Darwin and Wallace 1858

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Darwin and Wallace, chillin’
Let’s talk about Darwin and Wallace’s joint presentation on Natural Selection in 1858.

It is not usually the case that I write a blog post for a carnival. I usually just write for the blog, then now and then sit down and figure out which posts should go to with carnivals. That is not the case with this post.

Some time ago I thought, while writing a Peer Reviewed Research post, that it would be interesting to write up older papers, classics, or more recent papers that were of great interest for one reason or another but maybe a few years old. Just around that time, this idea of a classic carnival … a carnival of classic science papers … came around (details here and here), and I thought that was a very cool idea.

I have a plan to write a couple of different series of posts, one with Bob Trivers’ papers (see this for a taste), which will come along very easily, as I have taught a course based primarily on his work. Another would be on papers regarding Race and Racism. Again, this would draw heavily on my course on Race and Gender. A third stream of posts may come from the Bioanthropology tutorial I taught at Harvard. That was some years ago, so even the ‘current’ papers from that effort may now be classics (Tim Caro’s work with hyenas springs instantly to mind). Thinking about that approach led me to consider the first paper I usually assigned in that tutorial, and in fact, ‘the’ first paper in the field of evolutionary biology (perhaps, depending on your perspective).

That paper, I thought, is what this post should be about. Darwin and Wallace’s first composite paper on Natural Selection.

The only question remains: How many other people are going to do the same thing? Probably scads of them. So, I’ll have to make this a little different…..


You all know the story, and if not, I provide links a number of excellent recent writeups below. Darwin was part of the established academic elite in Britain at the time that young upstart Wallace came along with an idea very close to what everyone knew Darwin was working on. So key members of those established patched together a talk and a publication so Darwin would not be scooped and Wallace would not be ignored. Exactly who did what and how well it went can be debated, but we do have these two side by side manuscripts to compare two different perspectives.

Here, all I want to do is to present, with minimal analysis, what I see as representative excerpts of each of the two works for you to make an efficient side by side comparison. The full text can be obtained here.

Darwin

The Malthusian Imperative:

for animals without artificial means, the amount of food for each species must, on an average, be constant, whereas the increase of all organisms tends to be geometrical, and in a vast majority of cases at an enormous ratio. Suppose in a certain spot there are eight pairs of birds, and that only four pairs of them annually (including double hatches) rear only four young, and that these go on rearing their young at the same rate, then at the end of seven years (a short life, excluding violent deaths, for any bird) there will be 2048 birds, instead of the original sixteen. As this increase is quite impossible, we must conclude either that birds do not rear nearly half their young, or that the average life of a bird is, from accident, not nearly seven years. Both checks probably concur. The same kind of calculation applied to all plants and animals affords results more or less striking, but in very few instances more striking than in man

Variation in context and adaptation:

…let the external conditions of a country alter. If in a small degree, the relative proportions of the inhabitants will in most cases simply be slightly changed; …Now, can it be doubted, from the struggle each individual has to obtain subsistence, that any minute variation in structure, habits, or instincts, adapting that individual better to the new conditions, would tell upon its vigour and health? In the struggle it would have a better chance of surviving; and those of its offspring which inherited the variation, be it ever so slight, would also have a better chance.

Sexual selection:

Besides this natural means of selection, by which those individuals are preserved, whether in their egg, or larval, or mature state, which are best adapted to the place they fill in nature, there is a second agency at work in most unisexual animals, tending to produce the same effect, namely, the struggle of the males for the females.

Diversification and speciation:

Another principle, which may be called the principle of divergence, plays, I believe, an important part in the origin of species. The same spot will support more life if occupied by very diverse forms.

Wallace

Critique of the stability of ‘species’

…varieties [subspecies or breeds] … are … unstable, and often have a tendency … to return to the normal form of the parent species; …

[this observation]… has led to a very general and somewhat prejudiced belief in the stability of species. Equally general, however, is the belief in what are called “permanent or true varieties,”–races of animals which continually propagate their like, but which differ so slightly (although constantly) from some other race, that the one is considered to be a variety of the other. Which is the variety and which the original species, there is generally no means of determining, except in those rare cases in which the one race has been known to produce an offspring unlike itself and resembling the other. This, however, would seem quite incompatible with the “permanent invariability of species,”…

… it is the object of the present paper to show that … that there is a general principle in nature which will cause many varieties to survive the parent species, and to give rise to successive variations departing further and further from the original type…

Selection

The life of wild animals is a struggle for existence. The full exertion of all their faculties and all their energies is required to preserve their own existence and provide for that of their infant offspring. The possibility of procuring food during the least favourable seasons, and of escaping the attacks of their most dangerous enemies, are the primary conditions which determine the existence both of individuals and of entire species. …

Overproduction

Even the least prolific of animals would increase rapidly if unchecked, whereas it is evident that the animal population of the globe must be stationary, or perhaps, through the influence of man, decreasing. Fluctuations there may be; but permanent increase, except in restricted localities, is almost impossible….

And more selection

… so long as a country remains physically unchanged, the numbers of its animal population cannot materially increase. If one species does so, some others requiring the same kind of food must diminish in proportion. The numbers that die annually must be immense; and as the individual existence of each animal depends upon itself, those that die must be the weakest–the very young, the aged, and the diseased,–while those that prolong their existence can only be the most perfect in health and vigour–those who are best able to obtain food regularly, and avoid their numerous enemies. It is, as we commenced by remarking, “a struggle for existence,” in which the weakest and least perfectly organized must always succumb.

