[SolarCross]

That particular combination is extremely rare, you would need it to at least happen twice with opposite sex offspring and then a couple dozen more times to have a genetically viable pool. That scenario is astronomically unlikely.

Also note that in your own quote it says the females are generally poorly fertile and the males are sterile.

Ah so you are coming down from "bah impossible!" to "well it is really unlikely", which is good. You will note that all viable natural genetic mutations rely on the "really unlikely" becomes "likely" over very long time scales argument. Or are you into intelligent design these days?

[mikema63]

Evolution is cumulative, this is not. If another such example was likely enough to occur once a generation naturally (it isn't) you would still only ever have 1 alive at any one time. It's not going to stay alive forever waiting for a viable starting population to develop.

Your mischaracterization of me not withstanding.

[SolarCross]

Evolution is cumulative, this is not. If another such example was likely enough to occur once a generation naturally (it isn't) you would still only ever have 1 alive at any one time. It's not going to stay alive forever waiting for a viable starting population to develop.

Your mischaracterization of me not withstanding.

Backcrossing. Female chimp gets rutted or raped by a boar, the offspring is female and barely fertile but enough that later she mates and produces offspring with a male chimp. These females of the offspring are sufficiently fertile to allow further matings to produce offspring. Maybe on occasion a fresh load of boar cum gets injected into the genepool dosing up the level of pig genes. These extra genes although compromising fertility introduce new phenotypic advantages such that they are allowed by natural selection to propagate until a new species is born.

I just noticed this "A hybrid has a number of chromosomes somewhere in between (the parent species)."

So chimps have 48 chromosomes.
Humans have 46.
Pigs have 38.

How do you explain the loss of 2 chromosomes from the transition from chimp ancestor to human ancestor? Hybridisation has that nailed.

[mikema63]

We have 46 because chromosomes fused together and we have the molecular evidence if the event.

http://www.evolutionpages.com/chromosome_2.htm

FYI your example would simply lead to dilution of thise genes due to weaker fertility, they would be selected against and die out within the chimp population.

[SolarCross]

We have 46 because chromosomes fused together and we have the molecular evidence if the event.

http://www.evolutionpages.com/chromosome_2.htm

FYI your example would simply lead to dilution of thise genes due to weaker fertility, they would be selected against and die out within the chimp population.

Could the fusion event that caused the loss of 2 chromosomes have not occured as consequence of hybridisation? Is that a mutually exclusive scenario? What specifically, if not hybridisation, caused the fusion? Are fused chromosomes found in other hybrids such as the zedonk?

Weaker fertility is a adverse selection pressure yes, however if those genes introduced (as McCarthy argues) other favourable characteristics such as the pig's ability to rapidly cool or warm its body through variable blood flow through the skin (an ability that humans also have but no other ape has) then that would mitigate or even trump that adverse pressure. You are being too selective looking only at fertility and disregarding that fertility is only one of many phenotypic characteristics that influence gene propagation or dilution.

Humans are noted for having unusually low fertility compared with our close relatives (which in itself is an indication of hybridisation) yet there are 7+ billion of us on this planet while our more reliably fertile relatives are hovering on the brink of extinction. Fertility is not everything.

[mikema63]

No, hybridization wouldn't fuse chromosomes.

Edit: whoops

[SolarCross]

No, hybridization would fuse chromosomes.

Ah so you acknowledge that the fusion event you mentioned as being part of the story for how humans came to have less chromosomes than chimps could have been a consequence of hybridisation?

[mikema63]

My apologies, serious typo, I blame my phone.

[SolarCross]

My apologies, serious typo, I blame my phone.

Okay, what does hybridisation do then to create an intermediate number of chromosomes in the progeny, if not at least partly through fusion?

What, if not hybridisation, exactly and specifically did cause the fusion of chimp chromosomes into the human number of chromosomes?

Btw - I suggest you actually read the hypothesis linked in the OP before dismissing it as heretical.

[mikema63]

Okay, what does hybridisation do then to create an intermediate number of chromosomes in the progeny, if not at least partly through fusion?

Let's assume an animal with 30 chromosomes and an animal with 20 mates. In meiosis each parent creates haploid sex cells with half the normal number of chromosomes. So now it's 15 and 10. Those two cells come together and you get a total of 25 chromosomes. Obviously I skipped a lot of steps and explanation but that's the gist of the process, there isn't any fusion.

For reference a pig and a chimpanzee offspring would end up with 43 chromosomes.

What, if not hybridisation, exactly and specifically did cause the fusion of chimp chromosomes into the human number of chromosomes?

