One of the main reason why trees were made sacred was because they were useful. The oaks were not the only useful trees which became holy trees. One thing that I noticed while I was researching the holy trees in Slavic and Celtic tradition was that all the holy trees fell into the category of extremely useful trees. I noticed that all holy trees of old either had edible fruit or nuts (oak, hazelnut, apple, pear) or were good for making tools and particularly fire making equipment (alder, elder) or for making weapons like spears (ash), or for making boats (oak, linden-lime) or for making cordage (heather, birch, willow, hazel, beech, yew, pine, spruce, linden-lime). Basically making them holy ensured that they are spared and preserved during the slash and burn land clearing practices.

Now have a look at the Celtic holy trees: 

1.1 Oak

1.2 Ash

1.3 Apple

1.4 Hazel

1.5 Alder

1.6 Elder

1.7 Yew

http://en.wikipedia.org/wiki/Celtic_sacred_trees - Celtic sacred trees - Wikipedia, the free encyclopedia

In my last post I talked about Oaks and how useful they were and are to people. The last thing that I said in my last post is that acorns had been eaten by humans since at least late Paleolithic times right up to modern times, and that I would write about acorns and acorn eaters in my next few posts. In this post I write about archaeological evidence we have for human consumption of acorns during the Paleolithic, Mesolithic, Neolithic, Copper age, Bronze age and Iron age. I hope you find the data presented in this post as eye opening as I did find it, and that you will start seeing acorns in a completely different light from now on.  

You can read more here

http://oldeuropeanculture.blogspot.ie/2014/11/acorns-in-archaeology.html - Old European culture: Acorns in archaeology

It is very interesting that I could not find any data for acorns being found on the sites of the Yamna culture and Cucuteni Trypillian cultre. Why? Did I just miss the available data or were these two cultures different from the rest of the Old European cultures? Is it because these two cultures were the true Steppe cultures as opposed to all the other European cultures which were forest cultures? 

I also could not find any data for acorns being found on the sites in Britain and Ireland. Again did I just miss the available data or are Britain and Ireland in some way different from the rest of Europe? 

I would greatly appreciate any help in answering these two questions.