Biology Before Darwin: Crash Course History of Science #19


In physics, questions about astronomy led
to revolutionaries such as Kepler and Newton, who provided a new theoretical framework that
replaced the old Aristotelian one. But when it came to the study of living things,
this shift didn’t happen until a little later, in the 1800s. You’ve probably heard of Charles Darwin,
but before we get to him, and I’m ecited to get to him, you really need to understand how different people, throughout the seventeenth and eighteenth centuries, tried to answer the same question: “what
is life?” [INTRO MUSIC PLAYS} During the Scientific Revolution and Enlightenment,
there was no biology—that term was first used in 1799. Instead, there was natural history, the observation-based
study of living things, based on the work of Aristotle. For Aristotle, living things were all of one
kind, but animated by different types of soul. So, plants have a vegetative soul and can
grow. Animals have a sensitive soul and can move. And humans alone have a rational soul, capable
of reason. Organisms could be compared by imagining their
position on a great chain, leading upward in complexity and worth from grass to starfish
to humans. This Great Chain of Being gave people throughout
Europe and parts of Asia and Africa a way to understand differences in form between
things. But it didn’t include an element of time. Did living things change over time? That is, did they evolve? What sorts of evidence would prove this, and
would this proof contradict the bible? Would God let extinctions happen!? Let’s set the stage for these questions,
which would rock the world of natural history. Alongside the first microscopists, other brilliant
people were creating knowledge about living things in the 1600s. Two notable natural historians jump out—a
great experimentalist and a great observer. In 1634, the Spanish Inquisition arrested
Flemish alchemist Joannes Baptista van Helmont for the crime of… studying plants! He was put under house arrest, but this experience
didn’t deter him: like Galileo, it made him want to science even harder. Van Helmont really wanted to understand how
plants grow, so he devised his famous willow tree experiment to provide some answers. Van Helmont wanted to test the theory that
plants grow by eating soil, so he weighed a willow tree—it was five pounds—as well
as some soil—two hundred pounds of it. He planted the willow in the soil, in a pot,
and then tended to the plant’s needs, observing its growth over five years. After that time, he weighed the tree again,
then dried the soil and weighed it, too. The mass of the soil had remained the same
over five years, but the tree’s mass had significantly increased. Van Helmont concluded that the tree grew not
by eating soil but by drinking water. Published in 1648, after Van Helmont had died,
this willow-weighing became the first quantitative experiment in biology! Another major seventeenth-century natural
historian was Maria Sibylla Merian. Born in Frankfurt in 1647, Merian was the
leading entomologist, or insect expert, of her day, as well as a highly skilled scientific
illustrator. Merian became well known for her work on how
some insects metamorphose, or change shape. Her careful observations of the life cycle
of the butterfly became a benchmark for other natural historians. In 1699, Merian traveled to the Dutch colony
of Suriname in South America to study tropical insects. She was horrified by the slavery she encountered
there, but was also aided by an enslaved person, which was typical of many European natural
historians. In 1705, Merian published the heavily illustrated
Metamorphosis Insectorum Surinamensium, cementing her reputation in both art and science. The next major shift in natural history came
thanks to Carl Linnaeus. Born in 1707, Linnaeus sought to discover
the order of nature. He reasoned that, if you could just compare
every species along the same axis—say, sexual organs, or limbs—then you could create a
gigantic table, showing every living thing on earth, side by side. Think about that supremely Enlightenment-style
visual metaphor: life was a static table full of information. Lots of other people were trying to figure
out how to classify living things. But Linnaeus’s system won out. Linnaeus invented the binomial system that
biologists still use. The first name or genus represents a more
general category. The second name or species is based on a specific
characteristic. Humans, for example, are Homo sapiens, or
the “intelligent men,” as opposed to our extinct relatives, Homo erectus, the “standing
men,” or our closest living relatives, the bonobos, who some scientists classify as Homo
sylvestris—the “forest men.” Linnaeus introduced the binomial system in
Systema Naturæ in 1735. We can compare this text to Galileo’s Two
Sciences or Newton’s Principia, in that it provided natural historians with a new
paradigm for how to do their jobs. Beyond the binomial, Systema also addressed
higher-level classification. Say you encounter a thing. First, you decide on its kingdom—meaning
whether it’s an animal, vegetable, or mineral, as per tradition. Then you assign it to a class, such as such
as mammal or bird, and an order based on some characteristic, such as, say, eels or spiny-finned
fishes. FYI, Linnaeus was the first to assign bats
to Team Mammal instead of Team Bird. Then you assign genus and species. And all of these decisions you make rationally,
based on some observable and comparable feature: does the thing have wings or arms? Spines or no spines? How many ventricles in its heart? Internal or external gills? Although it’s evolved a lot over three centuries,
we still use Linnaeus’s system today! Linnaeus was called the “Second Adam”
because he named so many organisms, mostly plants. He didn’t go out collecting plants, but
he inspired a generation of European natural historians who did. They had a new tool at their disposal that
allowed them to rapidly concentrate thousands of botanical samples in a small number of
botanical gardens: empire. With tall-ships constantly sailing from London,
Antwerp, Stockholm, and Calais for distant continents, the naturalists of the 1700s used
military might to make knowledge about ecosystems that Europe didn’t have. A perfect example of a statesman–scientist
