This is an interesting question.
Indeed, the human race is blessed with intelligence, and is totally different from that of animals. On the contrary, it is true that the animals are equally intelligent too. Then the question arises, where does the difference exist.
The answer is quite straight. there is difference been vision and wisdom. We all are blessed with intelligence and wisdom, some with more, some with less. But the concept over-population does not effect anyone, despite their wisdom. This is so, because human beings lack vision in this sphere.
There are multiple campaigns that help educate about over-population, there are firms that help with family planning. But, people do not understand the consequences, and moreover, research claim that over-population is widely growing due to carelessness.
People in rural areas, are considered not ready to understand the importance of contraceptives. People in urban areas too, fail to understand the consequences, they are uneducated literates.
In order to control the conditions, it is important to fix these problems.
I hope this answer helps!😊