Although animals and plants could all turn into creatures of wisdom, there were many prerequisites.
Some of them were manually made, such as demons. Their brain cells and bodies underwent world-shaking evolutions within several hundred years. After being filtered harshly, one in ten thousand might become powerful biological weapons.
Some other creatures might have lived on rough foreign planets that boasted special radiations and mother lodes. Against all the odds, the wisdom of the natives was triggered, and they became intelligent.
Before Yan Xinjian entered the secret training room, he had calculated everything. But he did not expect that he would be forced to enter the bodies of mice one day.
Therefore, although he had prepared a lot of techniques for training as a spectral Cultivator, he did not have any training methods for animals.