I've just got a copy of "Weapons: The Diagram Group" and saw that there were simple clubs and simple bows made out of one material such as wood or bone and placed into their own category. I was wondering if there could be a category made for simple spears, just as there are simple clubs and simple bows? Spears can made out of one material such as an all wooden or all metal spear? Some examples are the all steel short javelin called a jarid and the all wooden spear from hawaii. These are listed on pg. 83 of the book.

I don't think that is a useful way to categorise weapons. Better off lumping all spears together, all bows together, etc.

I apologize for the way I wrote the paragraph on the topic, its confusing. What I'm trying to say is a spear (including javelins, darts, etc.) that were to be made of a single material such as the all wooden spear with a fire-hardened point used in prehistoric times, could it be classified as a simple spear because it is made of a single material (wood). For example, since most simple clubs are made of single material such as wood and they are classified as a simple club.

Certainly a spear made of a single material is still a spear. It would also very likely be simple (though I have seen often enough that simple seeming things can be quite complex). So yes, a spear that is simple could be called a simple spear.

My question is why would it matter? If one were making a spear typology, I suspect that there are other factors, such as shape, diameter, etc. that would have a greater bearing on classification than the fact of it's simple construction. If you are simply discussing spears, stating that a given example is a "simple spear" would be sufficient to tell us that it is a) a spear and b) not a complicated one. I see it more as a description than as a classification.

While I find the Diagram Group book to be entertaining and occasionally a good source for ideas, I would not say that it is the best source of information. It is prone to over-simplification, and things tend to be grouped together based on what worked best in the authors' opinions, not always on shared design or any actual concrete similarities.

I really hope this does not seem rude, condescending, or mean. I am not trying to be any of those things.

-Grey

What are the strings made of on simple bows?

They're not "simple" bows. Bows made from a single piece of wood are called "self" bows.

The string material varied from place to place. English longbowmen used hemp. Many Asian cultures used twisted or braided silk. Some used horsehair. Still others used leather. The only constant thing among them is that the material is flexible enough not to break, but not flexible enough to significantly reduce the mechanical effect of the elastic action from the bow's limbs because it's the limbs that are supposed to do the work, not the string.

Actually there might have been bowstrings made from bark. I haven't seen any examples, but I've heard of it and it's definitely not impossible.