a person from your family that lived in the past the variation in an environment, the number of different types of life found there a scientist who studies living things one of the very large areas of land on Earth that are usually divided into several countries to treat someone without respect; to reduce in amount or strength sensible; based on facts not deep; a small distance between the lowest and highest point to make something stable or consistent, with no major changes an agreement between nations happening or existing in many places; affecting many people