You'll appreciate your thumb so much more after this.
We are primates, as are monkeys, apes, and those cute little lemurs in Madagascar. Primates are one of the newer orders of eutherian mammals. See if some of this sounds familiar. Primates have:
Early primates were tree-dwellers. Many primates still hang out in trees and spend a lot of time in them looking for food, sleeping and moving around. Many primate traits developed to support life in the trees.
Primates are divided into two groups, prosimians ("premonkeys") and anthropoids. ("Anthro" means human, so these are the ones more shaped like us. We did the naming after all). The prosimians are primates like lemurs, lorises, and tarsiers and generally still keep to the trees. They are found in parts of Africa and Asia.
Slow lorises are monkey-like, without all the monkeying around. Image from here.
Monkeys, apes and humans are anthropoids. Monkeys can be divided into New World and Old World monkeys. (Europeans did the naming when North America was fresher in their minds.)
Apes include gibbons, orangutans, gorillas, and chimpanzees. There are no non-human apes in North or South America, unless you are visiting a zoo. Monkeys and apes are related but are separate groups.
These ape traits hold for humans too, but we lose the hair, get completely out of the trees, stand up straight and our behavior gets even more complex, to say the least. Still, there is more overlap than we used to think between ape and human behavior, including tool use, cultural differences, and war.
For the record, humans did not descend from monkeys. We are a kind of ape, but we didn't descend from chimpanzees or gorillas either. We share a common ancestor. So, we are more like distant cousins. We're not a monkey's uncle and he isn't ours.
Two hominids, just hanging out together. Image from here.
After diverging from other apes around six million years ago, human ancestors began to walk upright. Stand on your own two feet. Other primates can't for long. The human skeleton is set up differently than that of other primates in order to be bipedal, or walk on two legs. Humans have a wide pelvis to support more weight. The spine enters into the skull more directly beneath the head. Human legs are larger and more specialized for walking while the front limbs are freed up to do other things.
Humans have the ability to interact with and alter their environment like no other creature. With our large brains and talented hands, humans make elaborate tools. Don't just think bow and arrow, think smartphone. We radically change our environments to suit our needs. Human brains work with symbols and language and sort through complex abstractions like mathematics and philosophy and who's going to win the Super Bowl. From religion to politics to YouTube, we take social behavior to a new level.
We are not the first hominids, or human-like primates. Scientists debate and restructure our family tree as we discover new fossils and find new ways to test them. In general, though, we are the single remaining branch of what was a complicated family tree with more than a few dead ends.
The "missing link" between humans and apes might just be all about winning the genetic lottery.