dubois@uwmacc.UUCP (Paul DuBois) (04/19/85)
> [Stanley Friesen] > In article <733@uwmacc.UUCP> dubois@uwmacc.UUCP (Paul DuBois) writes: >>> Chapter 13 to this subject. Ray claims that all these species were >>> contemporaries of each other. The facts: Eohippus is found in the Eocene, >>> Mesohippus in the Ogliocene, Parahippus in the Miocene, Pliohippus in the >>> Pliocene, and Equus (modern horse) does not arise until the late Pliocene. >>Hitching [1982] comments: >>(ii) The first horse (Eohippus) didn't look much like one - in fact it >>looks a lot more like an animal that lives *today* - the Hyrax (or >>daman). Also, Eohippus fossils have been found alongside two modern >>horses (Equus nevadensis and Equus occidentalis) in surface strata. > Exactly as expected under evolutionary theory! the first of > a series of intermediates will *natuallly* resemble the source group > more than the end group! All this says is that the Hyrax is a modern > member of the horse ancestral group. It is also perfectly acceptible > for an ancestral form to continue along side of its decendants. The > only evidence which would contradict the basic series is for a modern > horse(Equus) to be found in Eocene sediments. Also has the possibility > of "reworked" fossils been ruled out in the "modern" Eohippus specimens. If reworking is to be claimed, the burden of proof is on the one making the claim to demonstrate it. Failing that, one may show that the original investigators haave not considered this as a possibility. Although both of these are possible accounts, you have shown neither. >>(iii) Trends are not so pretty as often depicted. The first three horse >>fossils (Eohippus, Orohippus, Epihippus) decline (not increase) in size. >>The sequence from many toes to one toe is similarly irregular - replete >>with regressions and contradictions. > Again, *exactly* as expected!! Evolution is based on direct > natural selection, thus at any given time it procedes in the direction > appropriate to the immediate environment, there is *no* mechanism for > anticipation or long term co-ordination. Trends are nothing more > than time averages of succesive short term changes, and mainly > indicate consistant environmental change over time. Sure - exactly as expected. Pure grandstanding, as Bill says. If they get more complex, we expect it. If they regress, we expect it. If they stay exactly the same, we expected that, too. So no matter what happens, we expect it. So, as always, evolution reduces to description, not explanation or mechanism. This is not very compelling as an "expectation". And if the response is to environmental modification (and it might very well be, I grant you) then we ought to be able to (or trying to be able to) formulate some principles about environmental change that allow REAL predictions about what should happen. Maybe such principles have been formulated, but I don't know of any. (If you do, I'd be interested - and probably others would, too. Post them if you know of some.) If we know enough about the environment to say "Evolution is based on direct natural selection, thus at any given time it procedes [sic] in the direction appropriate to the immediate environment", we know enough to say why, and whether, hyrax split and one group stayed the same, while another didn't. But we don't, so we can't. We can guess if we want to - but that's all. Sermon: This stuff is a positive hindrence to science. We say "natural selection" and our brains stop thinking. But until we understand the physiological and biochemical basis of organismal response to environmental stimuli, we're going to STAY STUCK, invoking the magical incantation "natural selection" whenever a problem comes up, and we're going to continue to remain ignorant. Phooey. We say "Natural selection - Ah! Now I understand." But do we? Of course we don't. What do you understand? It's a buzzword that tells us exactly nothing except that what happened, happened. Now, surely we could have deduced that without natural selection. I'm not denying the concept _per se_. Of course selection occurs. But the real question is why one thing should be selected and not another. I don't get it. You guys all KNOW this. I'n not telling you one single thing that you don't already know. Yet this pretense of the idea that natural selection means something or tells us something, is maintained. Why? Why do you do it? End of sermon. >>Davidheiser notes [pp. 325-326]: "The brains of living horses are >>highly convoluted. Therefore, evolutionists who believe that only >>modern horses (including zebras, etc.) evolved from these 'early horses' >>must logically admit that any similarity between the convolutions of the >>brains of horses and of other animals is coincidental or a case of >>'parallelism'. For example, Sisson and Grossman in their book _The >>Anatomy of Domestic Animals_, diagram and describe the brains of the >>horse and cow. Of fourteen fissures named, all but two have the same >>name in both horse and cow and correspond in location. The other two >>also correspond in location but are given different names." > You forgot an alternative, the convolutions could be inherited > from a common ancestor, perhaps the basic pattern of brain convolutions > was established *before* the split between horse and cow. I didn't forget. But just how likely does it seem to you that two independent lines of development from a smooth-brained ancestor with no convolutions, to two different animals with convolutions, will result in EXACTLY the same number of fissures, and that all 14 will be in corresponding locations? I confess skepticism (that healthy quality so highly touted). One gets an udder, the other doesn't. One gets a single hoof, the other, split. One gets horns, the other, not. One becomes a ruminant, the other, not. But the brain, the most complex structure of all, develops (independently in two lines) so remarkably similarly. I can hear it now: "there is nothing in evolutionary theory to contradict this." Of course not. Because there is nothing in evolutionary theory to predict this. More succinctly: there is nothing in evolutionary theory? -- | Paul DuBois {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois --+-- | "Danger signs, a creeping independence" |
js2j@mhuxt.UUCP (sonntag) (04/23/85)
Paul Dubois, talking about the differences between horsies and cows: > > One gets an udder, the other doesn't. One gets a single hoof, the > other, split. One gets horns, the other, not. One becomes a ruminant, > the other, not. But the brain, the most complex structure of all, > develops (independently in two lines) so remarkably similarly. Horses don't have udders? You should get away from your terminal more often, Paul. Get out and see some real animals. And just in case you're wondering why you never see udders in the westerns, it's because they're pretty small (compared to a cow's) unless they've given birth fairly recently, in which case they are unlikely to be starring in cowboy movies. -- Jeff Sonntag ihnp4!mhuxt!js2j "But if we took out the bones, it wouldn't be crunchy, now, would it?"
mrh@cybvax0.UUCP (Mike Huybensz) (04/23/85)
In article <948@uwmacc.UUCP> dubois@uwmacc.UUCP (Paul DuBois) writes: > Sermon: > > This stuff is a positive hindrence to science. We say "natural > selection" and our brains stop thinking. But until we understand the > physiological and biochemical basis of organismal response to > environmental stimuli, we're going to STAY STUCK, invoking the magical > incantation "natural selection" whenever a problem comes up, and we're > going to continue to remain ignorant. Phooey. > > We say "Natural selection - Ah! Now I understand." But do we? Of > course we don't. What do you understand? It's a buzzword that tells > us exactly nothing except that what happened, happened. Now, surely we > could have deduced that without natural selection. I'm not denying the > concept _per se_. Of course selection occurs. But the real question > is why one thing should be selected and not another. > > I don't get it. You guys all KNOW this. I'n not telling you one > single thing that you don't already know. Yet this pretense of the > idea that natural selection means something or tells us something, is > maintained. Why? Why do you do it? Natural selection IS being intensively studied. Studies of predation, parasitism, preferred foods and their nutritional values, quantitizing factors of reproductive success, and a host of other things illustrate the factors that compose and give direction to natural selection. > I didn't forget. But just how likely does it seem to you that two > independent lines of development from a smooth-brained ancestor with no > convolutions, to two different animals with convolutions, will result > in EXACTLY the same number of fissures, and that all 14 will be in > corresponding locations? I confess skepticism (that healthy quality so > highly touted). The neocortex of all mammals is convoluted. Which smooth-brained ancestor are you talking about? And what makes you think it was smooth brained? -- Mike Huybensz ...decvax!genrad!mit-eddie!cybvax0!mrh
dubois@uwmacc.UUCP (Paul DuBois) (04/25/85)
