Wrap Up

Review of the main topics and ideas you encountered in Unit 11.

Easy Come, Easy Go--Evolution and Extinction

• Kids include experiments--are not identical to parents
• Differences affect ability to survive to have kids (natural selection)
• Kids are similar to parents--kids receive a bit more or less of what makes parents biologically successful
• This over time gives evolution--successful experiments accumulate, unsuccessful ones eliminated, changing living things over time
• Changes to living organisms are not passed on (kids of pierced-ear parents don’t have pierced ears!)--just reproductive experiments are passed on

The Unbroken Chain

• Law of Faunal Succession suggests evolution
• Evolution predicts transitional forms over time, special creation or catastrophism don’t
• Transitions found, strongly supporting evolution:
  • Transitions common in commonly fossilized types
  • And less common in less-commonly-fossilized types
  • New species often emerge geologically rapidly from small populations (changing smaller group easier)
  • Transitions found as often as evolution predicts; fossil record incompatible with competing hypotheses.

Taking Care of Business

• Theory of evolution is explanatory, predictive, and useful
• Germs are evolving antibiotic resistance, and the scientists trying to keep us alive are using knowledge of evolution
• Computer scientists mimic evolution to solve complex problems (evolutionary computing).

Teach the Conflict?

• Scientifically, there is no conflict--much to learn and do, but no serious problems or competitors
• In particular, evolution is:
  • Consistent with second law of thermodynamics
  • Supported by fossil record and age dating
  • Not anti-religion (supported by many religious groups)
• Widespread scientific consensus that so-called competitors (e.g., “intelligent design”) are not science
• “Teaching the conflict” means not teaching science (note that to question evolution, Kansas School Board invented a new definition of science…)

Extinction Can Ruin Your Whole Day

• Slow background of extinction (population fluctuations sometimes hit zero, which is extinct)
• Occasional mass extinctions:
  • end-Paleozoic: heat-caused loss of ocean oxygen?
  • end-Mesozoic: meteorite
• Dinosaurs doing just fine until meteorite got them
• Freed ecological jobs (“niches”), allowing evolution to produce large mammals over last 65 million years.

The Dinosaur Killer

• Evidence: extinction at odd bed with much iridium (common in meteorites), soot, high-pressure shocked quartz, melted-rock droplets, Caribbean giant-wave deposit; right-age giant crater Yucatan Peninsula
• Mechanisms: meteorite blasted things up, fire from heat of fast-falling things, then cold from sun-block of slow-falling things, with acid rain
• Still big rocks out there--averaged over millions of years, perhaps as dangerous as commercial airline crashes, but not nearly so dangerous as car crashes.