who took advantage of colonial empire in order to fill in the table of nature was Sir Joseph
Banks. Born in 1743, Banks became the preeminent
British naturalist of his day. Appointed by the Royal Navy and the Royal
Society, Banks sailed with James Cook aboard the HMS Endeavour from 1768 to 1771, traveling
to Brazil, Tahiti, New Zealand, and Australia. When he returned home, famous and full of
ideas about the great variety of living things, Banks became advisor to the king on the Royal
Botanic Gardens at Kew. He also rose to become president of the Royal
Society, holding the position for over forty years. In order to build Kew into one of the greatest
botanical gardens in the world, Banks directed other botanists to travel the world, collecting
plants, and bringing them back to the center of the British Empire. There, they were classified using the Linnaean
system and shown off to the public. So, Linnaeus was hugely influential in thinking
about how to classify organisms, and Banks pushed the powerful British Empire to make
tabulating nature a project of prestige. But they didn’t raise deep epistemic questions
about what living things are, like if species change over time or not. Those questions would come into the mainstream
of science thanks to a trio of French thinkers who we can think of as the “Transformists”:
Buffon, Lamarck, and Cuvier. Georges-Louis Leclerc, AKA the Comte de Buffon,
was born in 1707. He became superintendent of the Royal Garden
in Paris and argued with Thomas Jefferson about whether animals and plants in the Americas
were inferior to those in Eurasia. (We’ll come back to the Americas.) But, importantly for natural history, Buffon
thought that living things are degenerating, or slowly becoming worse than God originally
designed. He didn’t provide a mechanism for how this
devolution worked, and he later recanted his controversial views. But Buffon did at least open the door among
well-connected, university-trained philosophers to the idea that species changed. This idea was pushed further by a more humble
botanist. Jean-Baptiste Lamarck, born in 1744, he was a
peasant, but he became a professor of invertebrates: actually, he coined the term “invertebrate!” Lamarck was an expert on marine worms and marine snails, mostly focused on shells. Although he also published Flowers of France, in 1778. And, influenced by Buffon, Lamarck criticized
the fixity of Linnaeus, moving toward an evolutionary theory. ThoughtBubble, What did that theory look like? The reason we remember Lamarck as the almost-Darwin is that he developed a specific theory of
“transformisme” to describe how species changed—providing a how and, perhaps more
importantly, a why. Lamarck believed that individuals inherited
the traits that their parents had acquired during life. In life, individuals use certain body parts
more than others, changing them ever so slightly, and then pass those changed parts down to
their kids. Although this idea has been proven wrong since
Lamarck’s time, some historians still credit him with essentially predicting epigenetics,
or changes in living things made by changes to which gene are expressed rather than by
changing the genetic code itself. Gradually, Lamarck thought, creatures would
become more complex. This progressive evolution was the opposite
of Buffon’s devolution. Lamarck’s famous example was the giraffe:
according to Lamarck, its neck elongated as the animal stretched up to reach leaves that
were higher on trees. Over time, short giraffes grew slightly longer
and slightly longer necks until—voila—they could reach those high leaves. Of course, Lamarck never actually studied
or even saw a giraffe—although he almost got the chance. The Pasha of Egypt had given France a giraffe
in 1827, shortly before Lamarck died… but after Lamarck had gone blind. Lamarck’s transformisme was not exactly
a full framework for doing natural history. But he did argue that, essentially, the environment
is what pulls an organism along into a new form… which makes historiographical sense. After all, Lamarck lived in a setting of rapid,
radical change for humans like himself: the French Revolution. He saw the transition from a post-Revolution
republic into the empire of Napoleon Bonaparte. And he saw how different individuals responded
to environmental shifts. Thanks, ThoughtBubble.
Finally, there was Georges Cuvier, born in 1773, and he added a different wrinkle to
the theory of biological transformation: extinction. Cuvier was an immensely famous professor,
known as the “Napoleon of natural history.” Cuvier met Ben Franklin, corresponded with
Thomas Jefferson, and advised the real Napoleon. Scientifically, Cuvier established modern
comparative anatomy as a discipline, specializing in the study of elephants. Cuvier believed each species was perfectly
adapted to its environment, and that you can reconstruct an organism from only one or two
bones, if you understand how anatomical systems function. Cuvier opposed any theory of evolution, vigorously
arguing against Lamarck’s progressive one. But Cuvier also built his entire personal
scientific empire on the careful study of fossilized animal remains, comparing living
and dead animals and classifying them by their bone structure. He could see that some types of animals
simply no longer existed! How did Cuvier square the fossil record with
a belief in a divinely ordered, mostly unchanging creation? He argued for catastrophism, the idea that
major changes in species come about due to catastrophic events—such as the Flood of
Noah. At the end of the 1700s, natural historians
had a system for comparing and naming everything alive. They had state support. And they had some ideas about how life changed
over time. But they didn’t have a new paradigm for
researching this change. They didn’t have a biology. Next time—let’s follow the fossil trail,
hunt for mines, learn the true age of the earth, and further clear the way for Darwin’s
biology: first, we need the birth of geology! Crash Course History of Science is filmed in the Dr. Cheryl C. Kinney studio and is made with the help of these nice people and our animation team is Thought Cafe. Crash Course is a Complexly production. If you wanna keep imagining the world complexly
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