Field of Science

Blogging the Origin: Chapter III: Struggle for Existence

Alright, this is a nice short and sweet chapter that goes one step further in making Darwin's case. Let's recall that Darwin is attempting to provide an answer to the question, where do species come from? While several potential answers to this question already existed, they lacked a mechanistic component that could provide explanatory power.

So far we have established the variation within a population of organisms obviously exists in domesticated animals (think of all the variants of dogs and apples). We have also established that variation exists in the wild, although we often overlook it. If anyone has doubts about the existence of variation within populations, please leave your point or issue in the comments and I'll try to address it.

Now Darwin is laying out another, albeit distinct, fact. Namely that populations increase to the point where there is competition between individuals within and without the population. First, he lays out the idea of a 'struggle for existence' incorporating both within a population and between populations in one beautiful paragraph:

I should premise that I use this term in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny. Two canine animals, in a time of dearth, may be truly said to struggle with each other which shall get food and live. But a plant on the edge of a desert is said to struggle for life against the drought, though more properly it should be said to be dependent on the moisture. A plant which annually produces a thousand seeds, of which only one of an average comes to maturity, may be more truly said to struggle with the plants of the same and other kinds which already clothe the ground. The mistletoe 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 languishes and dies. But several seedling mistletoes, growing close together on the same branch, may more truly be said to struggle with each other. As the mistletoe is disseminated by birds, its existence depends on them; and it may metaphorically be said to struggle with other fruit-bearing plants, in tempting the birds to devour and thus disseminate its seeds. In these several senses, which pass into each other, I use for convenience sake the general term of Struggle for Existence.
Purves et al., Life: The Science of Biology, 4th Edition
It is trivial to think of examples, add your favorites to the comments. However, I want to add a popular figure that I think shows a between group 'struggle for existence' remarkably well. The old moose-wolf population change over time. I think it is important to consider the competition between wolves when the moose population is low (~1977) or between moose when their population is high (~1972 or 1987).

S. pneumoniae strains
growing in MS medium
It is obvious that all organisms 'struggle for existence', now Darwin folds in the concept of geometric growth. The point here is that organisms tend to increase in population at a high rate. For example, here is the growth of bacteria in culture. You can clearly see the rapid increase in population size (the vertical y-axis labelled OD620) over time (the horizontal x-axis in minutes). This kind of growth is termed exponential growth (geometric growth in Darwin's day).

A generic version of exponential growth looks like this.  The 
real data with S. pneumoniae shown above only has the A, B, and C aspects of the growth curve on it (we'll come back to the D aspect). So in a normal bacterial growth curve there is an A (lag) phase, a B (logarithmic) phase, a C (stationary) phase, and a D (death) phase. This also appears to be the case with other organisms including mammals (see the same phases for both moose and wolves above). Hell let's look at the human population:

There's a clear A and B phase. Where's C and D?
Alright, so life is tough (aka struggle for existence) and organisms tend to grow without end. However, Darwin points out the obvious. Nature puts constrictions on the ability of an organism to grow without end. In fact, the vast majority of most offspring don't make it, and by make it, I mean make it until able to reproduce. There are limitations on food or other resources (including space, try finding affordable housing in any urban center without competing with rats or roaches). There are limitations based on climate, mosquitoes will thrive this year from the lack of a winter in the US, mosquitoes probably won't be doing as well in Europe for the same reason. There are limitations by predation, already the chickadees and junckos have easily taken out several thousands seeds in my backyard this year or just look at the moose-wolf graph above. And don't even get me started on parasites:
Perhaps Paraguay offers the most curious instance of this; for here neither cattle nor horses nor dogs have ever run wild, though they swarm southward and northward in a feral state; and Azara and Rengger have shown that this is caused by the greater number in Paraguay of a certain fly, which lays its eggs in the navels of these animals when first born. The increase of these flies, numerous as they are, must be habitually checked by some means, probably by other parasitic insects. Hence, if certain insectivorous birds were to decrease in Paraguay, the parasitic insects would probably increase; and this would lessen the number of the navel-frequenting flies--then cattle and horses would become feral, and this would certainly greatly alter (as indeed I have observed in parts of South America) the vegetation: this again would largely affect the insects; and this, as we have just seen in Staffordshire, the insectivorous birds, and so onwards in ever-increasing circles of complexity.
From this one example, we see an obvious check on the growth of a population, but also the interconnectedness of many distinct species and how disrupting one (to benefit another) can have dramatic consequences. You can insert your favorite invasive species here as an example.

Shortly after the above statement, Darwin eloquently states:
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 the forms of life!
I cannot help but wonder what critique or 'reviewer' this was addressed to.

