Chapter+02

Place your questions and answers for Chapter 2 here.

A: It would be advantageous because now that fish has access to the resources (mainly food) offered by terrestrial and aquatic environments. The more available resources there are for the fish, the higher its fitness (on the species level, that is). (N. Braun)
 * Q: Why might it be advantageous for creatures such as the Lungfish to have the fins and scales of a fish but the lungs of a land animal? (I. Perler)**

A: It would be advantageous for a certain fish to have to have these features because if they were "walking" on the bottom of a stream, pond, or on a mudflat they need to be able to support themselves. It would also be beneficial--in terms of survival--in order to be able to go on land (such as a mudflat) to escape a predator, look for new food sources, and have less competition. (T Gebhart).
 * Q: Tiktaalik showed the first steps of the evolution of the wrist, palm, and finger area. Why would it be advantageous to have these features for a fish that lives underwater? (N. Sarkar)**

A: All creatures with limbs, whatever the design may be all share this common route which is one bone which leads to two bones which then leads to a bunch of little bones that lastly connect to the fingers. This can bee seen in the legs of all limbed organisms as well. It was Sir Richard Owen who first noted these exceptional similarities between limbed organisms. The spot where humans and Tikaalik differ is where that first bone connects. In humans and Tikaalik, that bone connects to the shoulder that allow for a push-up like position to help movement on land. (J. Speelman)
 * Q: According to Shubin, all organisms' limbs have a common plan. What is this plan and where do humans and the Tiktaalik differ - why? (M. Blanchard)**

Charles Darwin's theory of evolution was supported by Sir Richard Owen's " one-two-blobs-digits" structure of limbs was seen across all skeletal limbs. While not all identical, strong similarities between these skeletal formations supported Darwin's theory. These similarities showed linkage between species, and an interconnecteness throughout animals with limbs, be it fins in fish or forearms in humans(C.King)
 * Q: How does Charles Darwins theory explain the similarities that were observed by Sir Richard Owen? (A. Schmidt)**

A: Tiktaalik's ability to do a pushup originates from evolution -- SInce Tiktaalik likely dwelled on the floor of shallow streams and ponds, it was very necessary for the creature to be able to support its own body. This trait likely helped them survive and get food, and was therefore "selected" by nature. The specific traits that allow Tiktaalik to perform this motion are its capability to bend its elbows like a human, and its ability to bend its wrist so that its palm is face down. Also, Tiktaalik had an abundance of chest muscles. (L. Bercz)
 * Q: What are the specifics of the origin of the Tiktaalik's ability to do a push-up and what traits allow the Tiktaalik to perform this motion? (C. Nikolai)**


 * Q: Shubin describes the evolution of an organism's limb plan and says the first true fingers and toes were present, after Tiktaalik, in what animal? This being a major evolutionary change, what future evolutionary changes could occur within humans a million years from now? Why would they be needed? (L. Bentley)**

R: The three strategies were to get big, get armor, or get out of the water. No, I do not think that aquatic environments are still strictly a "fish-eat-fish world." While, of course, there are some fish who eat other fish, there are also many other fish who eat plants, such as algae, or animals other than fish (worms, for example). The fish these days have a much more variable diet than those who lived 375 million years ago when the Tiktaalik existed, so they do not live in just a "fish-eat-fish world." (A. Nolan)
 * Q: Shubin describes three strategies to help aquatic animals survive in their "fish-eat-fish world." What are these strategies? Would you consider aquatic environments now a "fish-eat-fish world?" If so, explain why and which of the three strategies would be beneficial for the animals. If not, explain why. (J. terHorst)**

A: Because of their complexity and they way the bones are purposely arranged, Sir Charles Bell's believed the hand was "perfect," and therefore, must have had a divine origin. In today's world, we know that evolution can be proven through science. While many people believe that some sort of divine origin could be involved initially, science proves that hands evolved from earlier structures in other organisms. The development of hands has more to do with which structures and traits were more advantageous. (C. Sanders)
 * Q: Explain Sir Charles Bell's theory. Why did he think the hand was so "perfect" in shape? Give your opinion on if you agree with Bell or not, and why. (H. Schwarz)**

