Humans have both direct and indirect impacts on biological diversity. Where humans live, they must exploit the natural resources to survive. As the level of human population has grown and their consumption patterns increased, simple exploitation has led to over exploitation. Over exploitation of resources has led to many species extinctions.
Extinction is the primary vehicle through which biological diversity is lost.
Extinction is a process that occurs naturally, but usually at a very low rate, perhaps one species lost every 100-1,000 years. We are currently experiencing a geometric growth in the rate of extinctions. In the 1980s and 1990s it has been estimated that we are losing one species every six months to a year, or 100 to 1,000 times the background rate of extinction. Humans have caused may extinctions directly through over exploitation, but more have been caused indirectly through habitat destruction and alteration, exotic species introduction and what is called the cascade effect. Habitat alteration and loss are the biggest culprits.