Somewhere this past week (I've lost the link), I saw a comment by ?Bill Nye. When asked why some people fail to believe in the concept of evolution, he said the fundamental thing they failed to grasp was the concept of "deep time" (geologic time scales).
Changes of adaptations that appear impossibly complicated (or illogically perfect) become understandable if/when one considers that the change has happened over the course of, say, 200 million years.
I encountered an example of the importance of "deep time" while reading an article in Smithsonian magazine yesterday:
The rock beneath me, which looks almost white in the glare of the sun, is full of fossils. Zillions of them. Back when these life-forms were alive—265 million years ago or so—the Guadalupe Mountains were underwater, part of a flourishing reef that once stretched about 400 miles around the edge of a long-vanished sea.Reefs are a fascinating fusion of biology and geology. They are, after all, made of stone—but built by life. Moreover, although the individual life-forms involved are typically tiny, the results of their activities can be gigantic, resulting in a massive transformation of the landscape. As usual, Charles Darwin put it better than anyone. Writing about corals, he said: “We feel surprise when travellers tell us of the vast dimensions of the Pyramids and other great ruins, but how utterly insignificant are the greatest of these, when compared to these mountains of stone accumulated by the agency of various minute and tender animals!”
Mountains built by life. Literally. To give a couple of examples, the volume of coral built up on the Enewetak Atoll in the Marshall Islands is around 250 cubic miles. This is equivalent to building the Great Pyramid of Giza more than 416,000 times. And that’s just one atoll: The Earth has scores. The Great Barrier Reef, which runs for more than 1,800 miles along the northeastern coast of Australia, comprises about 3,000 reefs and 900 islands. It is the largest structure built by living beings in the modern world.Lots more at the link.
A few years ago, I realized I had no sense of deep time. Did homo sapiens leave Africa 6,000 years ago, 60,000 years ago, 600,000 years ago? I had no idea. When did humans and chimpanzees diverge in the family tree of life? No idea.
ReplyDeleteI now have a reasonable map of deep time in my head, going back a couple hundred million years. If I learn something new, I can place it on that map and get a better understanding of, well, everything! This gives me a lot of pleasure.
I can recommend Dawkins's book The Ancestor's Tale. Also the web site OneZoom is fantastic. It allow you to zoom in on the tree of life and see when various branches diverged. There are good books about human migration, say over the past 50-100 thousand years, but unfortunately I can't remember any titles.
If you have children, one of the best teaching methods about deep time is to compress earth's history into one year. There are a variety of sources for the info on the web -
Deletehttp://www.timetoast.com/timelines/63215
http://www.slate.com/blogs/bad_astronomy/2012/12/31/history_of_earth_video_of_earth_s_timeline_compressed_into_one_minute.html
Each day at breakfast or dinner you talk about what happened to the earth. There's nothing to talk about for most of the years (not even any nucleated cells until July, none of the dinosaurs they expect until December.
But you will be busy talking for the last hour of New Year's Eve.
The most effective method I've used teaching deep time to intro geology labs is to map out the time scale on a roll of paper from one of those old-style calculators and have them unroll it down the hall outside the labroom. I put the boundaries between periods on there and make doodles for various major events (like a dead Tyrannosaurus with a small mammal sniffing it for the K-Pg extinction).
ReplyDeleteI think I do 1.5mm per 200,000 years? That leaves 1.5mm at the end for the emergence of modern humans (basically the width of the pen line).
It takes so incredibly long for them to get from single-celled creatures to the Ediacaran fauna (the first multicellular fauna). By the end of the exercise, when they see how short a time modern humans have been around and look back down the hall to see how far away I am, holding the Cambrian end, most of them have huge, astounded eyes, and repeatedly exclaim how much their minds have been blown by how deep deep time really is. That's when I bring up the relative size of the entire Precambrian to what they saw and blow their minds even more.
"Ediacaran" -
DeleteThe Ediacaran Period, named after the Ediacara Hills of South Australia, is the last geological period of the Neoproterozoic Era and of the Proterozoic Eon, immediately preceding the Cambrian Period, the first period of the Paleozoic Era and of the Phanerozoic Eon.
- new word for me. Thank you, dear Lady.
No problem! The Ediacaran fauna fascinate me. All sorts of wacky critters.
DeleteOh, and you can just call me Aritê. Lady's the title I was awarded in my living history group, but I really don't hold anyone to calling me that. :)
Deleteo.k. :.)
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