>> [Paul DuBois] >> I didn't forget. But just how likely does it seem to you that two >> independent lines of development from a smooth-brained ancestor with no >> convolutions, to two different animals with convolutions, will result >> in EXACTLY the same number of fissures, and that all 14 will be in >> corresponding locations? I confess skepticism (that healthy quality so >> highly touted). > [Mike Huybensz] > The neocortex of all mammals is convoluted. Which smooth-brained ancestor > are you talking about? And what makes you think it was smooth brained? A reasonable question. The information comes from a study of endocranial casts obtained from fossil skulls. Early horses were smooth-brained. More information may be obtained from: Tilly Edinger, "Evolution of the Horse Brain". Geol Soc Amer Memoir, 25, 16 Feb 1948. -- | Paul DuBois {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois --+-- | "Danger signs, a creeping independence" |
dubois@uwmacc.UUCP (Paul DuBois) (04/25/85)
> Paul Dubois, talking about the differences between horsies and cows: > > > > One gets an udder, the other doesn't. One gets a single hoof, the > > other, split. One gets horns, the other, not. One becomes a ruminant, > > the other, not. But the brain, the most complex structure of all, > > develops (independently in two lines) so remarkably similarly. > [Jeff Sonntag] > Horses don't have udders? You should get away from your terminal > more often, Paul. Get out and see some real animals. And just in case > you're wondering why you never see udders in the westerns, it's because > they're pretty small (compared to a cow's) unless they've given birth > fairly recently, in which case they are unlikely to be starring in > cowboy movies. Hair-splitting. Would you call horse mammary glands "udders" normally? I wouldn't. Maybe you would, but you say "And just in case you're wondering why you never see udders in the westerns, it's because they're pretty small (compared to a cow's)..." but ^^^^^^^^^^^^^^^^^^^ was exactly the point... -- | Paul DuBois {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois --+-- | "Danger signs, a creeping independence" |
draves@harvard.ARPA (Richard Draves) (04/25/85)
> [Paul DuBois] > A reasonable question. The information comes from a study of > endocranial casts obtained from fossil skulls. Early horses were > smooth-brained. More information may be obtained from: > > Tilly Edinger, "Evolution of the Horse Brain". > Geol Soc Amer Memoir, 25, 16 Feb 1948. I don't know much biochemistry, so take this hypothesis with a grain of salt. Much of the genetic code is never expressed. Some mutation in an early horse resulted in the genetic material that produces convoluted brains being "hidden". Later, another mutation resulted in the reappearance of this trait. Rich -- "a picture in the head is a gory murder in an art gallery" -- Stephen Kosslyn
friesen@psivax.UUCP (Stanley Friesen) (04/26/85)
In article <948@uwmacc.UUCP> dubois@uwmacc.UUCP (Paul DuBois) writes: > > >> Exactly as expected under evolutionary theory! the first of >> a series of intermediates will *natuallly* resemble the source group >> more than the end group! All this says is that the Hyrax is a modern >> member of the horse ancestral group. It is also perfectly acceptible >> for an ancestral form to continue along side of its decendants. The >> only evidence which would contradict the basic series is for a modern >> horse(Equus) to be found in Eocene sediments. Also has the possibility >> of "reworked" fossils been ruled out in the "modern" Eohippus specimens. > >If reworking is to be claimed, the burden of proof is on the one >making the claim to demonstrate it. Failing that, one may show that the >original investigators haave not considered this as a possibility. >Although both of these are possible accounts, you have shown neither. > You missed my main point, which is that co-occurance of ancestor/descendant pairs are entirely compatible with current evolutionary theory. The reworking comment was more along the lines of a postscript or addendum. > >> You forgot an alternative, the convolutions could be inherited >> from a common ancestor, perhaps the basic pattern of brain convolutions >> was established *before* the split between horse and cow. > >I didn't forget. But just how likely does it seem to you that two >independent lines of development from a smooth-brained ancestor with no >convolutions, to two different animals with convolutions, will result >in EXACTLY the same number of fissures, and that all 14 will be in >corresponding locations? I confess skepticism (that healthy quality so >highly touted). > This is not what I said, I said "inherited from a common ancestor", which means that the said common ancestor *also* had *exactly* the same convolations. Your response is more appropriate to a "parallel evolution" scenario. -- Sarima (Stanley Friesen) {trwrb|allegra|cbosgd|hplabs|ihnp4|aero!uscvax!akgua}!sdcrdcf!psivax!friesen or {ttdica|quad1|bellcore|scgvaxd}!psivax!friesen
dag@tellab2.UUCP (Donald Graft) (04/26/85)
I believe there are mammals with non-convoluted neocortex. Check out the rat.