The chapter finishes by coming back to where we began. There is an obvious struggle between and among individuals of the same and distinct species. Furthermore, there exists variation in essentially all traits between individuals of the same species. From these two well established facts, the deduction that the variation within a species can serve to benefit or hinder the ability of an individual in its struggle for existence. I'll let Darwin express it himself:
This ought to convince us of our ignorance on the mutual relations of all organic beings; a conviction as necessary, as it is difficult to acquire. All that we can do is to keep steadily in mind that each organic being is striving to increase in a geometrical ratio; that each, at some period of its life, during some season of the year, during each generation, or at intervals, has to struggle for life and to suffer great destruction. 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.
Please add your own thoughts and comments below and get cracking on chapter 4, it's great but a longer one.  I also want to thank RBH and CMB for reading and letting me know these posts matter at least a little.

Due to a coin flip, I get to control my sex life.

Because the sperm cell that happened to fertilize the egg, which ultimately came to be me, carried a Y chromosome instead of an X chromosome, I am a male human. There was an additional Y carrying sperm cell and two X carrying sperm cells resulting from the meiotic division that gave rise to the sperm cell that yielded slightly less than half of my DNA. (Slightly less than half because my mitochondrial DNA came from the egg.) Thus, I was born male because chance had a certain sperm cell win and others not. (I guess it's possible gremlins in my mother's uterus blasted the other sperm with lasers, guaranteeing the success of a specific sperm, but I doubt it.) I begin this way to make the point that based on essentially a coin flip, I happen to be male. If a different sperm had won, I would be a woman and my life and ability to make my own reproductive choices would be fundamentally different. This is true even though I live in a country that likes to express how free it is.

Consider that this year (though it is really only slightly worse than other years), the freedom of a woman to choose to have an abortion is being limited in a significant way. This includes women, like a fourteen year old girl raped by her grandfather. This includes women who are gestating a defective fetus that has no chance of survival or is even dead. This includes women who have a high chance of dying during the delivery. This is the year, we have declared birth control to be the reprehensible tool of the whore. This is the year, when women who wish to discuss birth control are sluts and hypersexual subversives who just aren't real Americans.

Women who want to have an abortion must have a medical device jammed in their vaginas for no reason other than to punish them (the law got watered down to remove the rape but the initial version sought forced penetration of medical device). I assume they are being punished not for getting an abortion (they haven't yet), but because they were dirty little sluts who couldn't hold the aspirin between their legs. Where are the punishments for the men who couldn't find a woman who just wanted to make babies? How about a law that says a woman who wants an abortion must identify the father and then after the abortion, the father must forcibly be vasectomized? (It's potentially reversible so it's not sterilizing, and the man has already demonstrated he cannot be trusted to wait until a baby-ready woman is available.) As much as we hate the vagina, a woman can, at most, have one baby a year, but a man can make hundreds of women pregnant in the same time span.

The Catholic church has been crystal clear in its opinion. A woman cannot get an abortion, even if it means she will die without it. If you happen to be Catholic and save a woman's life by helping her have an abortion, you will be excommunicated. Women have one purpose in the Catholic church. Brood mares. As much strife as there has been between Protestants and Catholics in this country (the town I grew up in was divided up into the Protestant and Catholic side by the Presumpscot River), Protestants win no prizes here. The laws being written and in some cases passed around the country are written and voted on almost universally by members of Protestant churches. When women were trying to obtain the right to vote, which only became ratified in 1920 it was opposed by many men. (Think about it, this is less than 100 years ago. When one of your grandmothers or great grandmothers was born, she probably was born knowing she could not participate in the election of her leaders.)

This is just a short list: think of your own and add them to the comments. For example, we still hear the claim that women deserve to be raped or assaulted if they do not dress in specific ways. (At the same time we ridicule Muslims for requiring women to wear Burkas, which is ironic.)

It has seemed to me that since I was born, women have achieved greater and greater parity. Working women are respected, salaries and benefits are more akin to their male counterparts (not equal but the situation has improved). Sexual harassment is something we at least discuss and generally frown on as a society.  However, I said 'seemed' because it has become clear that these achievements are illusion, or maybe a better word is fragile. I cannot help but wonder at the current fad of jumping on the rights of women and defining them as walking uteruses who should not have control of themselves.

Blogging the Origin: Chapter II: Variation Under Nature

As you may recall in Darwin's long argument, the point of the previous chapter was establish that variation exists within well understood domesticated plants and animals. In this chapter, Darwin extends his examples into the natural world.

