Today, I’ll be taking us back to the beginning of life science, and discussing the evolution of, well, the way we think about evolution. All science has philosophy at its roots, and evolutionary biology is certainly no exception. The field of biology can trace a path back to Plato and Aristotle, who both subscribed to the essentialist view. Essentialism says that for any specific entity there is a set of attributes which are necessary to its identity. For example, a chair has a set of attributes (legs, seat, back) that make it a chair rather than, say, a stool. Any given species also has a set of identifying attributes, and an individual can be classified as a member of that species if it satisfies that list.
Figure 1. A chair has a set of attributes (legs, seat, back) that make it a chair rather than, say, a stool. But how does a chair compare to a throne? (Source: public domain)
Carl Linnaeus, the famous Swedish botanist, physician, and zoologist who formalized the modern system of naming organisms we know today as binomial nomenclature, epitomized the essentialist view of biology. He named and grouped organisms based on their similarities and differences – as any good essentialist would do. Linnaeus was, by all accounts, a religious man who believed that he could find a deeper understanding of God by studying his creation. Many naturalists of his day, and before, were similarly minded – religion was omnipresent, and most scientists of the time were religious.
Figure 2. Carl Linnaeus formalized the modern system of naming organisms we know today as binomial nomenclature. Shown here is the cover page of Linnaeus’ magnum opus, published in 1735. (Source: public domain)
Over the next fifty years, naturalists began moving away from a strictly religious interpretation of their science. James Hutton and Charles Lyell dared to suggest that the Earth was older than the Bible might indicate. Georges Cuvier noticed that fossils of animals were found in locations that did not include extant populations of those animals, suggesting local extinctions were possible, contrary to the predominant religious beliefs of the time. By the late eighteenth century, the idea that life might not have been completely static since the beginning of creation had begun to percolate through the scientific community, though these ideas were mainly restricted to the fringes of academia and society.
Contrary to what you might think, Darwin was not the first to suggest a mechanism by which species could change over time. Jean Baptiste Lamarck argued in favor of evolution via the use and disuse of certain body parts. For example, a giraffe originally had a short neck, but over its lifetime of stretching in order to reach leaves on taller branches, its neck grew. The longer-necked giraffe would pass that change down to its offspring, who would then stretch that neck even further, and so on until we reach the long-necked giraffe seen today. However, his mechanism for evolution lacked plausibility; after all, people could certainly gain muscles through repeated use, but a very heavily muscled parent did not necessarily lead to a heavily muscled baby.
Figure 3.Lamarckian evolution, as exemplified by a giraffe. (Source: public domain)
Another naturalist would shortly propose a more believable mechanism to explain changes in species over time. Charles Darwin, influenced by Thomas Malthus and by his own travels in South America and the Galapagos Islands, saw all life as a struggle for existence. He suggested that such a struggle led to a natural selection of organisms that were more “fit”, better able to survive and reproduce and thereby pass on those traits which made them well-suited for their environment. He believed that all living things are related. Over 150 years later, countless lines of evidence have verified Darwin’s crucial ideas – that all living creatures are related, that evolution is responsible for the differences between them, and that natural selection has a large role in shaping evolution. Of course, how those traits were passed on was still very much a mystery to Darwin, but that mechanism too would soon be elucidated.
Figure 4.The first known drawing of a phylogenetic tree, a diagram describing the relatedness of organisms. (Source: public domain)
Gregor Mendel, a German monk, would posthumously become known as the father of modern genetics. His simple research growing pea plants would go on to establish foundational principles in the field of inheritance. For example, he found that by crossing a pure-bred green pea plant to a pure-bred yellow plant, all of the offspring would be yellow; however, if he allowed those offspring to self-fertilize, approximately 3/4s of the next generation would be yellow, but some would be green. He proposed that each offspring plant inherited a copy of the color gene from each of its parents and believed that the green copy was masked by the yellow. He was operating at the same time as Darwin, yet there is no substantial proof that Darwin would have heard of Mendel or his work before Darwin died in 1882. And yet, Mendel’s research provided the very mechanism by which traits were passed on that was missing in Darwin’s theory of evolution, and it would go largely unnoticed until the early twentieth century.
