Evolutionary Medicine

Modern medicine does need an evolutionary perspective, because one must know how the lock and key metaphor works. As diseases develop, the body must find a way to protect itself so it evolves a defense system which the disease or virus ultimately will find a key for. It is this battle between evolutionary developments of locks and keys that it is vital to know about evolution in treating a patient. If a doctor hands out antibiotics like it is candy, the bacteria are likely to find the key to surviving even in the presence of that antibiotic. Then, all the antibiotics become pointless. Just like a mechanic needs to understand each individual part, how a car was made, and technological advances to fix a car, so a doctor does the body and the things that can go wrong with it. If a mechanic does not understand the new technology, he may install old outdated things that no longer work with the rest of the newer components, just like an older antibiotic will not work on a bacteria that already has a resistance to it.

Bipedality blog

The forces of natural selection that led to the evolution of bipedality would be the environment. Ardipithecus was a forest dweller and may have evolved walking on two legs to be able to carry food. The other benefit of bipedality is it freed up the hands for use of tools. They were not a aggressive creature (found potentially by the smaller canines which are used in other primates for aggressive interactions). They may have had to reach up into the trees for their nutrition as well. Their hands were not made for walking on, but for grasping.
Brain size may well have evolved if the social groups were gettting more and more complex. The ability to store information of past meetings to remember for future encounters, and problem solving.

ancestor's tale

In the Ancestor's Tale Chapter 1 Dawkins warns the reader to avoid looking for repeating patterns in nature's past. Dawkins also warns of the assumption that we are the ultimate creation, that all other species that have ever lived monumentally lead to us and that was their purpose. Patterns of course do exist, however they are generally patterns in random. As for the thought that all species ultimately having us as the end result is thrown off by evolution and the fact that things are ever changing.
To look at history out of Africa Dawkins states that one must look at haplotypes, or the long lasting tightly bound parts of DNA that survive over many generations. Y chromosomes only pass through the male line, and contain the material to switch an embryo into male pattern development. On the other hand, Mitochondrial DNA is passed exclusively down the female line. Y chromosomes are useful in studying recent populations, while mtDNA are more effective for studying ancient patterns. Not as easy to use Y-chromosomes for that purpose. This is not the whole story because you cannot rely solely on a single gene. The out of Africa story holds that all people outside of Africa descend from a single exodus around a hundred thousand years ago. Each gene tells a different story so could be several stories.

Ultimately Altruism can only develop if the act of altruism by an individual is as big as the gain that individual gets in return... One example of this is mutualism. Cleaner fish set up cleaner shops to clean large fish of any parasites. This is highly dangerous because at any time the big fish could decide to eat the cleaner fish. But these large fish are recieving the benefit of having less harmful parasites and the cleaner fish are getting a meal in exchange. So ultimately it works. As for the example of donating to a blood bank it could be said that a person does it to just be nice, however one could argue that ultimately a person may at some point also need the benefit of having someone else's blood. Dawkins talks of the Cave theory and the never break ranks theory which at first glance seem altruistic by putting a warning individual at risk of being found by predators, when it really is quite selfishly just trying to keep other individuals quite so he is not found. Stotting also at first glance seems to be altruistic by diverting predators attention away from the group but really says to the predator, " I am not an easy meal, I am strong and will fight hard for my life, pick an easier target!" Symbiotic relationships also could have developed altruistic behavior.
In a simple game of prisoner's dilemma, there is no way of ensuring trust so it does not lead to altruism only best strategy which is both defect. In an Iterated or more repeated gamme of prisoner's dilemma repeated indefinitely, there is opportunity to build trust and to give that back. Tit for tat strategy in that you trust your opponent but do to him what he does to you in the previous round. Defectors are punished so to teach them a lesson. Looking at the British versus the Germans and their live and let live strategy, both had something to gain in this situation... their lives. As for the Vampire bats, their lives hang in the balance at any given moment when a meal is not available, so they share as they know they will be ultimately share with when theirtime of need comes, and the benefit to the one individual is much greater than the cost to the donator so it works!

