Rethinking history and picturing deep time

Louis Figuier’s 1863 book The World Before the Deluge was a time machine between two covers.  By the mid-nineteenth century, geologists knew that different rock layers and the fossils entombed in them corresponded to distinct periods of time, ages when animals and plants unlike any known to modern man had populated the globe.  Figuier took his readers on a grand tour of these geologic periods—or rather, he did so with the assistance of Édouard Riou, whose evocative engravings brought these extinct environments back to life.

Each engraving showed readers a primordial landscape characteristic of a phase of prehistory.  The result was a sort of highlights reel of earth history, a sequential arrangement of what the historian of science Martin J.S. Rudwick calls “scenes from deep time.”

Riou’s illustrations have long since lost their scientific value, but they still pack a visual wallop.  In this image, torrential rains hammer the surface of a newborn globe:

Trilobites and other marine invertebrates wash up on the shore of the Silurian sea:

The forests of the Carboniferous:

Two dinosaurs, depicted as the stocky and elephantine reptiles that early Victorians assumed they were, engage in mortal combat:

The emergence of large mammals:

A primeval flood inundates northern Europe:

The appearance of (notably white and European) humans:

And finally, a later, “Asiatic” flood, perhaps the one described in Genesis and other ancient texts:

If you’ve ever read a paleontology textbook, visited a natural history museum, watched a documentary on evolution, or stepped into a science classroom, you’ve probably seen a modern variation of these sequential deep time scenes.  Paintings in books, dioramas in museums, and CGI clips on TV often take the form of the “prehistoric highlights reel” that Figuier and Riou helped popularize.

And although the science of paleontology has changed a great deal since the 1860s, the organisms that populate our own scenes from deep time tend to correspond with those Riou associated with specific periods.  The dates assigned to the scenes have changed (and in the case of he dinosaurs, the physiology of the animals has changed, too), but the cast has remained much the same.  The scenes start out with marine invertebrates, then move on to primitive chordates and fish, then amphibians and early terrestrial organisms, then dinosaurs and other Mesozoic reptiles, then mammalian megafauna, and finally humans.  I had a lot of books on prehistoric life when I was a kid, and the sequence of illustrations was pretty consistent across most of them: marine invertebrates, jawless fish, jawed fish, amphibians, dinosaurs, mammals, and Homo sapiens.

This sequence may seem inevitable; after all, it’s the order in which the major groups of organisms appeared.  But there’s a sense in which it’s misleading.  The illustrations tend to be much better at highlighting when groups of organisms appeared or were especially prominent than they are at indicating how long they flourished.

Take reptiles, for example. Many illustrators will throw one in around the late Carboniferous to mark the emergence of the first reptiles, or perhaps include a picture of the sail-backed Dimetrodon in the Permian. Pictures of reptiles then dominate the Mesozoic, and then tend to disappear from pictorial sequences and time charts altogether after the age of dinosaurs.

But reptiles didn’t go extinct 65 million years ago.  Nor, for that matter, did the dinosaurs themselves.  Birds are advanced theropod dinosaurs, and living bird species outnumber mammals species by two to one.  Extant reptile species outnumber mammal species, too.  But you wouldn’t know this from looking at pictorial deep time sequences and geologic time scales.  Illustrators are keen on reptiles and birds when they first appear, or when they’re the biggest terrestrial animals going.  Once you hit the end of the Cretaceous Period, however, it’s as if we assume that reptiles and their descendants ceased to exist, or at least ceased to be relevant.  Indeed, we call our own time the “Age of Mammals,” but it would be just as accurate to keep calling it the “Age of Reptiles.”

The artificiality of deep time imagery is even more apparent when you look at fish.  Illustrators highlight fish when they’re the only vertebrates around, but once amphibians show up and start colonizing the land, fish more or less vanish from the pictures.  Likewise, you don’t see many amphibians in illustrations of scenes dating from after the first appearance of reptiles.  And invertebrates tend to disappear entirely once animals with backbones evolve, even though they make up more than 95% of all extant species described so far.

These charts and sequential images also tend to favor terrestrial over aquatic life.  Marine organisms are plentiful in scenes of early eras, when there’s no life on land.  But once terrestrial animals appear, many geologic time scales omit marine life altogether, except for the occasional aquatic reptile from the Mesozoic (presumably included because they look really cool).

You can see the same sequence of organisms in illustrated charts and tables of geologic time.  Take a look at this one produced by CliffsNotes.  Invertebrates for the earliest periods populate the oldest periods at the bottom, and then it’s fish, terrestrial animals, dinosaurs, and mammals.  Not a single invertebrate after the first appearance of insects.

Here’s another one from a professional development site for teachers.  It’s pretty consistent with the one above.  Invertebrates, fish, plants, amphibians, dinosaurs, large mammals, and finally man up at the top.

The point I’m belaboring here is that pictorial sequences of earth history and illustrated geologic time charts are as notable for their omissions as they are for what they include.  There’s a sort of implicit narrative thrust at work here, focused on organisms that are vertebrate, terrestrial, and warm-blooded.  Organisms, in other words, that seem most relevant to our own origins.

Now, I’ve never needed an excuse to discuss extinct organisms here before, but this post isn’t one of my gratuitous prehistoric indulgences.  I raise the issue of scenes from deep time because it offers insights into the ways we think about the more recent, human past.

We might compare the treatment of some historical subjects in textbooks and survey courses to depictions of organisms in pictorial sequences of deep time.  Just as illustrators render some animal groups invisible once a more recent group arrives on the scene, so we tend to render Indians invisible after, say, King Philip’s War, Jacksonian removal, or Wounded Knee.  But Native Americans didn’t vanish after these important turning points.  They might have ended up in a different location, but they didn’t become extinct or irrelevant, any more than amphibians became extinct once animals started laying amniotic eggs.

And the descendants of Spanish colonists in the American Southwest didn’t cease to exist after the mid-1800s, when Anglophone Americans took political control of the region.  They were there the whole time, just as birds kept fluttering along through the mass extinction of 65 million years ago and the emergence of large mammals afterward.

In the same way, just as it’s misleading to ignore marine life and focus exclusively on terrestrial life after the movement of the first organisms into land, it’s also misleading for history books and courses to ignore the Southwest after the passage of the “frontier” era, or to be attentive to southern history only during the Civil War, New South, and civil rights eras.  And our discussions of such important changes as the Industrial Revolution shouldn’t blind us to the fact that most Americans remained tied to agriculture long after the first steam engines started puttering, just as most organisms remained invertebrates long after the first backbones appeared.

Our selective memory of history suffers from the same problems as our selective memory of the story of the life on this planet.  We need to remind ourselves to step away from selective scenes of the past to take in the sweep of the whole drama.  And we need to stop thinking of history in terms of a “highlights reel” of status scenes, and start thinking of it as a totality.


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Filed under History and Memory, Teaching History

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