Natural philosophy transcends a mere description of Nature. It does not consist of a sterile accumulation of facts. It is the privilege of the curious and active mind of humanity to occasionally drift out of the present and into the darkness of prehistory, to gain a sense of what cannot yet be clearly discerned, and thus to take delight in the ancient myths of geognosy in their many recurring forms. -- Alexander von Humboldt, Views of Nature (1808)
We admire the power by which the human mind has measured the movements of the globes, which nature seemed to have concealed forever from our view; genius and science have burst the limits of space, and observation interpreted by reason have unveiled the mechanism of the world. Would there not also be some glory for man to know how to burst the limits of time and, by observations, to recover the history of this world and the succession of events that preceded the birth of the human species? -- Georges Cuvier, Preliminary Discourses on Researches on Fossil Bones (1812)
Introduction to Course
Let's go straight to some definitions:
Paleontology: the study of fossils and prehistoric life.
Fossils: the physical remains or traces of behavior of organisms preserved in the rock record
Prehistoric: before written history
Paleontology sits at the nexus of two major other sciences: biology (the study of life) and geology
(the study of the Earth). (For example, here at University of Maryland there are paleontology classes taught in GEOL and in
BSCI). Within geology, paleontology intersects with sedimentology, stratigraphy, geochronology, paleoenvironmental analysis,
paleoclimatology, and geochemistry; within biology, it intersects with organismal and evolutionary biology, ecology, evo-devo,
and many other subdisciplines. And when you add in the fossils of early humans and their activities, it intersects with
archaeology (the study of human artifacts) and anthropology (the study of humans). We will explore all these
different fields of study in our quest to examine the primary question of this course:
How can we reconstruct what things were like in the ancient past?
(where "things" include both "conditions of the world" and "the living things that were there", and the "ancient past" can be as
recent as the melting back of the last major glaciation 11,700 years ago or as far back as the dawn of Life well before 3,800,000,000 years ago.)
In this course we will examining the principles and methods that paleontologists and allied scientists use to discover, reconstruct,
and interpret organisms and events of the prehistoric past. We will look at several case studies from the "Age of Animals" (basically the
last 600 million years), including the origins of animal life; dinosaurs and their diversity; and the origin of our own species. We will also look at major events that have effected the diversity of life: in particular, major episodes of environmental change, up to and including the great mass extinctions.
We will also look at issues of Paleontology (and Science in general) as a human activity: how is Science done? We will look at the
role paleontology plays in addressing some of the challenges of modern times, such as climate change and the biodiversity crisis. We will
look at the interactions (sometimes good, sometimes not so much) between the science of paleontology and the popular media. And we
will look at the perplexing problem that sizable percentages of the American public (far out of scale compared to other industrialized,
literate, wealthy, technologically-adept countries) fail to accept the discoveries of the scale of geologic time and the fact
of the evolutionary origins of all living things.
Some things to keep in mind about this course:
This is an I-Series Course. Despite some widespread thoughts to the contrary, I-Series classes (and indeed other gen-ed) classes are NOT supposed to be "easy A" classes. Indeed, I-Series classes are intended to be the most challenging courses you take outside your upper-level major requirements. (As they say in commercials, "your mileage may vary".) I'm not going to go out of my way to make this course intentionally difficult, but I'm not watering it down, either! You will be expected to learn a large number of particular facts if you expect to pass this course. You will be required to be an active participant in the discussions. Although there is no required textbook, there are occasionally readings or viewings of lecture videos to do outside of class.
I have found that many students sometimes can use some help or suggestions on effective techniques for taking notes, studying for exams, and so forth. Some of you may find some of these videos helpful:
I-Series classes are NOT supposed to be general survey courses; they are intended for you to learn about the perspectives, approaches, and societal implications of different fields of human endeavor. In this case, that endeavor is the attempt to reconstruct the prehistoric world and its relevance for today. In order to understand HOW we understand the past, we need to look at the approaches people have used before to get to our modern understanding. This will entail us looking at the history of discovery of the different ideas, which also means we are going to look at ideas that turned out to be wrong.
For some reason, there are students who feel cheated because we spend time talking about ideas that turned out to be incorrect. But really, that is a very important thing to cover. I don't want to you simply learn factoids about our current understanding: you can just check out Wikipedia for that! Instead, it is critical for this course to see how we got to our modern understanding, and why we accept certain interpretations rather than other ones. If you are uncomfortable with having to learn about blind ends in the pursuit of knowledge, this probably isn't the class for you.
Speaking about comfort issues, a note on content: Science is demonstrably Humanity's most effective way of assessing reality about the natural world. Many of its discoveries contradict deeply held traditional, religious, political, or personal beliefs. In this particular course, we shall examine what Science has uncovered about the age of the Earth and its inhabitants, the origin and interrelationships of species (including our own), and the reality of climate change (including human contribution to this phenomenon). We will not shy from indicating where the scientific discoveries demonstrate that other beliefs about these aspects of the natural world are in error. If you find it distressing to hear people’s beliefs called inaccurate (whether you hold them or not), this may not be the course for you: there are many other courses available at the University which fulfill the same requirement. If, however, you wish to understand not merely what Science has discovered but also HOW it discovered it-regardless of its implications for traditional, religious, political, or personal beliefs-then we encourage your active participation.
