The next-to-skin base layer should be the foundation to your layering system - whether you are climbing Everest, or stalking antelope in Eastern Montana, there is no debating the first step in combatting cold weather conditions.
Synthetics may be standard issue for military use, though KUIU champions Merino wool over artificial alternatives.
Why? Merino is naturally odor-resistant, thermo regulating, provides insulation while wet, and is ideal in arid climates 👊
Nature provides the solutions
Further reading via Jason Hairston 📚