Which Ionian philosopher was the first person known to have used fossils as evidence for a theory of the history of the Earth?
Xenophanes (died ca. 490 BCE)
Who were the two main philosophers in Ancient Greece?
- Plato (~400 BCE); “fixed essences”
- Aristotle (~350 BCE); systematic classification of species, each believed to be unchanging
What is the “Great Chain of Being”?
- From the Dark Ages
God’s creation must follow a plan:
- Complete and without gaps (God would not leave arbitrary gaps)
- Permanent and unchanging (Otherwise, this would deny perfection of the original creation
- Divinely designed harmony of nature with a fixed role for each being
- Humans form the link between animals and angels
Who were the main scientists behind “The Enlightenment”?
- Carolus Linnaeus (Carl Von Linne, 1707-1778)
- Immanuel Kant (late 1700s)
- James Hutton (late 1700s)
- Jean Baptiste Pierre Antoine de Monet, Chevalier de Lamarck (Jean-Baptiste Lamarck, 1744-1829)
- Mary Anning (1799-1847)
- Georges Cuvier (1769-1832)
- Charles Lyell (1797-1875)
- Thomas Malthus (1766-1834)
What are Lamarck’s 2 laws?
First law: Change in the environment –> changes in the needs of organisms –> changes in their behaviour –> more use of structure would cause the structure to increase in size over several generations, whereas disuse would cause it to shrink or even disappear
Second law: All such changes are heritable
What were Darwin’s influences?
Charles Robert Darwin (1809-1882)
- Thomas Malthus & Charles Lyell
- Animal breeding
- Observations that Galapagos species were unique but most similar to species found in South America
There are 5 parts of the theory of evolution. What are they? Briefly expand on each.
- Evolution as such: Not new, but most convincingly portrayed
- Common descent: Darwin was the first to argue that all of life could be portrayed as a single family tree
- Gradualness: Large differences between organisms evolve through innumerable small steps and intermediate forms
- Populational speciation: Evolutionary change occurs by changes in the proportions of individuals within a population that differ in hereditary characteristics. (Vs. sudden appearance of new species, and vs. Lamarck’s transformation within individuals)
- Natural selection: Darwin and Wallace recognised that differential survival of individuals would result in adaptations. Revolutionised biology and all of Western thought
According to Mendel’s experiments, what is the ratio of dominant: recessive?
2.98 dominant: 1 recessive
Which scientists refined Mendel’s conclusions?
- Erich von Tschermak (1871-1962)
- Carl Erich Correns (1864-1933)
- Hugo de Vries (1848-1935)
What are the 4 main parts of Mendel’s refined hypothesis?
- Alternative versions of genes (alleles) account for variations in inherited traits
- For each trait, an organism inherits two genes, one from each parent
- If the two alleles differ the dominant allele is fully expressed & the recessive allele has no noticeable effect
- The two genes segregate during gamete production
What is meant by the “central paradigm”?
The set of concepts and practices that define a scientific discipline at any particular period of time
The modern synthesis established evolution as the central paradigm of biology. What are the 5 conclusions of this?
- Populations contain genetic variation that arises by random mutation and recombination
- Populations evolve by changes in gene frequency through genetic drift, gene flow and especially natural selection
- Most adaptive genetic variants have individually slight phenotypic effects so that phenotypic changes are gradual
- Speciation normally entails the gradual evolution of reproductive isolation among populations
- These processes, continued for sufficiently long, give rise to changes of such great magnitude as to warrant the designation of higher taxonomic levels
What are “atavisms”?
The reappearance of a once-lost ancestral trait