Social Insect Blog

We saw last week how Kin Selection explained the altruism seen in the social insects and in animals that direct their benefits to kin. But even in the social insects there is some room for selfishness. Explain the conflict between queens and workers. Who wins and why? Are there any exceptions?





The ultimate conflict is explained by Trivers and Hare. They state that insects of the group Hymenoptera has a sex determination system that there is a queen who has made one mating flight to store up sperm for the rest of her life. Females have a father and therefor have a double set of chromosomes, whereas a male has only a single set of genes in each body cell and therefore all males in a colony are identical. The relatedness between hymenoptera sisters is 3/4 which is very different from other species in that the relatedness by full sisters is normally 1/2. It means that a hymenoptera female is more closely related to her full sisters than she is to her offspring of either sex. Hamilton realized that this predisposes females to "farm" thier own mothers as a sister making machine, but they must curb her natural tendency to give the 1:1 sex ration of equal sisters and brothers. From the workers point of view, the chance of any brother containing one of her genes is only 1/4, so for the profit of the workers, she cannot produce children in equal ratios. A worker always wants a 3:1 and a queen always wants a 1:1 sex ratio. THe conflict of interest is the queen trying to invest equally in males and females, while the workers try to shift the ratio to a 3 females to every male. Trivers and Hare took 20 species of ants and investigated the sex ratio and found very close to the 3:1 ratio. It turns out that the genes trying to manipulate the world through the queen bodies are outmanuevered by genes manipulating the world through workers bodies.
There are a couple exceptions to this is the slave making species which the queens can disguise male eggs to appear females to the workers. Some queens could mate with multiple males on the mating flight as well and the relatedness would thus decrease.

Blog week 4 Sexual Versus Natural Selection

Natural Selection is defined as a selection where only the organisms best able to adapt in their environment tend to survive and transmit their genetic characteristics in grater numbers to following generations while those less adapted tend to be eliminated all together. Sexual Selection is considered by some, to be a type of natural selection, that affects traits that influence an individuals ability to choose or get a sexual partner, rather than traits that effect a beings ability to survive. Sexual Selection is thought to be responsible for the evolution of many extravagant physical features, such as long plumes in birds, bright colors in many animals, and complex display behaviors to attract a mate.

Darwin defined sexual selection as the effects of the "struggle between the individuals of one sex, generally the males, for the possession of the other sex". In sexual selection, a male individual may have better traits for fighting other males so that he may be selected for by a female, or may just have ornamental traits that may catch the eye of a potential mate and increase mating success. Darwin states that, "The sexual struggle is of two kinds: in the one it is between the individuals of the same sex, generally the males, in order to drive away or kill their rivals, the females remaining passive; while in the other, the struggle is likewise between the individuals of the same sex, in order to excite or charm those of the opposite sex, generally the females, which no longer remain passive, but select the more agreeable partners." This is where sexual dimorphism comes into play and why many males and females differ in size, color, and other physical differences.

Dawkins talks more about why natural selection does not favor a shifted sex ratio and why it is that so many males exist when there need not be so many. He states that Darwin did not solve this, but Fisher did. Dawkins takes the stand stated in the first paragraph that sexual selection is a type of natural selection. The selfish gene must be passed forward so you must find a suitable mate to help that occur.

Week 3 blog response ESS

Dawkins states that an ESS is the best strategy for an individual depending on what the majority of the population are doing. An ESS is most important because it is applicable wherever we find conflict of interest and that is everywhere! Fisher states that a sex ratio of 50:50 is an ESS. This is due to the fact that if at any point a single sex outnumbered the other, the mating numbers would be disproportionate. If males outnumbered females, the opportunity for each male to have a mate is thus decreased and vice-versa. If each individual is trying to maximize his "own" success, then there must be an equal sex ratio being the 50:50 half males half females.
Conversely if you were to look at sex ratios of autosomal nuclear genes are transmitted to offspring through both of the sexes, so the sex ratio that must be favored is a balance between producing male and female offspring a 50:50 ratio. One can argue however that due to the fact that male species cannot produce offspring themselves, they are not necessary which would discount the male altogether. In contrast, cytoplasmic genes are mainly inherited through the egg cytoplasm and thus transmitted to offspring only through females. This means there is a strong selective pressure for cytoplasmic genes that distort sex ratio toward female production placing the sex ratio to 100:0 in favor of the females. And as previously stated, the sex chromosomes favor the 50:50 ratio potentially solely for mating purposes.
Two of these sex ratios could be the same because of the passing of genetic information through both sex chromosomes and autosomal chromosomes(as long as males were not discounted for not having the ability to produce progeny). The sex ratio of cytoplastic elements is different because that is only passed on through the mother and the male can completely be discounted.

