Ridley, Matt. The Red Queen
Chapter 3: The Power of Parasites
Sexual reproduction is something that has puzzled scientists for many decades. With sexual reproduction, each of the offspring is slightly different than its parent which is unlike species that reproduce asexually and have identical offspring. Matt Ridley calls this “The art of being slightly different” (56) and says that most ecologists agree that it is this difference that is the purpose of sex.
In 1966, George Williams noticed something peculiar about sexual reproduction. He noticed that sexual reproduction requires animals to focus on the survival of the species in a way that also requires them to ignore their short-term interests. He also felt that this “form of self-restraint...could have evolved only under very peculiar circumstances” (56). Williams noticed a connection between sex and dispersal and decided that if a species wants its young to travel then the young should be varied through sex so that they have a better chance of survival away from home.
John Maynard Smith, in 1971, elaborates on the problem that Williams noticed. Maynard Smith’s idea “suggested that sex was needed for those cases in which two different creatures migrate into a new habitat in which it helps to combine both their characters” (57). Williams returns and says that if the young are going to travel then it will be only the fittest that will survive and it would be better to have a few exceptional young rather than many average young. This means that “sex is useful to the individual rather than the species when the offspring are likely to face changed or unusual conditions” (57). Williams was intrigued by creatures that were able to reproduce both sexually and asexually ( like aphids and rotifers) because he felt that they further proved his theory;
While conditions were favorable and predictable, it paid to
reproduce as fast as possible-asexually. When the little world
came to an end and the next generation of aphid or rotifer faced
the uncertainty of finding a new home or waited for the old one to reappear, then it paid to produce a variety of different young in
the hope that one would prove ideal (57).
William’s theory was criticized because it only works if the rewards are high; “only if a very few of the dispersers survive and do spectacularly well does sex pay its way” (58). Graham Bell from Montreal decided to catalog species according to their ecology and sexuality. The results of his finding were different than from what was expected as a result of William’s theory. Bell found that asexual species were living in harsh environments where, according to Williams, they should be producing sexually. Also, William’s example of the aphids and rotifers turned out to be a myth because it is not the winter or a drought that made them turn sexual, but overcrowding which affects the food supply. Graham Bell calls this the “tangled bank” theory. Basically, the “tangled bank” theory states that “sexual organisms in saturated environments, rather than churning out more of the same offspring, would be better off varying them a bit in the hope of producing offspring that could avoid the competition by adapting to a new niche” (60).
A student of Bell’s, Austin Burt, looked at the recombination that occurs in the genes of mammals to see if the tangled bank theory fit the facts. He found that the tangled bank theory did not fit because “the amount of recombination bears no relation to the number of young, little relation to body size, and close relation to age at maturity. The tangled-bank theory would predict the opposite” (62).
Next came Leigh Van Valen, the person who started a theory called the Red Queen Theory. He came upon this theory when he was studying marine fossils. He discovered that “the probability a family of animals would become extinct does not depend on how long that family has already existed. Their chances of extinction are random” (64). A species cannot afford to relax and stop adapting to its environment because the enemies which the adaptation is trying to protect the species from is also adapting. This theory is called the Red Queen theory after the character in Alice in Wonderland who ran and ran, but got nowhere. In the world, and in evolution, there is change, but not necessarily progress. Therefore, “sex, according to the Red Queen theory, has nothing to do with adapting to the inanimate world – becoming bigger or better camouflaged or more tolerant of cold or better at flying – but is all about combating the enemy that fights back” (65).
The biggest enemy that fights back are parasites, predators, and competitors. In the past most of the deaths were caused by Smallpox, tuberculosis, influenza, pneumonia, diarrhea, etc. Recently Richard Dawkins said that “Parasites are touted as the prime movers in the evolution of sex, promising a final solution to that problem of problems” (66). In fact, parasites are more deadly than predators for two reasons. The first reason is that there are more of them which makes them a huge threat. The second reason is that parasites are smaller than their host which means that their life spans are shorter. The shorter life span allows for a parasite to go through many generations in one host which then allows them to multiply and adapt faster than the host can. In fact, “the more successful the parasite’s attack, the more the host’s chances of survival will depend on whether it can invent a defense. The better the host defends, the more natural selection will promote the parasites that can overcome the defense” (66). It is the parasites that provide the genes incentive to change. This has even been proven with the use of artificial viruses in computers.
Animals have only three ways of defending themselves against parasites. The first way, usually used by plants, is to grow and divide faster than the parasites. The second defense is sex and the third defense is the immune system which is only used by the descendants of reptiles. Other species, like plants and amphibians, use a chemical defense like antibiotics.
