What do you stand unter to get out of the sun on a hot sunny day? A tree! Isn't the sand cooler o your feet under the shade of a palm tree than the sand in the direct sun?
Therefore, trees cause global cooling. All that forest cover prevents rocks from warming up during the day and radiating their heat at night, keeping cavemen warm.
Here's a better theory. Aboriginals caused the massive deforestation spoken of in this article. they chopped down all the trees so that their caves would stay warmer.
When white man came, they planted trees around their homes they made out of all that lumber the aboriginals left laying around, plus the white man burnt it in wood stoves inside their wooden homes. The caves become cooler because of all the trees white man planted, causing aboriginals to make wig-wams and tee-pees and make fires of their own inside them to keep warm.
The first aboriginal "sweat lodge" was discovered after an aboriginal pee'd on the hot rocks around his fire because it was too hot in his wig-wam. He created a "sauna" and had "spiritual dreams" as he slept in that urine steam.
See how easy it is to create a plausible theory?
I can do better than that. The first Ice Age is tied directly to the evolving of the first white tribe from the other ethnic tribes that existed then. This white tribe cut down trees for heat and cooking and this made the earth too warm, and then when they didn’t have to burn trees anymore for warmth and could cook their food off of hot rocks heated by the sun, the trees all grew back and caused the first known Ice Age, all attributable to the first white tribe. Neat huh?(Don’t bother to ask me why there wasn’t an Ice Age before the white tribe cut down the trees for fire wood, logic is no good here)