You don't see grain growing naturally on trees or plants. It must be cultivated artificially, and has become one of our staple foods. Grain has been derived and hybridized from simple grasses over millennia and is the basis for our bread, pasta, baked goods and all other flour-based products we love. That is the problem; grain or flour is highly addictive, basically no different than any other hard drug, and trying to give it up can be a nightmare.
There are many kinds of grains or cereals, dating back thousands of years. Some(the softer variety), such as barley, oats, and quinoa, are less harmful, but they're all basically unnatural and therefore bad for us. The goddesses Isis and/or Ceres, introduced grains to humanity, and agriculture in general. This may have occurred thousands of years BC, or as recently as 600 BC, the dates are debatable. The fact is we are currently a grain-based society and suffer all of the diseases that come with it.
Being of Italian origin myself, bread or flour is a main staple of our diet. Italians are pasta lovers and have spread their love worldwide. I basically gave up bread and white flour decades ago for health reasons, but never completely. Every so often I indulge in some home made bread or something my mom makes, and everytime shortly after I do so I feel my joints start to ache. Being a raw vegan, it usually takes about two weeks to start to feel the pain. It's especially noticeable in the knee area after a five to ten-minute walk. Then when I stop consuming wheat or flour it takes some 3 to 4 days for the pain to go away. It works every time like clockwork so I know whereof I speak.
Bread or flour is NOT the only cause of arthritis, but it is a major one. If you are unable or unwilling to give up grain, try the softer, moister, varieties, like millet or quinoa, and the less you need to cook or heat them the better. Also avoid putting salt or sugar in your bread and other chemicals which can also contribute to arthritis and bad health in general. Better yet, make your own chemical-free grain products, and be sure to eat lots of fruit(often in combination with your grain) as well. Water(moisture) and softness is the key. The harder or drier a food is the more injurious it will be for your body.