The Kidneys.
The plasma passes through the kidney where it is filtered, a special filtration unit called "glomeruli" and then excreted as a low molecular weighted product into the urine. The purpose of our urine is to secrete waste products from the body. So you can see how the glomerular filtration mechanism of the kidneys plays a major role in the function of our bodies. The primary function of our kidneys is to filter out all the "bad stuff" in lamest terms.
-Current Medical Student (College Level)
The brain is most of the ape's main gimmicks, aside from the opposable thumb. It allows us to not die without claws, fangs, and other evolutionary benefits.
