PART PIG?

SUS SCROFA
http://popsci.com/article/science/humans-share-food-chain-level-pigs-study-finds
http://interruptingcow.libsyn.com/dr-eugene-mc-carthy-and-the-chimp-pig-hybrid
http://phys.org/news/2013-07-chimp-pig-hybrid-humans.html
A chimp-pig hybrid origin for humans?
by John Hewitt / Jul 03, 2013

“These days, getting a Ph.D. is probably the last thing you want to do if you are out to revolutionize the world. If, however, what you propose is an idea, rather than a technology, it can still be a valuable asset to have. 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.

Generally speaking, interspecies hybrids—like mules, ligers (lion-tiger hybrids), or zedonks (zebra-donkey hybrids)—are less fertile than the parents that produced them. However, as McCarthy has documented in his years of research into hybrids, many crosses produce hybrids that can produce offspring themselves. The mule, he notes, is an exceptionally sterile hybrid and not representative of hybrids as a whole. When it comes time to play the old nuclear musical chairs and produce gametes, some types of hybrids do a much better job. Liger females, for example, can produce offspring in backcrosses with both lions and tigers. McCarthy also points out that fertility can be increased through successive backcrossing with one of the parents, a common technique used by breeders. In the case of chimp – pig hybridization, the “direction of the cross” would likely have been a male boar or pig (Sus scrofa) with a female chimp (Pan troglodytes), and the offspring would have been nurtured by a chimp mother among chimpanzees (shades of Tarzan!). The physical evidence for this is convincing, as you can discover for yourself with a trip over to macroevolution.net.

When I asked McCarthy if he could give a date estimate for the hybridization event, he said that there are a couple broad possibilities: (1) It might be that hybridization between pigs and apes produced the earliest hominids millions of years ago and that subsequent mating within this hybrid swarm eventually led to the various hominid types and to modern humans; (2) separate crosses between pigs and apes could have produced separate hominids (and there’s even a creepy possibility that hybridization might even still be occurring in regions where Sus and Pan still seem to come into contact, like Southern Sudan). This latter possibility may not sound so far-fetched after you read the riveting details suggesting that the origin of the gorilla may be best explained by hybridization with the equally massive forest hog. This hog is found within the same habitat as the gorilla, and shares many uncommon physical features and habits. Furthermore, well-known hybridization effects can explain many of the fertility issues and other peculiarities of gorilla physiology.

It is not yet clear if or when genetic data might support, or refute, our hybrid origins. The list of anatomical specializations we may have gained from porcine philandering is too long to detail here. Suffice it to say, similarities in the face, skin and organ microstructure alone are hard to explain away. A short list of differential features, for example, would include, multipyramidal kidney structure, presence of dermal melanocytes, melanoma, absence of a primate baculum (penis bone), surface lipid and carbohydrate composition of cell membranes, vocal cord structure, laryngeal sacs, diverticuli of the fetal stomach, intestinal “valves of Kerkring,” heart chamber symmetry, skin and cranial vasculature and method of cooling, and tooth structure. Other features occasionally seen in humans, like bicornuate uteruses and supernumerary nipples, would also be difficult to incorporate into a purely primate tree.

McCarthy has done extensive research into the broader issues, and shortcomings, of our currently incomplete theory of evolution. As the increasing apparent, magnificent, speed with which morphological change can occur continues to present itself for us to comprehend, the standard theory of random mutation followed by slow environmental selection, seems to stall. In my own opinion, female choice undoubtedly provides much of the functional “speed-up” we observe, but other mechanisms of mutation, or pathways for acquired characteristics to be fed back to the gonads (through retroviral transfer?), now need to be considered anew. The role of hybridization in driving morphological change, as McCarthy has observed time and time again, particularly in his studies of avian species (Oxford University Press, 2006), may be the most powerful mechanism of all.”

the OTHER PARENT
http://macroevolution.net/human-origins.html
http://macroevolution.net/human-origins-2.html
the Ordinary Pig / by Eugene McCarthy, PHD

“I’m a geneticist whose work focuses on hybrids and, particularly, the role of hybridization in the evolutionary process. Here, I report certain facts, which seem to indicate that human origins can be traced to hybridization, specifically to hybridization involving the chimpanzee (but not the kind of hybridization you might suppose!). You can access detailed and documented discussions supporting this claim from links on this page. But I’ll summarize the basic reasoning here, without a lot of citations and footnotes. (If you would like to read an even briefer summary, click here; read about some objections to the theory here; also, a recent news story)

Rationale
So why do I think humans are hybrids? Well, first of all, I’ve had a different experience from most people. I’ve spent most of my life (the last thirty years) studying hybrids, particularly avian and mammalian hybrids. I’ve read thousands, really tens of thousands, of reports describing them. And this experience has dispelled some mistaken ideas I once had about hybrids, notions that I think many other people continue to take for granted. For example, one widespread, but erroneous, belief is that all hybrids are sterile. This idea keeps a lot of people from even considering the possibility that humans might be of hybrid origin. This assertion is absolutely false — though I have in fact heard lots of people make it. For instance, in reviewing the reports I collected for my book on hybridization in birds (Handbook of Avian Hybrids of the World, Oxford University Press, 2006), which documents some 4,000 different kinds of hybrid crosses among birds, I found that those crosses producing partially fertile hybrids are about eight times as common as crosses known to produce sterile ones. The usual result is a reduction in fertility, not absolute sterility. My current work documenting hybridization among mammals shows that partially fertile natural hybrids are common, too, in Class Mammalia. And yet, it seems most people base their ideas of hybrids on the common mule (horse x ass), which is an exceptionally sterile hybrid, and not at all representative of hybrids as a whole.

I should, perhaps, also mention that differences in parental chromosome counts, even rather large ones, do not preclude the production of fertile hybrids. While differences of this sort do bode ill for the fertility of the resulting progeny, it is only a rule of thumb. For example, female geeps, the products of hybridization between sheep (2n=54) and goats (2n=60), can produce offspring in backcrosses. Likewise, female zeedonks (Burchell’s Zebra, 2n=44 x Ass, 2n=62) have also been fertile in backcrosses. There are many other examples of this sort among mammalian hybrids. Therefore, such differences between the parents in a cross do not in any way guarantee an absolute sterility in the hybrid offspring. (For those readers who do not know, backcross hybrids are produced when hybrids from a first cross mate with either of the two types of parents that produced them. When the resulting progeny mate again with the same parental type, the result is the second backcross generation, and so forth.)

