Wednesday, September 30, 2009

Geological Distribution Continued

A new born baby enters the world and is at once corrupted, just like oceanic islands. Soon the migration on the island resembles the nearest mainland. The further away the island is from the mainland the harder it is for new plants and animals to arrive. A prime example is Krakatau, for it was an experiment in evolution that humans got to witness. Why were islands so beneficial to Darwin’s theory, and could you still use islands today to prove his theory? Is there any other models with which one can witness evolution instead of waiting around for a new island to form.

Islands are a good example of how genes will play an effective role within the first few generations. Large amount of genes will be lost, because their bearers can not successfully reproduce. This mishap causes a bottleneck effect, but eventually diversity will win and explode. However, the world has other islands such as rivers and lakes. It may seem that bodies of water are isolated when in fact they are not. Floods are a good example of how migration can happen, and many freshwater plants and animals have adapted ability to sufficiently travel. There are a few lakes that follow the same rules of an island. How is a lake able to stay isolated long enough in order to house distinct variety of life forms?


Why is it that islands exposed to the outside world, their life forms are driven to extinction? Shouldn’t the plants and animals living on the island be better adapted than the outsiders.

Humans themselves are great at exploiting a new territory. Soon many products of evolution will disappear. If all the products of evolution disappear on so-called islands of isolation, how would one be able to notice evolution?

Tuesday, September 29, 2009

Geological Distribution Continued

The example on where varies places grapes can grow would seem that alternate places can, given the chance, will support identical forms of life. However, grapevines that produce wine may look and taste the same, but are in fact distinct. Why does evolution drive species to be distinct even if the land regions are identical? Are there certain barriers, past or present, that have influence distinct species, and if so are they the major driving force behind natural selection? Are there ways to get around a barrier? Do you think humans can influence the laws of life in order to produce the same species in identical land regions?

Why do you think there are twice as many left shoes as right shoes washed ashore in Holland?

Water is affected by climate change, which in turn affects migrations of plants and animals. Throughout the history of the planet there have been several cooling phases and warming periods. Today a few of the environmental issues are the green house effect and depletion of the ozone layer. It has been manifested that humans and their pollution have affected the ozone layer, causing further warming of the planet. Do you think that human involvement is affecting the outcome? Or is Earth following its usual course of moving between warming and cooling periods.


“There is a striking parallelism in the laws of life throughout time and space: the laws governing the succession of past times being nearly the same as those governing at the present time the differences in different areas (2360.” Why does the southern beech tree of South America have close kin in Australia, in South Africa, Antarctica? The land itself is on the move rather than the ocean. The information on the theory of Pangaea can be found on the first two websites.

http://library.thinkquest.org/17701/high/pangaea/

http://pubs.usgs.gov/gip/dynamic/historical.html

The following link talks about Pangaea today. This is their mission statement: In a world where people are often divided by borders, difference, and conflict, it's easy to lose sight of what we all have in common. Pangea Day seeks to overcome that and to help people see themselves in others through the power of film.
http://www.pangeaday.org/

