extinction [ik-stingk-shuhn] n.  process of complete disappearance of a species from Earth (National Geographic Education).

Throughout history, species have come and gone.  Remember the dinosaurs?  Well, maybe not, seeing as they were gone from this planet over 50 million years before humans (or a hominid ancestor) set foot on it.  

The process of extinction is complex, and involves various factors.  In ecology and biology, extinction is considered the end of an organism, namely, a species.  It occurs when the last member of that species dies off, and the reproductive cycle can no longer continue. Throughout history, various extinctions have taken place, primarily caused by natural, planetary occurrences.  But in recent history, humans have had an ever-increasing presence on planet Earth, one that has lead hundreds of species to the brink of, and ultimately on to, extinction.

The latest notable extinction occurred on Monday, as the giant tortoise “Lonesome George” of the Pinta Island subspecies of Galapagos tortoise passed away at the Charles Darwin Research Station on Santa Cruz Island, Galapagos, Ecuador, where he was residing.  George is estimated to have been around 100 years old, although scientists are not sure of his exact age.