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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."
Dr McCarthy suggests that Charles Darwin told only half the story of human
evolution.
"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. | b*w
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【在 b*w 的大作中提到】
: 为神马不是母猪公猩猩？
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