THE ORIGINS OF LIFE Other ideas

Panspermia (aka cosmozoan) Life came from somewhere else and seeded Earth The support for this depends up on evidence that life exists elsewhere than on Earth and the evidence that it may travel through open space © 2008 Paul Billiet ODWSODWS

Exobiology Mars Viking Probe (1976) revealed conflicting evidence of life Mariner Probe (1997) did not reveal any more evidence Tantalising evidence of water on Mars Venus has inhospitable conditions (surface temperatures of over +400°C) Viking © 2008 Paul Billiet ODWSODWS

Water and geothermal energy is the key The moons of Jupiter and Saturn could provide the right conditions Europa appears to be covered in ice Io shows volcanic activity Titan has organic molecules present Europa © 2008 Paul Billiet ODWSODWS

Life can survive in outer space Bacteria, inadvertently left on a lunar probe Collected and cultured successfully after nearly 2 years in space Meteorites of Martian origin show that its early atmosphere would have been similar to Earth’s early atmosphere They also showed (debatable) evidence of bacteria transported by meteorites Surveyor 3 © 2008 Paul Billiet ODWSODWS

Alien Earth Life has been shown to exist on Earth in very inhospitable conditions that could exist on other planets Antarctic dry valleys Mid-ocean ridges earth science australia Antarctica © 2008 Paul Billiet ODWSODWS

Earliest evidence of life The origin of the Earth itself is estimated as 4.5 billion years Earliest evidence of life processes 3.9 billion years ago This leaves little time for biochemical evolution © 2008 Paul Billiet ODWSODWS

The eternal question If it can be shown that life came from an extraterrestrial source the question still remains… How did life evolve in the first place? © 2008 Paul Billiet ODWSODWS

Special creation The non-scientific hypothesis Some supernatural being brought life into existence from nothing Literal interpretation of religious documents 9:00am on 23rd October 4004BC © 2008 Paul Billiet ODWSODWS

Intelligent Design Creationists have tried to imply that life is so complex and specialised that it could only have come about through the design of a supernatural creator Once created it remained the same through time They accept microevolution They reject the fact that new species can come about by the natural selection of chance mutations © 2008 Paul Billiet ODWSODWS

Special creation is based on belief As these ideas are developed from a theological view point they are impossible to test Creationists focus on trying to disprove the theory of evolution rather than by testing their own hypothesis A scientific fact is an observation that has been repeatedly confirmed and for practical purposes is accepted as true Special creation fails this criterion © 2008 Paul Billiet ODWSODWS