Monday, September 28, 2009

On the Geological Record and its Imperfections

Chapters nine and ten explore the geological record. Death, decay, and dissolution all help to solve the greatest puzzle, the fossil record. However, it is difficult to piece the past together with the present; for only small portions of the earth have been explored carefully, and only certain classes of organisms have been preserved in a fossil state. “Not much is left of the great tree of life that fills with its dead and broken branches the crust of the Earth, creatures are its twigs, and so few remnants of its limbs have been preserved that to work out what controlled their growth while they were themselves still young may be impossible.” Thus, we can conclude that the geological record is extremely imperfect. Chapter nine starts off with the claim that species were immutable productions this was almost unavoidable as long as history of the world was thought to be a short duration. Thanks to thinkers like Copernicus, Galileo, and Hutton, we were able to dismiss the biblical date of earth, and make it possible for intermediate and transitional links between all living and extinct species. Unfortunately, acquiring an accurate date is more complicated than it actually seems. Nothing is laid out in a nice ordered sequence. Such bench marks as volcanic ashes blanket the ground in layers that can be read as pages, and the use of Carbon 14 and Potassium dating have helped to define these grey areas.
A main factor that inhibits an accurate geological record is water. Water destroys or builds, and thus edits the records. It washes away fossils and sediments, erodes the land, making the rivers like a soup of slit and bones. It makes any single place retain mere fragments of the past. Either large parts of a small timeline or a glimpse of a longer period, which in turn our own museums lack degradation; for the number of incalculable generations that have failed to resist decay.
Secondly, the sudden appearance of a group of species would seem to be a fatal contradiction to the transmutation of species, but has been proven wrong by finding forms that are much older than those thought to be pioneer forms. Even genes can fill the gap where fossils haven’t been able to. Further criticism of natural selection is the notion that life started in the Cambrian stage; an explosion of life where most of the division of the animal kingdom started here. This so called explosion has been a failure to geology and not to Darwin’s machine. The Cambrian period is not the start of life, but a time where more life forms could be preserved. Take for example: Trilobites, the first to claim jointed limbs. During the Cambrian period there were several distinct types of Trilobites. Showing that they were in the middle stage of evolution and that their existence can be found in a older stage. The Geological record is a history of imperfect records that are written in changing dialect. Having the last volume, we only have a few short chapters, and for those chapters few pages, have few lines still exist.
Chapter ten focuses more on the power of gradual and sudden change within the fossil record. The theory of descent with modification through natural selection explains how new species gradually come in to existence slowly and successfully. It will also explain that species of different classes don’t change together or even at the same rate, but all species in time will modify to some degree. Thus, the dominant life forms of that species will continue to produce and the inferior species will become extinct. The dominant forms will reproduce new sub-groups and groups. This is an ongoing process where the next modified dominant life forms generally overtake the inferior species, for every life form faces extinction and can not be produced again in later generations. Hence, after long intervals of time, the world will have appeared to change simultaneously. Finally, the laws of variation are in motion around us, and are kept in check by natural selection.

  • What other markers can be used to explain or support the age of the earth, and how would you properly construct a flawless agreement when debating with a creationist?
  • Where have genes filled the gap created when fossils provided insufficient information about the past?
  • Mass extinctions are inevitable and are seen throughout the geological history, and natural selection is seen as a gradual process. How is this still possible, and can you think of any examples?

Wednesday, September 23, 2009

Hybrids

The chapter on hybridism applies the same definition of species that we have discussed in class a couple of times already. This is the biological definition of species which states that organisms able to breed fertile offspring with each other are of the same species and those that cannot are of separate species. This does, however, have to limited to acts in nature and not in captivity as captive animals often play by different rules than their wild counterparts. Some species can and do interbreed both in the wild and in captivity. This act between species is hindered and often prevented by a number of obstacles, such as space, time, mating preference, unsuccessful fertilization, ability produce viable offspring or ability to produce fertile offspring (175).

Let's briefly take each in turn. 1)Time can be the opposite seasons in which two species living in the same area become fertile. 2)The distance two species are away from each other (space) needs no explanation. 3)Mating preference refers to sexual selection which through either genetic-based or learned inclinations cause an individual to choose one mate over the other. 4)Unsuccessful fertilization can mean many things. It could be due to physical constraints occurring during attempted intercourse, female defense systems fighting off unfamiliar sperm or the females preference of one sperm over another when two types are present, to name a few. 5)Finally, both spontaneous abortions, the result of nonviable offspring, and successful birth of sterile offspring represent other barriers for interspecies breeding.

It is important to remember that healthy, fertile offspring are produced in nature and in the lab. This is possible because all species were at one time mere varieties, or races, within a species, so the lingering similarities between the two can allow reproduction.

