Week 1 - Historical Influences on Darwin

Week 1 – Historical Influences on Darwin

 

1. Thomas Robert Malthus (1766-1834)



2. I consider Thomas Malthus to have been the most influential over Darwin's refinement of his theory of Natural Selection. Malthus, an ordained minister, and English political economist, is
known for his influential theories of population growth. In his Essay on the Principle of Population (1798), he describes how increases in population would diminish the world’s ability to feed itself, for population growth would always overpower food supply growth.

Population growth is exponential/geometrically
 
       1                       2                                           4

Food supply growth is arithmetical
 
     1                  2                             3                                   
This in turn created a constant struggle for resources which are crucial for survival.

The following quoted passage from Darwin’s autobiography (1876) helps confirm my thoughts on the matter. “In October 1838, that is, fifteen months after I had begun my systematic inquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The results of this would be the formation of a new species. Here, then, I had at last got a theory by which to work”.

http://www.econlib.org/library/Enc/bios/Malthus

3. The points that I feel are most affected by Thomas Malthus’ work are:

All organisms have the potential of reproducing exponentially - Two rabbits are roughly capable of producing approximately 200 rabbits in their lifetime. Imagine if all 200 baby bunnies had 200 hundred more baby bunnies…and so on…. and so on… That is exponential growth.

Resources are limited - Our planet has a limit of how much it can hold and produce. There will not be enough resources available for all organisms to reproduce as many offspring as they can.

What is preventing organisms from reproducing at their potential – Something is keeping those rabbits from producing all those bunnies. Baby rabbits are costly to the parent to produce. The parent needs time, shelter, food, water and protection from predators. These needs are called “resources”. Resources are limited – Our planet has a limit of how much it can hold and produce. There will not be enough resources available for all organisms to reproduce as many offspring as they can.


In his essay, Thomas Malthus explains how population growth vs. food supply growth creates a struggle for resources. As he described, humans reproduce exponentially, but the manner in which food supply (resource) grows prevents survival, for resources are the crucial ingredients and the key to population growth. This concept had a positive effect on Darwin. Not only did he expand it to include all organisms (not just humans), but he also understood the importance it had on the process of natural selection, for a limited supply of food and water would create competition. This competition is the key to understanding natural selection. As a matter of fact, he made it one of the four components of his process of Natural Selection; “High rate of population growth – Most populations have more offspring each year than local resources can support leading to a struggle for resources. Each generation experiences substantial mortality"(TheGlobalChangeProgramattheUniversityofMichigan.edu).



4. Charles Darwin was not only influenced by people like Jean-Baptiste Lamark, his
grandfather Erasmus Darwin, Charles Lyell, Thomas Malthus, but also by the observations made during his voyage as a naturalist on the British ship Beagle. The core of Darwin’s theory of evolution is natural selection, and although he had other sources from which he developed this theory it was Thomas Malthus’ work that enabled him to refine it. “If evolution was the machine, and natural selection was the engine, then Malthus’ perpetual struggle for resources was the fuel” (AllAboutScience.org).

5. During Darwin’s time, the church’s explanation to the diversity of life could be found in
the bible; God was the divine force that created all of the species found on earth and these stayed fixed. He knew that his theory of evolution would anger many, and possibly ruin his career. This fear prevented him from sharing his ideas with others. But in 1859, after 23 years of conducting experiments, gathering an abundance of evidence and finally building up the courage, he published his book, On the Origins of Species. This book is “considered to be the foundation of evolutionary biology” (Wikipedia.org) .

Book of Genesis order of creation

vs.

On Origins of Species by Charles Darwin