Belief system of Buddhism and Taoism
Buddhists believe in cause and effect. This means that the good you do in this life will be repaid in the next and vice versa. If you do a lot of evil, you will be born into a lesser life form, e.g. humans becoming animals in the next life. This is called transmigration of souls.
The question we need to ask is why human population going up if the theory is true. If a human being did evil, he may be born as an animal or plant. Animals or plants cannot become humans because they don’t have any concept of good deeds. So there is downward mobility but no upward mobility. This means that human population should do down, not up as what we are seeing.

There are no absolutes
If there are no absolutes even Buddhism is not absolute truth.
I ching says there is something unchangeable.

Concept of no self