In Nature Notes on December 22, I talked about the value of a trusty stick to prop you up on your countryside explorations, but I failed to mention the woods that have propped us humans up throughout most of our desperate times.

It is even questionable as to whether without these trees our civilisation would have flourished at all in this green and pleasant isle.

Around 10,000 years ago, Britain was far from green and pleasant. Standing here in Wyre Forest, we would be looking up at the end of an ice sheet at least 100ft tall and extending right up to the North Pole.

To the south there were tough tundra conditions, plenty of big game, mammoths etc, but little in the way of shelter. In this environment the first of our trees come in.

Silver birch is quick growing and would be the first tree to move into an area that had been freed up by the ice.

This tree gave early man the tinder to light fire and a strong burning wood to provide much-needed heat to survive the cold conditions.

The bark, which is easily stripped, is waterproof and was used to help improvise shelters, build utensils such as cups and bowls and even to construct canoes.

If you were to live naturally in the wild, finding enough food to survive would be your daily priority.

As we all know, there are three main food groups - fats, carbohydrates and proteins. Fats and protein are quite easy to obtain from big game, but carbohydrates (the food that gives us ready to use energy), is at a premium.

This is probably why we as a species have a sweet tooth as the pleasant tastes of sugary foods encourages us to seek them out. There are fruits and berries, which are only seasonally available, and also honey.

Silver birch also exudes a sugary sap in spring to further help things out, but for most of the year it is quite hard to think of a good source of carbohydrate. This is where our second tree comes in, the oak.

Oaks, at first glance, would appear devoid of any form of food unless you are prepared to count the odd squirrel or wood pigeon.

During autumn, though, there is a bounty of acorns. If you were to eat these just as they are you would make yourself very ill as they are filled with the poison, tannin.

However, if you boil them up and throw away the water several times, the brown tannins are removed from the acorns and you are left with a starchy, floury material that is rich in carbohydrates.

This may seem to be a lot of effort to go to, especially in the autumn when there are plenty of alternates in the form of fruit and berries.

The advantage of this flour, though, is that once dry it can be kept for a long time, thus maintaining human life through the bleakness of winter.