In considering the influences on Charles Darwin's development of his theory of natural selection, I choose to consider Thomas Robert Malthus.
"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". Charles Darwin, from his autobiography. (1876)
(As Quoted on http://www.ucmp.berkeley.edu/history/malthus.html )
Thomas Malthus was a 19th Century Economist who in his essay On the Principle of Population (1798) made the observation that the rate of population grew faster than the growth rate of the available resources. It was an observation made along the way to another point (that there must me economic factors at work that prevented the complete collapse of the human population, and that those economic factors are worth studying), it was this observation that inspired both Charles Darwin and Alfred Russel Wallace, respectively. The principle was basically that there are limited resources (food, water, shelter and so forth) and that population, unchecked, will grow beyond the resources ability to support the population. Darwin, and separately Wallace, then moved forward to say that there were specific traits that made certain animals that had them more likely to be able to secure resources than were those animals and species without those traits. The favored traits would then be more likely to reproduce and therefore to continue and influence the population of that species towards a change from a mix of traits towards a more homogeneous state of containing the favored trait. It was Malthus' observation that raised the framework for evolution by natural selection.
The points of Darwin's theory most clearly influenced by Malthus are absolutely the potentiality of exponential population growth, the obvious fact that there were limiting factors on this growth, and limited resources and the ability to gain these resources.
It's also interesting to consider the other potential outcomes of Thomas Malthus' ideas, including the proponents of eugenics and proponents of population control. It's frightening to consider that the absolute twisting of these ideas could lead to policies like the genocidal policies of Nazi Germany during WW2 as well as the one child policy in China. Less horrific ideas that were given forth from the idea that population grows beyond the resources with which to support it would be that of the birth control (and subsequent abortion) movement. Margaret Sanger would have been very much on the same page as Malthus in the belief that large families are not to the benefit of society (though I do not agree with Ms Sanger, who would have found it to her detriment if her parents had stopped having children sooner, since she felt the sting of being in a large family, but also was one of the youngest of the siblings).
Beyond Mathus' influence over the development of the idea of natural selection (central to the theories about species that Darwin developed), but also had a secondary effect of finally spurring Darwin to publish his ideas when independent of himself, and through the reading of Thomas Malthus' work, Alfred Russel Wallace came to the same conclusion about natural selection (even calling it that) totally independent of Darwin. And Alfred's confirmation pushed Darwin to publish, finally, two decades after the Beagle docked and he left her. Malthus was most certainly one of the giants upon whose shoulders Darwin stood.
There seems little chance of Darwin (or Wallace) having arrived at the idea of evolution by natural selection without the foundational ideas of Thomas Malthus. Thomas Malthus' ideas are so central (and so much of) the theory of natural selection, as to be integral. Without the concept of population growth and limited resources, how does Darwin bridge the gap produced by inherited traits being favored and thus changing the population of a species over time, even to diverging into separate species over much time.
Some argue that the 20 year delay for Darwin in publishing his theory was due to his fear of the social and political ramifications of his theory because it defied the Christian Biblical belief, held as an immutable doctrine at the time when the church had a wide reaching influence in all areas of public life. There was a very real potential for being black balled at the best, from social interactions or punished by the church or the government. Yet, there is also much evidence that a significant factor in Darwin's long delay in publishing his theories had to do with his desire to gather as much evidence as possible, and have as solid a case in favor of his argument as possible, as to not seem premature, but also as to be able to refute arguments regarding his ideas of common ancestry as well as those of natural selection. It may be that the power of the church and his discovery which flew in the face of what some believed the Bible to be saying caused Darwin's delays, but it is also quite likely that he was as conscientious and careful in his research as one would think, and chose to not be too quick to publish an idea that would throw the world on it's ear before he'd throughoughly investigated it's possibilities and provided as much evidence as possible
Resources:
http://www.ucmp.berkeley.edu/history/malthus.html
http://www.bbc.co.uk/history/historic_figures/malthus_thomas.shtml
An Introduction to Biological Evolution by Kenneth V. Kardong
Introduction to Physical Anthropology by Robert Jurmain et. al.
http://home.uchicago.edu/~rjr6/articles/Why%20Darwin%20Delayed.pdf
Great choice of quote. That, to me, sums up the discussion for question 3.
ReplyDeleteA minor clarification on Malthus' work. Malthus drew conclusions for human populations based upon his observation of non-human populations. He observed that non-human populations seemed to be subjected to natural limiting factors that prevented overpopulation, factors such as limited resources. He compared that to human populations and was concerned by an apparent absence of any such limiting factors. Unless humans chose to self-regulate their reproduction, they ran the risk of overpopulation, famine and disease. It was his observations on non-human populations, along with these "natural regulating factors" that intrigued by Darwin and Wallace and led them to identifying natural selection as the non-random selecting factor.
Good choice of bullet points.
Great tangent discussion on the distorting of these concepts, though while Malthus was a strong proponent of birth control, I'm not sure how he would have felt about abortion, except perhaps to suggest that, like famine and disease, abortion is the necessary result of inadequate use of birth control. But I digress...
As I stated in the first sentence, that quote from Darwin offers strong support as the the indispensable nature of Malthus' ideas to the development of Darwin's theory.
"Yet, there is also much evidence that a significant factor in Darwin's long delay in publishing his theories had to do with his desire to gather as much evidence as possible, and have as solid a case in favor of his argument as possible, as to not seem premature, but also as to be able to refute arguments regarding his ideas of common ancestry as well as those of natural selection."
This doesn't rule out that both were a factor, does it? In fact, a sound argument would have helped him gain support from his fellow scientists in the face of challenges from the church.
I've read Richard's article (and John van Wyhe's more recent writings). They seem to suggest that Darwin didn't "delay" at all, but was still publishing during this time period and just perfecting his pet publication But that fails to recognize some stark realities. Darwin was well aware that his work would be considered controversial. To think that this didn't come into play in his decision to delay (or perfect his writings, if you'd rather), at least in part, is absurd, giving the relationship between science and the church at that time and the vigorous and sometimes ugly debate that arose after he did publish. It also completely ignores the influence of Darwin's very religious wife and his devotion to her and his family, particularly after the loss of his daughter, Annie. And yet, isn't it great to be able to debate this? :-)
Good post.