I believe Darwin made the conscious decision to start with domesticated organisms first, because his argument is something any educated person could agree with. We have all seen litters of kittens or puppies, raised fish, or grown flowers, or at least known people who have done these things. Even today, which has much greater urbanization than existed in Darwin's time, we are aware that dog breeds are exquisitely different from each other, yet all German Shepherds are not alike. If you want to argue about variation within a population, you do not start with white oak trees, brown bear, and large-mouthed bass. Only a specialist would be aware of the intrinsic variation within distinct members of these organisms. But take a dog or feral cat or farm animal/plant as an example and most people would be inherently familiar with the idea of variation, even if they had never considered it. Darwin makes us consider it. Once we have recognized the diversity within organisms for which we have a great deal of experience, we can then appreciate the diversity that exists in organisms for which we have much less experience.

The first part of this chapter is somewhat derivative with the previous chapter. Variation exists. What I found compelling was Darwin begins to address the species concept in this chapter and notes the difficulties inherent with it. We also discuss varieties aka breeds or sub-species and the subjectiveness of classification.

An example of the first:

Some few naturalists maintain that animals never present varieties; but then these same naturalists rank the slightest difference as of specific value; and when the same identical form is met with in two distant countries, or in two geological formations, they believe that two distinct species are hidden under the same dress. The term species thus comes to be a mere useless abstraction, implying and assuming a separate act of creation. It is certain that many forms, considered by highly competent judges to be varieties, resemble species so completely in character that they have been thus ranked by other highly competent judges. But to discuss whether they ought to be called species or varieties, before any definition of these terms has been generally accepted, is vainly to beat the air. (emphasis mine)
From these remarks it will be seen that I look at the term species as one arbitrarily given, for the sake of convenience, to a set of individuals closely resembling each other, and that it does not essentially differ from the term variety, which is given to less distinct and more fluctuating forms. The term variety, again, in comparison with mere individual differences, is also applied arbitrarily, for convenience sake. (emphasis mine)
Darwin then gets into a discussion of the amount of variation within common species and within larger genera. The idea here is that members of a species that is wide-spread and colonizes/survives in a variety of different environments has more variation than members of a species that is only found in precise or limited environments. He then takes these arguments to make the following predictions:
From looking at species as only strongly marked and well-defined varieties, I was led to anticipate that the species of the larger genera in each country would oftener present varieties, than the species of the smaller genera; for wherever many closely related species (i.e., species of the same genus) have been formed, many varieties or incipient species ought, as a general rule, to be now forming. Where many large trees grow, we expect to find saplings. Where many species of a genus have been formed through variation, circumstances have been favourable for variation; and hence we might expect that the circumstances would generally still be favourable to variation. On the other hand, if we look at each species as a special act of creation, there is no apparent reason why more varieties should occur in a group having many species, than in one having few.
and the test of these predictions
To test the truth of this anticipation I have arranged the plants of twelve countries, and the coleopterous insects of two districts, into two nearly equal masses, the species of the larger genera on one side, and those of the smaller genera on the other side, and it has invariably proved to be the case that a larger proportion of the species on the side of the larger genera presented varieties, than on the side of the smaller genera. Moreover, the species of the large genera which present any varieties, invariably present a larger average number of varieties than do the species of the small genera. Both these results follow when another division is made, and when all the least genera, with from only one to four species, are altogether excluded from the tables. These facts are of plain signification on the view that species are only strongly marked and permanent varieties; for wherever many species of the same genus have been formed, or where, if we may use the expression, the manufactory of species has been active, we ought generally to find the manufactory still in action, more especially as we have every reason to believe the process of manufacturing new species to be a slow one. And this certainly holds true if varieties be looked at as incipient species; for my tables clearly show, as a general rule, that, wherever many species of a genus have been formed, the species of that genus present a number of varieties, that is, of incipient species, beyond the average. It is not that all large genera are now varying much, and are thus increasing in the number of their species, or that no small genera are now varying and increasing; for if this had been so, it would have been fatal to my theory; inasmuch as geology plainly tells us that small genera have in the lapse of time often increased greatly in size; and that large genera have often come to their maxima, declined, and disappeared. All that we want to show is, that where many species of a genus have been formed, on an average many are still forming; and this certainly holds good. (emphasis mine)
Finally, Darwin leaves us with a synopsis of species differences within large genera that, in my mind, serves as an initial argument for incipient speciation. This is the 'MANY OF THE SPECIES INCLUDED WITHIN THE LARGER GENERA RESEMBLE VARIETIES IN BEING VERY CLOSELY, BUT UNEQUALLY, RELATED TO EACH OTHER, AND IN HAVING RESTRICTED RANGES.' section.

What are your thoughts?

