We simply splash colors on things and call it art. Art wasn't always that easy to make. People like to recreate the moment, look at all the photographs there are. Look at what I saw today. That didn't start yesterday. Over a 5 million year old timeline, 40,000 years is a drop in the bucket. It's like yesterday. There is a huge amount of effort spent to explain the meaning of art, from individuals to entire groups. That includes everything from whim of the moment to personal convictions. Including wish lists and dreams. More than likely there was a range of meanings, from spur of the moment graffiti to expressing dearly held beliefs.
Originally artists made their own paint, made their own brushes, picked what they wanted to paint on. This link can only be looked at once.
Plenty of time to think about what was being done. That basic process never changed for tens of thousands of years. Its unlikely that thinking about what was being done only came later.
A lot of effort went into getting the pigments that made the paint. Chemistry was used to process the colors, trading was done to obtain minerals not found in the location the artwork was created in. Some materials had to be heated or mixed with other materials or both and common formulas were found over great distances in the prehistoric world. Color production workshops existed 100,000 years ago. All this work just for a whim seems so unlikely. That's all stuff we take for granted when we go to a store and buy painting supplies.
There would be a lot less artists around if one was required to produce their own materials. It required serious thought to make the colors and to make them permanently stick to the wall is another whole different problem. Since the techniques used were very similar or identical there was either a lot of communications going on between groups and individuals or a lot of parallel development among individuals involving chemistry, physics, knowledge of materials, either way it would indicate a great deal of intelligence. Colors and painting was already known from the practice of tattooing. Applying it to cave walls was just more step in appreciating and using art to express beliefs and opinions.
"From analysis of the things found, it’s clear that in the Palaeolithic period many colours of pigments were obtained from both inorganic sources such as minerals and organic materials like as dyes from such things as plants or animals. These were used to paint various surfaces such as rock, leather, clothing, tools, and indeed the human body."
With such a widespread use of color, it is very unlikely that they were not aware of the theory of color and how it affected people. It has also been proposed that
the ability to detect colors in great deal only happened 23 million years ago. It could have been used to determine the difference between good food sources and poor food sources. For modern day people, describing a color is more about indicating what color it is. From writing it has been seen that ancient people described colors by the impact they had, not the color they appeared to be. Prehistoric people would also have been using colors to express ideas and beliefs.
Under microscopic investigation plain looking stone and wood statues and sculptures from thousands of years ago show that they were colored, painted, even coated with gold. Over the years the colors disappeared and without that microscopic examination we wouldn't know they weren't just made of stone or wood. This brings up the interesting question of where else did prehistoric painters paint their work. Inside a cave the work is protected from the weather and lasts 40,000 years which leads us to believe that pictures were only painted in caves. The simple logic is that the paintings were only preserved in caves. All the rest of the work that was not protected has been lost. Just because we can't find something we do today back in prehistoric times doesn't mean prehistoric people weren't also practicing some form of it back then. Every year we make discoveries that show us that prehistoric people were a lot more like us than we believed.
Tools for working with leather have been dated as far back as 120,000 years ago. Even though we can't the clothing from back then it is highly unlikely that people were just hanging the skins on the walls for decoration.