Week 7 Flashcards
What is the scale of nature ?
“Scale of Nature”: a continuous hierarchy of all beings arranged in order of “perfection.”
Also known as “The Great Chain of Being,” this system had religious roots and pictured beings rising in a linear order, starting with inanimate minerals, and rising through fossils (which were considered something between the
mineral and the living) to plants, animals, humans, celestial beings, and ultimately, God.
What did european society consider nature to be in the 1600-1800
Constant (no extinctions, no change)
4,000 years old.
Created intentionally by a single
higher being (a Christian God)
Inferior to humans, and to be
controlled
(but also dangerous and
uncontrollable)
predictable
Was natural history a field of study accesible to all ?
Travel was dangerous and expensive, but exotic things were extremely popular and highly valued.
Therefore natural history and “scientific” studies were often hobbies of wealthy gentlemen who attended universities, formed clubs, and funded their own extensive collections of exotic specimens.
Alternatively, science was carried out by monks and clergymen who had the time,
security, and liberty to study the natural world.
However, it was within the context of God’s creation.
Nicholas Steno
(1638-86)
One of first naturalists to identify fossils as once living organisms
Identified tongue stones as shark’s teeth
Explained how seashells could be found on top of certain mountains
Argued that the Earth itself kept a record of its history
Believed in a biblical Earth just a few thousand years old
Steno is credited with 4 of the
defining principles of
stratigraphy!
◦ Law of superposition
◦ Principle of original horizontality
◦ Principle of lateral continuity
◦ Principle of cross-cutting
relationships
Carl Linnaeus (L.)
1707 - 1778
Swedish botanist
Invented a system to classify species into groups
based on shared traits
System still used today
◦ Kingdom
◦ Phylum
◦ Class
◦ Order
◦ Family
◦ Genus
◦ Species
Believed diversity of life was a divine creation
with NO extinction
Georges Buffon
(1707-88)
18th century French nobleman
Director of King’s garden in Paris
Proposed that Earth formed according to laws of physics
(70,000+ years ago)
Same particles make up living and non-living things
Extinction was real
Argued that life changed over time
Proposed (with others) the concept of monogenism – the
concept that all races of humans came from a single origin….
…But then proposed degeneration theory: that Adam and Eve were Caucasian and that all other races had ‘degenerated’ due to climate factors such as sun and wind.
He believed other races could ‘revert’ to Caucasian if they
lived in a beneficial environment!
Buffon and Ernst Mayr
Buffon (1707–1788) was a French naturalist who developed early ideas about the “unity of type,” which later influenced comparative anatomy. He was also one of the first to suggest that species might have common ancestors, as seen in his observations about the similarities between elephants and mammoths. However, Buffon also contradicted these evolutionary ideas by maintaining that species were immutable (unchangeable), which hindered the acceptance of evolutionary theory during his time.
Ernst Mayr (1904–2005) was a 20th-century biologist and a major figure in the modern evolutionary synthesis, known for his contributions to species concepts and evolutionary biology. He did not endorse the immutability of species; rather, he supported and expanded on Darwinian evolutionary theory.
Georges Cuvier
(1769-1832)
French paleontologist
Created the field of comparative anatomy in animals.
Compared elephant fossils to skeletons of living elephants in Africa and India
Discovered a new species: an extinct mastodon
◦ Extinction took place 11,000 years ago
◦ Late 1700’s marks the recognition that some
species no longer existed (life did not stay the same)
Believed extinctions took place in “great catastrophes”
William Smith
(1769-1839)
British canal surveyor
Discovered that layers of rocks contain distinct groups of fossils
Found same sets of fossils in rocks separated by hundreds of miles
Produced first detailed geological map
Jean-Baptiste Lamarck (1744-
1829)
Argued that:
◦ complex species evolved from simple ones
◦ humans and other large species descended from microbes
◦ primitive life was being
spontaneously generated all the time
◦ Time was important, and the earth immensely old.
◦ extinction did not exist, but instead species continually evolved into living
forms
Lamarck’s mechanism for evolutionary change:
traits used in life due to environmental needs were enhanced. Traits that were disused (like legs in whales) shrank or disappeared.
