Sinanthropus is Peking Man which was considered by some to be a direct ancestor of modern humans.

Primate closest to man regarding organic evolution

Introduction:
The question asks about the primate that is closest to humans in terms of organic evolution. Organic evolution refers to the process of biological change over generations, leading to the development of new species. In order to answer this question, we need to consider the characteristics and evolutionary relationships of different primate species.

Gibbon:
Gibbons are small apes that belong to the family Hylobatidae. They are known for their long arms, which allow them to swing from tree to tree. While gibbons share some similarities with humans, such as opposable thumbs and complex social structures, they are not considered to be the primate closest to humans in terms of organic evolution.

Gorilla:
Gorillas are the largest living primates and belong to the family Hominidae. They share a common ancestor with humans, making them more closely related to humans than gibbons. However, they are not the closest primate to humans in terms of organic evolution.

Sinanthropus:
Sinanthropus, also known as Peking Man, is an extinct hominin species that lived in China approximately 500,000 years ago. While Sinanthropus is an important species in human evolution, it is not the closest primate to humans in terms of organic evolution because it is not a primate species.

Orangutan:
Orangutans are large apes that belong to the family Hominidae, making them closely related to humans. They share a common ancestor with humans, making them the closest primate to humans in terms of organic evolution. Orangutans are known for their high degree of intelligence, similar to humans, and their ability to use tools.

Conclusion:
Among the given options, the primate closest to humans in terms of organic evolution is the orangutan. Orangutans share a common ancestor with humans and exhibit many similarities in terms of intelligence and behavior. Understanding the evolutionary relationships between different primate species helps us to better understand our own place in the animal kingdom.