The Bible's lex talionis – "Eye for eye, tooth for tooth, hand for hand, foot for foot" (Exodus 21:24-27) – has captured the human imagination for millennia.

The human body has different parts that help us do things like walk ... Most of us have the same kind of body parts in the same places. You have a head and a neck. You have arms, elbows, hands ...

Some human body parts serve no purpose despite once having a specific function among our ancestors. The appendix, for example, is not an essential body part (though some research suggests it may ...

Scientists are exploring that futuristic vision by using special 3-D printers to make living body parts. Called bioprinters, these machines use human cells as “ink.” A standard 3-D printer ...