Not just wood, but walnut. The following is a translation from "Espengarda Perfeyta", written in Portugal in 1717:
" There are various woods of which Stockmakers make Stocks, but all must choose Walnut, for it is the best, and possesses those qualities which make it more proper for being worked, and also for its security, this being what makes it more durable. It is light to handle,attractive by nature, and lastly it keeps straight, a singular quality for our purpose...
Thus, only Walnut should be chosen, and from the heart of the timber, where are to be found the good qualities we have described."
Therefore, the properties of walnut as pertains to firearms have been known for centuries, and nothing has changed today. Of course, the Portugese in the 1700's did not have carbon fibre and GRP. I can see the validity of using synthetics in a precision rifle, as they are resistant to changes due to environmental conditions. Military styled rifles such as the AR-15 or PE-90 are better served with plastic (although the AK-47 seems to get along just fine with wood). For virtually all other purposes, walnut is superior. To put a synthetic stock on a shotgun should be a punishable crime.
Sharptail