evolution
The crouched stance developed to compensate for the growth of larger forelimbs that eventually made flight possible, according to new research that digitally "fleshed out" fossils to show physical changes over the eons as bipedal dinosaurs evolved into birds.
Via National Post
People have been getting rid of cockroaches for decades by setting out bait mixed with poison. But in the late 1980s, in an apartment test kitchen in Florida, something went very wrong. A killer product stopped working. Cockroach populations there kept rising. Mystified researchers tested and discarded theory after theory until they finally hit on the explanation: In a remarkably rapid display of evolution at work, many of the cockroaches had lost their sweet tooth, rejecting the corn syrup meant to attract them.
By Unknown
It gets especially good right around the time humans evolve into "fat" a la Wall.E.
Via Vox
You've probably learned about vestigial organs in Biology class by now. There are a lot of things that aren't important to humans any more but we've still held onto them in some way. If you've ever seen someone wiggle their ears, it's obvious.
This video shows some of those unnecessary parts and why we used to have them. It also goes into detail about the way that some humans have actually lost those extra pieces. 
That's evolution at work.