A second so-called fact, which might make it seem impossible for humans to have had a hybrid origin, is the equally erroneous notion that hybrids, especially successful hybrids, do not occur in a state of nature. A third is the mistaken idea that only plants hybridize, and never animals. In fact, however, natural, viable, fertile animal hybrids are abundant. A wide variety of such hybrids occur on an ongoing basis (read a detailed discussion documenting these facts). For example, of the 5,000 different types of hybrid crosses listed in my book on hybridization in birds, approximately half are known to occur in a natural setting (download a PowerPoint presentation summarizing data on hybridization in birds). My current research indicates a comparable rate for mammals.

Sequence data. And I must now emphasize a fact that I, as a geneticist, find somewhat disappointing: With nucleotide sequence data, it can be very difficult to identify later-generation backcross hybrids derived from several repeated generations of backcrossing (to understand the basic problem, see diagram at right). Instead, as is the case with other later-generation backcross hybrids, the most revealing data is of an anatomical and/or physiological nature. And this is exactly the kind of hybrid that it looks like we are — that is, it appears that humans are the result of multiple generations of backcrossing to the chimpanzee. The thing that makes backcross hybrids hard to analyze using genetic techniques is that, in terms of nucleotide sequences, they can differ very little from the parent to which backcrossing occurs. It’s important to realize, however, that a lack of such differences does not prevent them from differing anatomically. Sequence differences are not necessary for anatomical differences to be present. An obvious example of this phenomenon is Down’s syndrome. Individuals affected by Down’s regularly exhibit certain distinctive anatomical features, and yet in terms of their nucleotide sequences they do not differ in any way from other humans. To detect someone with Down’s syndrome, sequence data is completely useless. But with anatomical data, detecting affected individuals is easy. This issue is discussed in more detail in a subsequent section. But for the present, take a careful look at the diagram explaining the genomic effects of backcrossing.

Human infertility. Another observation that appears significant in connection with the hypothesis under consideration is that it has been well known for decades that human sperm is abnormal in comparison with that of the typical mammal. Human spermatozoa are not of one uniform type as in the vast majority of all other types of animals. Moreover, human sperm is not merely abnormal in appearance — a high percentage of human spermatozoa are actually dysfunctional. These and other facts demonstrate that human fertility is low in comparison with that of other mammals (for detailed documentation of this fact see the article Evidence of Human Infertility). Infertility and sperm abnormalities are characteristic of hybrids. So this finding suggests that it’s reasonable to suppose, at least for the sake of argument, that humans might be of hybrid origin. It is also consistent with the idea that the hybridization in question was between two rather distinct and genetically incompatible types of animals, that is, it was a distant cross.

Methodology. The chimpanzee is plausible in the role of one of the parents that crossed to produce the human race because they are generally recognized as being closest to humans in terms of their genetics (here, I use the term chimpanzee loosely to refer to either the common chimpanzee or to the bonobo, also known as the pygmy chimpanzee; the specific roles of these two rather similar apes within the context of the present hypothesis will be explained in a subsequent section). But then the question arises: If an ancient cross between the chimpanzee and some parental form “X” produced the first humans, then what was that parent? Does it still exist? What was it like? As the reader might imagine, if the assumption is correct that one of our parents is the chimpanzee, then it should be possible actually to identify the other parent as well. A hybrid combines traits otherwise seen only separately in the two parental forms from which it is derived, and it is typically intermediate to those parents with respect to a wide range of characters. Naturalists routinely use these facts to identify the parents of hybrids of unknown origin, even backcross hybrids. First they posit a particular type of organism as similar to the putative hybrid (in the present case, this organism is the chimpanzee). They then list traits distinguishing the hybrid from the hypothesized parent, and this list of distinguishing traits will describe the second parent. A detailed analysis of such a triad will often establish the parentage of the hybrid. The traits in question in such studies are generally anatomical, not genetic. DNA evidence is used in only a very small percentage of such identifications (and even then, rarely in efforts to identify backcross hybrids), and yet firm conclusions can generally be reached.

Comparison of human and chimp chromosomes

So in the specific case of humans, if the two assumptions made thus far are correct (i.e., (1) that humans actually are hybrids, and (2) that the chimpanzee actually is one of our two parents), then a list of traits distinguishing human beings from chimpanzees should describe the other parent involved in the cross. And by applying this sort of methodology, I have in fact succeeded in narrowing things down to a particular candidate. That is, I looked up every human distinction that I could find and, so long as it was cited by an expert (physical anthropologist, anatomist, etc), I put it on a list. And that list, which includes many, many traits (see the lengthy table), consistently describes a particular animal. And why might one suppose that humans are backcross hybrids of the sort just described? Well, the most obvious reason is that humans are highly similar to chimpanzees at the genetic level, closer than they are to any other animal. If we were descended from F₁ hybrids without any backcrossing we would be about halfway, genetically speaking, between chimpanzees and whatever organism was the other parent. But we’re not. Genetically, we’re close to chimpanzees, and yet we have many physical traits that distinguish us from chimpanzees. This exactly fits the backcross hypothesis.

Moreover, in mammalian hybrid crosses, the male hybrids are usually more sterile than are the females. In a commercial context, this fact means that livestock breeders typically backcross F₁ hybrids of the fertile sex back to one parent or the other. They do not, as a rule, produce new breeds by breeding the first cross hybrids among themselves. Often, even after a backcross, only the females are fertile among the resulting hybrids. So repeated backcrossing is typical. Commonly there are two or more generations of backcrossing before fertile hybrids of both sexes are obtained and the new breed can be maintained via matings among the hybrids themselves. More backcrossing tends to be necessary in cases where the parents participating in the original cross are more distantly related. Many characteristics that clearly distinguish humans from chimps have been noted by various authorities over the years. The task of preliminarily identifying a likely pair of parents, then, is straightforward: Make a list of all such characteristics and then see if it describes a particular animal. 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.

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.

