Origins of Life. The Scientific View

1. Origins of Life. The Scientific View • Big Bang about 14.4 billion years ago. • Expansion of universe – earth forms around 4.5 billion years ago. • One theory – life originates from cells in dust from passing comets which interact with earth chemicals. • Another theory – simple molecules develop into simple cells. • These cells develop in the inhospitable environment of early earth to form more complex cells and groups of cells. • From then on further development – over billions of years – leads to increasingly more complex forms of life in sea, on land and in the air as creatures evolve to fit environments….natural selection! • This process leads more recently to the varied forms of life on earth we now have knowledge of. • Humans – “homo sapien sapien” develop around 600,00 years ago. • Single molecule to language, music, abstract thought – 3.5 billion years! Worth waiting for?

2. Theory of Evolution. Darwinism • All forms of life on earth have evolved and are evolving now. • Complex forms of life are developments of simpler forms. • All life forms share ancestors – ultimately single cells! All life is therefore related to all other forms of life • Life has evolved from non living material. • The process is slow but there has been lots of time. • Natural Selection means nature favours those most fitted to survive in their environment. • The characteristics that assist survival are passed on because the creatures with these characteristics are the ones who survive! • Giraffes, long legged rabbits are examples. • This is “Survival of the Fittest”

3. Evolution. The Evidence • Darwin’s experiences on HMS Beagle and on the Galapagos made him think of the theory but he gathered evidence all his life and since his death huge amounts of supportive evidence has been gathered. • Fossil evidence shows development from species to species. • “Missing links” have been found – halfway creatures between species. • From life on a single continent we see varieties of a species with different characteristics developed to suit particular environments – e.g. the finches and tortoises of the Galapagos. • Study of anatomy and physiology shows identity, variation in species • DNA evidence establishes identities and variations – ourselves and chimpanzees. • Huge scientific consensus that evolution is true.