Various Environmental Stimuli for Evolution:
How does intelligence arise?

Or Does it?

Psssive (Millions of years timescale):

Dispersal of Parental Units by a variety of mechanisms:

Passive: (slowly alters gene pool over time)

• Migratory Random Walks
• Continental Drift
• Mountain Building
• Climate Changes (Periodic Ice ages this one is on timescales of 100,000 years recently)

Active (catastrophe "overnight" change in ecosystem)

• Asteroid Impacts
• Large Floods (from Ice Ages)
• Volcanic eruption
• massive earthquake
• the rapid emergence of 6.5 billion humans

Survival of the fittest works in well-defined, slowly evolving ecosystems (like the ocean); On long time scales, the role of random catastrophe is more important

Mass Extinctions in Geological History
Startling evidence for many events

Pay attention to Percent of Species Extincted

Some Evidence for Periodic Extinction Events of varying amplitude

Mass extinctions mean:

• 1/2 to 2/3 of all species (plant and animal) eliminated
• plankton in the ocean is extincted
• both land and water are affected

The evolution of intelligence? The rate of increase of EL as measured by the fossil record.

What Can we Conclude from the above Graph:

• Increase in Relative EL exhibits a well defined pattern over the last 200 million years
• Fastest growth was from 600--250 million years ago when species first emerged on the land
• Mass extinctions clearly are important as they substantially alter the rate of growth
• Unaltered rate would have produced current human level of EL about 60 million years ago
• Continental rate is much higher than the oceanic rate
• Smooth extrapolation backwards from last few million years of continental data suggests it takes 20 billion years for intelligence to emerge

It seems likely than when terrestrial ecosystems developed, the flow of nutrients to the oceans became impaired which served to suppress that ecosystems growth rate over the rest of geologic time.