Before Darwin

Historical Examples show the Evolution of Evolutionary Theory

“Figured Stones”For centuries, people had noticed images of plants and animal remains in stones and wondered at them.

In China, people sometimes found “dragon bones” (fossils bones of ancient animals) which were used to make medicine.

“Tongue stones” (fossil shark’s teeth) were known in Italy as curiosities.

“Fossil”

The term “fossil” in 16th and 17th century Europe referred to just about anything dug from the earth: crystals, interesting mineral concretions, metal ores, and the “figured stones” that today are called fossils.

Early European theories

The rise of the Enlightenment brought new ideas about “figured stones”:

Did they grow from seeds or eggs trapped in rocks?

Were they remains of victims of the Biblical flood?

Were they organic at all?

Steno (Niels Stensen, 1638-1686)

Danish anatomist, studied medicine in the Netherlands and France.

Came to Florence at the request of the Duke of Tuscany to run a hospital and continue his research.

Steno and the Shark1666: Fishermen in Livorno, Italy, caught a giant shark. The local duke had it shipped to Steno for study.

Steno noticed similarities between the shark’s teeth and “tongue stones” that were well known at the time.

Corpuscle Theory of Matter

Steno used the Corpuscle Theory of Matter to explain the transformation of shark’s teeth into tongue stones.

Naturalists of the day hypothesized that matter was made of “corpuscles” (essentially molecules). Steno suggested that the corpuscles of the teeth had been gradually replaced by corpuscles of stone as the teeth sat in the rocks.

Thinking Challenge

• What was so radically different about Steno’s corpuscular hypothesis about tongue stones?

Johann Beringer (d. 1740)

Dr. Johann Bartholomew Adam Beringer, professor of Medicine in Würtzburg, lectured widely on fossils.

In 1726, Beringer published Lithographia Wirceburgensis, a catalog of fossils he and his assistants had unearthed near his home.

The Figured Stones of Würtzburg

More stonesSome “figured stones” even bore Hebrew letters, spelling out the name of God.

Beringer took these as possible signs that the stones were the work of the Creator, but also suggested they could be sports of nature formed by the “plastic power of the earth,” or that some that resembled living things might grow from trapped seeds or eggs.

Thinking Challenge

• Beringer may have been wrong in the end, but he was doing something right. What was it?

Georges-Louis LeClerk, Compte de

Buffon 1707-1788

Life work: Buffon believed that naturalists should search for a natural taxonomy, find the order in nature.

Asked by the King to catalog the Royal Garden collection, Buffon decided to catalog everything in nature.

Wrote 36 volume Histoire naturelle, générale et particulière.

The Moule Intérieur, said Buffon, was caused by particles inside of an organism.

Horses in Europe remain brown and distinctly horse-like

because their environment arranges the particles into a

horse shape.

Move the horses to Africa, and the environment

rearranges the particles, especially in the embryos,

which reshapes the animals over generations.

All animals are affected equally, and

over many generations, the

particles reshape the horses into zebras.

Thinking Challenge

• In Buffon’s time, nothing was known about genes and heredity. Does modern genetic knowledge support or refute his theory? Explain as best you can.

Georges Cuvier 1769-1832

Supported the “static model” of species — species do not change because they cannot survive changes.

Comparative anatomist: looking for patterns in structure, especially among vertebrate animals.

Set up a natural, non-hierarchical taxonomy of animals based on the nervous system.

Cuvier’s Principles

Correlation of parts: An organism is a functional unit with all part integrated. Each organism is adapted to its niche. Single parts can give clues about the entire organism.

Morphological “type” concept: Every taxon (group of organisms) can be defined sharply and is stable.

Explained changes in the fossil record as evidence of Catastrophism.

Thinking Challenge

• Think about Cuvier’s point: if an organism is well-adapted to its environment, there is no reason for it to change. Does this fit or not fit with modern evolutionary theory? Explain.

Jean-Baptiste Pierre Antoine de Monet de Lamarck 1744-1829

Protegé of Buffon. Interested in natural classification of living organisms.Background was in Botany, but later studied invertebrates.Primary questions: Where do you draw the line between species? How do you “rank” species?Favored a theory of inheritance of acquired characteristics.

Lamarck’s “Organic Law of Development”

Spontaneous Generation creates new, simple organisms, such as bacteria.

Woo-hoo, guys, we’re alive!

Lamarck’s “Organic Law of Development”

Organisms are shaped by their environment.

Hmm, changes... I need to get organized here.

Ooh, a nucleus! Problem solved!

Lamarck’s “Organic Law of Development”

Change is teleological (goal-directed). Organisms have an internal drive to become more complex.

Being an amoeba is the pits. I can’t wait until we all become multicellular.Cool! Tissues! Maybe

we’ll get real organs soon.

Organs and bilateral symmetry! Yeah! Can’t wait until we turn into mammals!

Lamarck’s “Organic Law of Development”

Use and disuse of parts causes change that is passed on to the next generation.

Lamarck says it’s your fault, Stanley, that Junior’s legs are so short. If you weren’t such a couch potato and had gotten some exercise...

Sure, blame me, when you’re the one who hardly left the barn before he was born.I’m not short,

I’m vertically challenged.

Thinking Challenge

• Consider this statement: “Fruit flies exposed to pesticides slowly get used to the pesticides and are no longer killed by it. Each generation becomes more and more resistant.”

• Does this statement fit Lamarck’s ideas or modern ideas about evolution? Explain.

The Difficulties

While the theories of Lamarck and Buffon “made sense” in terms of logic, the evidence to support them was slight and they were not widely accepted.

Heredity was not understood. No one knew about genes or chromosomes, and even the nucleus of the cell had not been discovered.

Until a hereditary mechanism was discovered, there was little that could be done to evaluate these theories.