1.   A history professor uses a wealth of statistics in recounting the many ways in which humans have altered the earth.

2.   Ecologists say that humans have so altered the natural landscape that rules of migration that applied in the past may not apply as well in the future.

3.   Humans can alter their vocal tone by raising and lowering the larynx.

4.   In ways both subtle and obvious, humans are altering the terms on which these fluxes of nature take place.

5.   They inhabit a world heavily altered by humans.