You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Republic_of_the_Congo

Context:
In 2006–07, researchers from the Wildlife Conservation Society studied gorillas in heavily forested regions centered on the Ouesso district of the Sangha Region. They suggest a population on the order of 125,000 Western Lowland Gorillas, whose isolation from humans has been largely preserved by inhospitable swamps.

Question:
What was responsible for maintaining the separation between the gorillas and humans?

inhospitable swamps