I believe that what is meant with the phrase "older explanation" is none other that superstition. Therefore, I will give you one superstitious belief which is now explained by science.
In Southeast Asia, people used to believe that St. Elmo's fire appears in remote areas because a bloody battle occured in that place leaving disembodied souls of the dead wandering there in the night and even in sunshine!
For generations, many people believed that this is a fact and some even say that these apparitions are diabolical or demonic in nature. So often, caution is advised to people whenever a ball of fire appears out in the open.
However, recent breakthroughs in the 21st century helped scientists to explain this mysterious phenomena. They found out that St. Elmo's fire is actually plasma, nothing special. Now, plasma is considered one of the states of matter! But mind you, it still does not explain why St. Elmo's fire seems to have a mind of its own!
The genetic variations that are best suited for their enviornment
Explanation:
Those that are not well suited for their environment will die off, leaving only the ones that are suited for it. This species will slowly take hold until the species has adapted and become a completely different one.