As it turns out, “Austin Burt’s discovery of a correlation between generation length and amount of recombination is evidence of the Red Queen at work” (71) and Bell and Burt discovered that “the mere presence of a rogue parasitic chromosome...is enough to induce extra recombination in a species” (71). These things show that sex is necessary for combating parasites. The job of parasites such as viruses, fungi, and bacteria is to break into cells and either eat them or use their genes to make new cells. In order to break into the cells the parasites have to bind to them first. They do this by employing protein molecules that fit into the molecules on the surface of the cell. It is easier to think of the hosts having a lock that the parasites are the key to. When a parasite has the correct key to the lock, then the host changes the lock.
It is in this key & lock analogy where the advantages to sexual reproduction become apparent. Sexual reproduction creates a species to have lots of different locks, whereas species that reproduce asexually all have the same lock. If a parasite comes along with a key that works then the sexual species will be fine, but the asexual species will be completely wiped out. The idea of the Red Queen running and not going anywhere comes into play again because when a lock becomes rare, the parasite’s key becomes rare, so that lock is once again useful to the host. The host is right back where is started.
The Red Queen’s method of defense and the immune system are actually interconnected. Hans Bremermann of the University of California at Berkeley says that the immune system would not work without sex. Author or The Red Queen, Matt Ridley, explains it in the following way:
The immune system consists of white blood cells that
come in about 10 million different types. Each type has
a protein lock on it called an “antibody,” which corresponds
to a key carried by a bacterium called an “antigen.” If a key
enters that lock, the white cell starts multiplying ferociously
in order to produce an army of white cells to gobble up the
key-carrying invader (74).
There are a few things that the parasite can do to defend itself against the immune system. It can try to infect somebody else before it is killed by the immune system, it can hide inside host cells, it can keep changing its own keys, or it can try to imitate the password that the host’s cells have in an attempt to not be noticed. According to Bremermann, the parasites that imitate the host’s password put a pressure on the host to change the password which is where sex comes in; “sex keeps parasites guessing” (83). It is the Red Queen theory that expresses how sex helps organisms to be one step ahead of the parasites to better their chances of survival.
Chapter 4: Genetic Mutiny and Gender
Ridley, Matt. The Red Queen
Chapter 3: The Power of Parasites
I. Sexual Reproduction
A. Offspring is slightly different from parent
1. Focused on the survival of the species, not the individual.
2. Fittest will survive dispersal into new environments.
3. A few exceptional young is better than many average young.
II. “Tangled Bank” Theory
A. Graham Bell basically says that sexual organisms in saturated environments, are better of to produce different offspring to avoid the competition by taking on a new environment.
B. Austin Burt found that this theory proved the opposite, since varying offspring has nothing to do with body size, age at maturity, and number of young.
III. Red Queen Theory
A. Leigh Van Valen named this theory after the character in Alice in Wonderland who ran as fast as they could but stayed in the same place.
1. Thus, sex is about shuffling genes and keeping pathogens unable to
adapt, not about adapting to an environment.
IV. Parasites, Predators, and Competitors
A. Richard Dawkins found that parasites are the most deadly and are “the prime
movers in the evolution of sex” (66).
1. The number of parasites alone poses a huge threat.
2. The short life span of a parasite allows them to multiply and adapt
B. Computer programs and viruses, or artificial intelligence, has helped prove this theory.
C. Different ways animals defend themselves.
1. Grow and divide fast enough to leave the parasites behind.
a. Plants and plant breeders use this method usually.
a. This method of defense has been practiced by many.
3. An immune system.
a. Practices only by the descendants of reptiles
4. The use of antibiotics.
a. Fungi originally produced this chemical to kill bacteria.
V. Austin Burt and Graham Bell Show the Red Queen at Work.
A. Burt discovers more genetic mixing is needed the longer the generation time, in
order to stay ahead of the parasites.
B. Both discover that the presence of “B chromosome”, or rogue parasitic
chromosome, causes more genetic recombination.
VI. Virus, Bacteria, and Fungi, the Causes of Most Diseases
A. They brake into cells for two reasons.
1. Bacteria and fungi eat cells.
2. Viruses use them to make new viruses.
B. How they bind themselves on cell surfaces.
1. They “employ protein molecules that fit into other molecules on cell
VII. The Key and Lock Analogy
A. Parasites carry different keys to the locks of the host.
1. Sex shuffles genes, therefore creating new locks.
2. Asexual offspring are the same, all carrying the same locks.
3. When locks become rare, so do the parasites keys, making that rare lock
useful to host again, and so it repeats itself.
a. Hence the Red Queen runs as fast as she can, but never gets
VIII. What the Parasite Must Do to Win
A. Infect someone else before the immune response.
B. Conceal itself inside the host cells.
C. Change its own keys frequently.
D. Try to imitate the password that the host’s own cells use to escape attention.
Chapter 4: Genetic Mutiny and Gender
I. Intragenomic Conflict
A. Conflicts of interest between genes inside a body.
1. If genes could not cooperate, the body they inhibit would never get built,
never passing any genes to the future generations.
