1. When a pregnant woman has a seizure or heart attack, the fetus will send stem cells to its mother to help restore the damaged cells.
2. Numerous times today you could have developed cancer. Sometimes when a cell is about to go cancerous, it will commit suicide to keep itself from harming other cells.
3. You can see better in low light environments with your peripheral vision
4. Your nose and ears will continue to grow throughout your life. This is why older people tend to have large noses and ears.Y
5. Your eyes do not grow at all. This is why babies appear to have large eyes.
6. When bones are stressed from physical activity, the stress pushes fluids in our bones. Cells called osteocytes can detect this movement of fluid and signal for bone regeneration. This allows our bones to grow stronger over time to adjust to the load we put on them (and vice versa if we reduce physical activity).This is why tennis players have stronger bones in their arm that holds the racquet, and why astronauts have weakened bones after long periods in space.
7. The first structure to develop in a human embryo is the anus. Therefore, we all start out as assholes - some of us just grow out of it.

Source : Can you tell me something extraordinary about the human body? [serious]

There are more over there. Mind the language, I just copied from there. Thought more people should appreciate who we are and what we have.