How did plants evolve?

How did plants evolve to "know" that animals are attracted to glucose/sugar fruits?

• I was just wondering how or why plants developed the ability to attract animals by ways of making fruits seem "sweet" to animals. How is it that they were able to "figure out" or evolve this characteristic? I know glucose is essential for the body to help produce mitochondrial ATP. But, how would a plant "know" that glucose is essential to animals?

• Answer:

  By the quotes, you're certainly aware that the plants themselves don't "know" anything about what is happening. First of all, sugars are a form of energy storage that are used by most of the life forms on earth, certainly all common plants and animals. This means that sugar is already present and in use. The plants don't have to create that concept alone. Many organisms can detect sugars and seek it out, whether it's mammals tasting it or bacteria "sensing" it. The next step is one of random mutation. One day there were some plants that happened to have more sugar in the tissues near the seed-bearing parts than other plants had. If this caused animals to seek out that plant and distribute the seeds farther, it could give that plant an advantage over other plants. In a world of limited resources, that advantage can lead to preferential expansion of that species. No plant is deciding or developing anything directly. It is the force of natural selection that allows organisms with a particular trait to be more successful than organisms without it.