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1. i1. if life originated once on Earth, we might expectthat it should be able to originate again, much like Lamarckhypothesized, but we don%u2019t observe thishappening. All evidence points to a single origin oflife on earth. Why do you think we do not see lifeoriginating again and again from scratch?

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Deanna Hettinger
Deanna HettingerLv2
28 Sep 2019

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Related questions

As you may recall in the work of Triplett (1898), the presence of others in a bicycle race was found to enhance individual performance. This is called social facilitation (Williams, Harkins, & Karau, 2007). At times, however, the presence of others can detract from individual performance, which is termed social inhibition (Crisp & Turner, 2007). Similarly, social loafing can occur when an individual’s performance within a group decreases due to his or her reliance on others in the group (Crisp & Turner, 2007).

For this Discussion, review the media program, Week 5: The Virtual Office. Focus on the characters in the media and determine which characters displayed social facilitation, social inhibition, and social loafing.

With these thoughts in mind:

Post by Day 3 a description of the characters in the media program demonstrating social loafing, social inhibition, and social facilitation. Explain how you identified them. Then, select one of the characters and, using the current literature, explain two ways you might mitigate their behavior.

Media Program

(Onscreen Text: The employees at the United Cardboard Company often work individually on projects, but as with most environments, they are occasionally asked to participate in group projects. One such group is about to meet right now to plan a presentation for the Board of Directors. Observe the conversation and reactions of various group members to determine which group members exhibit signs of the following: Social Loafing, Social Inhibition, and Social Facilitation.)

(Interior of an office. Ken stands at the front of the conference room.)

KEN: OK, I guess we might as well all get started. As we all know, the big man has requested the five of us to get together and write and conceptualize a presentation to the board on our new packaging system. Maybe we can start by going around and throwing out some initial ideas.

KATHY: Sounds good to me. I think a PowerPoint presentation would do the job well.

GAVIN: I agree. We could follow it up with a physical demonstration of how the packaging looks and folds-- maybe a video of the larger pieces that won't fit into the boardroom.

KEN: Sounds perfect to me. Amanda, Brian, what do you guys think?

BRIAN: Yeah, what you guys said sounds fine.

(Amanda thinks, “I don’t know what to say!”)

KEN: Amanda?

AMANDA: I don't know. I didn't really get much chance to think about this. We only found out we needed to do this together three days ago.

KEN: OK, no worries. Let's focus on the PowerPoint idea. I've been doing a lot of them lately, so I'm happy to take the lead on the design aspect. What do you guys think we should all incorporate into the slides?

GAVIN: I think we should start with where we got the idea for this new packaging -- the company that designed it and the different sizes that it comes in.

KATHY: We should follow that with a graph comparing the old prices to the new ones to illustrate how much we'll be saving over time. Amanda, didn't you have most of that information collected at some point?

(Amanda thinks, “Oh no! What if I deleted that?)

AMANDA: I don't know, maybe, it's been so long. I didn't think I'd need it again for a group project like this.

(Gavin thinks, “I wonder what’s gotten into her. She’s not usually this tense.”)

KEN: That's OK, Amanda, I'm sure we can easily dig it up again. Brian, do you have any other ideas for the PowerPoint slides?

BRIAN: Nah, I think what you guys mentioned sounds right.

(Kathy thinks, “Wow. Way to contribute Brian.”)

KEN: OK then, Kathy and Gavin why don't you send me all of the info and I'll write it up and make the slides. Amanda, don't worry about the cost saving document, I'm sure I can dig it up from my old emails and put it into that slide too.

AMANDA: Are you sure? I'm happy to look. I mean I'm sure I have it somewhere. (Kathy thinks, “She really needs to get it together. Why is she so nervous?”) At least I think I have it somewhere. You won't tell the Board of Directors if I lost it, will you?

KEN: Of course not, we're in it together. So as I was saying, I'll write up and prepare all the PowerPoint slides. Then we can start our presentation with reading and explaining each slide. Then, what?

KATHY: Well, and then I think we should show them the packaging live, and the quick deconstructing techniques.

KEN: Great idea. You and Amanda can demonstrate the folding, while I narrate what you're doing.

(Amanda thinks, “Is he doing too much of the work? And what if I drop everything while he’s talking?”)

GAVIN: And after you all demonstrate the smaller packaging, we could show a quick video of how the really big ones function down at the warehouse. Brian, would you be able to go film that quickly one of these days?

BRIAN: I don't really have any experience with video cameras or anything like that, so...

(Gavin thinks, “I should have seen that one coming.”)

KEN: That's OK. My wife actually just got me this great little camera for our anniversary. It takes great videos. So I can just run down to the warehouse, get some footage, then put it together on this new editing software I just downloaded. Maybe add a little music. It's going to be really slick!

KATHY: Are you sure, I wouldn't mind doing that too.

KEN: Oh no, it's fine. I love this kind of stuff; just leave it to me. But I suppose that's enough planning. Now it's time to get to work and make the presentation a knock out. Go team!

