Question: How was the human body formed?

Beth Mortimer answered on 18 Jun 2012:

Humans (and other animals) develop the human body form inside a mother and give birth to live young. This is different from many other animals (e.g. using larvae like fly maggots, laying eggs with a shell, like birds, or in water like frogs etc). Most of the human body is therefore formed in the uterus.

In the very early stages of human formation you have a single cell which contains genetic information from mum and dad. This one cell has all the information needed to form the whole human body. This cell then starts to divide. When you start having a group of a few cells, the cells need to start deciding which is going to be the head end. The cells use small molecules as signals within the cell group to set up gradients, so a lot of one signal molecule may signify the head end, and none would give the ‘tail’ end. The signal molecules can change which genes are read, and so differ what form the cell turns into, whether skin or bone etc.

Therefore, in a very complicated process, a map is created by several gradients of these signal molecules, so the cells ‘know’ which kind of cells they are to become. The molecules then only read the genes needed to create that type of cell. Over 9 months, you get out a baby human!

(Or did you mean how was the human body formed to be different from apes and other animals?)