A Developing Evolution- 9/8

• Linnaean Classification

• Early Evolutionary Theories of the 1800s

  • Catastrophism and Uniformitarianism

  • Thomas Malthus and Carrying Capacity (environment pressure)

  • Lamarckian Evolution

• The Emergence of Modern Evolution

  • Charles Darwin

  • Origin of Species

  • Alfred Russel Wallace

  • Natural Selection

Biological Classification - Linnaeus, Ray 17th and 18th centuries (250-350 y/a)

• 2 major development in the 17th and 18th centuries dramatically transform how scholars conceived of the various plant and animal specimens they encountered

• Beginning in 1686, the English naturalist John Ray Published a sequence of three volumes called the Historia Plantarum (history of plants), in which he offered a biological definition of species derived from observation:

  • a group of morphologically similar organisms arising from a common ancestor

• A little under a century later, Carolus Linnaeus (Carl von Linne, b. 5/23/1707, d. 1/10/1778) became the first to formalize what we now refer to in the biological science as binomial nomenclature, the use of 2 names (often but not always in Latin) to represent animal and plants by their genus and species

These 2 developments shaped the ways that naturalists (and later biologists, anthropologists, and other scientists) would not only name species, but how they would see their relationships to one another

Carl’s Adventures in Lapland

• 1732, Linnaeus traveled to Lapland, a region that stretches across the northern territories of modern-day Norway, Sweden, Finland, and Russia, ultimately describing over 100 new species of plants in his text, Flora Lapponica, which detailed more than 500 total flora specimens.

• Needed a way to classify them all

• 1st attempt, Linnaeus resorted to simple Latinate name, each making reference to characteristics or features of the specimens he documented

• This left Linnaeus unsatisfied. The system worked sufficiently to set one species apart from the others, but it granted no means to show which species were related. By the time of Flora Lapponica’s publication, he had adopted a new system that used two names - genus and species – to identify the plants he collected.

• This system – which we now call binomial nomenclature – gave way even further to a more involved system of taxonomy or classification that included three kingdoms (animal, vegetable, mineral) and in each a hierarchy descending from class, order, genus, and species.

Catastrophism vs. Uniformitarianism - 18th Century (300 y/a)

• Catastrophism held that change was the result of stark changes (most often but not always classified as floods or deluges) that caused rapid and sudden alterations to occur in relatively small numbers of generations of animal and plant species.  These environmental catastrophes led to the wholesale loss of entire species, explaining why fossil records held evidence of plants and animals that were unknown to scientists.

• Uniformitarianism offered a slower, more gradual timeline with evolutionary changes and the emergence of species happening over substantially longer periods of time. James Hutton, one of uniformitarianism’s earliest proponents, used geological evidence to demonstrate that the world was older than previously assumed, and that the earth underwent long periods of “deep time” for largescale changes to gradually occur.

Thomas Malthus and Carrying Capacity

• Carrying capacity is an (often roughly calculated) measure of how many individuals of a given population can be sustained under the present circumstances. Environmental considerations such as the availability of food, presence of severe hazards or predators, climatic events, and illness factor into the total which can likewise be impacted by behavioral or even cultural changes (see for example the emergence of agriculture).

Lamarckian Evolution

• One of the early European scholars to introduce a theory of evolution was Jean-Baptiste Lamarck, an 18^th century French naturalist. His theory of species changes posited that physiological changes in an individual could be passed on to later generations, allowing biological advantages to be inherited in offspring. (The inheritance of acquired characteristics.)

Charles Darwin (Feb. 12, 1809 - April 19, 1882)

• Charles Darwin, an English Naturalist, Biologist, and geologist began his educational history in medicine but was eventually drawn to studies of nature.

• Beginning at the University of Edinburgh, then at Christ’s College in the university of Cambridge, and at last with his famous five-year voyage with the HMS Beagle, Darwin embarked on an in-depth study of the natural world.

• Among Darwin’s observations were detailed sketches that demonstrated variation within species and the first inklings of what would become his evolutionary theory

Origin of Species

• Darwin penned On the Origin of Species in 1859, auguring one of the most fundamental changes to the biological sciences and the foundation of evolutionary thought to follow. However, it was in reality the abstract to a larger text Darwin had initially envisioned.

• The central treatise of the book is that novel species emerge from a process known as natural selection, an idea that he proposed alongside (or, depending on your reading of history, in competition with) Alfred Russel Wallace.

Alfred Russel Wallace (Jan. 8, 1823 - Nov. 7, 1913)

• Alfred Russel Wallace, like Charles Darwin, had broad interests that included biology but also extended to geography and anthropology

• By 1858, Wallace had begun publishing a series of essays outlining his own observations on the emergence of new species, which mirrored closely those of Charles Darwin, whose exploits of the HMS Beagle had gained fame and inspired Wallace’s own voyages to the Amazon River Basin

Presentation to the Linnaean Society, 1885

• Darwin and Russell co-delivered a presentation to the Linnaean Society, a prestigious body of naturalists and other scientists

• The Talk was a flop.

• The annual newsletter of the society would later remark that no major theories of any import has been introduced that year

Natural Selection

• Darwin’s theory of Natural Selection posited like Lamarck, that environmental pressures played a role in evolutionary change

• However, where they differed was in the mechanism that transmitted change from one generation to the next

• While Lamarck focused on the notion that individual change over the lifetime was transmitted forward, Darwin saw social pressures that impacted reproduction as the source of intergenerational change

Fitness, Biologically Speaking

• Darwin’s concept of fitness boils down to one variable - an individual’s ability successfully reproduce.

  • Darwinian fitness isn’t about strength, speed, intelligence, or other common misconceptions, but specifically, about how well an individual fits to their circumstances

• On the face of it, this seems quite simple, but consider all the different intervening pressures that might intercede:

  • Environmental pressures: predation, availability of food, stability of habitat

  • Social/group: disruption of the social or group unit, intraspecies violence

  • Individual: pathology (also potentially environmental), disadvantageous mutation, infertility, unwise choices, sheer dumb luck

Turtles All The Way Down (finches, armadillos, beetles…)

• Darwin’s observations of living and extinct animals occupying the coastal regions of South America were instrumental in providing the initial research base upon which he would develop the theory of evolution laid out in The Origin of Species

• It would take another 20 years of careful observation and experimentation (and correspondence with other scientists like Wallace) before he would be prepared to release his findings

Who Was John Edmonstone

• A key figure in Darwin’s personal journey, and a scholar in his own right, John Edmonstone began life born into slavery in present-day Guyana.

• When the plantation at which Edmonstone was enslaved was visited by the naturalist Charles Waterton, he mentored Edmonstone in taxidermy.

• Edmonstone was freed in Edinburgh Scotland where he took up his taxidermy trade and eventually completed work for the Royal Museum of the University.

• There, his tales of the Amazon and his skill at taxidermy served as both inspiration and instruction for Darwin who would later embark on his journey with the HMS Beagle.