If, so far, you've been finding Mr Darwin's book tough going (it's OK, there's no shame in admitting it), here's what you should do: skip all that flannel about variation, and start here. This is where it gets serious.
Chapter 3 of the Origin, as its opening pages explain, faces in two directions. In chapters one and two, we've established the fact of variation, and the fluidity of living forms -- both in space, as shown by the blurry boundaries between species, and in time, as shown by the effect of artificial selection on domestic species. In the chapter to come, says Darwin, we'll be seeing how natural selection mimics human farmers. But why does nature select -- why does variation become adaptation?
Because, he says, life is hard, and not everyone can cope:
"We behold the face of nature bright with gladness, we often see superabundance of food; we do not see, or we forget, that the birds which are idly singing round us mostly live on insects or seeds, and are thus constantly destroying life; or we forget how largely these songsters, or their eggs, or their nestlings are destroyed by birds and beasts of prey; we do not always bear in mind, that though food may be now superabundant, it is not so at all seasons of each recurring year."
But if this chapter is transitional, reading it is less like crossing a bridge than jumping a canyon on a motorbike.
Ecologists in particular will see their scientific life flash before their eyes. As I read, I scribbled the contemporary jargon for the concepts that Darwin raises in the margin. Here's that list (if you don't know what they all are, don't worry; the point is that there are A Lot):
intraspecific competition, population biology, invasive species, r & K selection, diversity gradients, top-down vs bottom-up population control, niches, abiotic vs biotic population control, epidemiology, density dependence, parasitology, predator satiation, minimum viable population size, succession, food webs, pollination ecology, coevolution, interspecific competition, competitive exclusion, convergent evolution.
The intellectual pace is feverish, but the writing is always lucid: these are not half-baked speculations that Darwin is throwing out, they are fully formed insights. Here, for example, is density-dependent mortality -- the idea that population growth is curbed because crowding increases the death rate -- in a nutshell, with a side of epidemiology:
When a species, owing to highly favourable circumstances, increases inordinately in numbers in a small tract, epidemics -- at least, this seems generally to occur with our game animals -- often ensue: and here we have a limiting check independent of the struggle for life. But even some of these so-called epidemics appear to be due to parasitic worms, which have from some cause, possibly in part through facility of diffusion amongst the crowded animals, been disproportionably favoured: and here comes in a sort of struggle between the parasite and its prey.
On other occasions, he doesn't spell an idea out, but you can see a seed from which many careers have sprouted. Here, for example, is the germ of the notion that parasites will (sometimes) evolve to become less virulent: "The missletoe is dependent on the apple and a few other trees, but can only in a far-fetched sense be said to struggle with these trees, for if too many of these parasites grow on the same tree, it will languish and die."
If I were running an undergraduate ecology course (which, for everyone's sake, we can be glad that I am not), I would make this chapter the first thing on the reading list. It's a capsule textbook, and about twenty-eight times more exciting than any of the required reading I encountered as a student. (No offence, Begon, Harper and Townsend.)
According to Janet Browne's biography of the Origin, it wasn't the move away from a literal interpretation of Genesis that shocked Darwin's readers -- that was already well underway in diverse branches of science and theology. It was the vision of nature as ruthless and chaotic.
And this vision hasn't lost its power to shock. That word 'struggle' is repeated over and over at the chapter's beginning, until it becomes like a chant -- Fight! Fight! Fight!, as the audience used to say during playground bust-ups at my school (and that was just the teachers). When did 'struggle' turn into the substantially more wishy-washy 'competition'?
Darwin does claim that he uses the term Struggle for Existence "in a large and metaphorical sense, including dependence of one being on another". That's an important point, but in my ears such qualification was drowned out by the sound of what Bertie Wooster would call nature r. in t. and c.:
"[H]eavy destruction inevitably falls either on the young or old";
"I estimated that the winter of 1854-55 destroyed four-fifths of the birds in my own grounds";
"Battle within battle must ever be recurring".