For the present, I ask the reader to reserve judgment concerning the plausibility of such a cross. I’m an expert on hybrids and I can assure you that our understanding of hybridization at the molecular level is still far too vague to rule out the idea of a chimpanzee crossing with a nonprimate. Anyone who speaks with certainty on this point speaks from prejudice, not knowledge. No systematic attempts to cross distantly related mammals have been reported. However, in the only animal class (Pisces) where distant crosses have been investigated scientifically, the results have been surprisingly successful (399.6, 399.7, 399.8). In fact, there seems to be absolutely nothing to support the idea that interordinal crosses (such as a cross between a primate and a nonprimate) are impossible, except what Thomas Huxley termed “the general and natural belief that deliberate and reiterated assertions must have some foundation.” Besides, to deny that interordinal mammalian crosses are possible would be to draw, at the outset of our investigation, a definite conclusion concerning the very hypothesis that we have chosen to investigate. Obviously, if humans were the product of such a cross,then such crosses would, in fact, be possible.We cannot tell, simply by supposing, whether such a thing is possible — we have to look at data.

The Other Parent
Let’s begin, then, by considering a condensed list of traits distinguishing humans from chimpanzees — and all other nonhuman primates. Take the time to read this list and to consider what creature — of any kind — it might describe. Most of the items listed are of such an obscure nature that the reader might be hard pressed to say what animal might have them (only a specialist would be familiar with many of the terms listed, but all the necessary jargon will be defined and explained). For example, consider multipyramidal kidneys. It’s a fact that humans have this trait, and that chimpanzees and other primates do not, but the average person on the street would probably have no idea what animals do have this feature. Looking at a subset of the listed traits, 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. These traits may bring a particular creature to mind. In fact, a particular nonprimate does have, not only each of the few traits just mentioned, but every one of the many traits listed in th sidebar. Ask yourself: Is it likely that an animal unrelated to humans would possess so many of the “human” characteristics that distinguish us from primates? That is, could it be a mere coincidence? It’s only my opinion, but I don’t think so. Of course, it must be admitted that two human traits do, at first, seem to pose a contradiction. The animal in question lacks a large brain and it is not bipedal. An analysis of the relevant anatomy, however, reveals that these two human features can be understood as synergistic (or heterotic) effects, resulting from the combination (in humans) of certain traits previously found only separately, in the two posited parent forms. (The origins of human bipedality is explained in terms of the the hybrid hypothesis in a subsequent section. Another section offers an explanation of the factors underlying human brain expansion and, therefore, accounts not only for the large size of the human brain itself, but also for certain distinctive features of the human skull that are, themselves, obvious consequences of brain expansion).

Nevertheless, even initially, these two flies in the theoretical ointment fail to obscure the remarkable fact that a single nonprimate has all of the simple, non-synergistic traits distinguishing humans from their primate kin. Such a finding is strongly consistent with the hypothesis that this particular animal once hybridized with the chimpanzee to produce the first humans. In a very simple manner, this assumption immediately accounts for a large number of facts that otherwise appear to be entirely unrelated. 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. But perhaps Darwin told only half the story. 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. Given the facts presented in the discussion of stabilization theory on this website, it seems highly likely that humans are hybrids of some kind. This particular hypothesis concerning the nature of our parentage is, as we shall see, a fruitful one.

My response to a reader who recently wrote in to say that the only convincing evidence for this theory would be sequence data: I’m not saying pig DNA in the human genome “would not” be detectable. That’s putting words in my mouth. I’m saying “might not.” Or, better, “could easily have been missed without this guiding hypothesis.” You seem to somehow be assuming that it isn’t there. As far as I’m concerned, maybe it is, maybe it isn’t. But if it is, obviously, it’s not obvious. As to sequence data, in my opinion, your view of what constitutes evidence needs to be widened. It seems a bit much to insist that the only thing that can convince anyone of anything is sequence evidence. If that’s true, then law courts will have to throw out all the murder weapons, eyewitness testimony, alibis and everything else, and focus instead on DNA evidence alone, because DNA, if what you’re saying is true, is the only evidence that has any meaning. But you know that’s not right. And I think you therefore have to admit that you’re showing a certain bias here. Besides, I’m not making a strong statement. I’m only saying that, given the likely circumstances (an initial cross between chimpanzee and pig, followed by several generations of backcrossing to chimpanzee), analyzing the genetic data and reaching any strong conclusions is likely to be a pain. Maybe there is something there that can be found, but whatever it is, I think it will require lots of money and a team of well-equipped scientists to locate. And think about this: if sequence data is so great, what exactly has it told us about the basis of the many differences between a human and a chimpanzee? I’ll tell you: zero! Nothing whatsoever. Whereas the theory that I propose clearly explains virtually every one of those differences. So forgive me if I don’t race to embrace the sequence approach to understanding the origin of the distinctive features that make us human. So far as I can tell, sequence analysis has been absolutely uninformative on that front.

