Ice Age Physiology

[Guest]

JDL : "Antfoot, predators also reached megafauna proportions."

 

No predator that I am aware of reached proportions like those of the herbivores. While some were quite enormous, few were larger than tigers or brown bears. Giant hyenas were the size of a mastiff. Smilodon was also about as tall as a mastiff though possibly longer. These were not "giants" even as they were mega-fauna. Dire wolves were only marginally larger than modern wolves. The cave bear was truly enormous but was still only fractionally larger than its brown bear and polar bear kin. Most people are unaware of the fact that these animals weren't really giant but merely powerfully built animals. Most of the extinct mega-faunal predators were short-limbed critters that preyed on gargantuan herbivores of the time. The short-faced bear was most likely a scavenger from my readings: built for speed but not for agility.

 

I often like to imagine how giants might evolve (mermaids, angels, dragons etc.) and think they are possible but have yet to see any evidence that I find compelling that they exist. Six and seven foot tall humans are not giants in anything more than a relative manner as you point out yourself with respect to the Paiute. Not convinced here.

[JDL]

Giant is a relative term, as we agree.  The hypothesis is that ice age conditions permitted evolution to potential under conditions that were physiologically challenging, yet biologically nourishing at the cellular level.  Megafauna,, compared to present species, were larger and more powerful, but had greater requirements to sustain themselves.  This made them vulnerable to extinction, particularly if they lacked robustness or were particularly specialized and vulnerable to a changing environment.

 

I believe that there were two species of megafauna hominid.  The first, a species of near-humans that grew tall, but not robust, due to the ability to use tools, craft clothing, and rely on a cooperative societal structure that both multiplied group effectiveness and forgave individual frailty.  I believe that this less robust race became, in post ice age conditions with insufficient oxygenation to maintain cellular health, susceptible to all of the physical maladies that plague exceptionally tall people today, and that they both slowly died out and were absorbed into our species.  They may be our mystery ancestor.  If accounts of large remains discovered throughout the mound building culture are to be believed, and I believe some of them can, then this race was assimilated into the mound building culture.  In contrast, the Si-The-Cah of Paiute legend and archeological discovery, were unable to survive in armed competition with the Paiutes.  Other historical mentions include the Susquehanock and the Patagonian "giants".

 

The second megafauna hominid would be bigfoot.  The difference and advantage being that they grew more robust (with the key physiological feature being increased lung volume due to this robustness [depth and breadth of the torso as well as height]), and were able to sustain sufficient oxygenation to sustain cellular health in post ice age oxygen levels, though they are presumably smaller than they once were.  Robustness would have been a matter of selection in a species that did not rely heavily on tools, crafted items, or complex societies that permitted the frail to survive and pass on their genes.

[Guest]

I'm confused.

 

How would humans have not capitalized on the same conditions in the last ice age as Squatch?

Humans had bigger brains that we acquired in a hot and dry climate. When our ancestors moved into the colder north they had a high level of intelligence to help them figure out solutions to problems posed by their prey and environment. Tools required less energy and nutrients for production than muscle and bone. Bigfoot did not have these advantages and would have had to evolve strength and speed to survive.

[hiflier]

Hello antfoot,

 

Humans had bigger brains that we acquired in a hot and dry climate. When our ancestors moved into the colder north they had a high level of intelligence....

Are you saying the brain size was aquired as a result of climate? I would have to disagree. I think the climate was a factor in that it allowed for activities colder climes did not; it's effects being more indirect. This is actually great that the topic has gone this far as it's beginning to enter an area that I've looked into with regard to modern man's intelligence developement. OR SHOULD I SAY IMAGINATION. The shift in right brain activity is where I've been intrested the most.

Edited February 17, 2014 by hiflier

[Guest]

The environment in which Homo sapiens evolved was simply NOT a cold or high partial pressure for O2 is all I am saying. Humans likely acquired their intelligence due to a diverse ecosystem and diet facilitated by tools. Both "right brain" and "left brain" activity improved (from our perspective) during this time which was sometimes ice age and sometimes interglacial.

[JDL]

Certainly there have been fluctuations in O2 levels throughout human history.  To the extent that high O2 levels provide benefit, to the extent that the human body is capable of benefiting, and to the extent that such levels persisted long enough to permit beneficial adaptation, if only in isolated (high latitude) populations, then it is possible for racial divergence among humans.  I've never said that all humans grew taller, just that some may have and that there is sufficient evidence to indicate that some did.  I would also think that this racial divergence occured after the development of human intelligence.

[hiflier]

Hello antfoot,

I agree, no one factor was responsible but I also agree that the warmer regions or conditions played a fair role in a species intellectual developement. Your mention of diet espeially come to mind. In fact I think that during the period of time 40,000 years ago Cro-Magnon's diet history was THE critical factor in who and what Cro-Magnon became and achieved. Why they made it and Neanderthal didn't

Hello JDL,

The timeframe I mentioned was decisive for several reasons. It saw the beginning of the end for Neanderthal after 230,000 years existence; only to lose out to Cro-Magnon in their last ten thousand. One event was a severe cosmic ray bombardment around 40,000 years ago. It has had me thinking for the last several years of how Cro-Magnon survived it and Neanderthal in the long run did not. It's complicated. There's no good way to get it all into a post.

Edited February 18, 2014 by hiflier

[Guest]

Certainly there have been fluctuations in O2 levels throughout human history.  To the extent that high O2 levels provide benefit, to the extent that the human body is capable of benefiting, and to the extent that such levels persisted long enough to permit beneficial adaptation, if only in isolated (high latitude) populations, then it is possible for racial divergence among humans.  I've never said that all humans grew taller, just that some may have and that there is sufficient evidence to indicate that some did.  I would also think that this racial divergence occured after the development of human intelligence.

O2 fluctuations are certainly real and have likely occurred during our evolution. I'm only saying that I see no need to implicate them in the evolution of any species or breed of human. Except perhaps for the high alpine types who certainly do have adaptations to the lower pressure up there. However these people are adapted to less available O2 as opposed to more. I can see a population becoming dependent upon higher O2 levels but these people would be below modern sea levels and their remains would still be down there. Any species that became larger due to the increase in O2 would not be able to function with a significantly lower partial pressure. If they would be able to do okay with lower partial pressure, then there was no significant effect on their evolution via the higher partial pressure.

[JDL]

We about half agree and since we're talking about a hypothesis we need more information to further develop things.

[hiflier]

Hello JDL and antfoot,

Fluctuations in pressure happens all the time as highs and lows pass over the Earth's surface. One of the issues with the O2 levels as coupled with climate is that one deals with two kinds of O2. Oxygen16 is atmospheric and Oxygen18 is oceanic. When climates warm less Oxygen18 is held in the oceans. So the O2 level does fluctuate and it is demonstrated in atmospheric gasses trapped in the ice cores: as the ratio between O16 and O18 lessens it becomes a proxy for warmer climates. So maybe the culprit is the O18 which is more linked to temperature fluxes.

Edited February 19, 2014 by hiflier

[JDL]

I guess it would depend on if there's a difference between the uptake of O16 vs O18.

[hiflier]

Hello JDL,

It's only and idea until it's researched. I'm sure it isn't a new one and has certainly been looked at by those infinitely smarter than I.

Edited February 19, 2014 by hiflier