Humans and Apes
We actually came from fish. This is (as was my first post) sourced from a book called "The Magic of Reality". Here is the thought experiment. Imagine a photo of yourself. Now imagine a photo of your dad (or mom). And now imagine your grandfather (or grandmother). Continue this thought experiment all the way through your great-grandfather, then your great-great, and so on down the line. Indeed, do this for 185 million generations. It is hard to imagine. The book puts this into perspective. If each picture was a normal postcard, it would tower 220,000 feet high (or if you tipped it on its side, about 40 miles long).
So if you go back to the first postcard photo, 185 million generations ago, it looks like a fish. And if you were take stroll along your 40 miles of postcards, each photo you pull out would look very similar to the photos directly in front of it or behind it. The changes across those 40 miles of postcards are very, very gradual.
The book uses another example to bring to light these gradual changes. When did you stop being a baby? Or when did you become a child or middle-aged? The changes from baby to adult, or even from adult to old person are so gradual we can't really pin down when the change happened, but we don't dispute that at some point in our life, we looked radically different than we do now. But a picture of me yesterday looks about the same as a picture of me will look if I take it tomorrow or even next week.
The book goes on to say that because we're talking about 185 million generations, even going back 10,000 years to about your 400-greats-grandfather, you wouldn't notice any real difference. He would look human. I believe the anatomically similar human didn't appear on Earth until about 200,000 years ago, but again, we can't really say exactly when it happened because it was a gradual change.
If you go back 4,000 greats, you might see a slight change, and if you go back 50,000 greats, you would see enough of a change that we would call it a different species - Homo erectus.
Now whether or not you want to say God, aliens, or Joe Pesci did this doesn't really matter. However, there is pretty strong evidence to suggest that all living creatures on Earth are related to one another - DNA. The same mechanism that makes humans humans and birds birds and snakes snakes is DNA. Our DNA is different, but the fact that a single underlying mechanism is at work suggests that all living creatures on Earth are related. The degree of relation is what is different.
So did we evolve from monkeys? Well no, not the monkeys you see at the zoo. Those monkeys are on Earth today so we could not have evolved from them because they've had exactly the same amount of time to evolve as us. We do however share a common ancestor with them somewhere along our 40 miles of postcards. And that ancestor might look something like a monkey.