accepted as homo sapiens which is widely debated by many of the scientist. 

Iwould say overuse ( but not 100% sure ) in the u.s. we tend to overuse water by leaving it running, throwing it away, taking long showers, etc.