First of all, the notion is set forward strictly as a hypothesis. No claim whatever is made that it is actually a fact that humans somehow arose through hybridization of pigs with chimpanzees. In contrast, proponents of the idea that humans are closely related to apes (and not to pigs) often speak as if their case has been proved beyond doubt. But, of course, it has not. The wide acceptance of this idea may actually be due to the lack of any competitive theory. I merely propose an evaluation of two distinct hypotheses by the usual scientific criterion: The hypothesis less consistent with available data should be rejected.
Even if we could identify some objective unit of measure for “distance” or “similarity” (which is not at all a straightforward problem), we would still expect some crosses to be more distant than others — that is, the various types of possible crosses would constitute a continuum. Many would be “close” and some would be “distant.” But we would expect at least a rare few to be very distant. While these few might be rare, they might be among the most interesting, because they would offer an opportunity to obtain something radically different. Perhaps, it is only a subjective bias, but I believe that a human being, when taken as a whole, is radically different from a chimpanzee.
On the other hand, if we first compare humans with nonmammals or invertebrates (e.g, crocodile, bullfrog, octopus, dragonfly, starfish), then pigs and chimpanzees suddenly seem quite similar to humans. Relative impressions of “close” and “far” are subjective and depend on context.
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 have been no systematic, scientific surveys of the crossability of mammals belonging to different taxonomic orders (a cross between pig and chimpanzee would be interordinal). Any firm opinion on such a point must therefore, necessarily, be prejudiced. In fact, there is substantial evidence on this website supporting the idea that very distantly related mammals can mate and produce a hybrid (see the section on mammalian hybrids and, in particular, look at the videos shown there of ostensible rabbit-cat hybrids). In addition, certain fishes belonging to different orders have been successfully crossed, and available information on mammalian hybrids indicates that very distant crosses among mammals, too, have occurred. For example, evidence published in the journal Nature demonstrates that the platypus genome contains both bird and mammal chromosomes (223.2). As Franz Grützner, the lead author of the study, stated in a related news story, “The platypus actually links the bird sex chromosome system with the mammalian sex chromosome systems.” How could this be the case if a bird and a mammal did not at some time in the past hybridize to produce a fertile hybrid? Such a cross would, of course, be even more distant than one between a chimpanzee and a pig. And seemingly, a cross between a primate and a pig did occur only a few years ago, in 2008.
Ultimately, the interaction of gametes at the time of fertilization, and the subsequent interplay of genes (derived from two different types of parents) during the course of a hybrid’s development cannot be predicted by any known laws because the interaction is between a multitude of extremely complex chemical entities that each have an effect on others. It is for this reason that the degree of similarity perceived between two organisms is no sure indicator of their crossability.
Another suggestive fact, probably known to the reader, 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? (In subsequent sections, these issues are considered in detail.)
God did not place pigs and humans in different taxonomic orders. Taxonomists did. A great deal of evidence (read a discussion of this topic) exists to suggest that taxonomists are, in no way, infallible. Our ideas concerning the proper categorization of animals are shaped by bias and tradition to such an extent that it would be rash to reject, solely on taxonomic grounds, the feasibility of such a cross.
The general examination of the process of evolution as a whole (as presented elsewhere on this site) strongly suggests that most forms of life are of hybrid origin. Why should humans be any different?
It might seem unlikely that a pig and a chimpanzee would chose to mate, but their behavior patterns and reproductive anatomy do, in fact, make them compatible (this topic is considered in detail in a subsequent section). 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.
Accepted theory, which assumes that humans have been gradually shaped by natural selection for traits favorable to reproduction, does not begin to account for the relative infertility of human beings in comparison with nonhuman primates and other types of animals (see previous section). How would natural selection ever produce abnormal, dysfunctional spermatozoa? On the other hand, the idea that humans are descended from a hybrid cross — especially a relatively distant cross — provides a clear explanation for Homo’s puzzling and persistent fertility problems.
If we supposed standard theory to be correct, it would seem most peculiar that pigs and humans share features that distinguish human beings from chimpanzees, but that pigs and chimpanzees should not. Conventional theory (which assumes that pigs are equally as far removed from humans as from chimpanzees) says that pigs and chimpanzees would share about as many such traits as would pigs and humans. And yet, I have never been able to identify any such trait—despite assiduous investigation. The actual finding is that traits distinguishing chimpanzees from humans consistently link pigs with humans alone. It will be difficult to account in terms of natural selection for this fact. For each such feature, we will have to come up with a separate ad hoc argument, explaining how the feature has helped both pigs and humans to survive and reproduce. On the other hand, a single, simple assumption (that modern humans, or earlier hominids that gave rise to modern humans, arose from a cross between pig and chimpanzee) will account for all of these features at a single stroke.

For my own part, curiosity has carried me away from my old idea of reality. I no longer know what to believe. Is it possible that so many biologists might be wrong about the nature of human origins? Is it possible for a pig to hybridize with a chimpanzee? I have no way of knowing at present, but I have no logical or evidential basis for rejecting the idea. Before dismissing such a notion, I would want to be sure on some logical, evidentiary basis that I actually should dismiss it. The ramifications of any misconception on this point seem immense. As Huxley put it long ago, “The question of questions for mankind — the problem which underlies all others, and is more deeply interesting than any other —is the ascertainment of the place which Man occupies in nature.” Are we simply another type of primate, like the chimpanzee or the baboon? Or are we a complex melange, an alloy of two very distinct forms of life? These are questions that can only be resolved by examining the evidence. I invite the reader to consider these two possibilities as simple hypotheses, to consider the data coldly, and then to determine which of the two is more consistent with available evidence.”

Human hybrids: a closer look at the theory and evidence.

HYBRIDS
http://macroevolution.net/
http://macroevolution.net/mammalian-hybrids.html
http://phys.org/news/2013-07-human-hybrids-closer-theory-evidence.html
A closer look at the theory and evidence
by John Hewitt / Jul 25, 2013

“There was considerable fallout, both positive and negative, from our first story covering the radical pig-chimp hybrid theory put forth by Dr. Eugene McCarthy, a geneticist who’s proposing that humans first arose from an ancient hybrid cross between pigs and chimpanzees. Despite the large number of comments, here at Phys.org, on macroevolution.net, and on several other discussion forums, little in the way of a scientific consensus has emerged. By and large, those coming out against the theory had surprisingly little science to offer in their sometimes personal attacks against McCarthy. As any skilled listener might observe, the most important thing in communication is not always hearing what is said, but rather, hearing what isn’t said. One thing we have not heard here is objection from those writer-scientists who have any kind of public reputation in the evolutionary sciences. I don’t think that is because they didn’t hear about the story. Talk show host Jimmy Kimmel found the article, or at least parts of it, to be rather revealing, and he used segments from it on his show. Commenters on the O’Reilly Factor also called in asking for his opinion on the story. The reason for the silence from above, so to speak, is that they have nothing to gain in being right, but much to lose when any statement they might offer is picked apart by someone with a little more conceptual fluidity, and who has substantial research vested in the theory.As many critics noted, the advancement of scientific knowledge does not require disproving every radical theory that comes along. Lots of incorrect theories exist that cannot, for all practical purposes, be formally disproven. It seems, however, that decent arguments against the hybrid origins theory are surprisingly hard to find, and moreover, the established elders of the field, well, they know it.We decided it would be worthwhile to take a closer look at the objections that were most commonly offered against the hybrid hypothesis. Chief among them was that the chromosome differences here are just too large to support a viable hybrid. One of the previous examples we gave, the zedonk (zebra parent, 2n=44, donkey parent, 2n=62), can and does result in female hybrid offspring that have been reported to produce offspring in backcrosses. The same is true for the geep (sheep, 2n=54, and goat 2n=60). While the reduction in fertility associated with large differences of this sort is often severe, the existence of fertile hybrids, particularly in backcrosses, invalidates this objection.