Figure 5. An example of Mendel’s experiments with genetics. (Source: The Tech Museum of Innovation).
The marriage of Mendelian genetics with Darwinian evolution early in the twentieth century has proven to be incredibly fruitful. This Modern Synthesis of biology, and the steps we’ve made since then, will form the basis of my next post. Until then, I hope you’ve enjoyed this brief walk through evolutionary history!
More From Thats Life [Science]
- Biology Superpowers: X-Ray Vision
- How to Expand Your Senses by Reading a Blog Post
- What's up with bat echolocation?
- Seeing is Believing - How Can We Visualize Tiny Colorless Bacteria?
- Saving water is no longer a matter of how short our showers are · Water balance in a man-made world
- Double Digestion in Rabbits · Why Does Mopsy Eat Her Own Poop?
- Should I say sex or gender? Pt. 2
- Should I say sex or gender? Pt. 1
- How To Catch Hard-to-Catch Fish?
- Finding the Perfect Partner
- Is your gut trying to kill your resolve? · Mind over microbe
- Why Do Mothers Mother?
- GMO! The Places You'll Go!
- New-Fangled Paleontology · Really Old Fossils, Really Strong Predators, and Cool New Tech
- A Brief History of Evolutionary Thought, part III
- Saving face: transplanting our most distinctive features
- A Brief History of Evolutionary Thought, part II
- DNA as a solution for data storage · DNA - Nature’s Hard Drive
- A Crash Course in the Coolness of Mitochondria · Mitochondria: The Underrated Organelles
- A Pollinator’s Job Description and Why We Should All Care About Them · Pollination 101
- You May Say I’m Biased, But I’m Not the Only One
- The evolution of one of the greatest medical discoveries in history. · The Path of Least Resistance: Our Relationship with Antibiotics
- Mother Nature’s History Book · Estimating the Age of Life Long-Gone
- Proprioception as a vital sense · Know Your Limb-its
- Man’s Best Artificially-Selected Friend · Your Dog is a GMO Wolf
- Better Safe Than Sorry: The Pesticide Industry is Getting a Revamp
- Sometimes scientists have to get creative in order to effectively do science – especially on a budget. · The Bizarre Shopping List of a Determined Scientist
- Insects Get Sick Too: The Study of Insect Pathology
- Our teeny tiny friends and their huge potential · Employee of the Month - Hire a Microbe to Do Your Work
- A Brief History of Evolutionary Thought - Part I
- The Effects of Custom Build Paradise · Artificial Islands
- To B(PA) Or To Not B(PA): Regulating Endocrine Disruptors
- Bioluminescence truly looks like it is nothing short of sorcery, and although this naturally occurring phenomenon is well studied and explained, that does not take away from its beauty. · Fireflies of the Ocean: Lighting up the Dark with Science
- Part II - Cases of altruism in the animal kingdom · Charity cases in nature - when are animals more likely to be altruistic?
- Part I - Why true altruism is a rare behavior in the animal kingdom · Being selfish means staying alive
- Penguins and other strange things we study from space
- Pseudoreplication and the Art of Biological Statistics
- What is wrong with my tomatoes?...And other plant disease questions · Why did orange prices increase?
- How fecal microbiota transplants can improve lives and possibly save them · The Wonders of Fecal Transplants
- The scientific facts behind the safety and efficacy of childhood vaccines · Calling the Shots - Discussing Vaccines
- 3D Printing for Fun and Science
- What is wrong with my tomatoes?...And other plant disease questions · What is Phytopathology?
- Medical Mysteries Still Surrounding Zika Virus
- More ›