I (not an expert) checked him out for 10 minutes just now.. He wrote a book about bird hybrids, and seems to see hybrids everywhere. Check out his pages on all kinds of hybrids, which reads like a crank website. e.g. the very wacky page on cabbits (cat + rabbit)
But his pig+chimp theory is serious, and it seems it makes some sense in explaining numerous pig-like anatomical features of humans, but there can be no genetic evidence, so only he believes it, it seems.
First of all, the coincidences become a lot less coincidence when you look at convergent evolution. For example tooth shape is tied to what you eat. Since we and pigs are both omnivores, we wind up with similar teeth.
Second, only related species can form hybrids. Lions and tigers split probably a bit under 4 million years ago. Donkeys and horses split a bit before that. We don't know when humans and chimps split, but you can find estimates everywhere from 7-12 million years. The split between primates and pigs appears to be about 80 million years ago. And the result is that lions and tigers can interbreed and the child can be fertile. Donkeys and horses can interbreed and the child is usually NOT fertile. We have no evidence that humans and chimps can have children, and it has probably been tried. As for more distant than that, farmers have been having regular sex with farm animals since farms existed, with no babies.
"We have no evidence that humans and chimps can have children, and it has probably been tried. "
Indeed Ilya Ivanov spent a lot of time and money trying to do just that, with no success.
https://en.wikipedia.org/wiki/Ilya_Ivanov
The liger is a hybrid offspring of a male lion (Panthera leo) and a female tiger (Panthera tigris). The liger has parents in the same genus but of different species. The liger is distinct from the similar hybrid called the tigon, and is the largest of all known extant felines. They enjoy swimming, which is a characteristic of tigers, and are very sociable like lions. Notably, ligers typically grow larger than either parent species, unlike tigons.
It's not a joke, but the evidence cited is being interpreted rather freely; the chromosomal and genetic evidence doesn't support the hypothesis at all.
I'd buy horizontal gene transfer via a viral vector (which is still damn unlikely for all those traits) over hybridization any day of the week.
Interspecies sex happen a whole lot more often than that. Having viable offspring might have been the rare part.
Dr. Eugene McCarthy has a theory that humans are a hybrid between pigs and chimpanzees https://phys.org/news/2013-07-chimp-pig-hybrid-humans.html