It happens randomly, it's hard to say why it happened in humans.

Btw - I suggest you actually read the hypothesis linked in the OP before dismissing it as heretical.

I did, he has a strange focus on morphology and none on molecular biology. Morphology can be explained through convergent evolution, you have to actually look at the molecular evidence to support such a hypothesis, and there isn't any.

[Rancid]

Don't they say that burn human flesh smells like cooked pork? Don't people say that fire fighters don't eat pork?

[SolarCross]

Let's assume an animal with 30 chromosomes and an animal with 20 mates. In meiosis each parent creates haploid sex cells with half the normal number of chromosomes. So now it's 15 and 10. Those two cells come together and you get a total of 25 chromosomes. Obviously I skipped a lot of steps and explanation but that's the gist of the process, there isn't any fusion.

For reference a pig and a chimpanzee offspring would end up with 43 chromosomes.

Ok would back crossing with the species with the larger chromosome set not fill up the number of chromosomes to the same level as that parent species?
As in pre-human (post-chromosome fusion event) 46 chromosomes crosses with pig 38 chromosomes.
so 23 + 19 = 42 chromosomes in say a female offspring.
That hybrid mates with another 46 chromosome pre-human.
So 46/2 + 42/2 = 44 chromosomes, this offspring then mates with another 46 chromosome pre-human.
So the resulting hybrid is 46/2 + 44/2 = 45 chromosomes.
Yet another backcross and we get.
46/2 + 45/2 - Now I think if one divides 45 chromosomes in half you should either get 22 or 23 chromosomes in the gamete because chromosomes are not chopped in half only separated from their pair. So this combination would result in either 23 + 23 or 23 + 22. If this mating involved 23 + 23 then the chromosome count is restored to 46.

I did, he has a strange focus on morphology and none on molecular biology. Morphology can be explained through convergent evolution, you have to actually look at the molecular evidence to support such a hypothesis, and there isn't any.

Once one has the hypothesis that a species is a hybrid, surely morphology is the first approach to identifying potential source species? Once you have narrowed down which species are likely sources you can then do the molecular biology to confirm it. Let's say some one gave you a zedonk for christmas but couldn't tell you anything of its lineage. You thought it looked a bit odd and that maybe it was a hybrid, what do you do now? Would you a) compare its genetic code with every other species on the planet? Or b) notice that the zedonk had zebra characteristics and donkey characteristics and then compare its genome to that of zebras and donkeys?

McCarthy addresses convergence in his hypothesis. He says that convergance can reproduce the macroscopic similarities but not fine detail similarities (I am paraphrasing). So for example dolphins converged on the fish morphology macroscopically ie: sleek form and limbs that are paddle and fin like. But that convergance did not and could not reproduce scales and gills and what not. McCarthy claims that the morphological similarities with pigs extend to the fine detail more than they do to the macroscopic. Moreover there isn't any selection pressures that could cause humans to converge on those pig features. What selection pressures would give humans extra tail bones over chimpanzees for example?

Now I agree the final proof must be in the molecular genetics and hopefully that will be done at some point. A general rule though hypotheses tend to come first.

He does offer this little nugget of molecular evidence..

Mitochondrial DNA (mtDNA)
Analysis of available data suggests humans are derived from an ancient cross involving a female chimpanzee

Such difficulties do not arise under the assumption that humans are derived from hybridization between chimpanzees and some other kind of animal. If a female chimpanzee mated with a male that was not a chimpanzee, the hybrid offspring would have exactly the same mtDNA as the mother chimpanzee, but different, hybrid nuclear DNA derived in part from the “father’s side of the family.” A hybrid race descended from such a mating would have highly invariant mtDNA (which might very well be similar to that of certain living chimpanzees because the same mitochondrial type could have survived in both humans and chimpanzees, and thus be one of the extant chimpanzee varieties). But the intense mutation process (chromosomal recombination and restructuring), which would occur during hybrid meiosis in the generations after the cross, would increase nuclear variability beyond that seen in chimpanzees (meiosis has no mutational effect on mtDNA).

An extreme bottleneck involving human beings alone would, of course, have the same effect on mtDNA variability. But imagine the effect on human diversity if a single female were selected today to mother a new human race. The variability would go to nearly zero. Why, then, would our nuclear genes in actuality be five times more variable than those of chimpanzees when there is no evidence that chimps passed through a similar bottleneck? And why is our mtDNA indistinguishable from that of certain chimpanzees? These findings are consistent with the idea that humans are descended from a cross between one or more female chimpanzees and one or more non-chimpanzee males.

