The closest relative of modern day man is considered to be

Many people would say it's the close genetic similarity between humans and chimpanzees. Proponents of the evolutionary paradigm assert that the structure of human chromosome 2 provides axiomatic evidence that humans evolved from a shared ancestor with chimpanzees and bonobos. Each species has a characteristic number of chromosomes differing in size and shape. For example, humans have 46 chromosomes, chimpanzees and other apes have 48. When exposed to certain dyes, chromosomes will stain in unique ways yielding a pattern of bands along their length. The bands vary in number, location, thickness and intensity. And the unique banding profile of each chromosome helps geneticists identify them under a microscope. In the early 1980s, evolutionary biologists compared the chromosomes of humans, chimpanzees, gorillas, and orangutans. These studies revealed an exceptional degree of similarity between human and chimp chromosomes. When aligned, the human and corresponding chimpanzee chromosomes display near-identical banding patterns, band locations, band size, and band stain intensity. To evolutionary biologists, this resemblance reveals powerful evidence for human and chimpanzee shared ancestry. So, the closest relative of modern day man is considered to be chimpanzee compared to orangutan, apes and gibbon.