How does overpopulation affect economic growth?
Overpopulation is an issue on ecology, environment and economic growth
Population growth has an effect on economic development if and only if each individual contributes something. As long as the marginal products is on the positive side, one additional person means additional production in economy. Due to the fact that this is not a fully restrictive situation, it shall be true, in general.
On the other hand, the existence of a positive marginal product is not a very appropriate trial of the wish of high population growth. Whenever the marginal product of an additional individual is lower than the average product, adding more individuals simply limits the welfare of an average lay person.
Therefore, overpopulation (especially illiterate, not educated, not skilled people) means slower economic growth in today's competitive economy.
However, there are other factors affecting economic growth (such as age structure, average education, innovation, etc.) in countries.