The technical name for what we do to heat-treat our wood is "torrefaction".
My understanding is that sometime in the mid 1980's a farmer in Scandanavia lost a fence line to a grass fire. He dismantled the fence and threw the charred fence posts into a drainage ditch. When his next fence rotted off in about 20 years (spruce fence posts rot quickly) he threw those posts in the same ditch. To his surprise the remains of his original charred fence were still intact, despite laying in a wet ditch for 20 odd years. Hmm.... He had a brother at the University.... hmm.... A sophisticated process for intentionally heat treating wood was developed.
We heat our wood to about 600°F; a temperature higher than the wood's actual combustion temperature. As the wood smokes in the chamber, the oxygen is displaced, preventing the wood from bursting into flame. While some of the volatiles escape the wood as smoke, others turn to carbon within and throughout the wood itself. This gives the wood its beautiful honey gold color and reduces its ability to absorb water.
This process really alters wood as a material. It becomes very stable and resistant to absorbing water and other fluids. This allows us to make thin cutting boards that stay very flat and can withstand dishwasher conditions without degrade.
Of course our ancient ancestors were heat-treating wood when they hardened their spear points in a fire. Our relationship with wood and fire is so old — very cool.