Does Charles Darwin believe that nature, on the whole, is kind? No, on the whole, I think we must conclude that he does not.
And if there's one thing more likely to give your stereotypical prudish Victorian the creeps than all the death, it's all the sex. Nature's power to multiply, says Darwin, is not the harvest-festival fertility of a garden or orchard. Every living thing is straining to overrun the world. There is "no prudential restraint from marriage": reproduction is both the reason that existence is a struggle and one of the most potent weapons in that struggle.
In which case, thank goodness for the 360° carnage wrought on every species by predators, disease, the climate and, most especially, the other members of its own kind. "Lighten any check, mitigate the destruction ever so little, and the number of the species will almost instantaneously increase to any amount."
Phew. Then after all that excitement, we come to this last sentence:
"When we reflect on this struggle, we may console ourselves with the full belief, that the war of nature is not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy, and the happy survive and multiply."
Isn't that just the biggest copout of all time? It's as if William Golding finished Lord of the Flies and thought: 'That's a bit bleak. I know (writes): "But Piggy wasn't dead, he had just bruised his elbow, and all the boys went home to their mummies for tea and buns. The End." There! Much better -- don't want to bring everybody down.'
Sorry Chuck, the damage is done.
Next, Natural Selection. It's the longest chapter in the book, but you've got the weekend to read it.
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I was a little disappointed in Darwin's "better evidence" of Rapid Increase of Naturalized Animals and Plants. Since the intrinsic rate of increase is so central to his argument for selection, I would have thought that rather than a hand-waving "no one supposes that the fertility of these animals or plants has been suddenly and temporarily increased in any sensible degree" he'd have made some effort to measure whether the fertility rate changed in these situations. The 6th edition is no different. The Origin is sprinkled with quantitative studies by Darwin, so I wish he'd done better here. Does anyone know of any papers since Darwin that study this?
It is clear that this chapter has created a new excitement in your mind⦠There is nothing more powerful then a completely original idea.
A couple more questions:
For the ecologists: Is it true that elephant and rhino populations are unaffected by predation?
For the historians: Darwin says: "Nevertheless, so profound is our ignorance, and so high our presumption that we marvel when we hear of the extinction of an organic being; and as we do not see the cause, we invoke cataclysms to desolate the world, or invent laws on the duration of forms of life." What were the "laws on the duration of forms of life?" Is he refering to Charles Babbage's Ninth Bridgewater Treatise?
The "laws on the duration of forms of life" idea was put forward by Giovanni Battista Brocchi, who thought that species had an internally determined life in the same way that individuals have a limited lifetime. Lyell posited "centres of creation" with species dying out when conditions gradually changed, but when Darwin was reading this on the Beagle, he found fossils of giant mammals such as Megatheriums in undisturbed strata which went against the ideas of cataclysms or significant environmental change, and rejected Lyell's explanation in favour of Brocchi's explanation. Darwin entertained this idea until 1838 and it appears in the first edition of The Voyage of the Beagle, then his ideas of natural selection explained extinctions.
http://darwin-online.org.uk/EditorialIntroductions/Chancellor_fieldNote…
"When did 'struggle' turn into the substantially more wishy-washy 'competition'?"
"Struggle" is one of those emotionally loaded words, even anthropomorphic, that scientists wanted to steer clear of. "Competition" is more suitably sanitized, dry, politically correct -- yeah, wishy-washy.
It's worth noting, in re: the shift from 'struggle' to 'competition', that struggles need not be goal-directed whereas competitions tend to be. You can struggle to do something, yes. But one competes with the competition for a goal that both cannot win. Competition seems to me to better encapsulate the idea of natural selection, despite being wishy-washier, in addition to avoiding the emotionally loaded and anthropomorphic nature of "struggle."
in reply to chuck's second post: elephant and rhinoceros populations are "affected," as you say, by predation, as the very young and the very old are susceptible to attack by any number of terrestrial and aquatic predators. On top of that, there's human poaching, which is predation that affects the entire population, irrespective of age. Seriously, where did you get that idea?
there was a spectacular bbc clip a few years ago of a tribe of Lions which specialized on fully grown single elephants and brought them down. team work wins.
http://www.youtube.com/watch?v=NuX6O7QYDzk
never mind the link, was the wrong one.
