Tuesday, June 23, 2009
Friday, June 19, 2009
More on Bird Evolution
PZ Myers posted something about the fossil I blogged on yesterday:
What's especially interesting about it is that it catches an evolutionary hypothesis in the act, and is another genuine transitional fossil. The hypothesis is about how fingers were modified over time to produce the patterns we see in dinosaurs and birds.
Birds have greatly reduced digits, but when we examine them embryologically, we can see precisely what has happened: they've lost the outermost digits, the thumb (I) and pinky (V), and retain the forefinger, middle finger, and ring finger (II-IV), which have been reduced and fused together. This is called Bilateral Digit Reduction, BDR, because they've lost digits from the medial and lateral sides, leaving the middle set intact.
Dinosaurs, when examined anatomically, seem to have a different pattern: they have a thumb (I), forefinger (II) and middle finger (III), and have lost the lateral two digits, the ring and pinky finger (IV-V). This arrangement has been advanced as evidence that birds did not evolve from dinosaurs, since they have different bones in their hands, and getting from one pattern to the other is complicated and difficult and very unlikely.
The alternative hypothesis is that there is no conflict, and that dinosaurs actually underwent BDR and their digits are II-III-IV…but that what has also happened is a frame shift in digit identities. So dinosaurs actually have three digits, which are the index, middle, and ring finger, but they've undergone a subtle shift in morphology so that their forefinger develops as a thumb, and so forth.
Now we could resolve all this easily if only the physicists would get to work and build that time machine so we could go back to the Mesozoic and study dinosaur embryology, but they're too busy playing with strings and quanta and dark matter to do the important experiments, so we've got to settle for another plan: find intermediate forms in the fossil record. That's where Limusaurus steps in.
Limusaurus has a thumb, a tiny vestigial nubbin, and has lost its pinky completely. This is a (I)-II-III-IV pattern, and is evidence of bilateral digit reduction in a basal ceratosaur. In addition, the forefinger has become very robust, and while still distinctly a digit II, has been caught in the early stages of a transformation into a saurian first digit. It's evidence in support of the dinosaurian II-III-IV hypothesis and the frameshift in digit identity! It's almost as good as having a time machine.
What's especially interesting about it is that it catches an evolutionary hypothesis in the act, and is another genuine transitional fossil. The hypothesis is about how fingers were modified over time to produce the patterns we see in dinosaurs and birds.
Birds have greatly reduced digits, but when we examine them embryologically, we can see precisely what has happened: they've lost the outermost digits, the thumb (I) and pinky (V), and retain the forefinger, middle finger, and ring finger (II-IV), which have been reduced and fused together. This is called Bilateral Digit Reduction, BDR, because they've lost digits from the medial and lateral sides, leaving the middle set intact.
Dinosaurs, when examined anatomically, seem to have a different pattern: they have a thumb (I), forefinger (II) and middle finger (III), and have lost the lateral two digits, the ring and pinky finger (IV-V). This arrangement has been advanced as evidence that birds did not evolve from dinosaurs, since they have different bones in their hands, and getting from one pattern to the other is complicated and difficult and very unlikely.
The alternative hypothesis is that there is no conflict, and that dinosaurs actually underwent BDR and their digits are II-III-IV…but that what has also happened is a frame shift in digit identities. So dinosaurs actually have three digits, which are the index, middle, and ring finger, but they've undergone a subtle shift in morphology so that their forefinger develops as a thumb, and so forth.
Now we could resolve all this easily if only the physicists would get to work and build that time machine so we could go back to the Mesozoic and study dinosaur embryology, but they're too busy playing with strings and quanta and dark matter to do the important experiments, so we've got to settle for another plan: find intermediate forms in the fossil record. That's where Limusaurus steps in.
Limusaurus has a thumb, a tiny vestigial nubbin, and has lost its pinky completely. This is a (I)-II-III-IV pattern, and is evidence of bilateral digit reduction in a basal ceratosaur. In addition, the forefinger has become very robust, and while still distinctly a digit II, has been caught in the early stages of a transformation into a saurian first digit. It's evidence in support of the dinosaurian II-III-IV hypothesis and the frameshift in digit identity! It's almost as good as having a time machine.
Thursday, June 18, 2009
New Discovery Sheds Light on Bird Evolution
From LiveScience:
"[T]he most primitive theropods had five digits or fingers. Remains from theropods that are more recent, evolutionarily speaking, show these dinosaurs had three fingers. And until now, scientists have suspected those digits were the inner three (starting with the thumb with respect to our hands). But embryos of living birds suggest the wings are made up of the middle digits, with the inner- and outer-most digits missing. So there's a discrepancy.
