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Author | Topic: Neanderthals | |||||||||||||||||||
Mammuthus Member (Idle past 6475 days) Posts: 3085 From: Munich, Germany Joined: |
quote: I do have a book written by Gingerich (read it 7 years ago so have to dig it up) on the subject where he did do a calorie expenditure versus calorie gain calculation based on traditional hunting of African elephants. Also because of the thickness of the skin and the high muscle to fat ratio the meat of an elephant is not as good as other large herbivores. This still does not address the extreme lack of kill sites.
quote: Aside from the fungi that live on Choloepus, I can hardly imagine anyone subsisting on sloth meat..but I could be wrong. In any case, Mylodon, Nothrotheriops to a lesser extent, was full of ossicles throughout the skin and probably not so easy to kill. It is at least not thought that the giant ground sloths were as slow moving and defenseless as tree sloths.
quote: This assumes that the immigrants practiced a more non-economical form of subsistance i.e. killing more than you need in the lands they came from. I don't know that there is any evidence for this. That there was social adaptation and adaptive behavior of the animals in North America say, probably also occurred. One other point, the end Pleistocene was anythig but stable. With the mass extinction of predominantly megafauna, both the flora and fauna would have been in transition for some time following their disappearance. cheers,M
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Mammuthus Member (Idle past 6475 days) Posts: 3085 From: Munich, Germany Joined: |
quote: However, this ignores several modern viruses which jump species boundaries and cause mass mortality. The problem we have had in trying to detect viruses in ancient samples is that they are mostly RNA viruses and it is hard enough getting DNA from such samples, RNA is impossible. In any case, if you have populations separated for extended periods of time i.e. North American megafauna, and pathogens then are introduced from another location, mass mortality could ensue and knock the populations down to a level where they cannot recover and then become extinct from other simultaneous pressure such as environment change and novel predators...not much different than the effect of the Spanish bringing european disease to South America except on a much greater times scale with regard to population separation...and as you point out, it would only require that several keystone species become extinct to completely change the environment for other species which could result in extinction of animals that were dependent on the effects of the key species. Note: If you and Rei are interested in discussing extinction in more detail, should I make a separate thread? We are drifting off of the topic but I think the discussion is interesting and am up for it. [This message has been edited by Mammuthus, 10-15-2003]
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Speel-yi Inactive Member |
quote: Sure, that'd be great although I do have some ideas about the effect primative humans have had on megafauna, so in that way it isn't too far off topic.
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Mammuthus Member (Idle past 6475 days) Posts: 3085 From: Munich, Germany Joined: |
Great! I will start a topic in the Misc. Topics forum called
Overkill, Overchill, Overill? Megafaunal extinction causes.
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Rei Member (Idle past 7013 days) Posts: 1546 From: Iowa City, IA Joined: |
(Edit: Moved to the Megafauna extinction thread)
[This message has been edited by Rei, 10-15-2003]
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sfs Member (Idle past 2534 days) Posts: 464 From: Cambridge, MA USA Joined: |
quote: That model fails for two reasons, I think. First, a population of 10,000 with such a high degree of isolation between subpopulations would have an effective population size much higher than 10,000. Once again, the diversity would be high than we see. Second, the genetic distances between geographically distant subpopulations would be large. The largest genetic distances we see are pretty modest, with Fst in the range of 0.1 to 0.15.
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Speel-yi Inactive Member |
Hmmm...still stunned from the game tonight. Feeling funkier than usual.
I'm saying that the isolation was not that large. I'm also saying that the inbreeding would lead to a significant loss of genetic diversity.
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sfs Member (Idle past 2534 days) Posts: 464 From: Cambridge, MA USA Joined: |
quote:I lost interest in the season at the same time Pedro Martinez lost his control in the seventh game of the ALCS. quote:Small populations lead to loss of a lot of genetic diversity, but you lose much less diversity if your population is subdivided, since different subpopulations retain different subsets of diversity. If I ever get time I'll try simulating your toy model, to see what kind of migration rate would be needed to maintain small genetic distances across the entire range. (Note, by the way, that the distance between demes in your model is something like 500 miles, and that's if they're strung out in a line from Iberia to Java. Scattered about, they'd be even farther apart. That's a long way to walk for a wife.) [Note added later: "toy model" is not disparaging -- I look at toy models all the time.] [This message has been edited by sfs, 10-21-2003]
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Speel-yi Inactive Member |
I don't think 500 miles would be too far to walk for some sex, especially if there was none available nearby.
Also consider that the population would not be evenly distributed throughout the range, they would not be living on the slopes of the Himalayas for example and they would also probably congregate at resources such as water and stone for tool making. Kick it around and if you are ever in the mood, try and disprove the Out of Africa hypothesis. If it's a sound hypothesis, it will stand up to the abuse. I have not always been a devotee of the MRH, I only began to take a look at it about 10 years ago. I also wonder sometimes at my sanity, yelling at a TV screen is a bad thing sometimes. But I didn't feel so bad after Boone hit that homer and my neighbor was really raising hell. His voice really carries sometimes. ------------------Bringer of fire, trickster, teacher.
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