According to organic evolution, the ape closely related to humans is Sinanthropus. Here's an explanation of this answer:

Sinanthropus, also known as Peking Man, is an extinct species of human that lived in China approximately 500,000 years ago. It is classified as an ape because it shares many anatomical and genetic similarities with modern humans.

Key Points:
- Sinanthropus, or Peking Man, is an extinct species of human closely related to modern humans.
- Sinanthropus lived in China around 500,000 years ago.
- Sinanthropus is classified as an ape due to its anatomical and genetic similarities with humans.

Explanation:
1. Definition of Organic Evolution:
- Organic evolution is the process by which species change over time through the mechanisms of natural selection, genetic variation, and genetic drift.

2. Classification of Apes and Humans:
- Humans are classified as a species of ape known as Homo sapiens.
- Apes are a group of primates that includes humans, chimpanzees, bonobos, gorillas, orangutans, and gibbons.
- Humans share a common ancestor with other apes, and through organic evolution, have diverged from these ancestral species over millions of years.

3. Relation between Sinanthropus and Humans:
- Sinanthropus, or Peking Man, is an extinct species of human that lived in China during the Middle Pleistocene.
- Sinanthropus is closely related to humans because it shares many anatomical and genetic similarities.
- Fossil evidence of Sinanthropus shows a combination of primitive and advanced features, including a large brain, similar dental characteristics to modern humans, and evidence of tool use.
- Genetic studies have also shown that Sinanthropus shares a common ancestor with modern humans.

4. Other Apes Related to Humans:
- While Sinanthropus is the specific ape species closely related to humans in this context, it's important to note that all apes, including gorillas, chimpanzees, bonobos, and orangutans, share a common ancestry with humans.
- Humans and these other apes diverged from a common ancestor around 7-8 million years ago.
- Genetic studies have revealed a high degree of genetic similarity between humans and these other apes, further supporting the evolutionary connection.

In summary, according to organic evolution, the ape closely related to humans is Sinanthropus, an extinct species of human that lived in China around 500,000 years ago. Sinanthropus shares many anatomical and genetic similarities with modern humans, placing it within the ape classification. However, it's essential to recognize that all apes, including gorillas, chimpanzees, bonobos, and orangutans, are also closely related to humans through a common ancestry.