The high amount of children causes for lots of little differences and the ones fit to survive go on to pass on their gene causing them to always adapting to their environment.
They animals will compete for food and the ones who do not have the advantages to survive will die out and not pass on her genes.
Variations in the animals changes their moods and physical stature giving them advantages and disadvantages when surviving in the wild.
The giant pandas have adapted their jaw strength and teeth to better fit their bamboo eating lifestyle.
The process were the animals that are stronger and more fit for living in there environment so the less suited animals die off and the surviving more suitable animals end up passing on their genes to the next generation.
species arise from existing species through gradual change, Panda Bears could have evolved from black bears or brown bears.