For those who reached Level 2 New Humans or Level 3 New Humans by swallowing the Evolution Crystal Core instead of natural evolution, their brains suffer permanent damage. Unlike naturally evolved New Humans, they cannot use their hands to increase the activity of their brain cells. Only natural evolution can bring about growth.
Although some recovery happens through evolution, their intelligence does not increase. This might not seem like much of a setback, but when compared to naturally evolved New Humans, the difference is apparent.
Great minds think ahead and would not resort to damaging their own potential.
However, Li Songhua now has no other option. After becoming a New Human for a year, he stayed at Level 1. Those who had evolved with him were already at Level 2 or even Level 3, while he was still stuck at Level 1!