For those of you who haven't read much about hypothermia, it's quite interesting, in that people have survived for days or longer, wearing improper clothing and out in the snow. For example, more than 20 years before the DPI, a 23 year old woman got lost skiing and had to wait until the next day for rescuers to find her. She either sat on a log or walked around it all that time, and was shivering uncontrollably when found, but was otherwise fine. In 1946, a 25 year old male got lost in the snow and was found on the eleventh day of searching. Here are some details:
"Lost and nearly blind, William Jacobs had bumbled the wrong way through that first storm but had stumbled upon a small, wooden NPS cache containing a rescue toboggan and blankets. Using these he had constructed a lean-to shelter in which he bivouacked, awaiting rescue." From "Off the Wall: Death in Yosemite."
He walked away on his own but two of his toes were frozen (it doesn't say whether those had to be amputated).
In 1970, a 34 year old male collapsed during a "snowshoeing trip" (apparently fatigue) and those he traveled with set him up in the tent. He was found the next day: "Ranger James Holcomb, still alone, finally found the elusive tent. It had collapsed and had been partly snowed under. This explains his difficulty in finding it. As Holcomb neared it, he next saw that the door of the flattened tent lay open. Klingenberg, hatless, lay sprawled within this opening. Eclipsing any hope that Holcomb had arrived in the nick of time, snow now covered the prone man’s lower body. The autopsy revealed Klingenberg had died of 'cold and exposure' a day earlier, on Monday morning." From "Off the Wall: Death in Yosemite."
In 1973, a 21 year old male, not wearing proper footwear for cold weather, "slid off the path and tumbled 200 feet down the steep snow-covered, granite talus, bouncing and banging all the way... crippled and stranded off trail at nearly 6,000 feet elevation in the middle of winter..." He was rescued nine days later but lost a foot to frostbite. From "Off the Wall: Death in Yosemite."
There are a lot of cases where people died, of course, but Igor or others in his group may have read these kinds of stories and thought that surving that night in 1959 would not have been difficult (I don't read or understand spoken Russian so there may evidence that speaks to this). It is also true that familiarity with snow, ice, cold weather, etc. may lead many to overestimate how well they can deal with these. One thing I've noticed is that cold weather does not bother me unless there is some wind, and then it tends to bother me a lot. I'd guess they or at least Igor miscalculated a few things that led to them dying of hypothermia so quickly relative to these other cases. For one, why not take their blankets with them (assuming the heavy coats and boots had frozen), perhaps designating one person as the holder of those blankets while the others started the fire, dug the "den," or started/maintained the fire? Igor apparently believed that sitting on the tree branches in front of the fire would be enough, or that it would be temporary and then they would huddle in the den.
Why did the "two Yuris" die first? It's now known that for some people, core body temperature drops significantly when the person stops being active while out in the cold. If this occurred to them, it may have frightened at least Zina into thinking it was a terrible plan overall, so she tried to go back to the tent and Slobodin then Igor go after her to convince her to come back. But if they had kept moving, why couldn't they survive longer before hypothermia rendered them unconscious? One possibility is that they sat down for a while in front of the fire but their core temperature actually decreased even if their hands or some other body parts felt warmer, and they started sweating heavily, leading to quick hypothermia once away from the fire and facing the winds coming down from the mountain top. If they never sat down and kept active, at some point they likely tired out and were sweated up. Again, going back up the mountain, without proper clothing and facing the winds would have been enough, but there's also the mental affects hypothermia can have, so this may have influenced the decision to attempt to return to the tent by one or more of them.
In 1997, on Denali, a group got caught in a terrible storm. The two guides had a two person bivouac, then built igloo type structures for their other clients, but they then had to figure out how to survive for themselves:
"...the two guides went back to the task of trying to build a shelter for themselves. In retrospect, Smith believes it was the constant activity that had kept them alive through the storm. Then, minutes after returning to the task of building a shelter, they felt the wind begin to diminish. By 11:00 A.M., it was over.
“If it had lasted a few more hours,” he said, 'we would have died.'" From "Denali's Howl."
Of course, they were all wearing proper outdoor clothing, circa late 1990s, not indoor clothing, circa late 1950s! However, "a few fingers and toes were lost to the mountain" nonetheless. If the Dyatlov Group's tent was about to collapse or blow open, and they wanted to secure it (which they apparently did well) and then find a place to survive until morning, it would seem they should have taken their blankets and found a spot to create a shelter from the wind, then huddled together with the blankets acting as a kind of makeshift tent. They may have needed tree branches to place on the ground to avoid losing too much heat to the snow they would be sitting or lying on, but to me a key question that will likely never be known is, how much hypothermia danger did they think they were in after they secured the tent?