A: During Shubin's first human dissection, the first area of the body he experienced genuine emotional connection with was the hands of the cadaver. Another area that would be likely to feel connection to would be the face. This is the part of the human body seen in almost all interaction with other people, and arguably the most visible part of what makes up 'human'. Any area within the ventral cavity (ie guts) would be far less likely to cause response. While it is known that these organs are part of a human body, there is very little to tie them to a specific person, like the more visible areas of the hands and face. (M. Purdon)
 * Q: During Shubin's first human dissection lab, which area/organ of the body did he have an emotional connection with? In your opinion, what would be another area that would possibly evoke an emotional connection? What would be an area that would not? (R. Heis)**

A: The specific bone that //Tiktaalic// possessed was the wrist bone. The bone that Shubin and his colleagues uncovered resembled a wrist bone due to the presence of a joint at the end that had spaces for four other bones. Along with this original finding, there was another fin found that had this same bone yet this fin had that bone along with four other bones attached. This fin was the millions of years old origin of a piece of our own bodies, yet it was found in a fish. If I were in Shubin's shoes I would have been at a loss for words. This discovery came after almost 10 years of countless trips to the arctic and was ultimately what made the trip worth it. It would have been very satisfactory and in some ways a relief to possess a find like this. (O. Heltman)
 * Q: What was the specific bone that //Tiktaalic// possessed that made it such an important find? How would you have reacted if you were in Shubin's shoes at the bottom of that quarry? (P Oakes)**

A: I do agree with his statement that the hand is the visible connection between us. I feel this way because as humans, our hands are one of our most impressive features (with the types of movements we can do, having thumbs, etc.), as well as one of the most unique. I personally think that most (if not all) organisms with similarity to us involving their hands are more than likely connected to us, due to the complexity and advancement of our hands. (A. Gatje)
 * Q: Shubin consider the hand to be visible connection between us. Do you agree with his statement that is the hand is the visible connection between us or do you feel there is a better body part that we form a stronger connection with? (C. Hurst)**

A. the radius rotates around a pivot point in the elbow joint which allows humans to rotate the thumb relative to the elbow. The humerus ends in a ball which fits into a socket at the top of the radius. the //Tiktaalik// showed the very beginnings of this ability in its fins but many small adjustments were needed to make the hand as functional as it is today. (E.Olson)
 * Q: There are many impressive similarities between the "hands" of the //Tiktaalik //and the hands of humans. However, what is one major difference between the "hands" of the //Tiktaalik// and human hands that allows humans to do useful motions such as grabbing and catching? (T. Russell)**

A: The Tiktaalik fish were able to do push-ups. They have a shoulder, a wrist, and an elbow which allowed them to do a push up. When a human does a push up, our hands will be flat against the ground, have our elbows bent, and we will use our chest muscles to move up and down. The elbow and the wrist of the Tiktaalik fish are able to bend like a humans and this fish most likely had an abundance of chest muscles which allowed them to specialize in this function. (A. Schmidt)
 * Q: What type of exercise could the Tiktaalik fish do, and what enabled it to do this? (A. Gatje)**

A: The Ichthyostega soderberghi was a bit of a let down when determining the evolution of limbs. This showed an organism that already had fully formed fingers and toes but unlike Tiktaalik, showed little insight to how limbs/fingers/toes came to be. Tiktaalik was significant because it still had fins of a fish, but within that fin were bones similar to those of a human hand, showing one of the first bridges between fish and us today. (M. McKinney)
 * Q: What makes the //Ichthyostega soder-berghi// found by Save-Soderbergh less significant to the evolution of limbs than Tiktaalik found by Shubin's team? (T. McDaniel)**