[mikema63]

Ok would back crossing with the species with the larger chromosome set not fill up the number of chromosomes to the same level as that parent species?
As in pre-human (post-chromosome fusion event) 46 chromosomes crosses with pig 38 chromosomes.
so 23 + 19 = 42 chromosomes in say a female offspring.
That hybrid mates with another 46 chromosome pre-human.
So 46/2 + 42/2 = 44 chromosomes, this offspring then mates with another 46 chromosome pre-human.
So the resulting hybrid is 46/2 + 44/2 = 45 chromosomes.
Yet another backcross and we get.
46/2 + 45/2 - Now I think if one divides 45 chromosomes in half you should either get 22 or 23 chromosomes in the gamete because chromosomes are not chopped in half only separated from their pair. So this combination would result in either 23 + 23 or 23 + 22. If this mating involved 23 + 23 then the chromosome count is restored to 46.

It could but you still have all those nasty fertility problems, so when you back cross into a larger population who is more fertile you will be out competed and your genes will be selected against until they are removed from the gene pool.

Once one has the hypothesis that a species is a hybrid, surely morphology is the first approach to identifying potential source species?

Before the advent of molecular biology sure, but nowadays you look at the gene and protein level first.

Once you have narrowed down which species are likely sources you can then do the molecular biology to confirm it.

I'll point out that molecular biology has already disproven the hypothesis, a pig is no more related to us than it should be given it's evoloutionary distance.

Let's say some one gave you a zedonk for christmas but couldn't tell you anything of its lineage. You thought it looked a bit odd and that maybe it was a hybrid, what do you do now? Would you a) compare its genetic code with every other species on the planet? Or b) notice that the zedonk had zebra characteristics and donkey characteristics and then compare its genome to that of zebras and donkeys?

To guess sure, but you don't found a hypothesis on that. You have to do an experiment based on your hunch to actually publish something like this. To prove something like this you would need molecular biology. Part of what annoys me about this hypothesis is that he didn't even do basic experimentation before he tried to popularize his idea with the public, which is a huge no no.

McCarthy addresses convergence in his hypothesis. He says that convergance can reproduce the macroscopic similarities but not fine detail similarities (I am paraphrasing).

That's not true, every detail of the body is created by evolution and can be convergent. This is also part of where I say he cherry picks, he looks at everything about us that is very similar to pigs, and ignores anything significantly different.

So for example dolphins converged on the fish morphology macroscopically ie: sleek form and limbs that are paddle and fin like. But that convergance did not and could not reproduce scales and gills and what not.

Very true, and we have some similarities to pigs, but we walk upright and a quite a bit more intelligent and don't need to wallow in mud.

McCarthy claims that the morphological similarities with pigs extend to the fine detail more than they do to the macroscopic. Moreover there isn't any selection pressures that could cause humans to converge on those pig features. What selection pressures would give humans extra tail bones over chimpanzees for example?

We aren't descended directly from chimps, we share a common ancestor with chimps. Chimps had a tailbone fuse to their sacrum in their evolutionary history and we didn't.

Mitochondrial DNA comes strictly from the mother, so if it's chimp mtDNA (which it wouldn't be, it would be the common ancestor between chimps and humans) then that wouldn't really prove anything about the pig thing.

[SolarCross]

It could but you still have all those nasty fertility problems, so when you back cross into a larger population who is more fertile you will be out competed and your genes will be selected against until they are removed from the gene pool.

The fertility problem is harshest at the initial cross, providing that initial cross produced at least a minimally fertile female then subsequent back crosses will mitigate the fertility until even male offspring are fertile enough for mating. Only 4 generations of backcrossing from the initial cross and a hybrids chromosome count matches a pure. Genes aren't only selected for fertility they are also selected for all manner of characteristics that enable the organism to survive and thrive. Maybe the initial cross happened in group of pre-humans that were fairly isolated from other pre-human bands allowing the alien genes to bed in until the band was a distinct proto-species in its own right. The consequent special characteristics may have allowed that band to move out of the typical forest environments of normal apes furthering the isolation from fertility competition with pure pre-humans apes.

I'll point out that molecular biology has already disproven the hypothesis, a pig is no more related to us than it should be given it's evoloutionary distance.

Could you link to that proof? I doubt that specific study has been done yet, you are just assuming.

To guess sure, but you don't found a hypothesis on that. You have to do an experiment based on your hunch to actually publish something like this. To prove something like this you would need molecular biology. Part of what annoys me about this hypothesis is that he didn't even do basic experimentation before he tried to popularize his idea with the public, which is a huge no no.