Blog response week 2

Reading both Mayhew and Dawkins, I tend to lean a bit more towards Dawkins in his primordial soup theory. This is the theory that I personally have been taught my entire life. I feel that Dawkins tends to agree more with Darwin in the theory of evolution by natural selection than maybe Mayhew expresses. Dawkins tells of the primordial soup which contained purines and pyrimidines, the "building blocks of DNA itself." Dawkins idea that, "the situation only had to arise once" appeals to my understanding because that is all nature really is, is chance meetings at the right place and right time. Dawkins view also holds that mistakes happen (that is why evolution happens) and that is how eventually the survival machines he speaks of came to exist. In order to protect themselves, the genes had to develop some sort of defense, then develop the capability to compete for resources, and later to pass on that information to future generations.



Mayhew on the other hand looks at an autotrophic origin of life which recently has re-emerged. his argument is that early life probably lacked protein enzymes to catalyze reactions, using RNA instead. The problem that I tend to have with this is that Dawkins idea of a primordial soup contained the precursors for DNA. And, laboratory experiments done on inorganic materials exposed to ultraviolet light and or "lightening" produced something along the order of amino acids. I do not think that Mayhew recognizes such studies have been performed.

It is obvious that not a single person was around at the time of creation and that we may never know what truly happened at the origin of life, but that is why scientist formulate hypothesis... educated guesses... We can only speculate and thus will be divided in theories.

In regard to Darwin's statement that, "The origin of most of our domesticated animals will probably forever remain vague", scientific advancements in genetic mapping may well have far exceeded his expectations. Molecular comparisons on canines have been a fairly recent phenomenon that have and continue to yield the answers to the origin, at least of the canine. If indeed, as Darwin stated, that "all our races of dogs have been produced by the crossing of a few aboriginal species" why was it that he concluded that pigeons were derived from one single species? The modes of reproduction are essentially the same as is the transfer of genetic materials to offspring...random. Where is the wild poodle, if in fact Darwin is correct about crossing a few aboriginal species? Darwin's theory of Evolution by Natural Selection could, in fact, account for one common ancestor which had attributes that made it strong enough to survive in a particular environment. I am not clear as to why that appeared to be lacking in his conclusion about the origin of the canine.

Unfortunately, Darwin overlooked Mendel's studies of inheritance. An example of this was when Darwin bred snap dragons for only one generation. His result was that the offspring were an average of its parents, which we well know is untrue today. People can select for specific traits in animals. If you look at the Labradoodle as an example, a Labrador and a poodle were bred. The resulting individuals were a mix of parents genetics. But if you breed them with another Labradoodle, the result will revert back to the parental type.

Dawkins looks at this from a different point of view. He states that,"a predominant quality to be expected in a successful gene is ruthless selfishness." Any species with altruistic qualities will eventually die out and the selfish ones will be the only ones to survive. Dawkins also states that the fundamental unit of selection, and therefore of self-interest, is the gene. You must compete to survive, and if the unit is stable then it will survive.

One possibility of domestication of the dog is that after ancient hunters had made a kill, the less fearful wolves, or aboriginal species, gathered around to scavenge the remains the humans left over. After repeated times of doing this, the wolves may have learned to follow the humans back to their homes and stick around in hopes of stealing food supplies, receiving hand outs, or even just a more sheltered area. If this happened, the hunters possibly gained companionship and potential protection from outside groups of more aggressive wolves or any other predators. If the more tame wolves began to eventually rely on humans, they possibly were more comfortable giving birth in close proximity to human living areas. And, if this were true, as the progeny grew, they would have been around humans from day one and perhaps would have been accustomed to even letting humans touch or harness them as long as they received something in return such as food or shelter.