Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.

Saturday, July 6, 2013

Grandpa the pig

It bears mention that having a Ph.D. (or other advanced credentials) is no guarantee against being a complete wingnut.  This topic comes up because of a website link sent to me by a regular reader of Skeptophilia that was authored by Eugene McCarthy, Ph.D. in genetics, and author of Handbook of Avian Hybrids of the World.

It starts off reasonably enough; McCarthy describes the fact that, contrary to our perception of species as being little watertight compartments, hybridization (and thus gene flow between species) is rather common.  Not all hybrids are sterile, like the familiar example of the mule; a lot of them are back-fertile to either parental species (an example is the "Brewster's Warbler," which was once thought to be a separate species and is now known to be a hybrid between the Golden-winged and Blue-winged Warblers).

So McCarthy asks an interesting question: are humans a hybrid?  The answer, apparently, is yes; recent studies have shown that most human populations show the genetic signature of three ancestral populations -- modern humans, Neanderthals, and Denisovans.  (Biologists disagree, however, as to whether these three represent different species -- a distinction that, in reality, probably doesn't mean very much.  The concept of species is one of the hardest-to-pin-down terms in all of biological science.)

But, unfortunately, it isn't this intermixing between three proto-hominins that McCarthy is talking about.  He thinks we're a much more interesting hybrid than that.  He gives his evidence first: humans have low fertility, and males produce a great many abnormal sperm (kind of a surprise given our reproductive success -- you have to wonder, if this is true, how there can be seven billion of us).

What?  You want more evidence than that?  Sorry, that's it.  Guys produce lots of abnormal sperm, and allegedly we have low fertility.  So we're hybrids.  That's enough, right?

Of course right.  So now, if we're hybrids, we have to figure out which two species gave rise to humans.  One of them, McCarthy says, was clearly something like a chimp.  But he states, in all apparent seriousness, "Many characteristics that clearly distinguish humans from chimps have been noted by various authorities over the years."  Can't argue with that.  But then he goes right off the edge of the cliff:
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 nonprimate — an unusual, distant cross to create an unusual creature.
If this sets alarm bells off, good -- because this would require a fertile hybrid being produced from a mating of animals not just from two different genera, or two different families, but two different orders.  Entirely possible, McCarthy says, despite the fact that there is not a single example -- not one -- of an interordinal hybrid known from nature.  Anywhere.  That includes animals, plants, fungi, and so on.

Nevertheless, that doesn't stop McCarthy:
Looking at a subset of the listed traits [unique features of humans are listed in the sidebar on page two of his website; there are too many to list here], however, it's clear that the other parent in this hypothetical cross that produced the first human would be an intelligent animal with a protrusive, cartilaginous nose, a thick layer of subcutaneous fat, short digits, and a naked skin. It would be terrestrial, not arboreal, and adaptable to a wide range of foods and environments. 
So, let's not dillydally any more; if a chimp is one of our parental species, what's the other?
What is this other animal that has all these traits? The answer is Sus scrofa, the ordinary pig. What are we to think of this fact? If we conclude that pigs did in fact cross with apes to produce the human race, then an avalanche of old ideas must crash to the earth. But, of course, the usual response to any new perspective is "That can't be right, because I don't already believe it." This is the very response that many people had when Darwin first proposed that humans might be descended from apes, an idea that was perceived as ridiculous, or even as subversive and dangerous. And yet, today this exact viewpoint is widely entertained. Its wide acceptance can be attributed primarily to the established fact that humans hold many traits in common with primates. That's what made it convincing... Let us take it as our hypothesis, then, that humans are the product of ancient hybridization between pig and chimpanzee.
So, basically, the logic is, "people laughed at Darwin, and he turned out to be right, so if people laugh at me, I must be right?"

But I don't want to be accused of jumping to conclusions ("That can't be right, because I don't already believe it"), so I took what I think is a critical look at the list of allegedly unique features of humans -- ones that, in McCarthy's view, must have come from our other, non-primate parental species.  And most of them have to do with quantities and sizes -- "sparse" hair, "large amounts" of elastic fiber in the skin, "richly" vascularized dermis, "narrow" eye opening, "heavy" eyelashes, and so on.  Traits involving quantities and sizes are highly responsive to selective pressures, the idea being once you have genes for the production of a feature, it is relatively straightforward to evolve to produce more or less of it.

Of the features he claims are found only in humans and pigs, it appears that in several cases, he is simply wrong.  Take multipyramidal kidneys -- he is correct that only humans have this feature amongst primates, but it is hardly unique in the mammalian world.  Besides humans and pigs, elephants have multipyramidal kidneys, as do bears, rhinoceroses, bison, and "nearly all marine mammals," according to a paper by M. F. Williams (available here).  Williams' contention is that multipyramidal kidneys evolved in animals that lived in coastal or marine environments in order to deal with high levels of salt -- and that each of these lineages evolved it independently, as it represents a unique feature on separate, distantly related branches of the phylogenetic tree (evolutionary biologists call these features "apomorphies").

