DO THIS:

In class exercise:

In 25 words or less, write down your definition of what constitutes intelligence.

Put your definition on the table in the front of the room.

Climatic Change

Food/crop/plant production is very sensitive to climate; many zones exist

Climate results from the uneven distribution of heating over the surface of the earth caused by the earth's tilt. This tilt is the angle between the earth's rotational axis and its orbital plane around the sun. Currently this angle is 23.5 degrees.

Long term climate is also affected by the heat balance of the earth which is driven mostly by the concentration of CO₂ in the atmosphere.

Climate change can result if the pattern or solar radiation is changed and/or if the amount of CO₂ changes. There is abundant evidence that the earth does undergo climatic change. Climatic change can be a limiting factor for the evolution of many species.

Climate Change:

• Periodic Ice Ages - Glacial-Interglacial Periods
  • Major Period: - 100,000 years; 9 degree F decrease
  • Minor Period: - 12,000 years; 5 degree F decrease
  • Smaller Periods??: - 1,000 years; 3 degree F decrease

  We currently are nearing the end of a small, minor interglacial period

• Major Ice Ages: Most of the Planet is Covered
• Minor Ice Ages: 40^o Latitude and Above. The most recent one of these occurred about 15,000 years ago and the coverage of the ice sheet is shown here
• Little Ice Age: (1000-1850 AD; Irish Potato Famine; Nisqually Glacier)

Effects of Ice Ages

• Changes sea level by 100 meters exposes continental shelfs
• changes continental shelf composition due to increased deposition during melt
• changes hydrological cycle through less evaporation
• changes landscape Great Lakes; Seattle; Stoss and Lee
• Changes drainage patterns
• changes topsoil characteristics
• massive flooding episodes Eastern Washington

Causes of Ice Ages needs to be PERIODIC!

• Solar Cycle no evidence
• Volcanic Dust in Atmosphere why periodic?
• CO₂ Cycle why periodic? factor 2 reduction causes 7 F drop Record of CO₂ and temperature variations
• Increased precipitation at poles due to changing orientation of continental land masses
• Changes in mean temperatures of ocean currents what mechanism?

The most Probable Cause:

• Orbital Variations of the Earth!

• Eccentricity variation 90,000 years 5 variation around mean value. This is due to Jupiter.
• Change of tilt of axis 24,000 years

More About Ice Ages

Let's Melt the Polar Caps

Is there Intelligent Life on the Earth

Evolution of Intelligence:

• We know little about this
• We do know that the brain size of mammals has slowly increased over geologic time
• Brain size is proportional to body weight Life:

Define Relative Intelligence:

• Amount of brain tissue in excess of that required for basic body function
• This is known as Encephalization level (EL)

  

• P = body mass; EL is basically measured by K
• K can be recovered from the fossil record to some extent

What is Intelligence?:

• Biological Intelligence: environmental conditions determine the rate of growth of intelligence
• Artificial Intelligence: number of neurons basically correlates with learning ability

EL Scale

The point of this scale is one of RELATIVE intelligence there is nothing absolute about it.

Causes of Mass Extinction (Dinosaurs/Plankton)

Clearly are the result in reducing the amount of sunlight that reaches the surface.

Possible Mechanisms of Extinction

What do we know about the last extinction event 65 million years ago?

• We know there was an impact event
• The impact site was the Yucatan Penisula
• We know the dinosaurs became extinct at this time
• We know that much of the plankton became extinct

But we don't know the causal connection between the impact and the extinction cycle but clearly something basically put a halt to photosynthesis for some period of time.

Possibilities for blocking out the sunlight:

• Sulfur Clouds that Persisted? this is a recent theory, perhaps somewhat farfetched. There might also be a component of acid rain from this event that could have harmed much of the plant life that large plant-eaters fed on.

• Dust ejecta from the impact problem is that the residence time of dust in the atmosphere is fairly short

• Soot from global forest fire induced by the impact this is more promising as soot is very fine particulate matter that will find its way to the strasophere where the residence time is long

When will the next mass extinction event happen? (one of course could argue that its happening now)

Sometime in the next few 10's of millions of years the earth is likely to be hit again but an object 10--100 kilometers in diameter.

Learn More about NEAR EARTH OBJECTS

Is there Intelligent Life on the Earth

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.

Factors that might contribute to rate of growth of intelligence:

• Temperature: Many species function/learn best in a constant temperature environment. Large temperature variations are then not conducive to learning (this applies mostly to reptiles)
• Time - clearly EL evolves slowly upwards with time. Doubling time appears to be about 2 million years
• Biogenic Environmental Diversity the more diverse the ecosystem the more competition for scarce resources (food) there is could be strong environmental stimulus for growth of intelligence. Suppression of diversity by environmental disaster, climate change, or nutrient depletion would then reduce this growth
• Trophic Level is important where you are in the food chain does this favor growth in predator or prey?
• Adaptation: Species defense mechanisms are a signature of of evolution of intelligence. For instance, Coral defends itself statically but glue-secreting frogs have ingenious method for fending up predators.
• Metabolism: large metabolism of mammals demands larger brain and hence establishes initial capacity for evolution of intelligence in mammals

But clearly the role of mass extinction is paramount and allows the survivors to fill the newly opened ecological niches

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