Question

Darwin realized that the economist Matheus's theory of population control..

Answer 1

I'm sorry, I'm not understanding if this is a question. Are you supposed to continue the sentence? If so: Darwin realized that the economist Malthus's theory of population control could be applied to all living organisms. If you read up on Malthus's theory I'm sure that you'll see what Darwin means. If not, I can explain further. Here is a helpful website: https://www.boundless.com/sociology/textbooks/boundless-sociology-textbook/population-and-urbanization-17/population-growth-122/malthus-theory-of-population-growth-689-9631/

Answer 2

Or I guess instead of "all living organisms" it would be more accurate to say "populations of living organisms".