What hybrids can look like:

real: http://www.worldsamazings.com/2009_02_01_archive.html

not as real: http://www.freakingnews.com/Hybrid-Animals-Pictures--563-0.asp

Instinct

Instinct, as Jones defines it, is any action that does not require learning or experience for the animal to perform it and is done without the animal necessarily knowing what the benefits or consequences of that action will be. It is important not to forget that behavior, like physical attributes, evolve because it is both inherited and varies between individuals. Although behavior is not completely controlled by genes, much of it is. Instinct follows the same basic rule that all other characteristics organisms possess, which is to do whatever it takes to ensure that genes, either one's own or a similar set, are passed on. This causes a variety of behaviors that include altruism, cannibalism, violence, enslavement and rape to name a few. In each situation that instinct applies itself its choice of tactic is governed by cost-benefit ratio. Even behaviors that end in an individual's death are not altruistic in the sense that we typically use the term, but are actually motivated by selfishness.

Jones first discusses the enslavement instinct and utilizes the example of ants to do so. Ant society is impressive from both an architectural and a logistical view and all of it is built upon the foundation of slavery with all players in the game, even the slaves, interdependent on one another. The slavemakers will sometimes raid other colonies and steal their cocoons so the inhabitants are born into enslavement without knowing that they are helping promote the success ants with dissimiliar genes than their own. Without the mutual need of each other, the master-slave relationship would soon tip and once the cost of a relationship outweighs the benefits, it quickly collapses.

Ostrich nests are a site of what might first appear to be altruistic behavior. Several female ostriches share the territory of a male with one female in charge. The dominant female is supposed to be the only one with mating rights, but of course life happens and other females become pregnant. The dominant female will allow the others to deposit their eggs in the colony's nest, not because she is concerned at all about their eggs survival, but because she cares about the fate of her own eggs. The lower-ranked eggs are distributed around the outside of dominant females, thus decreasing the chances of the inner eggs falling victim to poaching. What appears as charity is in the end nothing more than an act dripping of deciet and motivated solely by self-interest.

Natural selection, Jones states, is interested in the passing of DNA and not the vessels that DNA is carried by. Therefore, kinship becomes important because, just as with the ant colony, cooperation leads to success and by relatives helping each other their very similar, and in some cases identical, DNA have a better chance of surviving to the next generation. Many animals are born sterile with the sole purpose of defending their family's territory so that their fertile siblings can reproduce. The example provided in the text involves naked mole rats of Africa. Though the mole rat 'soldiers' are not born sterile, the intense stress caused by their role prevents them from reaching puberty. This is easily proven by removing them from their home environment and witnessing their sexual maturity begin immediately. This is similar to the development of secondary sexual characteristics in orangutan populations.

-I have heard people state that they have identified their purpose in life to enriching the lives of relatives and helping ensure the success of their kin's offspring. Do you think that this is instinct? Did they settle on this decision from learning about evolution? Is it a coping mechanism do deal with how life worked out for them as individuals and their own reproductive success? Or something else?

-I have read that some male earthworms rape other males when they come in contact with each other. By doing so they render the raped male sterile and eliminate that him as a sexual competitor. What other examples of behavior do we see in nature that are driven by instinct and directly increase an animals' reproductive success?

Monday, September 21, 2009

Some interesting and semi-relevant links

The tale of the Flying Spaghetti Monster and its followers the Pastafarians (seriously).....

-The initial letter sent to Kansas State Board of Education: http://www.venganza.org/about/open-letter/

-The official church site: http://www.venganza.org/

Responding to creationist arguments

http://www.talkorigins.org/indexcc/list.html

Belief in evolution

http://richarddawkins.net/article,706,Public-Acceptance-of-Evolution,Science-Magazine-Jon-D-Miller-Eugenie-C-Scott-Shinji-Okamoto

Some shenanigans

http://www.youtube.com/watch?v=hnn3wmni46w

http://www.youtube.com/watch?v=GceRG1XUzvw

Variation and the Difficulties of Evolutionary Theory

This week's readings cover Jones' chapters on the laws of variation and difficulties that arise from Darwinism. One common theme interwoven between the two chapters is the misunderstanding of the innately complex process of inheritance. Below are some of the important concepts from the readings and a couple of (hopefully useful) discussion questions to start things off.