Another argument was that the morphological distance, or genetic differences besides chromosome number, are just too great. Most of us are familiar with the platypus. A paper published in Nature a few years ago demonstrated that the platypus genome contains both bird and mammal chromosomes, and therefore that the vastly different bird and mammal sex chromosome systems have been successfully bridged by this creature. This example is not offered as any kind of proof. But it does suggest that sometime, long ago, a cross occurred that would have been even more distant than that between a chimpanzee and a pig – one between a otter-like mammal and a duck-like bird. And if such was the case, the hybrids from the cross must have been able to produce offspring (otherwise they would have died out, and the platypus would not exist today). The objection that mating between such different animals is just too strange has been addressed at length on McCarthy’s website. Ample counterexamples have been given there and elsewhere, including the evidence for matings, without issue, between such strange pairings as a buck rabbit with female cat (or even with a domestic hen), or a dog with a monkey, or with a swan goose. In general, as McCarthy points out, it has long been known that many organisms, as adults, prefer to mate with whatever animal they are exposed to at the critical early stage in their lives when sexual imprinting occurs. He also notes that it is not as if his hypothesis that humans are pig-chimp hybrids has not been tested. Under the alternative hypothesis (humans are not pig-chimp hybrids), the assumption is that humans and chimpanzees are equally distant from pigs. You would therefore expect chimp traits not seen in humans to be present in pigs at about the same rate as are human traits not found in chimps. However, when he searched the literature for traits that distinguish humans and chimps, and compiled a lengthy list of such traits, he found that it was always humans who were similar to pigs with respect to these traits. This finding is inconsistent with the possibility that humans are not pig-chimp hybrids, that is, it rejects that hypothesis.

Human hybrids: a closer look at the theory and evidence.
http://skullsite.co.uk/Pig/pigdom.htm

Also raised was the argument that pigs and humans might have converged anatomically as a result of longstanding animal husbandry, not limited to but perhaps including genes carried over by retroviruses. If that is, in fact, a general mechanism that operates behind the scenes, then we might justifiably ask—why don’t a lot of the traits that distinguish us from primates connect us with dogs, with whom we have obviously lived, at close quarters, since prehistoric times? Why is it only pigs? One objection which seems to have really stretched the genetic exclusion argument was an appeal to junk DNA as a mechanism that can prevent two species from reproducing. The reference was to a paper in PLoS Biology which revealed interesting phenomena occurring in Drosophila (fruit flies) that can prevent embryos from developing. The study points to faster mutation rates found for noncoding DNA, and outlines a mechanism where mutation in a segment on the X chromosome of the father prevents proper separation of the whole chromosome. Clearly, a unique situation in this particular species, however interesting, does not invalidate the documented existence of successful hybrids produced in thousands of other species crosses. In moving forward, we hope to see more discussion on this issue from both sides of the argument. Nothing is preventing anyone from taking a closer look at the genetic picture. In fact, doing so has never been easier. Sites like eEnsembl let you “browse a genome” with unprecedented ease. Sequence data, or genome organization can be curated to support both observation and idea, as it can also be done to oppose the same. For the matter at hand, we might expect each side to continue to accuse the other of cherry-picking their arguments. Eventually though, sufficient data will fall from the collisions between example-fed discussion and informed search to deliver an elevated consensus. One particular approach recommended McCarthy is in silico chromosome painting of the human genome with random pig and chimp sequences in an effort to find hotspots of similarity to pig.

Another possibility that McCarthy does not recommend, but which several scientists have suggested to him, is producing an actual hybrid. He objects to this approach, not on scientific, but humanitarian grounds. After all, he says, such an experiment might result in an intelligent but non-human creature, much more piglike than any human being, who would have no happy place in our world. He in fact includes such a hybrid, an F1 female, as one of the major characters in The Department, his kindle book satire of academic life. In it he observes, “I hope never to meet her in the flesh.” You can see McCarthy address some of the issues raised above in greater depth in a podcast that has just been released.”

The mystery of the human intelligence explosion

SMART as a PIG?
http://io9.com/a-long-anthropological-debate-may-be-on-the-cusp-of-res-512864731
http://io9.com/the-mystery-of-the-human-intelligence-explosion-1477208203
http://io9.com/the-mystery-of-the-human-intelligence-explosion-1477208203

“Over the past 200,000 years since Homo sapiens evolved, something extraordinary happened. Somehow, we went from being clever monkeys with stone tools, to being insanely brilliant masterminds who use complex language, and control the planet with agriculture and technology. How did we start the intelligence explosion that anthropologists call the “human revolution”? Perhaps one of the biggest mysteries in our evolution is how humans developed symbolic culture, a very general catch-all term that includes things like art, language, personal adornment, weapons, and rituals like funerals. Symbolic culture is what sets humans apart from other species, and yet it also seems to pre-date the emergence of Homo sapiens. We find plenty of stone tools in Africa before 200,000 years ago, as well as evidence of fire pits and art-making. Our Homo erectus ancestors were throwing spears and making colorful paint from pigments thousands of years before we evolved.

The mystery of the human intelligence explosion
{photo Patrick Gruban}

So question is, when did these symbolic practices start to define humanity? There is no easy answer, and we may never gather enough evidence to come up with a definitive timeline. But there are two broad theories about how it happened. One suggests humanity made a great cultural leap forward roughly 80-60 thousand years ago, during the “revolution” when humans hightailed it out of Africa and into Eurasia. And the other suggests culture evolved gradually, in Africa, over Homo sapiens‘ entire species lifespan.

The Revolutionaries
The term “human revolution” is often attributed to anthropologist Paul Mellars, who that this event was an “accelerated episode of change” between 80-60 thousand years ago, right before the Middle Paleolithic (or middle stone age) transitioned into the Upper Paleolithic (or late stone age). For this reason, this change is also sometimes called the Upper Paleolithic revolution. At this point in time, the anthropological record yields rich evidence that humans had gone way beyond their ancestors in terms of technological sophistication. We had graduated from stone tools to bone (see image below), and those tools were specialized for a wide range of activities from tanning skins to hammering. Humans were fishing, transporting over great distances (probably due to their value as jewelry), heating pigments to create different colored paints, burning areas near their homes to help desirable plants flourish, burying their dead with special items, and painting elaborate motifs on cave walls.

The mystery of the human intelligence explosion

There is also evidence that these new human behaviors included larger groups of humans living together, in social groups that were far more hierarchically organized than previous bands of hunter/gatherers. At the same time, these more structured groups were heading out of Africa into Eurasia, bringing their culture with them. Eventually, these revolutionaries absorbed or replaced the other human populations of Neanderthals, Denisovans and possibly others in Eurasia. What could have caused the revolution? Mellars is agnostic on this point, suggesting that it might have been a genetic mutation that spread swiftly through Africa. Or it might have been “stimulated by the economic and demographic pressures imposed by the rapid succession of climatic and related environmental changes.” This was a period of rapid cooling, partly caused by the Mount Toba mega-volcano that erupted in Sumatra about 74 thousand years ago.People might have been innovating because of genetic changes, environmental ones, or both.