Erasmus Darwin
(1731 – 1802).
A leading intellectual in his era, Erasmus had ideas on evolution very similar to Lamarck, although they do not appear to have known of each other.
He also discussed the importance of competition
and sexual selection.
Darwin’s voyage
on HMS Beagle
Gathered fossils
Trapped birds
Collected barnacles
Observed ecological complexity of jungles
Experienced an earthquake and observed the shoreline lift
Agreed with Lyell’s claim that Earth’s landscapes were
created by a series of many small changes and not by
gigantic catastrophes
Darwin’s new idea… years later!
Galapagos finches helped Darwin conclude that all life had evolved
Darwin rejected Lamarck’s ladder of progress (giraffe example)
Darwin’s idea was a process based on variation and selection
Tree of life
1859 Origin of Species published
Darwin established evolution as a subject that could be studied
scientifically
Illustrates how different lineages evolve from a common ancestor
Showed the world that all species on Earth are related
homology
Human, seal, and bat limbs
have homologous bones
Homologies are found together
in the same groups of species
(humans, seals, and bats also
have hair and secrete milk)
Darwin viewed this as common
ancestry and descent with
modification
But how did descent with
modification happen?
Darwin argued that patterns in biology (homologies, fossil record) could be explained by evolution, but how?
Lamarck claimed that the history of life followed a
trend toward “higher” forms…
German biologists in early 1800s argued that life evolved from simple to complex
Darwin and Wallace proposed natural selection as a driver of evolution
◦ Natural process
◦ OBSERVABLE process
Was charles darwin a communist
No. Charles Darwin did not subscribe to, espouse, or support Marx or Communism.
Social Darwinism ≠ Theory of Natural Selection!
A misuse of the idea “survival of the fittest,” Social Darwinism justified the belief that some people are innately better, or stronger, than others, and enabled control of the “strong” over the “weak” through various social applications.
▪ Capitalism
▪ Racism
▪ Imperialism
▪ Eugenics
▪ Fascism
Social Darwinism is a pseudoscience.
Who independently arrived at the same theory of natural selection to explain
evolution.
ALFRED RUSSELL
WALLACE, 1823 - 1913
What Darwin & Wallace did
not know
Heredity was an essential element of Darwin’s theory yet
he did not know how it was that offspring resembled their parents
Gregor Mendel was discovering genetics while Darwin was writing the Origin of Species but nobody paid attention until early 1900s and the discovery of DNA
ernst haeckel
Ernst Haeckel – 1834 – 1919
Promoted and popularised Darwin’s work, but actually believed in Lamarckism (acquired traits) as opposed
to natural selection.
Based on work by earlier naturalists, Haeckel was famous for proposing that the development of the embryo of an animal, from fertilization to gestation or hatching (ontogeny), goes through stages
resembling or representing successive adult stages in the evolution of the animal’s remote ancestors (phylogeny).
Modern Theory: DNA as the
Basis for Heredity of Traits
In 1950s molecular biologists James Watson, Francis Crick, Maurice Wilkins & Rosalind Franklin came up with a theory that all organisms use a molecule called DNA to store genetic information
After 50+ years scientists have found this theory to hold true for all species.
The predictive power of this theory has allowed scientists to unravel the secrets of how evolution really works
The DNA for every species is not known but we can predict and test sequences based on species relatedness thanks to the theory of evolution
Name traits of Modern Evolutionary Theory
A. All of life is descended form a common ancestor.
B. Organisms inherit traits from their ancestors.
C. These traits are passed on in the form of DNA molecules.
D. Traits may be beneficial (good) or deleterious (bad) for individual organisms, enabling
others to survive and reproduce more than others. These individuals are considered
to be “selected” and have a greater contribution to the next generation. This is called
“natural selection” and is a non-random process.
E. Random survivorship also plays a large role in the evolutionary trajectory of
populations and species. These random processes are called “genetic drift”.
F. As individuals and populations take on new traits and experience new selection
pressures, isolation, genetic drift, and other processes, new species are formed.
G. Species go extinct. As some species go extinct, new opportunities become available
for evolving species.
