Humans emerged from male pig and female chimp,
world's top geneticist says
University of Georgia's Dr Eugene McCarthy
has suggested that humans didn't evolve from just apes but was a backcross
hybrid of a chimpanzee and pigs.
LONDON: Humans are actually hybrids, who
emerged as an offspring of a male pig and a female chimpanzee, according to one
of the world's leading geneticist.
Turning the theory of human ancestry on its head, Dr Eugene McCarthy — one of the world's leading authorities on
hybridization in animals from the University of Georgia has suggested that humans didn't evolve from
just apes but was a backcross hybrid of a chimpanzee and pigs.
His hypothesis is based on the fact that
though humans have many features in common with chimps, there are a lot more
that don't correspond to any other primates. He then suggests that there is
only one animal in the animal kingdom that has all of the traits which distinguish humans from our primate
cousins.
"What is this other animal that has all
these traits? The answer is Sus scrofa - the ordinary pig" he says.
He explains: "Genetically, we're close
to chimpanzees, and yet we have many physical traits that distinguish us from
chimpanzees. One fact, however, suggests the need for an open mind: as it turns
out, many features that distinguish humans from chimpanzees also distinguish
them from all other primates. Features found in human beings, but not in other
primates, cannot be accounted for by hybridization of a primate with some other
primate. If hybridization is to explain such features, the cross will have to
be between a chimpanzee and a non-primate - an unusual, distant cross to create
an unusual creature."
"We believe that humans are related to
chimpanzees because humans share so many traits with chimpanzees. Is it not
rational then also, if pigs have all the traits that distinguish humans from
other primates, to suppose that humans are also related to pigs? Let us take it
as our hypothesis, then, that humans are the product of ancient hybridization
between pig and chimpanzee," he said.
According to Dr McCarthy, if we compare humans
with non-mammals or invertebrates like the crocodile, bullfrog, octopus,
dragonfly and starfish, pigs and chimpanzees suddenly seem quite similar to
humans.
Pigs and chimpanzees differ in chromosome
counts. The opinion is often expressed that when two animals differ in this
way, they cannot produce fertile hybrids. This rule is, however, only a
generalization. While such differences do tend to have an adverse effect on the
fertility of hybrid offspring, it is also true that many different types of crosses
in which the parents differ in chromosome counts produce hybrids that capable
themselves of producing offspring.
There is substantial evidence supporting the
idea that very distantly related mammals can mate and produce a hybrid.
Another suggestive fact, Dr McCarthy says is
the frequent use of pigs in the surgical treatment of human beings. Pig heart valves are used to replace those of human coronary patients. Pig skin
is used in the treatment of human burn victims. "Serious efforts are now
underway to transplant kidneys and other organs from pigs into human beings.
Why are pigs suited for such purposes? Why not goats, dogs, or bears - animals
that, in terms of taxonomic classification, are no more distantly related to
human beings than pigs?," he said.
"It might seem unlikely that a pig and a
chimpanzee would choose to mate, but their behaviour patterns and reproductive
anatomy does, in fact, make them compatible. It is, of course, a
well-established fact that animals sometimes attempt to mate with individuals
that are unlike themselves, even in a natural setting, and that many of these
crosses successfully produce hybrid offspring," he adds.
Dr Eugene McCarthy says that the fact that
even modern-day humans are relatively infertile may be significant in this
connection.
"If a hybrid population does not die out
altogether, it will tend to improve in fertility with each passing generation
under the pressure of natural selection. Fossils indicate that we have had at
least 200,000 years to recover our fertility since the time that the first
modern humans (Homo sapiens) appeared. The earliest creatures generally
recognized as human ancestors (Ardipithecus, Orrorin) date to about six
million years ago. So our fertility has had a very long time to improve. If we
have been recovering for thousands of generations and still show obvious
symptoms of sterility, then our earliest human ancestors, if they were hybrids,
must have suffered from an infertility that was quite severe. This line of reasoning, too, suggests that the
chimpanzee might have produced Homo sapiens by crossing with a genetically
incompatible mate, possibly even one outside the primate order," he said.
