John Lars Shoberg 
De-Evolution [EPUB ebook] 

The Human colonists must hunt for two children taken captive during a devastating storm by a member of what they thought was wildlife, but when they finally find the human children, they are being cared for by natives who had a thriving culture as little as 100 years ago, but who are now little more than cave dwellers. The humans have been here over a year, and now they start to realize that their memories are being effected, much like the memories of the natives. If they don’t figure out what is causing this de-evolution fast, they might be in the same situation as the natives.