A

The beginnings of life provide scientists with some of the most difficult questions of modern science. Our knowledge of the development of cells， from which all forms of life are made， is not complete because we do not understand very well the conditions on our planet four billion years ago. Why and how did cells first appear？ Was this very likely to happen under the conditions then， or was it due to chance？ Might this happen in other places in the universe？

B

A group of scientists at University College London are trying to answer these questions. They started by studying the ways in which the first cells on Earth might have been formed. Next they will use a powerful new telescope to look at places far away in the universe. The scientists hope that the results will improve our understanding of the development of life on Earth and help us to find life on other planets.

C

Dr Nick Lane， who is in charge of the University College London team， has suggested that 4 billion years ago warm water springs on the floor of the Earth’s ocean might have helped to create life. Each spring consists of tiny connected holes that water passes through. The team have created models of these springs in their lab. They have found that they encourage chemical reactions between hydrogen in the liquids that come out of them and the carbon dioxide in the sea water. These chemical reactions can create the ‘building blocks’ of life. These building blocks are not living themselves， but when there are enough of them joined together in the right way， they can make living things. The water in the system of springs moves the building blocks around until there are a lot of them in a small area. Things that look very much like real living cells can be made in this way.

D

These reactions and changes show us how life on Earth and on other planets could begin. When sea water goes through tiny holes in the Earth’s surface， it gets very hot and causes a chemical reaction with rocks. When this very hot water goes back up and