Mellars compares the human revolution of 80 thousand years ago to a more recent one called the Neolithic revolution that led to the rapid development of agriculture and cities roughly 13-10 thousand years ago. He and prominent anthropologist that this parallel with the Neolithic is evidence that humans tend to develop in moments of cultural acceleration. We go through phases of rapid innovation, punctuated by periods of relative stability and even devolution. Given that this is the case, they argue, it seems likely that symbolic behavior was the result of a revolutionary change. That also helps to explain why the fossil record shows an abundance of art and complex tools in the Upper Paleolithic, all over the world.

The mystery of the human intelligence explosion

The Gradualists
The problem with the “human revolution” account of events is that the past few decades have yielded more and more evidence that humans in Africa had symbolic culture long before the so-called acceleration. Anthropologist Sally McBrearty explores this evidence in an essay called “Down with the Revolution,” (this builds off her earlier essay with Alison Brooks called “The Revolution That Wasn’t”) where she fleshes out many of the assertions you see in the figure above. Based on new digs in Africa and the Middle East, we now have evidence that humans were making paint and burying their dead in symbolic ways over 180 thousand years ago, long before that “acceleration.” Long-distance exchange of items and shellfishing also appear to have emerged before 100 thousand years ago. Of particular interest to McBrearty is the fact that ostrich eggshell beads, used as personal adornments, date back 75 thousand years.

In addition, as Alison George notes in a great article in New Scientist, there’s now genetic evidence that a gene associated with human communication, FOXP2, might have spurred human symbolic thought 170 thousand years ago. Archaeologist Johan Lind told George that the “modern mind” might have actually emerged as early as 500 thousand years ago, with our ancestor Homo erectus. That would make sense, if we consider that Homo erectus used tools and fire.

The problem, as McBrearty and many others point out, is that evidence for human behavior in Africa is almost non-existent before 130 thousand years ago. At that time, sea level changes overtook some of the most widely-studied coastal human settlements in South Africa and swept away anything that had been deposited before that.

The mystery of the human intelligence explosion

Related to that, evidence of the human revolution advocated by Mellars is found mostly in Eurasia, not Africa. McBrearty suggests that we have to integrate the very early evidence we do have from Africa into the story of symbolism, which gives us a very different picture of gradual development over hundreds of thousands of years, rather than accelerated change over a few thousand.

There are also questions about whether what happened in Eurasia should properly be called a revolution at all, since the sudden shift in the anthropological record is the result of an influx of Homo sapiens immigrants. “The word revolution implies a home-grown development,” McBreaty writes. “It does not imply that the changes were the product of a population replacement.” In other words, it’s not a revolution if a bunch of outsiders come in and convert the locals to a new way of life. Those outsiders are just continuing to build on a culture that started long ago, in Africa.

The mystery of the human intelligence explosion

Or maybe they weren’t just in Africa, after all. Gorgeous and strange paintings discovered at El Castillo cave in Spain suggest that the local Neanderthals were engaging in pretty sophisticated symbolism 40 thousand years ago, long before Homo sapiens arrived in that part of Europe. The cave was occupied for thousands of years, and its many chambers are decorated with animal drawings, handprints, and intricate, abstract designs made of dots. It’s possible that our ancestors had the capacity for symbolic thought long before Homo sapiens evolved. The hominins who left Africa before modern humans did, like the Neanderthals’ ancestors, may have been developing symbolic behaviors in Spain, while Homo sapiens did it in South Africa. That would explain El Castillo cave, as well as why Homo sapiens was able to integrate the local Eurasians into their cultures so easily. But to return to the question we began with, the answer may ultimately lie somewhere in between the revolutionaries and the gradualists. It’s likely that humans were gradually developing symbolic behavior over 200 thousand years or more. But it’s also possible that there were several thousand years during which this symbolic activity was popularized around the world, and became more sophisticated through cultural exchange with Neanderthals, Denisovans, and other hominin groups who found each other in various parts of Eurasia. It’s undeniable that humanity has gone through periodic growth spurts, during the Neolithic revolution, and during the Industrial revolution as well. But that doesn’t mean we aren’t also developing key innovations during all those stable centuries too. A brilliant invention (like, say, typesetting) may be around for a long time before it explodes into popularity. Are those moments revolutions, or just times when already-existing technologies become widely fashionable?

Modern culture emerged in Africa 20,000 years earlier than anybody realized
“Items that can be seen in the image above include a) a wooden digging stick; b) a wooden poison applicator; c) a bone arrow point decorated with a spiral incision filled with red pigment; d) a bone object with four sets of notches; e) a lump of beeswax; and f) ostrich eggshell beads and marine shell beads used as personal ornaments.” {image : Francesco d’Errico and Lucinda Backwell]

EARLIER THAN THOUGHT
http://phys.org/news/2013-12-discovery-partial-skeleton-ruggedly-built.html
http://io9.com/5675839/a-mysterious-group-of-early-humans-who-made-tools-that-were-55000-years-ahead-of-their-time
http://io9.com/5614061/human-ancestors-carved-meat-with-stone-tools-almost-a-million-years-earlier-than-expected
http://io9.com/5930463/modern-culture-emerged-in-africa-20000-years-earlier-than-anybody-realized
Modern culture emerged in Africa 20,000 years earlier than anybody realized
by George Dvorsky / 7/31/12

“Archeologists studying the remains of early humans in Africa have unveiled a number of ancient artifacts that push back the advent of modern culture to 44,000 years ago — way earlier than the previous estimates of 22,000 years ago. The new dates are based on the radiocarbon dating of tools and other items found at Border Cave in the Lebombo Mountains near South Africa. And these artifacts reveal a surprisingly sophisticated culture — one that had even learned to harness the power of poisons and beeswax. The study was conducted by an international team of experts, including researchers from South Africa, France, Italy, Norway, the USA, and Britain. Details of their findings were published yesterday (July 30) in the Proceedings of the National Academy of Sciences. The archaeological materials uncovered by the anthropologists portray a remarkably complex culture — and one that emerged far earlier than anyone could have imagined. This was around the same time that humans were making their way into Europe, but experts believe there were significant differences between the two groups. Anthropologists refer to this era (which we now know began as early as 44,000 years ago) as the Later Stone Age, comparable to the Upper Paleolithic. Specific artifacts left behind by these San hunter-gatherer peoples include ostrich eggshell beads, thin bone arrowhead points, wooden digging sticks, a gummy material called pitch that was used to affix bone and stone blades to shafts. There were also worked tusks from a boar-like creature that were used to plane wood, and notched bones that were likely used for counting.

