Male peacocks have large colorful tails that they spread in a fan shape to attract females during courtship. peahens (female peacocks) are more likely to mate with males that have larger and more colorful tails. as a result, few peacocks have tails with dull coloring. which concept is demonstrated by a decrease in dull coloring?

In an experiment examining the effects tai chi on arthritis pain, callahan (2010) selected a large sample of individuals with doctor-diagnosed arthritis. half of the participants immediately began a tai chi course and the other half (the control group) waited 8 weeks before beginning. at the end of 8 weeks, the individuals who had experienced tai chi had less arthritis pain that those who had not participated in the course.