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Author Topic:   Neanderthals
Mammuthus
Member (Idle past 6475 days)
Posts: 3085
From: Munich, Germany
Joined: 08-09-2002


Message 151 of 159 (60951)
10-15-2003 4:20 AM
Reply to: Message 145 by Rei
10-14-2003 3:44 PM


quote:
I do, however, think that you underestimate the value to a society of a megafauna kill. I don't have figures for mammoths, but after watching a show about the Donner party and cannibalism, they mention that the average adult male human has about 4.5 lbs of protein, enough for 60 people for one day. Assuming a 180lb human and a 8 ton mammoth, with simply scaling these figures up by body mass, we're looking at about 400 lbs of protein, feeding a whopping 5,400 people for a day (or more realistically, a smaller number for notably longer). Do you have more precise figures (also addressing things like calorie consumption)?
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:
Also, where did you get that sloth meat is bad? It's eaten in some parts of South America.
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:
I would argue that the reason some of North America's large mammals survived is that a steady state was reached before extinction. Early humans were no more migratory than many other predators, especially without horses. If left in a fairly stable environment for long enough, most species tend toward equilibrium. Not only do the buffalo, for example, adapt, but also do the social values of the native tribes. They are selected apon - through natural selection - based on their ability to not kill off all of the food supply in the area.
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

This message is a reply to:
 Message 145 by Rei, posted 10-14-2003 3:44 PM Rei has replied

Replies to this message:
 Message 155 by Rei, posted 10-15-2003 2:24 PM Mammuthus has not replied

  
Mammuthus
Member (Idle past 6475 days)
Posts: 3085
From: Munich, Germany
Joined: 08-09-2002


Message 152 of 159 (60952)
10-15-2003 4:25 AM
Reply to: Message 150 by Speel-yi
10-14-2003 8:55 PM


quote:
I really have a tough time with the pathogen hypothesis as well. We see very diverse species all disappearing at the same time. What it's going to take is a species by species evaluation of what happened and then we have to consider what effect each species has on the ecosystem as a whole
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]

This message is a reply to:
 Message 150 by Speel-yi, posted 10-14-2003 8:55 PM Speel-yi has replied

Replies to this message:
 Message 153 by Speel-yi, posted 10-15-2003 4:38 AM Mammuthus has replied

  
Speel-yi
Inactive Member


Message 153 of 159 (60954)
10-15-2003 4:38 AM
Reply to: Message 152 by Mammuthus
10-15-2003 4:25 AM


quote:
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.
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.

This message is a reply to:
 Message 152 by Mammuthus, posted 10-15-2003 4:25 AM Mammuthus has replied

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Mammuthus
Member (Idle past 6475 days)
Posts: 3085
From: Munich, Germany
Joined: 08-09-2002


Message 154 of 159 (60959)
10-15-2003 6:34 AM
Reply to: Message 153 by Speel-yi
10-15-2003 4:38 AM


Great! I will start a topic in the Misc. Topics forum called
Overkill, Overchill, Overill? Megafaunal extinction causes.

This message is a reply to:
 Message 153 by Speel-yi, posted 10-15-2003 4:38 AM Speel-yi has not replied

  
Rei
Member (Idle past 7013 days)
Posts: 1546
From: Iowa City, IA
Joined: 09-03-2003


Message 155 of 159 (61023)
10-15-2003 2:24 PM
Reply to: Message 151 by Mammuthus
10-15-2003 4:20 AM


(Edit: Moved to the Megafauna extinction thread)
[This message has been edited by Rei, 10-15-2003]

This message is a reply to:
 Message 151 by Mammuthus, posted 10-15-2003 4:20 AM Mammuthus has not replied

  
sfs
Member (Idle past 2534 days)
Posts: 464
From: Cambridge, MA USA
Joined: 08-27-2003


Message 156 of 159 (61699)
10-20-2003 12:34 AM
Reply to: Message 144 by Speel-yi
10-14-2003 1:12 PM


quote:
It would mean having an effective breeding population of around 10,000 spread over two continents. This would not be that big of a stretch at all. [...]
So we would see populations from demes with effective breeding populations of around 500 and then periodic mating between demes from adventurous youths traveling fairly great distances to find a suitable mate.
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.

This message is a reply to:
 Message 144 by Speel-yi, posted 10-14-2003 1:12 PM Speel-yi has replied

Replies to this message:
 Message 157 by Speel-yi, posted 10-20-2003 4:13 AM sfs has replied

  
Speel-yi
Inactive Member


Message 157 of 159 (61727)
10-20-2003 4:13 AM
Reply to: Message 156 by sfs
10-20-2003 12:34 AM


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.

This message is a reply to:
 Message 156 by sfs, posted 10-20-2003 12:34 AM sfs has replied

Replies to this message:
 Message 158 by sfs, posted 10-21-2003 10:49 PM Speel-yi has replied

  
sfs
Member (Idle past 2534 days)
Posts: 464
From: Cambridge, MA USA
Joined: 08-27-2003


Message 158 of 159 (62017)
10-21-2003 10:49 PM
Reply to: Message 157 by Speel-yi
10-20-2003 4:13 AM


Re: Truncation Selection
quote:
Hmmm...still stunned from the game tonight. Feeling funkier than usual.
I lost interest in the season at the same time Pedro Martinez lost his control in the seventh game of the ALCS.
quote:
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.
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]

This message is a reply to:
 Message 157 by Speel-yi, posted 10-20-2003 4:13 AM Speel-yi has replied

Replies to this message:
 Message 159 by Speel-yi, posted 10-22-2003 4:42 AM sfs has not replied

  
Speel-yi
Inactive Member


Message 159 of 159 (62084)
10-22-2003 4:42 AM
Reply to: Message 158 by sfs
10-21-2003 10:49 PM


Re: Truncation Selection
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.

This message is a reply to:
 Message 158 by sfs, posted 10-21-2003 10:49 PM sfs has not replied

  
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