A Day at the Zoo

Had a great afternoon with my son at the local zoo. The Como Zoo is a great place to spend a few hours at frequently. For anyone on a tight budget, it is free to visit both the zoo and the conservatory, and for those with the dollars, they request a donation of $2 for adults and $1 for children!!! Since I am not on a tight budget, or at least not that tight, my son and I 'donated' $10 to get in. ($10 for the both of us to spend a little over 3 hours out on a beautiful, albeit somewhat cool day.

My son wanted to check out the primates first, so off we went. The entrance we used put us right by the blue eyed black lemurs. There's a male (black) and female (brown). I got a picture of the male, but he was being a bit shy and I could only see him from behind. The female was sitting right out in the open watching us watch her. (This is the first time we got to really observe one of the lemurs as they are usually sleeping or hiding out when we visit.) The lemurs hold a special place in our hearts because a couple of years ago, the boy and I went to a 'feed the primates' class and got to prepare an active learning dinner for the lemurs (other people did the same for the gorillas, various monkeys, and orangutans, but we got to feed the lemurs. 

Checking out the male (below-not shown)

Preening break from people watching
Next up were some monkeys, they were cute (Emperor Tamarins) or not (White Faced Sakis), but were not particularly photogenic today. The orangutans were extremely photogenic today. They all their blankets, which they liked to cover themselves up in. Initially, the alpha male and two females had blankets, but the baby didn't. The female (with the juvenile below) went and took the blanket from the alpha male and played with two blankets, although the juvenile ultimately got one of them. It was fascinating just to watch them use the blankets, covering up their heads and trying to get them positioned just right.

Momma (I think)  playing with the baby (currently being chewed on).

Momma! Look at those ugly hairless things!
Finally, the gorillas. I don't know why, but my son spent a half hour just watching them. especially the silver back below (weight 525lb). They weren't doing much in general except eating from their Menard buckets of food. It was an interesting sociological experiment of a dad watching his son watching a gorilla.
Hey Maude, is that kid still back there?
We left the primates, checked out the aquarium area and some of the hoofed animals (bison were out). Then off to the big cats enclosure. This is another favorite as we spend another early weekend day setting up a raw chicken happy meal for the tiger. Usually there is not much to see as the cats are sleeping (except the tiger, he (she?) is usually walking around being all menacing and whatnot. However, much like the primates the cats were particularly active. One of the mountain lions was keeping an eye on the enclosure (this is the first time I have seen one out in plain sight).
Maybe there's something to eat over here.
More importantly, one of the cats was sleeping right next to the viewing window.

Close up

Sleeping after a hard day of lounging.

Just to give you a sense of how large these cats are, my son is about 3 feet from the cat (albeit with a large piece of plate glass between them). Needless to say, it's obvious to me who the predator is and who the prey is (hint: prey do not sleep by windows).
Here but for the grace of glass go I
Last picture the snow leopards. Again, we were fortunate that they were both out and about. Here we see some grooming in action. These are my favorite cats at the zoo (at least from the looks department.)
OK I do you, then you get me right? Right? Oh come on!
I am so glad we have the Como Zoo near our house and that the animals were so active on this trip. We get some decent backyard nature, flying squirrels being the big thing these days, but I'm glad my son can see these animals in 'real' life. Gearing up for a number of hikes this spring-summer, so hopefully we can work on our appreciation of nature.

Physicist Lawrence Krause on Atheist Talk Tomorrow

Calendar:Minnesota Atheists
Title:"Atheists Talk" Radio AM 950 KTNF
When:Mar 04 9:00 am - 10:00 am
Description:Sunday, March 4, 9:00am-10:00am “Atheists Talk” Radio
AM 950 KTNF in the Twin Cities or stream live at
Guest: Lawrence Krauss discusses “A Universe from Nothing” Chris Stedman discusses “Bridging the Religious-Secular Divide” Contact us during the show with questions or comments at (952) 946-6205 or

If you are not near a radio or not in Minnesota, you can stream AM950 live here. (Select Minnesota as your state.)   If you miss it you will probably be able to get the podcast later in the day.

Happy Birthday AbC!!

Angry by Choice first came online 5 years ago today. After two years of going solo, AbC joined the FoS collective. The number of hits has been creeping up since that time and for the first time broke 10,000 hits in a month. I know I know it's probably what Jerry Coyne gets in an hour, but it represents a milestone for AbC.

AbC hit another milestone last month: 100,000 total views (or as others will point out, what PZ Myers gets a day). AbC actually hit 100,000 earlier but I lost all the data from the pre-FoS days.

During the beat-down of a creationist AbC busted into the top 200 sciences sites on Technorati (How 2008 is that?). A post was also featured in a recent CoE, so that's all good.

Anyway, Happy Birthday AbC and thank you readers. Have some cake and enjoy a party tune.

BTW With music like this during my formative years, is it any wonder I'm so screwed up.