One of the major components of the theory of evolution is that most changes happen slowly and that (thankfully) the earth has been around for a long time.

Yet fully appreciating geological time is tricky.

First, lots of crazy names for the periods and eras can make studying this a pain.

Second, our comprehension of our lifespan and even that of human history distorts our mental understanding of the major changes in the history of life on earth.

The toilet paper roll of evolution is meant to help students fully comprehend the immense periods of time that the earth has been present.

Gradualism

How do you conceptualize big numbers?

Lebron James is the 2nd most highly paid athlete in the U.S.

He makes $72.3 million a year (with endorsements).

How many years would he have to work to pay off the US national debt ($17.6 trillion)?

Don't calculate it – just give me a number really quickly.

Now calculate it.

Problem with Evolutionary Time

• Most textbooks shows evolutionary time at a bunch of different scales using breaks in the timeline. This can be misleading.

Coyne's depiction of the history of major evolutionary events. This is from Chapter 2.

Figure 2-31

Let's Watch the TED Talk on Big HIstory

TED Talks: Big History

http://www.ted.com/talks/david_christian_big_history.html

Toilet Paper Roll of Evolution

• This can be used in earth science or biology. The task at hand is to roll out an entire roll of toilet paper with the first square as the beginning of the earth and the last as modern times. Then figure out which square the major evolutionary events occurred.

Some Major Evolutionary EventsProkaryotes began about 3.8 billion years ago (or 0.7 * 10^9 years from time 0).

Eukaryotes arose around 2.7 billion years ago.

Oxygen becomes abundant 2.5 billion years ago.

Jelly fishes, segmented worms, carol anemones, trilobties, etc. (Cambrian Explosion) around 600 million ears ago.

Jawed fish appeared about 500 million years ago.

Tetrapods and terrestrial plants appeared about 400 million years ago.

Spiders appeared 400 million years ago.

Ferns appeared around 350 million years ago.

Amphibians around 350 million years ago.

Reptiles around 300 million years ago.

Mammals appear around 250 million years ago.

Birds appear around 200 million years ago.

Humans appear around 7 million years ago.

Feel free to look up some other stuff online. Mass extinction events?

Plot your events on your roll of toilet paper.

Age of the earth is 4.5 billion ears (4.5X10^9).Count the number of squares and figure out how many years a square corresponds to.

Steps1. Count out the number of toilet paper roll pages.

2. Figure out how many years correspond to each page assuming the year is 4.5 billion years old.

3. Make one end of the toilet paper respond to the start of earth; Make the other end of the toilet paper respond to today.

4. Take the major events in evolutionary history and figure out where to put them.

5. There are two ways to do this. a. Method #1.

i. Figure out how many millions/billions of years ago something happened.

ii. Translate that into toilet paper roll units.iii. Subtract that from 'today'.

b. Method #2.i. Figure out how long it was before the event happened. (Today is

4.5 billion years since the start of the earth.ii. Translate that into toilet paper roll units.iii. Add that number on to the 'beginning'.

Possibilities for Elementary