In response to Tullar: Darwin p. 68 makes the claim "...in some cases, as with the elephant and rhinoceros, none are destroyed by beasts of prey: even the tiger in India most rarely dares to attack a young elephant." And I was hoping for data on predation rates rather than anecdotes.
When did 'struggle' turn into the substantially more wishy-washy 'competition'?
Like Judy said in her previous comment, competition is more politically correct than the term struggle is. Also, competition relates more to different species trying to survive to reproduce and pass on their adaptable traits to offspring for several generations. 'Struggle' is usually used to state that an animal needs to fight for its existence and has an extremely difficult time surviving to reproduction. Competition between individuals of the same species would be a more appropriate term because there are several more factors that affect an individual's chance of survival. It is a broader term, and can now relate to several types of animal behaviors that lead to reproduction.
On another note, Darwin uses the words struggle and competition interchangeably, even though they are some-what separate ideas. For example, in my own words Darwin basically said "Species evolve and form from the variation between individuals and the struggle of life,", but on the other hand he also said "All organic beings are exposed to severe competition." He does not distinguish the difference between struggling and fighting for survival through competition. In these two examples, Darwin states that species evolve because they must struggle to survive and at one point in every individual's lifetime they are involved in intense competition for survival.
I did enjoy reading this chapter of "On the Origin of Species" but i must say that I disagree with Darwin when he says "that the war of nature is not incessant." I think it definitely is. Natural selection is all about the concept that the animal who is best fit to their environment will be the one to survive. Animals in nature will always be trying their best to survive no matter the conditions. Their drive to survive can cause many "wars" within animal communities.
Chapter 3 of the Origin of Species was extremely interesting, especially the part in which Darwin talks in depth about the Struggle for Existence. He stated, "...We do not always bear in mind, that though food may now be superabundant, it is not so at all seasons of each recurring year." I found that to be very thought-provoking because I truly figured out how this lends itself to Natural Selection and variation among species. Because there is always a different atmosphere among organisms each year, whether it be because of overpopulation or just a lack of resources and food, the need to adapt is also different each year. As Darwin was saying, when more individuals are produced than can possibly survive, there is going to be greater competition and, therefore a "struggle for existence." Only the most fit (the ones most able to adapt) of animals will then survive, and they will pass their genes to their offspring, in the hopes that one day there will be a superior and near perfect variation of that species in existence. Of course, the animals don't actually think this way, but it is part of their genetic goal to survive to reproduce.
The chapter I read was really extrodinary on a few notes. First, It was astonishing on how Darwin devoted his life to studying the processes of evoultion in a species. Second, he gave a substantial amount of examples to support his theories. Towards the end of the chapter, Darwin talked about epidemics and evoultion. To my view, that was an extrememly fasinating fact about survival of a species. For example, some organisms that pass disease, such as worms or certain types of insects, must pass the disease to survive to reproduce. An example of this process that he stated that a certian type of worm must pass the disease that it is carrying by means of eating blood or certain bacteria. The results can be life-threatening to the infected, but to the other side, it is a glorious feast. Therefore, if the worm does not feed (by means he will be passing the disease), the worm will not survive, and therefore not meet its biological goal.
Would Darwin's idea of existence is a struggle be applied to humans? Do humans compete for existence by fighting one another? And if so, wouldn't the higher class win due to Darwin's idea that a species that has adapted more to their environment will most likely survive longer than one who hasn't?
If Darwin's idea of the Struggle makes evolution seem like a competition, are there ways, in this current generation, we as humans are cheating or giving up? Can we assume promiscuity, rape, and test-tube babies in this generation are cheating in this "competition" and possibly creating the struggle harder for those pursuing natural selection? Those without children, or born with sexual differences, are they giving up in the competition?