article_snippet.sent: Chemists have found it is possible to create the three main molecular building blocks of life - DNA, proteins and lipids - from hydrogen cyanide, hydrogen sulphide and ultraviolet light.
article_snippet.sent: Over our lifetimes the proportions of these elements change as age and our pick up traces of other elements like heavy metals and gold.
article_snippet.sent: Dr Hanson said: 'Out of 98 naturally occurring elements, just over 30 are known to be essential to some form of life on Earth. '
article_snippet.sent: In ancient times scholars believed everything in the universe was made from just four elements - earth, water, fire and air. '
article_snippet.sent: Living things are made up of cells, cells are made up of molecules and molecules are made up of atoms. '
article_snippet.sent: Altogether, 97% of the mass all living matter is made of just four chemical elements.'