js2j@mhuxt.UUCP (sonntag) (04/29/85)
> > Paul Dubois, talking about the differences between horsies and cows: > > > > > > One gets an udder, the other doesn't. One gets a single hoof, the > because they're pretty small (compared to a cow's)..." > but ^^^^^^^^^^^^^^^^^^^ was exactly the point... > -- > Paul DuBois {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois --+-- If your point was that a horse's udders are small compared to a cow's, why did you say: 'One gets an udder, the other doesn't.'? The difference in size is really pretty small (unless you're talking about milch cows, which have been bred for large udders for centuries.). Would you say: 'One gets a neck, the other doesn't.' just because a horse's neck is longer? -- Jeff Sonntag ihnp4!mhuxt!js2j "This here's a story 'bout Minnie the Moocher. She was a low-down hoo-oochy koocher. She was the roughest, meanest frail. But Minnie had a heart as big as a whale." - idunno (mail me if you do!)
mrh@cybvax0.UUCP (Mike Huybensz) (04/29/85)
> >> [Paul DuBois] > >> I didn't forget. But just how likely does it seem to you that two > >> independent lines of development from a smooth-brained ancestor with no > >> convolutions, to two different animals with convolutions, will result > >> in EXACTLY the same number of fissures, and that all 14 will be in > >> corresponding locations? I confess skepticism (that healthy quality so > >> highly touted). > > > [Mike Huybensz] > > The neocortex of all mammals is convoluted. Which smooth-brained ancestor > > are you talking about? And what makes you think it was smooth brained? > > [Paul DuBois] > A reasonable question. The information comes from a study of > endocranial casts obtained from fossil skulls. Early horses were > smooth-brained. More information may be obtained from: > > Tilly Edinger, "Evolution of the Horse Brain". > Geol Soc Amer Memoir, 25, 16 Feb 1948. I don't think endocranial casts will show convolutions and fissures of the brain. Look at the inside of a human skull: it is smooth on top. I may get around to checking this one out.... -- Mike Huybensz ...decvax!genrad!mit-eddie!cybvax0!mrh
dubois@uwmacc.UUCP (Paul DuBois) (05/01/85)
>>> Paul Dubois, talking about the differences between horsies and cows: >>>> >>>> One gets an udder, the other doesn't. One gets a single hoof, the > >> because they're pretty small (compared to a cow's)..." >> but ^^^^^^^^^^^^^^^^^^^ was exactly the point... >> Paul DuBois {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois --+-- > If your point was that a horse's udders are small compared to a cow's, > why did you say: 'One gets an udder, the other doesn't.'? The difference > in size is really pretty small (unless you're talking about milch cows, > which have been bred for large udders for centuries.). Would you say: > 'One gets a neck, the other doesn't.' just because a horse's neck is longer? I willingly concede the point! -- | Paul DuBois {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois --+-- | "The presence of weeds in the garden is not explained by | saying that the gardener has not pulled them yet."
ward@hao.UUCP (Mike Ward) (05/03/85)
> "The presence of weeds in the garden is not explained by | > saying that the gardener has not pulled them yet." It is in MY garden (oh, my aching back (speaking of transitional forms))! :-) (-: :-()-:
dubois@uwmacc.UUCP (Paul DuBois) (05/03/85)
>>>> [Paul DuBois] >>>> I didn't forget. But just how likely does it seem to you that two >>>> independent lines of development from a smooth-brained ancestor with no >>>> convolutions, to two different animals with convolutions, will result >>>> in EXACTLY the same number of fissures, and that all 14 will be in >>>> corresponding locations? I confess skepticism (that healthy quality so >>>> highly touted). >>> [Mike Huybensz] >>> The neocortex of all mammals is convoluted. Which smooth-brained ancestor >>> are you talking about? And what makes you think it was smooth brained? >> [Paul DuBois] >> A reasonable question. The information comes from a study of >> endocranial casts obtained from fossil skulls. Early horses were >> smooth-brained. More information may be obtained from: >> Tilly Edinger, "Evolution of the Horse Brain". >> Geol Soc Amer Memoir, 25, 16 Feb 1948. > [Mike Huybensz] > I don't think endocranial casts will show convolutions and fissures of the > brain. Look at the inside of a human skull: it is smooth on top. > I may get around to checking this one out.... You must be awfully confident about it to make such a statement before seeing what you can find out. Here's some information in which you might be interested. G G Simpson, _Horses_, Natural History Library, Garden City NJ, 1961, pp235ff. "The brain itself, soft tissue that decays very rapidly, is not preserved in any fossil horse and study is really based on the cavity formerly occupied by the brain. This reflects most of the important features of the brain, although minor details