Importance of Genetics
Genetics, as Jones discusses, seems to bring as much confusion to our understanding of inheritance as it does answers, both of these contributions are asserted as being further proof of evolution rather than discrediting it. Jones begins with Mendellian genetics which provide our most basic understanding of inheritance and goes on to discuss mutations, the need for variation, and 'junk' DNA (though he does not use this term). As discussed in class, without variation there can be no evolution because all organisms would be identical, thus having nothing for evolutionary forces to act upon. Variation is rooted in the most primal and favorite pastime: sex. Sexual reproduction, as opposed to asexual reproduction, is the main mechanism behind variation. This particulate, not blending, process of reproduction provides an equal, random combination of parents' genetic make-up.

Mutations within genetic code can occur in several ways and are a primary force of evolutionary change. Jones points out that these mutations originate within male mammals more often than their female counterparts due to male gametes dividing throughout his lifetime, thus increasing the chance of error for subsequent generations of sperm. When mutations are beneficial to the reproductive success and survival of the offspring, natural selection will favor them.

Outside of Genetics
There is more to natural selection than genetics and he utilizes numerous examples of Lamarckian evolution, or inheritance of acquired characteristics, but never mentions this theory by name. The influence of this process on evolution cannot be dismissed just because it does not make sense biologically and Jones stresses this by emphasizing the importance of parents passing on education/social rank/nutrition to their offspring. There is not biological link between a mothers rank in the pecking order of the society she is about to bring offspring into, but whether or not she is able to provide sufficient nutrients while her young is in the womb, and later as a postpartum dependent, is directly related to that rank.

Difficulties on Theory
There are several holes, or apparent holes, within our understanding of evolution for ID proponents to build off of, but even these arguments tend to misapply and misinterpret evolutionary processes. The lack of intermediary forms is a popular, yet flawed, argument. In truth, everything is an intermediate form because evolution runs on an endless road, not a treadmill. I believe Jones provides a good example of intermediate forms when discussing forms of hawthorn fly. Variations, or subspecies, of this organism exploit different ecological niches and do not breed across those lines outside of the laboratory. It seems very likely that after more time passes by that these subspecies could adapt so well to there particular niches that they will no longer be capable of interbreeding even in a lab and, in biological terms, will speciate.

In Conclusion
The most valuable concept of this section might be that evolution works more as a "tinkerer" rather than as a "trained engineer". We cannot know where evolution will take organisms next because we cannot know what environmental changes are lying in wait for us to adapt to. Natural selection can only act on what is present and does not give consideration to whether a trait that is beneficial now will be deleterious later.

Some questions to promote discussion:

1) Aside from the few mentioned above, what are other apparent 'problems' or 'holes' are there in evolutionary theory that are explainable by someone with a good understanding of the subject?

2) What examples could you provide to explain natural selection to a creationist that hinges on the fact that there is no omniscient designer behind it all? In other words, what is a change that has evolved that could become or has already become possibly disadvantageous? In humans, a male's penis and testicles on the outside of the body would seem an obvious one.

Wednesday, September 16, 2009

Literary Darwinism

Here is the link to the article I mentioned in class on Literary Darwinism. Pretty fascinating stuff, but probably not the ultimate solution to the True Meaning of Literature!

I enjoyed the discussions in class this week and look forward to more of the same!

Dead White Males

You probably recognize Darwin on the left, but do you recognize the famous 19th century author on the right? (looks a little like Darwin, but it's not Darwin).