"The digit arrangement of L. inextricabilis, which Clark says is an evolutionary intermediate between the most primitive five-fingered dinosaurs and the three-fingered ones, matches up with birds' wings. The specimen had the three most central fingers (considered the second, third and fourth digits on a five-digit hand, counting the thumb as the first digit) while an inner, first finger or thumb was reduced to what Clark called "a nub."
"With the new discovery, the transition from a five-fingered forelimb to three digits in birds' wings makes sense: Basically, the middle three digits persisted and became modified as part of the wings of modern birds."
"[T]he most primitive theropods had five digits or fingers. Remains from theropods that are more recent, evolutionarily speaking, show these dinosaurs had three fingers. And until now, scientists have suspected those digits were the inner three (starting with the thumb with respect to our hands). But embryos of living birds suggest the wings are made up of the middle digits, with the inner- and outer-most digits missing. So there's a discrepancy.
"The digit arrangement of L. inextricabilis, which Clark says is an evolutionary intermediate between the most primitive five-fingered dinosaurs and the three-fingered ones, matches up with birds' wings. The specimen had the three most central fingers (considered the second, third and fourth digits on a five-digit hand, counting the thumb as the first digit) while an inner, first finger or thumb was reduced to what Clark called "a nub."
"With the new discovery, the transition from a five-fingered forelimb to three digits in birds' wings makes sense: Basically, the middle three digits persisted and became modified as part of the wings of modern birds."
Tuesday, June 16, 2009
Quick Update
I am preparing two articles right now to be published in the next few weeks: One will be about Francis Crick's speculation that aliens seeded life on earth (Crick is the co-discoverer of the structure of DNA and a highly respected scientist) the other will be a critical review of Hugh Ross' book "More than a theory: Revealing a Testable Creation Model".
Secondly, I just wanted to publish a little propaganda of book:
When I was writing the book, I emailed philosopher Paul Draper my section on "irreducible complexity". He read it and said: "I liked almost all of the excerpt you sent me. You make several solid points very clearly."
One member of my freethought group emailed me and said: "I'm about half way through your book. I've been enjoying and learning."
Over at lulu, I only have one review of my book, but it is positive:
"Fairly easy read with plenty of sources to use in debating or just honing your own ideas. There are many subjects that could have been expounded upon but the author does point out the book is brief for necessity. I had a little problem downloading but it suddenly did appear and the problem is solved. I particularly liked the chapter about the witness of the holy spirit as in the author's point of view not really valid as proof. I also appreciated some of the scripture comparisons that saves a lot of time hunting them down and I probably wouldn't have bothered-----thanks to Nick on that one. Well worth the download and price. Thanks Nick / thanks lulu"
So far I have had no negative feedback on the book. Amongst the few who have read, they like it, and chances are you will too, as I spent a lot of time researching it to make it as rigorous (and readable) as I could. Click here to purchase.
Secondly, I just wanted to publish a little propaganda of book:
When I was writing the book, I emailed philosopher Paul Draper my section on "irreducible complexity". He read it and said: "I liked almost all of the excerpt you sent me. You make several solid points very clearly."
One member of my freethought group emailed me and said: "I'm about half way through your book. I've been enjoying and learning."
Over at lulu, I only have one review of my book, but it is positive:
"Fairly easy read with plenty of sources to use in debating or just honing your own ideas. There are many subjects that could have been expounded upon but the author does point out the book is brief for necessity. I had a little problem downloading but it suddenly did appear and the problem is solved. I particularly liked the chapter about the witness of the holy spirit as in the author's point of view not really valid as proof. I also appreciated some of the scripture comparisons that saves a lot of time hunting them down and I probably wouldn't have bothered-----thanks to Nick on that one. Well worth the download and price. Thanks Nick / thanks lulu"
So far I have had no negative feedback on the book. Amongst the few who have read, they like it, and chances are you will too, as I spent a lot of time researching it to make it as rigorous (and readable) as I could. Click here to purchase.
Friday, June 12, 2009
Jesus The Hypnotist
This youtube video shows Tommy aka "Kabane the Christian" arguing with Matt Dillahunty of "The Atheist Experience" over the resurrection of Jesus.
Something Tommy said at about 3:20-3:30 of the video caught my attention: He mentioned that the testimony of alien encounters is invalid because they are usually caused by hypnotic suggestion, while the testimony of the resurrection stands up to scrutiny because there is no evidence that Jesus was a hypnotist.
However, I think there is some evidence. I am referring to "The Social Settings of Jesus and The Gospels" in particular page 104. There, J. J. Pilch explains how the best explanation for visions and paranormal experiences in the gospels is through altered states of consciousness (ASC). Shamans have their life and livelihood in the summoning of ASCs. In the Israelite setting, holy men/prophets/messiahs were the shamans. Furthermore, as Daniel Dennett explains on page 137 of "Breaking the Spell", some researchers now believe that shamanic performances and rituals actually have enough power to hypnotize (which about 15% of the population is vulnerable to).
So, here's my argument:
1. Jesus played the cultural equivalent of a shaman.
2. Shamans probably have some ability to hypnotize or provide powerful suggestion.
3. Therefore, Jesus probably had some ability to hypnotize his followers or provide very powerful mental suggestions.
And yet all of this only gets us so far. How could Jesus have caused his disciples to experience him after he was dead? There are two possibilities: One is that he predicted his own death, as the gospels say, and perhaps did something to cause them to believe he would return (and thus they came to believe that he had returned). A second possibility is that one of the disciples, perhaps one acting as "assistant shaman", stepped up after Jesus' death and used his shamanic performances/rituals to induce belief that Jesus had risen.
And yet it is funny that this isn't even the only possibility to explain the resurrection appearances, as I argue another (much stronger, in my opinion) point of view in my recent article on the subject. Those with further interest in the subject should download my book, "Atheism and Naturalism" which actually includes a calculation of the odds of supernatural resurrection versus naturalistic explanation of the facts.
Something Tommy said at about 3:20-3:30 of the video caught my attention: He mentioned that the testimony of alien encounters is invalid because they are usually caused by hypnotic suggestion, while the testimony of the resurrection stands up to scrutiny because there is no evidence that Jesus was a hypnotist.
However, I think there is some evidence. I am referring to "The Social Settings of Jesus and The Gospels" in particular page 104. There, J. J. Pilch explains how the best explanation for visions and paranormal experiences in the gospels is through altered states of consciousness (ASC). Shamans have their life and livelihood in the summoning of ASCs. In the Israelite setting, holy men/prophets/messiahs were the shamans. Furthermore, as Daniel Dennett explains on page 137 of "Breaking the Spell", some researchers now believe that shamanic performances and rituals actually have enough power to hypnotize (which about 15% of the population is vulnerable to).
So, here's my argument:
1. Jesus played the cultural equivalent of a shaman.
2. Shamans probably have some ability to hypnotize or provide powerful suggestion.
3. Therefore, Jesus probably had some ability to hypnotize his followers or provide very powerful mental suggestions.
And yet all of this only gets us so far. How could Jesus have caused his disciples to experience him after he was dead? There are two possibilities: One is that he predicted his own death, as the gospels say, and perhaps did something to cause them to believe he would return (and thus they came to believe that he had returned). A second possibility is that one of the disciples, perhaps one acting as "assistant shaman", stepped up after Jesus' death and used his shamanic performances/rituals to induce belief that Jesus had risen.
And yet it is funny that this isn't even the only possibility to explain the resurrection appearances, as I argue another (much stronger, in my opinion) point of view in my recent article on the subject. Those with further interest in the subject should download my book, "Atheism and Naturalism" which actually includes a calculation of the odds of supernatural resurrection versus naturalistic explanation of the facts.
Thursday, June 11, 2009
Birds and Dinosaurs: Related?
Science Daily reported on a new study which alleges that birds are probably not descended from dinosaurs:
I'm not exactly sure how this follows, and of course I don't have the credentials to assess this debate, but I do wonder what the dino-bird theorists would have to say about this.
"It's been known for decades that the femur, or thigh bone in birds is largely fixed and makes birds into "knee runners," unlike virtually all other land animals, the OSU experts say. What was just discovered, however, is that it's this fixed position of bird bones and musculature that keeps their air-sac lung from collapsing when the bird inhales.
"Warm-blooded birds need about 20 times more oxygen than cold-blooded reptiles, and have evolved a unique lung structure that allows for a high rate of gas exchange and high activity level. Their unusual thigh complex is what helps support the lung and prevent its collapse.
...
I'm not exactly sure how this follows, and of course I don't have the credentials to assess this debate, but I do wonder what the dino-bird theorists would have to say about this.
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