“When it was introduced in the 1940s, penicillin was a miracle drug, especially effective at curing infections caused by the bacterium Staphylococcus aureus (‘staph’). In 1941, the drug could wipe out every strain of staph in the world. Now, seventy years later, more than 95% of staph strains are resistant to penicillin.”
— Dr. Jerry Coyne, ‘Why Evolution is True’
You might not know this, but we see evolution every day. It is all around us. There is nothing on this planet that is static and unchanging. Rather, as the seconds tick by, cells replicate, errors are produced, mutations appear, and change takes hold. It takes a lot of time to see the outcome of these slight modifications, but if you wait long enough, you will certainly see them. As the quote from Dr. Coyne shows, we see great changes in organisms that have short lifespans. But we also see it in humanity, or at least, we see the remnants of it.
That's right, you can see evidence for evolution when you look in the mirror.
Through history, as humanity slowly evolved into modern man, we lost many traits.Things that were once useful became unnecessary, and so they disappeared, decreased, or changed into something else. Though many of the useful functions and parts of the human body eventually become unnecessary, interestingly, quite a few of these parts are still here in one form or another. Thus,looking at them allows us (in some ways) to trace our evolution and see how and where we have changed.
For example, humans no longer need goosebumps. At one point, they helped to provide a layer of insulation, and they also allowed us to raise our hair when we felt fearful or threatened (kind of like how a dog's hair will stand up). However, we no longer have enough hair for goosebumps to be effective, and we can use our voices to note our feelings, so we've no real need to raise our hair anyways. Yet, despite the fact that goosebumps now serve no purpose, we still have the mechanism in our bodies in order to control them.
We also have the remnants of a third eyelid. It's that little, fleshy thing that you see in the corner of your eye by your nose. It's believed that it once helped flush out debris. Of course, with hands, we no longer need this protection. We also have a vomeronasal organ in our nose that detects pheromones. These pheromones are signals that can trigger sexual desire, alarm etc. It is often used by other mammals in order to locate an appropriate mate and to avoid dangers. Humans are born with this organ; however, during our earliest years, its abilities dwindle to the point that it is useless. And of course, nearly everyone is familiar with the appendix, which (it is believed) once helped us process our leafy diet, and now serves no real purpose.
See other links to our evolutionary past in this video: