Ever come across the human hybrid theory ? The theory is that at some time a wild (male) boar mated with a (female) chimpanzee, which produced a hybrid and then, with a lot of backcrossing (further mating with chimps), a new species arose (humans).

Dr. Eugene McCarthy is a Ph.D. geneticist who has made a career out of studying hybridization in animals. He now curates a biological information website called Macroevolution.net where he has amassed an impressive body of evidence suggesting that human origins can be best explained by hybridization between pigs and chimpanzees. Extraordinary theories require extraordinary evidence and McCarthy does not disappoint. Rather than relying on genetic sequence comparisons, he instead offers extensive anatomical comparisons, each of which may be individually assailable, but startling when taken together. Why weren't these conclusions arrived at much sooner? McCarthy suggests it is because of an over-dependence on genetic data among biologists. He argues that humans are probably the result of multiple generations of backcrossing to chimpanzees, which in nucleotide sequence data comparisons would effectively mask any contribution from pig.

https://phys.org/news/2013-07-chimp-pig-hybrid-humans.html

https://www.macroevolution.net/hybrid-hypothesis-contents.html