Evolution - how far have we come?

Scientists say the sheer diversity of life is richer now than at any other period in Earth’s history: there are probably between five and thirty million species alive today. We have named two million but some species may have been described more than once so the actual number is lower. We don’t know the total number of species that have ever lived, but estimates range from two to five billion.

There have been at least five mass extinctions in the past. Some of these extinctions wiped out as much as 95% of all species. Researchers now say we are in the midst of another mass extinction. Unlike other mass extinctions, which were caused by asteroids, volcanic eruptions or climate change, many scientists think today’s mass extinction is caused by one particular species − humans − you and me.