Early in pregnancy, something surprising happens. Every human embryo develops a tail. It is not symbolic or imagined. A real extension forms at the base of the spine, complete with vertebrae. Later, ...

Only two weeks after fertilization, the first sign of the formation of the three axes of the human body (head/tail, ventral/dorsal, and right/left) begins to appear. At this stage, known as ...

Scientists are exploring ways to mimic the origins of human life without two fundamental components: sperm and egg. They are coaxing clusters of stem cells – programmable cells that can transform into ...

The formation of a human embryo is the point at which a human being begins to exist as a unique individual. There are complicating events, such as twinning, when an embryo splits into two — or ...