may be obscure or lacking. Sometimes the cavity became filled with mud after the brain had decayed and as the skull was buried. Hardened into rock, this filling may provide an excellent natural cast of the brain cavity. In other cases the cavity can be cleaned out in the laboratory and a rubber or gelatin cast made which can be reproduced in plaster for study and permanent preservation. "The most remarkable feature of the story of the horse brain, thus established, is at the beginning. In spite of its antiquitiy and many distinctive peculiarities, eohippus is often thoght of as simply a little horse. Most people would have guessed that it had a horse brain, smaller and simpler than in _Equus_ probably, but still distinctive of the brainy horse family. This is not the case. Eohippus turns out to have one of the most primitive brains known in any mammal. There is nothing horse-like about its brain, which more closely resembles the brain of a reptile or of the most primitive mmmals, such as the oppossum, notorious for stupidity. "A primitive mammal brain, seen from the side, seems to consist mainly of three rather lumpy and irregular parts stretched out in a line one behind the other. In front is the smallest and simplest part, the paired olfactory bulbs, concerned with nerves coming from the nose and with the sense of smell. Next come the likewise paired cerebral hemispheres, which are very complex in structure and function even in the most primitive animals, but in which the lower parts are mainly concerned with sensory and more or less instinctive functions while the outer layers (cortex) of the upper parts are more involved in association and functions related to intelligence. The most posterior main segment of the brain is the cerebellum, which has a median, central part (vermis), and a complex of paired swellings on each side (mainly the cerebellar hemispheres of paramedian lobes). This segment too is extremely complex in structure and function, but it is little concerned, directly, with conscious or intelligent behavior and has to do mainly with motor and motor-sensory coordination of the various parts of the body. "The most important feature of brain evolution among mammals is the development of the part especially concerned in intelligence, the outer layers of the upper part of the cerebrum, called the neo-cortex. Expansion of the neocortex is clearly required for the evolution of intelligent behavior and is correlated with higher types of mental functioning. It reaches an extreme in man, and is also, but less, well developed in the more intelligent subhumans, especially apes and also dogs, horse, and other fairly intelligent mammals. This expansion takes place in two ways, by absolute or relative increase in the size of the cerebrum, and by wrinkling of its upper surface. Development of numerous fissures on this region increases the surface area, which is the essential point, even without any increase in the volume of the cerebrum. "In eohippus, neocortex expansion either in size or by fissuring had hardly begun, and this is the most striking and primitive feature of the brain of that animal. The cerebrum was already the largest part of the brain, as it is in reptiles and many lower animals, but it was much smaller, relative, especially, to the olfactory bulbs, than in later horses or other mentally progressive mammals. The upper part, the neocortex, was small, only slightly swollen, no higher and barely wider than the cerebellum. It was almost smooth. Only three small fissures or sulci cn be seen. In eohippus the cerebellum also was much simpler and less fissured than in later horses, or most other mammals. Another very primtive feature that there is a gap between cerebellum and cerebrum and an intermediate part of the brain (midbrain) could still be seen here when the brain was viewed from above. "Eohippus must have been an extraordinarily stupid animal. Edinger remarks: 'The brain connects eohippus only with the past. The ancestral brain, an unspecialized mammalian brain, was held over in the equid body. No feature of this brain signals the future.'" --- I trust you no longer think I am making wild statements. The comment about the distinction between the brain of eohippus from its descendants is noteworthy, particularly as the similarity between eohippus and (currently extant) hyrax has been pointed out by other authors. Perhaps eohippus was not a horse at all. I think that it would be of interest to know if the hyrax has a convoluted brain. This would give us a better basis to evaluate the relationship. If the hyrax does have a convoluted brain, then we would have some reason to dissociate it from eohippus. Note that I am presenting a testable hypothesis here. Very scientific and all. -- | Paul DuBois {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois --+-- | "The presence of weeds in the garden is not explained by | saying that the gardener has not pulled them yet."