And now, a little historical background...
Into the Darkness of Prehistory: Our Long Quest for Origins
BIG QUESTION:How have people explained the origins of the Earth, Life, and Humanity in the past?
Humans have long sought explanations for where we, the rest of the living world, and the physical universe came from.
Every culture has its own creation myths, in which they provided these answers. Just a tiny fraction of these include:
Creation stories are as varied as the cultures they came from, so it is impossible to say anything universal or absolute about them. Indeed, there are many other cultures in which a single origin of the world wasn't accepted: instead, the world and its inhabitants are eternal. In these cosmogonies it is often thought that there are vast cycles of the rise and fall of civilizations, but in which the living creatures of the world and the landscapes in which they dwell remain largely unchanged.
Indeed, in both the traditional creation stories and eternal cosmogonies, there are certain commonalities found in the vast number of them:
The world is not much older than humanity (i.e., human origins were not long after the beginning of the world if there was a beginning, or humans have been present throughout eternity in the eternal view)
(In creation cosmogonies at least) Human history (either from folk tales or written records) comprises most of the duration of the world: that is, there is a record at least in story that connects the very first generation of people to exist right up to the "present day" when the story was told)
People have been living in something close to the "present day" conditions (that is, of the time of the recording of the stories) since very early in this history
Or, in other words, there is not much room (if any) for a "pre-history": either a long time before people, or a time after the origin of humans but for which there is no story or legend or writing
The life forms of the first days of the world by and large are the species present today (with maybe a few monstrous exceptions for the heroes of ancient times to fight)
The basic structure of the physical features of the landscape (the particular mountain ranges, valleys, oceans, etc.) present today were there at the beginning of the world, barring the effect of divine, demonic, heroic, or monstrous activity to explain a certain feature here and there
Rocks (out of which mountains are made, of course) are "aboriginal": that is, they were there at the beginning of the world, and were not produced by events in the history of the Earth
This is perfectly understandable: in the written and/or oral traditions of peoples, the world had remained largely the same: the mountains were mountains, goats were goats, and so on.
Fossils were of course present throughout the history of humans. There are stonetools that predate our own species that show earlier species of our genus Homo collected fossils. How were fossils explained?
In some cases, fossils might be thought to be unusual rocks that happened to look like the parts of living things. Or spill over from the Creation. Or attempts by diabolic forces to create life. Or the bones of dragons, giants, ogres, or other mythical beasts.
Of great importance, though, is how they got into rock in the first place. If rocks are as old as Creation, then they can't be
parts of once living things. Since the accumulating evidence showed that they WERE the parts of living things, then rocks
cannot be as old as Creation. In other words, rocks were formed sometime between the beginning of the Earth and the present
day, and fossils were the remains of living things incorporated into that rock.
The above idea was considered by various thinkers, but most importantly articulated by
Nicolas Steno (1638-1686): Danish priest, anatomist, early geologist and paleontologist, and recent honoree of a
Google doodle. His 1669 work De solido intra solidum naturaliter contento dissertationis prodromus argued exactly the above:
that rocks must be the product of activity within the history of the Earth rather than part of its beginning, and fossils are the
remains of dead organisms that were incorporated into their structure. He famously showed that "glossopetrae" ("tongue stones")
collected from rocks around the world were in fact the fossilized
teeth of sharks.
(Importantly, Steno was primarily an observational scientist rather than a theoretical/philosophical one: his explanations were
based on first hand observation of physical evidence (in the field or in the lab) rather than created as thought experiments to fit
a particular philosophy.)
Over the next two centuries (1660s to 1860s or so), the basic discoveries of paleontology were established:
That fossils were often the remains of unknown creatures:
For example, this
was not a flatfish, but a type of arthropod later called a "trilobite"; this
is not a human, but instead a giant salamander; this
was not a crocodile, but a type of marine reptile now called an "ichthyosaur", and many many other instances
That the reason that these fossils were unknown is that they were extinct
While some modern animals (dodo, great auk, Stellar's sea cow) had famously been driven to extinction during these same two centuries,
the idea of natural extinction was heretical. Baron Georges Cuvier (1769-1832) --
zoologist, geologist, comparative anatomist, and father of vertebrate paleontology -- argued strongly that the reason ichthyosaurs and
mammoths and ammonoids and pterodactyls and so forth were not present any more was that they had all died out
That there were different phases of Earth history, each with their own sets of organisms: in other words, not one "fossil world"
but a succession of many "fossil worlds"
That humans were only present at the very latest of these phases, in which the vast majority of living things were already
of modern form or very similar to them
That the duration of even this most recent phase was vastly longer than recorded human history, and that the history
of life was immensely old: a scale of many millions upon millions of years
We will come back to the modern understanding of these different concepts in the weeks to come.