The timeline of life is a vital part of cosmic education. It gives children a vision of how life has changed through time and an important perspective for appreciation of today’s life on Earth.

I have been frustrated with the many errors and misconceptions that are portrayed on the traditional Montessori timeline of life. Another material, not from the Montessori world, has come to my attention. It is from What on Earth? Books, https://www.whatonearthbooks.com/us/ . Author Christopher Lloyd and illustrator Andy Forshaw have done several “Big History” type timelines. These publications can give children a valuable framework of how life has developed and changed through time.

In order to show a variety of life and tie it into human civilization, the timeline uses different timescales across its length. This could lead children to a false picture of the time elapsed between the events depicted. You can help them understand the true duration of the various geologic time periods if you display the time periods to scale above the timeline in the What on Earth? Wallbook of Natural History: From the Dawn of Life to the Present Day. 

I did this for the 2.3 meter-long edition, published 2013. This book is 16.5 inches or 42 cm tall. I made a timeline that shows the true proportions of the geologic time periods. The second strip of paper beneath it shows the time periods as shown on the timeline. Here are the views from the formation of the Earth end and the present end. You can see that the Hadean Eon (black), Archean Eon (yellow), and Proterozoic Eon (pink) portions have vastly different shares on the two scales.

For example, the Hadean Eon is 31 cm long on the actual timescale, and 3.4 cm long on the timeline. The Cenozoic Era is 3.4 cm long on the actual scale, and the Holocene Epoch would be microscopic. On the What on Earth timeline, the Cenozoic Era is 46 cm, with 23.5 cm of that being devoted to the Holocene and Anthropocene. (If you would like the measurements for my two timelines, please email me.)

This timeline gives most of its length to the Phanerozoic Eon (Paleozoic, Mesozoic, and Cenozoic Eras), which is appropriate. The traditional Montessori timeline of life shows the events of the Phanerozoic Eon, even if it does not carry that label. When one looks at the What on Earth timeline from the end that shows the present, the Cenozoic Era has internal scale changes for emphasis on human events.

Nevertheless, I think the What on Earth timeline would be a good introduction to the changes in life through time. Having the life in the oceans shown separately from life on land helps children keep track of the two different environments. There are a few things you will need to correct/explain. The synapsid lineage is shown, but it is called “mammal-like reptiles,” an older term that paleontologists have dropped. Likewise, I would change the term “dicots” to “eudicots,” the term botanists use. Eudicots (true dicots) are the old dicots minus the magnoliids. At least the eudicots are there on the timeline, along with a good array of accurately portrayed prehistoric plants, a part that is often missing from timelines of life.

The What on Earth book or timeline is available in several sizes. There is a newer edition that is smaller and 6 feet long. You may need the magnifier, a flat, plastic Fresnel-type, that comes with the book, to read all the fine print. The timeline is available in a larger, 10-ft. edition as well. It is available on Amazon or on the What on Earth website. https://www.whatonearthbooks.com/us/shop/nature-timeline-posterbook-u-s-edition/ . It costs $40-50, and the smaller version costs $15-$20. At present, the nature (history of life) timeline is available in Japanese, Chinese, Korean, Taiwanese, American and Dutch. German, French, and Italian are in the works. The What on Earth Big History timeline is available in 15 languages, but the history of life takes up only about a third of it with human history displayed on the rest. See the What on Earth website of further information.

You may choose to make your own timeline. If so, my publication, Outline of Geologic Time and the History of Life, can help you. See https://big-picture-science.myshopify.com/collections/big-picture-science-digital-downloads/products/outline-of-geologic-time-and-the-history-of-life .

Happy explorations of life through time.