Part 1: Understanding How Populations Grow
Begin by opening the Human Populations Guided Data Exploration. The following questions will ask you to select values for the three variables; then, use the slider to examine how an initial population of 10,000 individuals changes over a 100-year period based on the conditions you specified.
Set up the following simulation: age of first childbirth = 15; mortality type = developing nations. The total fertility rate will be variable.
- How many children will the average woman have to have (or, what will the total fertility rate have to be) if the initial population is going to double (that is, be about 20,000) in 100 years?
- How many children will the average woman have to have (or, what will the total fertility rate have to be) if the initial population is going to quadruple (that is, be about 40,000) in 100 years?
- If you change the mortality type to “least developed nations” in this simulation (where age at first childbirth = 15, and total fertility rate = 3 or 4), how does the population after 100 years look different from the results you saw above? What happens when you change the mortality type to “highly developed nations”? Brainstorm a few reasons for these differences.
Part 2: Simulating Population Growth in Countries across the Globe
Examine the following two simulations:
Simulation A: Total fertility rate = 4; age of first childbirth = 15; mortality type = least developed nations.
Simulation B: Total fertility rate = 2; age of first childbirth = 25; mortality type = highly developed nations. - Which simulation (A or B) best represents population growth in a highly economically developed country like Japan?
- Which simulation (A or B) best represents the population in a country that is the least economically developed like Kenya?
- What types of programs, policies, or initiatives could be put in place in a “Simulation A” country that would make its population growth look more like a “Simulation B” country?
How the Climate and Biota Interact
Open the app EarthViewer on your iPad. On the bottom of your screen, touch “charts” and select “one chart”. Move the slider to between the Cambrian and Ordovician Periods.
- What was the average temperature at this time?
- What was the average percent oxygen?
- What was the average ppm of carbon dioxide?
- What is the average ppm of carbon dioxide today?
- The Cambrian and Ordovician Periods are notable for their diverse marine invertebrates, like trilobites (Fig. 1). Plants did not emerge on land until the Silurian Period. How do these facts explain the amount of carbon dioxide in the atmosphere during this time?
Greenhouse Gasses
Touch “in depth” and read “Greenhouse Effect”.
- Scrolling across time from the Cambrian to modern times, what is the relationship between temperature and carbon dioxide? Why does this relationship exist?
- Whisk your finger and thumb apart on the timeline to zoom in to the last 100 years. Move back in time slowly from today to the year 1912 watching the North Pole and then the South Pole. Which pole experienced the greater rise in temperature?
- Touch “one chart” and select CO2. By how much does CO2 increase from 1912 to 2012?
Measure a piece of adding machine tape 6 m long. Draw a vertical line near one end of the tape and label it “present”. In this exercise, 1mm = 1 million years. Use the table below to add major biological events to the timeline, working from the present back in time.
Shade the different Periods with colored pencil. Use the EarthViewer app for Period dates.
Event Age Distance measured from the line marked “The Present”
Present Today 0 mm
Homo sapiens 0.2 mya 0.2 mm
Genus Homo 2 mya 2 mm
Age of mammals begins 65 mya to present 65 mm
End of the age of dinosaurs 65 mya 65 mm
Flowering plants 125 mya 125 mm
Birds 165 mya 165 mm
Age of the dinosaurs begins 245 mya 245 mm
Mammal-like animals 275 mya 275 mm
Reptiles 350 mya 350 mm
Land plants 425 mya 425 mm
Amphibians 435 mya 435 mm
Fish 520 mya 520 mm
Shelled animals 600 mya 600 mm
Multicellular life 1500 mya 1500 mm (1.5 m)
Photosynthesis 3.5 bya 3500 mm (3.5 m)
Single-celled life 3.8 bya 3800 mm (3.8 m)
Formation of the Earth 4.5 bya 4.5 m
Discussion Questions
- How much longer have fish been on the Earth than birds?
- How long was it after dinosaurs disappeared before humans appeared?
- How does animal life on Earth compare with the age of the Earth?
- How long was it between the first reptile and the appearance of dinosaurs?
- How long was it between the first land plants and the first flowering plants?
- Why do you think the age of mammals began at the end of the age of dinosaurs?