Saturday, September 12, 2009

Some Questions to Consider About Darwin

Some Questions based on my reading of the Historical Sketch chapter.
  • Darwinism as a scientific revolution...like Freud, Galileo, and Marx, Charles Darwin is often considered to have revolutionized the way in which we think about ourselves and the world. In what revolutionary ways did Darwinism change our conception of our place in nature?
  • What is the significance of variation in Darwinian theory? From where does variation arise (at the biological or genetic level)? Can the presence of variation alone explain evolutionary change or adaptation? If not, what else is necessary?
  • What historical event "forced" Darwin to complete and publish The Origin, in spite of his worries that he needed even more evidence, and a much longer book, to be able to convince a skeptical world? Did the first edition of The Origin sell well?
  • Jones states (on p. xxv: "The Origin is two things: a bold statement of the idea of evolution, and a work of persuasion as to how it took place". Explain these two aspects of the book.
  • Jones is dismissive of the attempts by social scientists to utilize evolution and Darwinism to explain aspects of human society and social life. Can you think of and describe some of the things he is probably referring to? What kinds of uses have anthropologists put evolution to? Can you evaluate the success or failure of some of these ideas?

Darwin's Ghost: Introductory Thoughts

Our first text is Darwin's Ghost: The Origin of Species Updated, by Steve Jones (2000), and our first topic is, of course, evolutionary theory. We mentioned in class on Monday that, for biological anthropologists (as well as for some few archaeologists and even fewer cultural anthropologists), evolution is the major theoretical paradigm for all of our work: we see everything that we do through the lens of evolutionary theory. The famous Drosophila geneticist Theodosius Dobzhansky once said "nothing in Biology makes sense except in light of Evolution", and the same is true for biological anthropology. So we are very interested in this class in coming to terms with what Darwin's theory is all about.

What did Darwin say in the Origin (first published in 1859, 150 years ago), and what are the major modifications and additions to Darwin's version of evolution by natural selection that have accumulated over the past 150 years? Darwin's Ghost is an attempt to present a modern exposition of evolution by natural selection, retaining the structure of Darwin's great work, but filling in the details and gaps with the results of 150 years of scientific work. We will see that in nearly all major details, Darwin's work still stands today as relevant and, at times, astonishingly accurate: something which cannot be said for many scientific works produced in the middle 19th century. The one place where Darwin was simply wrong was in his groping attempts to understand the nature of heredity. We will see that his theory of "blending inheritance" was the one real error in his theory. Ironically, the true nature of inheritance (particulate, not blending) had been worked out in great detail by a contemporary, the Austrian monk Gregor Mendel, who published the results of his experiments in plant hybridization on the common pea plant in an obscure German language botanical journal in 1865 that was ignored by Darwin and most other biologists of the time. But in most respects, Darwin got things right, and much of the work of the past 150 years has been filling in the details. Darwin's Ghost will help us learn about these details and to answer the question, what evidence has modern science amassed in favor of Darwin's theory of evolution by natural selection?

2009 is being celebrated as the Year of Darwin since he was born 200 years ago on Feb.12, 1809 (the same day and year as Abraham Lincoln) and the Origin was published 150 years ago on November 26, 1859. Below are a few links to some excellent web sites about Darwin.

Thursday, September 3, 2009

BioAnth Seminar

Fall Semester 2009 Biological Anthropology Seminar: ANTh 6030.

This blog will be used to begin and to continue seminar discussions of issues and themes raised in our readings this semester. We will read three books in this class...Steve Jones' Darwin's Ghost, Steven Jay Gould's Mismeasure of Man, and Roger Lewin and Robert Foley's Principles of Human Evolution. For each class meeting, one member of class will be responsible for posting a detailed blog entry about the reading assignment. The rest of the class will comment on the initial blog post each week and extend the discussion of the reading through this online forum. At the first class meeting we will create a blogging schedule for the entire semester, which we will post here as soon as possible. So welcome to the course, and we'll see you next Wednesday!