And then there was the remarkable discovery of poison — what would have been (literally) the killer app of hunting technology back then. Chemical analysis indicated that poison was being applied to bone points, a substance that was likely derived from the seeds of castor oil plants (ricinoleic acid). The poison-tipped bone points would have been thrust through the thick hide of a medium or large-sized herbivore — but because this weapon lacked ‘knock-down’ power, it would have been part of a larger, highly skilled attack. Archeologists also found wooden digging sticks, which were found near bored and broken stones, likely to weigh the sticks down. These devices were probably used by the San culture to dig up bulbs and termite larvae — a practice that continued for tens of thousands of years. As for the beeswax, which was also dated to 40,000 years ago, it is the oldest specimen known to be used by humans. It was likely used as a kind of adhesive (what’s called hafting), while other specimens wrapped in plant fibers indicate that it was used to make the strings for hunting bows. The Upper Paleolithic era was characterized by the emergence of complex and new technologies that helped humans survive in both Africa and Europe. These tools included spear-throwers, bone needles with eyelets for sewing furs, bone fishing hooks, bone flutes, and ivory figurines carved from mammoth tusks. And astonishingly, this study suggests that Upper Paleolithic culture may have roots even earlier than 44,000 years ago — possibly as early as 50,000 to 60,000 years ago. If this is correct, and if new archaeological evidence reaffirms these suspicions, it is quite possible that the first humans to venture into Europe were actually influenced by this phase of African culture.”

Reference: Proceedings of the National Academy of Sciences
{DOI: 10.1073/pnas.1202629109 and 10.1073/pnas.1204213109}

the ‘MONKEY-FUCKED-a-PIG’ HYPOTHESIS
http://scienceblogs.com/pharyngula/2013/07/02/the-mfap-hypothesis-for-the-origins-of-homo-sapiens/
The MFAP Hypothesis for the origins of Homo sapiens
by PZ Myers / July 2, 2013

“I know you’re thinking we’ve had more than enough discussion of one simplistic umbrella hypothesis for the origin of unique human traits — the aquatic ape hypothesis — and it’s cruel of me to introduce another, but who knows, maybe the proponents of each will collide and mutually annihilate each other, and then we’ll all be happy. Besides, this new idea is hilarious. I’m calling it the MFAP hypothesis of human origins, which the original author probably wouldn’t care for (for reasons that will become clear in a moment), but I think it’s very accurate.

First, the author of this new hypothesis provides a convenient list of all the unique traits that distinguish humans from other primates. It falsely lists a number of traits that are completely non-unique (such as female orgasm and cancer), or are bizarre and irrelevant (“snuggling”, really?). It’s clearly a selective and distorted list made by someone with an agenda, so even though some items on the list are actually unusual traits, the list itself is a very poor bit of data. But set those objections to the list aside for a moment, and let’s consider the hypothesis proposed to explain their existence, the MFAP Hypothesis of Eugene McCarthy, geneticist. I will allow him to speak for himself at length; basically, though, he proposes that the way novel traits appear in evolution is by hybridization, by crosses between two different species to produce a third with unique properties.

Many characteristics that clearly distinguish humans from chimps have been noted by various authorities over the years. The task of preliminarily identifying a likely pair of parents, then, is straightforward: Make a list of all such characteristics and then see if it describes a particular animal. 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. For the present, I ask the reader to reserve judgment concerning the plausibility of such a cross. I’m an expert on hybrids and I can assure you that our understanding of hybridization at the molecular level is still far too vague to rule out the idea of a chimpanzee crossing with a nonprimate. Anyone who speaks with certainty on this point speaks from prejudice, not knowledge.

Let’s begin, then, by considering the list in the sidebar at right, which is a condensed list of traits distinguishing humans from chimpanzees — and all other nonhuman primates. Take the time to read this list and to consider what creature — of any kind — it might describe. Most of the items listed are of such an obscure nature that the reader might be hard pressed to say what animal might have them (only a specialist would be familiar with many of the terms listed, but all the necessary jargon will be defined and explained). For example, consider multipyramidal kidneys. It’s a fact that humans have this trait, and that chimpanzees and other primates do not, but the average person on the street would probably have no idea what animals do have this feature.

Looking at a subset of the listed traits, 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. These traits may bring a particular creature to mind. In fact, a particular nonprimate does have, not only each of the few traits just mentioned, but every one of the many traits listed in th sidebar. Ask yourself: Is it is likely that an animal unrelated to humans would possess so many of the “human” characteristics that distinguish us from primates? That is, could it be a mere coincidence? It’s only my opinion, but I don’t think so.

Look at the description of the putative non-primate parent in the last paragraph above. What animal are you thinking of? It’s probably the same one McCarthy imagined, which is why I’ve decided that this explanation for human origins must be called the Monkey-Fucked-A–Pig hypothesis, or MFAP for short. Let’s be perfectly clear about this. McCarthy’s hypothesis is that once upon a time, these two met and had sex.

And that they then had children that were… us. That’ll learn me. I thought this South Park clip was a joke.

https://youtu.be/o6ixfngoCH4]

One thing that struck me in reading McCarthy’s claim is how they are so similar to the claims of the soggy ape fans — they even use the very same physiological and anatomical features to argue for their delusion. For instance, I’ve read aquatic ape proponents’ arguments that the shape of our nose is adaptive for streamlining and for preventing water from flowing into the nostrils while propelling ourselves forward through the water…but compare that to the MFAP.

Neither is it clear how a protrusive cartilaginous nose might have aided early humans in their “savannah hunter lifestyle.” As Morris remarks, “It is interesting to note that the protuberant, fleshy nose of our species is another unique feature that the anatomists cannot explain.” This feature is neither characteristic of apes, nor even of other catarrhines. Obviously, pigs have a nose even more protuberant than our own. In a pig’s snout, the nasal wings and septum are cartilaginous as ours are. In contrast, a chimpanzee’s nose “is small, flat, and has no lateral cartilages”. A cartilaginous nose is apparently a rare trait in mammals. Primatologist Jeffrey Schwartz goes so far as to say that “it is the enlarged nasal wing cartilage that makes the human nose what it is, and which distinguishes humans from all other animals.” The cartilaginous structure of the pig’s snout is generally considered to be an “adaptation” for digging with the nose (rooting). Rooting is, apparently, a behavior pattern peculiar to pigs. Other animals dig with their feet.