Well maybe that is how it goes in biology. I know in physics, theoreticians popularise all kinds of hypotheses long before anyone has a crack at empirically proving them.

We aren't descended directly from chimps, we share a common ancestor with chimps. Chimps had a tailbone fuse to their sacrum in their evolutionary history and we didn't.

Except that would place the tail bone fusion event on the line between homini and pan yet all other apes even the gibbon have fewer coccyx elements than homo sapiens. Surely occam's razor would suggest tailbone fusion occured at least as far back as Hominoidea and that somewhere on the line from hominini to homo some tail bones were gained.

And yet, "man is distinct among higher primates by possessing the largest average number of coccygeal vertebrae, i.e., by having been so far affected least by the evolutionary trend to reduce the tail" (Schultz33). "In the human coccyx there may be as many as six elements, in the anthropoids there are quite commonly only two. The anthropoids have gone further than man in the reduction of the tail" (Jones34). This longer "tail" is difficult to account for in terms of natural selection. With respect to reproduction, it is clearly a negative factor. Nor does it have any evident utility in other respects.

link

Mitochondrial DNA comes strictly from the mother, so if it's chimp mtDNA (which it wouldn't be, it would be the common ancestor between chimps and humans) then that wouldn't really prove anything about the pig thing.

Ugh the point was that the variability of human mtDNA was much lower than that of chimps whereas human nuclear DNA is massively more variable than chimp DNA. This is consistent with hybridisation but not with the gradual divergence theory.

[Brother of Karl]

You guys are making this argument way more complicated than it needs to be. I can easily disprove the idea that we have pig cousins as closely related as chimps. Thousands, if not millions of randy farm boys have been shagging pigs for thousands of years. Yet, none of that has led to any offspring, viable or not. It just isn't possible by natural means. Same goes for all great apes. We sex with an ape just doesn't lead to pregnancy.

/thread

[SolarCross]

You guys are making this argument way more complicated than it needs to be. I can easily disprove the idea that we have pig cousins as closely related as chimps. Thousands, if not millions of randy farm boys have been shagging pigs for thousands of years. Yet, none of that has led to any offspring, viable or not. It just isn't possible by natural means. Same goes for all great apes. We sex with an ape just doesn't lead to pregnancy.

/thread

Sorry no that doesn't work. The cross if it occurred would have been between a female chimp being mounted by a male pig. Male pigs have large enough penises and produce copious enough sperm (up to a litre in a single squirt) to reach the needed parts of a female chimp. The reverse is much less likely as male chimps (and humans) have penises that are too small, with ejaculate too measly, to penetrate a sow. Just because farmboys can't inseminate a sow does not mean a boar cannot inseminate a female chimp (or human).

Moreover you are merely assuming that no farmboys have ever fathered a pig hybrid but you do not actually know that has never happened. The paper presented by McCarthy includes as supplementary material historical accounts, including one from no less a personage than John Locke, of human-pig like monsters being born to farm animals.

----

In Thailand this apparent human-cow hybrid was still born to a cow in 2009.

[Rancid]

Loves me some inter-species erotica.

[Zerogouki 2]

up to a litre in a single squirt

I call bullshit.

[anasawad]

i read many many articales about this thing....
few question ....
genes determine the neurological patterns and activity in ones body .....
also there is a very good percentage of genes ..(not sure how much exactly) to determine how we look...muscle fiber..bone structure..skin color...immunity systems...
the chemicals our body produce ...and our blood cells of all types....

so if we were 99% genetically identical to apes....
why cant apes speak to us ? cant we take blood transfusion ? why cant we move like apes ? why are we effected by deseases harder and worse than apes ??
why dont we have the same bone structure as apes ? do we look and sense so different than apes ??

either all these things is stuffed within the 1% different genes and the 99% other genes we have no idea what it does ...meaning this is all BS ,,,,
or ...the very idea of 99% simillarity is in its basis BS ....

and now .....the talk about pigs ........lets suppose that a whole generation of apes fucked pigs or the other way around (as if) .....and each sexual process ended up with pregnancy.....
1-whats the chance that the right genetic structure to result from this mixture to form a stable life form we call humans ??
2-if it did happen ....then there will be more than one type of hybrid life form created ....meaning there will be atleast a few other species that resulted from it ...
where are they ?
3-if apes fucked pigs or the other way around.....how did the pregnancy lasted and how did their bodies support a new type of hybrids created???
4- lets say a hybrid did come out ....it wouldn't be in the shape of the current human ....basically would be far less evolved ....so....where are the fossil records ??

[noemon]

I just can't help myself but Mr Cameron certainly has something to say on the subject.