Then, of course, he has some things on the list of allegedly unique human characteristics that are simply weird.  "Particular about place of defecation?"  (Has he ever owned a cat?)  "Snuggling?"  "Extended male copulation time?"  "Good swimmer?"

I'm sorry, Dr. McCarthy, but I'm calling bullshit on this.

Now, please understand; it's not like I have any particular problem with our having a checkered ancestry.  I'm an evolutionary biologist by training, for cryin' in the sink, I know we're animals.  But the idea that Homo sapiens arose when a chimp had sex with a pig... that stretches credulity too far.

Even if you do have a Ph.D.

7 comments:

  1. There is already a pretty solid case for human hair loss. Our Lineage was a much hairier one, though evolution decided it was time for humans to kick the lice habit and began stripping the body of hair so we wouldn't harbor so many diseased, filth-ridden parasites.

    www.pbs.org/wgbh/nova/evolution/lice.html

    http://www.newscientist.com/article/dn3807-early-humans-lost-hair-to-beat-bugs.html

    Humans have smooth skin because of pig DNA?

    Hilarious.

    (If you're going to reinvent the wheel, at least try to make it ROUND.)

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  2. God created humans. Anyone who has studied God's creation knows the mechanisms he uses to create new species and one that he uses a lot is sex. Why is it so hard to understand that one day God looked down on his creation and decided to create a creature that was more like God, one that could house a fragment of God's own spirit and use that fragment to express its god-nature. And God decided that an ape was a decent starting point but that it needed to be tempered in some way and that the ideal combo was pig and chimpanzee. And so God sent a boar to have sex with a female chimpanzee at just the right moment in time when the conditions were just right for a most improbable fertilization event. And it happened as God wished, because at that time he was still following the model of "my wish is a command to my creation". And he tweaked and tuned this new creature through a few hundred generations or so until it was just right to receive God's grace through the gift of free will. There is nothing in this theory that is inconsistent with religion.

    I've never understood why people believe in such nonsense as Creative Design and can't see that Evolution is a perfectly valid mechanism for God to create. After all he also created time and if there was no evolution at all, then time would hardly be necessary, would it.

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    Replies
    1. >>>"...Evolution is a perfectly valid mechanism for God to create."

      And a particularly elegant and subtle one, too.

      Regarding cross-order hybridizations:

      As I understand it, a significant percent of "our" cells are actually (generally symbiotic) bacteria and other life forms.

      And are not also significant portions of our genetic code similar or identical to that of other, widely varying, life forms?

      We live and breath in a "soup" of bacteria, viruses and genetic fragments. FWIU, work by Lynn Margulis suggests that evolution may be driven by symbiotic or cooperative relationships between species.

      The close match between hyman and chimp genetics? The actual source (i.e.: McCarthy's website, as opposed to giggling and commented fw: fw: fw: emails between conventional theory True Believers) suggests that this is due to multiple generations of backcrossing with chimps.

      Finally, McCarthy does not seem to be either a nut or an ignorant idiot. See his bio at: http://www.macroevolution.net/about-me.html

      All I can say is that I'm beginning to get very, very tired of so-called "scientists" and their groupies thinking and talking like religious fanatics, and of existing "acceptable" scientific theories increasingly taking on the stained patina of dogma. McCarthy appears to have the credentials; why don't those who disagree with his "outlandish" conclusions answer him with scientific rigor, rather than ad hominem?

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  3. You're wrong about this. An open mind is a terrible thing to waste...

    If you read the ENTIRE website written by McCarthy, you will find that there are mountains of evidence going back centuries to support "stabilization processes" being the true origin of species and that Darwin's and the Neo-Darwinian view that natural selection alone could account for the evolution of species is not supported by the fossil record or by common sense when compared to the changes brought about by the enormous chromosomal changes inherent ONLY through hybridization.

    Be a true skeptic. Read the WHOLE website and challenge everything you "know" about evolution.

    Get over the chimp-pig hybrid thing for now, because you haven't even begun to open your mind to that. This isn't quack science. It's a revolutionary shift in understanding evolution itself--not an understatement.

    His evidence doesn't stop at sperm abnormalities in human beings--to claim that indicates you didn't even read the entire article, let alone understand it. There is a mountain of evidence and observations that you are leaving out.

    The origin of ALL species is McCarthy's goal here, and he knocks it out of the park.

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  4. Hi oldguyinstanton and Wait Aminute!

    My wife ran across your comments and pointed them out to me. Thanks for your support. It's nice to know there are guys like you out there fighting back against the "stained patina of dogma" (great phrase!). Hope to hear from you sometime. Gene.

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  5. Does anyone have an email address for Dr. McCarthy? I'd like to pose a question to him. Thanks.

    P.S. To anyone who hasn't been to his paradigm-upending website, I highly recommend checking it out. It is fascinating; I spend hours there.

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