Point, MFAP. Of course, just as I would point out to aquatic ape people, we do have an explanation for the nose: recession of the facial bones associated with reduced dentition, along with retention of the bones associated with the respiratory apparatus. The protuberant nose is simply a ridge made apparent by the receding tide of our chewing apparatus. McCarthy uses evidence as badly as does every wet ape fan.

Now, why won’t this hybridization claim work? Well, there are the obvious behavioral difficulties, even if it were cytogenetically possible. We’d have to have pigs and chimps having sex and producing fertile offspring, and those human babies (remember, this is a saltational theory, so the progeny would have all the attributes of a third species, ours) would have to be raised by chimps. Or pigs. I don’t think either is a reasonable alternative, and a band of chimps would probably be no more charitable to a helpless fat blob of a baby than Mr Wu’s pigs. However, no one reasonably expects pigs and chimps to be interfertile. The primate and artiodactyl lineages have diverged for roughly 80 million years — just the gradual accumulation of molecular differences in sperm and egg recognition proteins would mean that pig sperm wouldn’t recognize a chimpanzee egg as a reasonable target for fusion. Heck, even two humans will have these sorts of mating incompatibilities. Two species that haven’t had any intermingling populations since the Cretaceous? No way.

But further, even if the sperm of one would fuse with the egg of another, there is another looming problem: chromosome incompatibilities. Pigs have 38 chromosomes, chimpanzees have 48. Cells are remarkably good at coping with variations in chromosome number, and even with translocations of regions from one chromosome to another; and further, pigs and people even retain similar genetic arrangements on some of their chromosomes. There are pig chromosomes that have almost the same arrangement of genes as a corresponding human chromosome. But there are limits to how much variation the cell division machinery can cope with. For instance, with fewer chromosomes than we primates have, that means you need to line up multiple primate chromosomes to match a single pig chromosome (this pairing up is essential for both mitosis and meiosis). Look at pig chromosome 7, for instance: it corresponds to scrambled and reassembled bits of human chromosomes 6, 14, and 15.

Blocks of conserved synteny between pig and human. (a) Pig SSC7 to human chromosomes 6, 14 and 15. (b) HSA13 compared to pig chromosome 11. Block inversions between pig and human are denoted with broken lines. Contig coverage is depicted by bars in the center of SSC7 and HSA13. Maybe that would work in mitosis within the hybrid progeny — you’d have three chromosomes from the human/chimp parent twisted around one chromosome, but they would be able to pair up, mostly, and then separate to form two daughter cells. But meiosis would be total chaos: any crossing over would lead to deletions and duplications, acentric and dicentric chromosomes, a jumble of broken chromosomes. That would represent sterile progeny and an evolutionary dead end. But we wouldn’t have to even get that far. Human and chimpanzee chromosomes are even more similar to one another, and there are no obvious chromosomal barriers to interfertility between one another. If hybridization in mammals were so easy that a pig and a chimp could do it, human-chimp hybrids ought to be trivial. Despite rumors of some experiments that attempted to test that, though, there have been no human-chimp hybrids observed, and I think they are highly unlikely to be possible. In this case, it’s a developmental problem.

For example, we have bigger brains than chimpanzees do. This is not a change that was effected with a single switch; multiple genes had to co-evolve together, ratcheting up the size in relatively incremental steps. So you could imagine a change that increased mitotic activity in neural precursors that would increase the number of neurons, but then you’d also need changes in how those cells are partitioned into different regions, and changes in the proliferation of cartilage and bone to generate a larger cranium, and greater investment in vascular tissue to provide that brain with an adequate blood supply. Development is like a ballet, in which multiple players have to be in the right place and with the right timing for everything to come off smoothly. If someone is out of place by a few feet or premature by a few seconds in a leap, the dancers could probably compensate because there are understood rules for the general interactions…but it would probably come off as rough and poorly executed. A hybrid between two closely related species would be like mixing and matching the dancers from two different troupes to dance similar versions of Swan Lake — everything would be a bit off, but they could probably compensate and muddle through the performance. Hybridizing a pig and a chimp is like taking half the dancers from a performance of Swan Lakeand the other half from a performance of Giselle and throwing them together on stage to assemble something. It’s going to be a catastrophe. But here’s the deal: maybe I’m completely wrong. This is an experiment that is easily and relatively cheaply done. Human sperm is easily obtained (McCarthy probably has a plentiful supply in his pants), while artificial insemination of swine is routine. Perhaps McCarthy can report back when he has actually done the work.”

“Pigs are even smarter than dogs or dolphins”

MEANWHILE [GROSS]
http://salon.com/2013/11/25/undercover_activist_who_exposed_animal_cruelty_is_cited_for_animal_cruelty/
http://rollingstone.com/feature/belly-beast-meat-factory-farms-animal-activists
http://theguardian.com/world/2013/dec/04/pig-semen-export-deal-china
UK and China agree £45m pig semen export deal
by Nicholas Watt in Chengdu / 4 December 2013

“Britain has won the right to export pig semen to China in a deal worth £45m a year. Owen Paterson, the environment secretary, who is accompanying David Cameron on his trip to China, has also embarked on negotiations to export pigs’ trotters – a local delicacy – to China. Under the deal with China, the “porcine semen” can be flown to the country in frozen and fresh form. Pigs will not be flying but their seed will take to the air. A No 10 spokesperson said: “We’re doing all we can to ensure that businesses up and down the country reap the rewards from our relationship with China. And that includes our pig farmers. This new deal to export pig semen will be worth £45m to UK firms and means Britain’s best pigs will help sustain the largest pig population in the world. “And we’re not stopping there, we’re talking to the Chinese about serving up pigs trotters on Beijing’s finest dining tables. That would be a real win-win – a multimillion pound boost for Britain and a gastronomic treat for Chinese diners.”

The exports start in the first quarter of next year. Four UK artificial insemination centres, based in England and Northern Ireland, will start making preparations for the exports in the new year. Half of the world’s pigs are in China but the country needs to improve pig genetics. A government source said: “China has an interest to increase the efficiency of their production, while minimising the environmental impact of increased production. The UK industry for pig production can play a large and important role in helping China achieve greater efficiency through the provision of high-quality genetic stock. “UK porcine semen will be key to help the Chinese improve their pig production and make the industry more productive in the long term. The quantities are not the important factor for this trade; it is the quality that is important.”