The gene pool. This is the series and combinations of genes in the environment. This can affect the human adaption of the environment and how they cope up with the species living with them. They interact with them in a way that the species can affect one another,
<em>The Jan. 21</em> total lunar eclipse will be the last one until May 2021, and the last one visible from the United States until 2022; the most recent total lunar eclipse previous to this one appeared in July 2018.
A gateway substance is something that may be menial but could lead to something bigger, an example is weed in the drugs world, weed is not hard to get and is usually a gateway drug to stronger types of drugs and potentially more dangerous