(Everyone except Ken thinks, “Team?”) ©2012 Laureate Education, Inc.

In the passages below, Darwin and Wallace both clearly define what a species is based on their observations of the natural world. They then provide explanations for how new species arise.

Excerpt from “The Origin of Species and Genera (S322: 1880), January 1880 issue of Nineteenth Century,” by Alfred R. Wallace ... A species may be defined as a group of individuals of animals or plants which breed together freely and reproduce their like; whence it follows that all the individuals of a species, now living or which have lived, have descended from a few common ancestors, or perhaps from a single pair. Thus all horses, whether Shetland ponies, racers, or cart-horses, form one species, because they freely breed together, and are known to have all descended from a common stock. By the same test the common ass, the kiang, the quagga, and the zebra, are each shown to be distinct species; for though sometimes two of these species will breed together, they do not do so freely, they do not reproduce their like but an intermediate form called a mule, and these mules are not capable of reproducing their kind, as are the offspring of any pairs of a single species.

Excerpt from “On the Origin of Species,” by Charles Darwin, 1859 ... So with natural species, if we look to forms very distinct, for instance to the horse and tapir, we have no reason to suppose that links ever existed directly intermediate between them, but between each and an unknown common parent. The common parent will have had in its whole organisation much general resemblance to the tapir and to the horse; but in some points of structure may have differed considerably from both, even perhaps more than they differ from each other. Hence in all such cases, we should be unable to recognise the parent-form of any two or more species, even if we closely compared the structure of the parent with that of its modified descendants, unless at the same time we had a nearly perfect chain of the intermediate links. ...

Excerpt from On the Origin of Species, Chapter 4, by Charles Darwin, 1859 ... On the view that each species has been independently created, I can see no explanation of this great fact in the classification of all organic beings; but, to the best of my judgment, it is explained through inheritance and the complex action of natural selection, entailing extinction and divergence of character, as we have seen illustrated in the diagram. ...

Question: From all these readings, is there evidence that both Darwin and Wallace independently formulated the theory of evolution by natural selection? Support your answer.

For years we have been able to analyze the fossils of extincthumans like those of Neanderthals. Their bones gave us clues to howthey looked, how they lived, and how they might be related to us.In the last few years, we have been able to get a better view intothese extinct species and their relationship to our species. Thanksto next generation genomic sequencing technologies, we have beenable to obtain genetic data on Neanderthals, Denisovans and othersthat have allowed us to make direct comparisons between our speciesand theirs. In addition, we have been able to observe the presenceof DNA from these extinct species within our own genomes which tellus that we had kids with these now extinct humans.

If we take Neanderthal DNA as an example, we find that we share99.5 percent of our DNA with them. Which means that we andNeanderthals were separated from each other for more than 500,000years. This also means that we were genetically similar enough tobe able to have offspring with each other. We see evidence of thisgenetic introgression between us and Neanderthals when we look atour DNA. Interestingly, if we obtain one thousand DNA samples fromGrossmont College students, we estimate that we would be able toextract at least 20% of the Neanderthal genome from them. Thismeans that 20% of our collective nucleotide sequences are sharedwith Neanderthals but this doesn’t mean that 20% of our genes areNeanderthal specific genes. Of the twenty-one thousand genes thatNeanderthals had, only a few dozen of their genes survive withinour genome. The same holds true for Denisovans. What is moreinteresting is that older versions of ourselves have a tendency tohave higher levels of DNA from extinct humans compared toourselves. In other words, over the course of thousands of years wehave been slowly weeding out the DNA of the other humans from ourgenome in favor of our genes.

One basic question that we might like to ask is why have we beenlosing Neanderthal and Denisovan genes over time? Also, why do westill have a significant amount of DNA segments that don’t seem tobe going anywhere? The answer to this has to do with selection.

The answer to the first part of the question has to do with thefact that we were not fully genetically compatible with the otherhuman species to begin with. Basically, to have had Neanderthal orDenisovan genes in the past meant that an individual's level offitness was reduced. To get rid of their genes in favor of our ownwould mean that the relative fitness of individuals would increaseovertime.

The answer to the second question has to do with the fact thatDNA segments from Neanderthals and Denisovans that did not code forproteins remained because there was little selective pressureagainst them. As far as genes are concerned, the only Neanderthaland Denisovan genes that remain only exist because they had aselective advantage or at least have been neutral to ourspecies.

DNA segments that that were neutral or that had a selectiveadvantage, whether genes or not, simply remained because they wereadvantages or there was little selective pressure against them.

Your task for this week is to look for information about oneNeanderthal or Denisovan gene that survive within our species andto tell me what function that gene has and how that gene mayincrease the fitness of modern human populations.

  • In your post, discussONE Neanderthal orDenisovan gene that is currently found within our species.
    • Tell us about the gene and its function. Explain what it doesfor us. (Make sure you give a citation.)
    • Explain in your own words any possible advantages that yourNeanderthal or Denisovan gene might have. Make sure you give ininformed opinion that is grounded in your research.

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