Astrobiologists, Wood & Brownlee postulate that the following 18 factors
prohibit or hinder bacteria from evolving into complex life, but first, the
Timeline of Evolution:
4.5 Billion Years Ago: Earth formed
4 BYA: "Life" (bacteria/archaea)
1 BYA: Multicelluar algae and seaweed i.e., "complex life" took 3.5 billion years!
600 Million YA: Sponges/Worms
475 MYA Plants/Fungi
450-365 MYA Non-flying insects, arthropods and fish
300 MYA: Reptiles on land
250 MYA: Mass extinction wipes out 95% of animal species
220 MYA: First mammals
200 MYA: Birds
65 MYA: 50% of animal species die from meteor cooling planet
1800 Thousand YA: Homo erectus
130 TYA: Neanderthals (Homo Neanderthenis)
100 TYA: Homo sapiens "intelligent life"
30 TYA: Man migrates to North America
27 TYA: Neanderthals extinct
4 TYA: Humans record history
|Rare Earth Factors:
Why Complex Life is Uncommon in the Universe
Right distance from star
Habitat for complex life.
Liquid water near surface.
Far enough to avoid tidal lock.
Right planetary mass
Retain atmosphere and ocean.
Enough heat for plate tectonics.
Build up land mass.
Enjance biotic diversity.
Enable magnetic field.
The right tilt
Seasons not too severe.
Maintenance of adequate temprature,
composition and pressure for plants
Right kind of galaxy
Enough heavy elements.
Not small, elliptical, or irregular.
Right mass of star (sun)
Long enough lifetime.
Not too much ultraviolet.
Clear out comets and asteroids.
Not too close, not too far.
Not too much.
Not too little.
Few giant impacts.
No global sterilizing impacts after an
Successful evolutionary pathway to
complex plants and animals.
Right position in galaxy
Not in center, edge or halo.
Stable planetary orbits
Giant planets do not create chaos.
Small neighbor as possible life source
to seed earth-like planet, if needed.
Right amount of carbon
Enough for life.
Not enough for Runaway greenhouse.
Evolution of oxygen
Invention of photosynthesis. Not too
much or too little. Evolves at the right
Snowball Earth. Cambrian explosion.
Inertial interchange event.
|Another proof: Aliens don't exist
By Dennis Overbye, New York Times, 11/11/03
|The Radiation Factor
New York Times, 12/09/03