VOA慢速英语:研究：穴居人是艺术家

artifact - n. a simple object (such as a tool or weapon) that was made by people in the past

drawing - n. a picture, image, etc., that is made by making lines on a surface with a pencil, pen, marker, chalk, etc., but usually not with paint

evolution - n. a theory that the differences between modern plants and animals are because of changes that happened by a natural process over a very long time

ladder - n. a device used for climbing that has two long pieces of wood, metal, or rope with a series of steps or rungs between them

species - n. a group of animals or plants that are similar and can produce young animals or plants