Good insight:
https://www.google.com/amp/s/taskand...r-fielded/amp/
Remarkable how long the US Poncho and Poncho Liner have been in service with little change other than materials. These are pieces for dirt, mud, rain, snow and wind this and some moca pulled out of the ruck for a few hours during the dark of night...bad weather, heavy loads begins to put the pieces into perspective.
You mentioned jungle, a challenging environment to be a foot in. Higher rain fall and humidity with greater frequency, storms, stagnant air circulation, heavy dew, wet ground, mud, elevation changes are some of the environmental concerns. Besides warmth, I think moisture and wetness are big factors in comfort and health.
Sacrilege, I known but materials have changed, light weight insulation today can absorb far less moisture due to very hydrophobic materials, the micro filaments along with structure and construction can create clo ratings nearly as warm when wet. Resistances within the “blanket” when differed can vector moisture out and away efficiently, protect exterior to a greater extent and maintain the breath ability we associate with comfort. Now that same system with a warm body inside is protecting you from the environments ( potentially hot weather as well) and drying you, your equipment and mind out more effectively.
MOO