Vestigial Organs

One of the difficulties with studying evolution is that nobody was around to see it happen from start to finish. The best we can do is look at what we can see and try to use that evidence to draw conclusions about the history of life on Earth. Fortunately, the natural world is full of physical clues that show us not only how evolution occurred (and continues to occur), but also how species of organisms alive today are "related" to each other in an evolutionary sense.

Today in biology class we will be discussing some of these clues, including the presence of vestigial organs. These are structures that modern species possess but really don't serve much of a purpose. (The human appendix and tailbone are classic examples.) But while these structures might not be useful to the organisms that possess them, they can help us to draw evolutionary relationships.*
*The appendix is what's left of our cecum, which is an organ that many mammals use to digest the tough fibers in grass and other plants...the tailbone also supports the idea that humans are descended from an ancestor common to all mammals.

Here's a link to an interesting website that details some of the vestigial organs found in different species. (Hat tip to Mrs. Gingrich for sharing this link.)