Species level selection (or macro patterns of evolution)

Now it is clear that what takes place among the individuals of a species must also occur among the several allied species of a group,–viz. that those which are best adapted to obtain a regular supply of food, and to defend themselves against the attacks of their enemies and the vicissitudes of the seasons, must necessarily obtain and preserve a superiority in population; while those species which from some defect of power or organization are the least capable of counteracting the vicissitudes of food, supply, &c., must diminish in numbers, and, in extreme cases, become altogether extinct. Between these extremes the species will present various degrees of capacity for ensuring the means of preserving life; and it is thus we account for the abundance or rarity of species…

The nature of the arguments are very different, but the principles at work are similar. Wallace and Darwin have different (but overlapping) mechanisms in mind for the source of variation, and both are pretty undeveloped at this stage. Both have strong Malthusian principles at work, both have a range of descriptions for the kinds of competition. Wallace sees more inter-species struggle than Darwin discusses here, but if you read the rest of Darwin, they are not too different in this respect. It has been fashionable to underscore the differences between them (and that is quite interesting) but if each of these writings were proffered as answers to an AP biology exam question asking “What is Natural Selection … how does it work and what is the evidence for it?” the two essays would score about the same grade.

I wonder what the grade would be?
___________

More about Darwin and Wallace at The Austringer and here at the Beagle Project.

Darwin, C. R. and A. R. Wallace. 1858. On the tendency of species to form varieties; and on the perpetuation of varieties and species by natural means of selection. [Read 1 July] Journal of the Proceedings of the Linnean Society of London. Zoology 3: 46-50. On line here.

I’m including this on the Sb peer Reviewed Journal Article Feed because I regard this as a peer reviewed article. If you don’t, let me know. We can talk.

Comments

  1. #1 Mark Bailey
    July 14, 2008

    Good comparison; I think the date in the title is a typo (1858, not 1958).

  2. #2 Andrew
    July 15, 2008

    An oldie but a goodie

  3. #3 Roy Davies
    July 16, 2008

    Your comparison of the ideas of both men is helpful but also misleading for those who have not studied the subject in depth. The clue is in Darwin’s statement…’let the external conditions of a country alter…’ and Wallace’s ..’so long as a country remains physically unchanged…’.
    This difference is crucial in understanding why Wallace deserves to be recognised as the true discoverer of the theory of evolution and why Darwin does not.
    Darwin’s theory of 1844 from which his Linnean extract was presented by Lyell and Hooker was still based on the idea that a state of perfect adaptation existed in the world. In Darwin’s mind, species perfectly adapted to their environment could not change into different species since new species could never survive in the new environment.
    Hence Darwin’s need for a change in physical conditions before new species could originate. Only by migration to newly formed environments could existing species change into new species.
    Darwin’s belief in the idea of perfect adaptation remained as a core belief until after the received his first letter from Wallace in January 1857 – only 18 months before the Linnean meeting.
    Wallace had no truck with such quasi-religious ideas. (Darwin had taken the idea of perfect adaptation from Lyell – a true believer – on his return from the Beagle voyage). Wallace had no need for a change in physical condtions and indicated to Darwin in that first letter that he believed species modified and diverged as a result of millions of tiny changed over vast periods of time.
    On his newly formed and bare oceanic islands Darwin knew that species could not take eons to change from one form into another otherwise the migrating parents would perish in the now non-perfect conditions. So, early on, he had come up with the idea of change by one species jumping into a form which was perfectly adapted to the new conditons.
    Darwin never explained when it was that he dropped such primitive ideas. Certainly his ideas had not changed in the natural selection mss. he was still writing when Wallace’s third letter arrived at his home on June 3, 1858.
    Two other things about that Linnean meeting:
    1. The Malthus extract was introduced simply to head off Wallace’s explicit tribute to Malthus’s ideas in giving him the final piece of his intellectual jigsaw. Even Francis Darwin was minded to ask how Malthus had influenced his father’s first theories when they had been written out a whole year before he read Malthus.
    2. Darwin’s futile attempt to define the workings of his principle of divergence to Asa Gray which was the third extract to be read out by Lyell and Hooker was risible. It gives no idea of how the so called principle worked and still reads today as if he is repeating a concept he doesn’t understand. Moreover Darwin never told Lyell or Hooker of Asa Gray’s response to his ideas of divergence as amounting to being ‘grievously hypothetical’.
    For all this and other evidence as to why it is Wallace and not Darwin who should now be feted as the man who discovered the theory of evolution you should get my book ‘The Darwin Conspiracy: Origins of a Scientific Crime’ published by Golden Square Books here in London and available through . Web: http://www.thedarwin-conspiracy.com.
    Your academic peers are trying to ignore it, hoping it will go away but it is slowly appearing in more and more bookshops here in the UK and hopefully, soon, in the USA.

  4. #4 Nigel
    August 7, 2008

    “Darwin was part of the established academic elite in Britain at the time that young upstart Wallace came along with an idea very close to what everyone knew Darwin was working on. So key members of those established patched together a talk and a publication so Darwin would not be scooped and Wallace would not be ignored.”

    My understanding is that by no means did “everyone” know what Darwin was working on. As I have always heard it, only a handful of his very closest scientific friends knew anything significant about his thoughts on evolution and natural selection. Lyell and Hooker knew (but even they only learned about it a couple of years before the Linnaean Society meeting, almost twenty years after Darwin had conceived the basic ideas), and Asa Gray in America knew something. Perhaps there were one or two others, I don’t know, but certainly these did not include even T.H. Huxley, despite the fact that Darwin knew him quite well, and he would turn out to be the theory’s most effective supporter.

    Also, it is just a quibble, but it is a bit misleading to call Darwin “part of the established academic elite.” True, he was a scientist who was well respected in academia by this time, and certainly much better known and better connected than Wallace, but he was never an academic at all in the sense of holding a university or other similar institutional post.