Biological Anthropology Midterm - Lecture 2

evolutionary theory

- explains the process of biological change

• - does not ask whether evolution occurs, but explains how evolution occurs

- accumulation of data and hypothesis testing explain phenomena

Bishop James Ussher (1581-1656)

- biblical chronology to determine the age of the Earth

- creation was October 23rd, 4004 BC

• - Young Earth

uniformitarianism

geological processes in operation today were operating at the same rates in the past

Georges-Louis Leclerc, comte de Buffon

- studied physical laws about heating and cooling objects of different size and constitution

- believed the Earth began as molten rock then solidified as it cooled

- calculated the Earth between 75,000 and 3 million years old

- professed an idea of biological change in relation to local environments, but no proposed mechanism of change

James Hutton

- studied rock formations and erosion

- found unconformities, boundaries, in rock type

- the surface of the Earth is not static; the layers must have been accumulated over a long period of time

- theory of uniformitarianism

Robert Hooke

- discovered that cells in petrified cork were identical in structure to living wood

- fossils = remains of once-living organisms

- coined the term “cell” from monks living in monasteries

Georges Cuvier

- founder of comparative anatomy and vertebrate paleontology

- validated concept of extinction

- catastrophism

• - species extinctions due to periodic “catastrophies”

- layers of strata (periods in which certain species thrived)

- species immutable

ancient greek essentialism

- ideal forms for every organism

- great chain of being (“scala naturae”)

• - hierarchical: God → angels → humans → (other) animals → plants → minerals → all biotic/abiotic entities

• - divinely ordained

• - static

John Ray

- searched for a divine organization of species

- used multiple features to group organisms

- used the term “species” as a primary unit of taxonomy

Carolus Linnaeus

- Systema Naturae

- taxonomic classification: binomial nomenclature

• - Genus, species | Homo sapiens

- followed great chain of being logic

- included humans in his taxonomy, which was controversial at the time

- many of the taxonomic terms derive from human social classes

• - kingdom, phylum, class, order, family, genus, species

Al-Jahiz

- one of the earliest scholars to propose theory of biological evolution

- suggested new traits develop for survival, given environment

- evolution followed divine will and guidance

Erasmus Darwin

- grandfather of Charles Darwin

- poet, not a scientist

- early ideas on species transformation; life evolved from single living filament

Jean-Baptiste Lamarck

- first detailed model for evolutionary change in Europe

- organisms willfully adapted to novel environmental conditions by modifying their behavior, which in turn modifies anatomy

• - new traits passed on to offspring

• - “inheritance of acquired characteristics”

Charles Lyell

- Principles of Geology (1830)

- reestablished uniformitarianism over catastrophism and influenced Darwin

Thomas Henry Huxley

- “Darwin’s Bulldog”

- Evidence on Man’s Place in Nature (1863)

- applied evolution to humans before Darwin

Charles Darwin

- studied biology and theology

- traveled the world as a naturalist onboard the HMS Beagle

- accredited for the bulk of evolutionary theory

- “no sharp distinction between species and varieties”

- gradualism — biological change occurs slowly; there isn’t a true end result for evolutionary change

- evolutionary change occurs through variation existing in the population

Darwin’s Voyage of the Beagle

- observation and collection of plants and animals

- Darwin identified small variations between species in close geographic proximity

• Galapagos finches resembled mainland birds in Ecuador more closely than birds in other volcanic regions globally

Alfred Russel Wallance

- independently theorized natural selection

Darwin’s gemmules

- blended inheritance

• no clear unit of variation for selection to act upon

• no way to account for new variation

Gregor Mendel

- pea plant experiments uncovered “particulate inheritance” (vs. blended inheritance)

- discrete units: genes

- unit variations: alleles

- expression pattern: dominant and recessive phenotypes

William Bateson

- coined “genetics”

- founded the Journal of Genetics in 1910 with Reginald Punnett (of Punnett squares)

Julian Huxley

- The Modern Evolutionary Synthesis

- unifies natural selection with genetic inheritance

• traits not inherited—alleles inherited

Friedrich Miescher

- 1869: discovered nucleic acids in cells (before genetics coined)

Phoebus Levene

- 1919: discovered nucleotide structure (after genetics coined)

• sugar, phosphate, and nitrogen base

• series of nucleotides structure = nucleic acid (in yeast)

- discovered the carbohydrate component of RNA (ribose) and DNA (deoxyribose)

Chargaff’s Rule

- 1950: Erwin Chargaff discovered that nucleotide sequences vary and proportions of nitrogen bases are similar

Watson and Crick

- 1953: propose double helix structure of DNA

Rosalind Franklin

- contributed to the double helix structure proposal with her X-ray crystallography, but her work went unpublished and unacknowledged

genome includes…

20,000 — 25,000 genes

overall timeline of evolutionary thought

the great chain of being → Al-Jahiz (species transformation) → Robert Hooke (fossil forms) → James Hutton (uniformitarianism), Carolus Linnaeus (taxonomy) → Georges Cuvier (extinction), Lamarck, Darwin, and Wallace (species transformation) → the modern synthesis: mechanism of inheritance → extended evolutionary synthesis