II. Cooperation and Competition
A. A gene is defined as, “the descendant of a gene that was good at getting into
future generations” (95).
1. Therefore, the genes have used cooperating to build a body as their
B. Competition led to the invention of gender.
A. Replicated molecules became numerous and began to assemble as chromosomes.
B. Chromosomes use cells to replicate chromosomes efficiently.
C. Chromosomes then merged several kinds of cells to form a supercell.
1. Thus, the invention of a modern cell from different bacteria.
D. These cells then grouped together, forming animals, plants, and fungi.
IV. Viruses and Bacteria
A. Disposable vehicles for simple teams of genes.
1. Each team is extremely competitive.
2. Team members are harmonious.
a. This harmony, however, breaks down when bacteria merge to
3. On rare occasions, some bacteria abandon their team for a better team,
1. The bacteria shunts some copies of genes across a narrow pipe to
V. Selfish Genes
A. Segregation disorder in a certain fruit fly.
1. This Cain gene kills all sperm with the other copy of chromosome two.
B. Meiotic-drive genes in flies, mice, and a few other creatures are rare.
1. Crossing over swaps certain chromosomes to keep chromosome division
2. The “mask” that protects Cain is swapped to Abel’s chromosomes.
C. This Cain gene on the sex chromosome of an X, can safely kill the Y
VI. The Invention of Two Genders
A. The alga called Chlamydomas has a plus and minus gender, they go to war
leaving 95% of the cell destroyed, plus gender left with the 5%.
1. The docile suicidal organelles, or minus gender, would proliferate.
a. Thus, two genders are invented: killer which provides the
organelles, and the victim, which does not.
B. The two genders are a consequence of sex by fusion.
1. Sperm only passes the nucleus into the egg to avoid introducing bacteria
C. Genders were, “invented as a means of resolving the conflict between the
cytoplasmic genes of the two parents” (104).
1. So an agreement was made, instead of destroying the offspring.
D. “Hermaphrodites are in a state of constant battle against rebellious organelle
genes trying to destroy their male parts” (105).
VII. Deciding Gender
A. The X and Y chromosome of a man’s sperm decides gender, the first on to the
B. Three different and better ways to determine gender.
1. Choose the gender appropriate to your sexual opportunities, for sedentary
a. Lots of female shoal fish mate with the single large male, and
when he dies, the largest female changes gender.
2. Leave it to the environment.
a. For alligators and crocodiles warm eggs hatch as larger babies than
the cool ones. Male size and competition for females.
3. Mother to choose the sex of her child.
a. Female bee and wasp eggs are the fertilized ones, and the
unfertilized are male.
C. “Lower down the social scale, daughters are preferred even today. A poor son
is often forced to remain single, but a poor daughter can marry a rich man”
A.) Three Interesting Points
1. Genes that kept one generation of a species protected from a parasite, can be
harmful to the next generation when the parasite adapts to them. Also that
parasites adapt so quickly.
2. How diseases like HIV lay dormant until they are reawakened by “rival”
infections. Then the HIV virus multiplies rapidly.
3. The idea that genes have formed a system of cooperation and competition, in
order survive natural selection and pass to future generations.
B.) Weak/ Confusing Cases
1. In the beginning he talks about species going from asexual to sexual. He
does not explain how that happened. Also, I do not understand if he means
two sexes appear or if one sex trades genetic material.
2. Chapter four seemed to jump around in strange directions without a clear
explanation. His writing style, thought process, and organization were not
as enjoyable as I had hoped. After about the fifth time I read chapter four it
started to make some sense.
3. His writing style in both chapter three and four were sometimes irritating!
In chapter three he ends one sentence, “…by vaccination or whatever” (74).
Also, in chapter four he ends another statement, “-whatever that may mean”
C.) Needed to Explain Further/ We had Questions About
1. In the beginning of chapter three the author states that sex is useful to the
individual and not the species. But if an individual is able to survive because
they were created sexually, then they will most likely be able to reproduce as
well. That seems to be for the good of the species.
2. In chapter three, the “B chromosome”, or rogue chromosome, was not fully
explained. It was also mentioned in chapter four, and I am still not sure
what its role is, other than cause more genetic recombination. Also, how does
it cause more?
3. In chapter four, segregation disorder and Meiotic-drive genes got rather
confusing, especially when he brought in the Cain and Abel metaphor.