Some 99.9% of all species that have ever lived on earth are now extinct. Extinction! explores why, then confronts a frightening notion: Are humans causing the next mass extinction - the sixth in the history of life on earth? Make sure to check all the other resources at http://www.pbs.org/wgbh/evolution/

Some 99.9% of all species that have ever lived on earth are now extinct. Extinction! explores why, then confronts a frightening notion: Are humans causing the next mass extinction - the sixth in the history of life on earth? Make sure to check all the other resources at http://www.pbs.org/wgbh/evolution/

Some 99.9% of all species that have ever lived on earth are now extinct. Extinction! explores why, then confronts a frightening notion: Are humans causing the next mass extinction - the sixth in the history of life on earth? Make sure to check all the other resources at http://www.pbs.org/wgbh/evolution/

Some 99.9% of all species that have ever lived on earth are now extinct. Extinction! explores why, then confronts a frightening notion: Are humans causing the next mass extinction - the sixth in the history of life on earth? Make sure to check all the other resources at http://www.pbs.org/wgbh/evolution/

Some 99.9% of all species that have ever lived on earth are now extinct. Extinction! explores why, then confronts a frightening notion: Are humans causing the next mass extinction - the sixth in the history of life on earth? Make sure to check all the other resources at http://www.pbs.org/wgbh/evolution/