Books Archive

Monday, November 22, 2010

Book Review - Thousands, Not Billions, Part I

A few months ago, I asked for a recommendation of the best book creationism had to offer. A friend of mine suggested Thousands... Not Billions: Challenging an Icon of Evolution, Questioning the Age of the Earth. So, I bought it and read it.

The book is a summary of a research project known as Radioisotopes and the Age of the Earth (RATE), associated with The Institute for Creation Research (ICR). The book was written by one of the Researchers, Dr. Don DeYoung.

The subtitle of the book, "Challenging an Icon of Evolution, Questioning the Age of the Earth", might lead you to think that there'd be a bit of discussion of evolution. There wasn't. The book looked only at the age of the Earth, and focused entirely on radiometric dating.

Now, I realize that books can only have a finite scope. This book's focus was radiometric dating. Fine. Just don't expect that pointing out a few anomolies in this one field is enough to overturn the diverse forms of evidence from other fields for an ancient Earth (particularly if your anomolies are down to bad methodology). Keep in mind that radioactivity wasn't discovered until 1896 by Henri Becquerel, and radiometric dating wasn't attempted until the early 1900s. When you consdier that Darwin published On the Origin of Species in 1859, it's obvious that radiometric dating didn't form one of the pillars of the theory. In fact, it was already known that the earth was ancient, though with less certainty of the exact age, from other sources. Uniformitarianism was first proposed in the 18th century by James Hutton, and later popularized by Charles Lyell's Principles of Geology in 1830. These geologists were looking to other forms evidence, such as the layers of sediment that had built up in different areas, and comparing those to known forms of deposition in the present. Just look at the White Cliffs of Dover for a formation that took countless years to form.

There was one passage that didn't come until near the end of the book, on page 169. However, I'm going to include it here at the beginning of the review, because it clearly shows the mindset of those involved.

Furthermore, the unchanging Scripture message has priority over all transient models of earth history. The RATE team concludes that Scripture is the standard to which interpretations of scientific data must conform. This does not imply the rejection of any data whatsoever. However, it does call for the positive channeling of data interpretation in a proper biblical perspective.

This is exactly the wrong way to do science. They've already decided on their conclusion, based on their interpretation of scripture, which, as they made clear elsewhere, is definitely a young earth. From that stance, there is no evidence at all that could convince them of an ancient universe, because they would just 'channel' that evidence to fit with their preconceived notions. They even hinted at this in the book, that where they run into a roadblock that isn't explainable by any other means, they can just invoke divine intervention. This is hardly any better than Last Thursdayism.

Throughout the book, the author indicated that accelerated nuclear decay was responsible for their findings. This hypothesis was mentioned many times throughout the book. Obviously, this raised some serious red flags. When I think of accelerated nuclear decay, I think of this:

Mushroom Cloud from Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Plumbbob_Fizeau.jpg

Now, depending on just how accelerated the decay might have been, it might not necessarily have set off an explosive chain reaction. But, it would still release huge amounts of energy. This, to me, is the biggest flaw in the whole hypothesis presented in the book, and is the reason why I've addressed it first, before getting to any of their other points. You simply can't propose that there was accelerated nuclear decay without accounting for the energy it would have created.

Given how huge of a problem this is for the hypothesis, I would have expected that they would have devoted considerable space to addressing it - a chapter, at the least. Instead, it received 3 paragraphs. Here, quoted in full, is their attempt at addressing the heat problem associated with accelerated nuclear decay, and in fact, since the first describes the problem, only the latter two attempt to address it.

HEAT DISSIPATION

The heat energy given off during nuclear decay raises an important question. What prevented the earth from melting completely during the rapid decay which amounted to millions of year's worth at present rates? Calculations show that this much decay of uranium and thorium atoms within a typical rock mass would raise the rock temperature as high as 22,000ºC. This temperature is nearly four times hotter than the surface of the sun and would likely vaporize entire rock masses in explosive events, but the crust of the earth did not melt during the Flood period. In fact, the presence of radiohalos and fission tracks in many rocks shows that rock temperatures remained below about 150ºC during the formation of the halos and tracks. Otherwise, these crystal defects would be thermally erased. Also, zircons in many rocks still contain helium atoms resulting from accelerated decay, yet the zircon crystals themselves were not melted during the nuclear decay process.

Somehow the enormous amount of heat resulting from isotope decay must have dissipated quickly. One tentative, rather novel proposal is called cosmological cooling (Humphreys, 2000). It is highly theoretical in nature and involves general relativity, higher dimensions, and a rapid expansion of space. Consider a kitchen refrigerator which is cooled by the expansion of a confined, compressed gas. In somewhat analagous fashion, an expansion of space would result in cooling on a universal scale. In this explanation, the heat energy generated by the nuclear decay goes into the expansion of the fabric of space itself. The key is to have accelerated decay simultaneously accompanied by a temporary, large-scale stretching of the space surrounding earth. Since there is evidence of much radioactive decay throughout the solar system and in space beyond, the expansion must be universal in its extent. There are definite hints in Scripture of an expansion of space during the Genesis flood (Humphreys, 2000). It is proposed that an enormous expansion of space, 20-fold times or greater, occured during the Flood event.

Big-bang enthusiasts also propose an inflationary stretching of space. However, their inflationary big bang occurs at the very beginning of time, within the first second, and only increases the universe from atom size to that of approximately a marble. In contrast, the cosmological cooling model places its expansion in the time frame of the Flood. Such an extreme alteration of the physical universe actually might drop the temperature too far and cause the reverse problem of over-heating, that is, a frozen earth. Further theoretical work is ongoing regarding the amount of heat produced by nuclear decay and the possible mechanisms for its removal. The RATE team views the extreme heat generation associated with accelerated decay as a serious issue, but not an insurmountable problem. (page 152)

Just to be thorough, here is the only other mention of the problem, from the Challenges for the Future section of the conclusion.

1. Accelerated nuclear decay involves millions or billions of years worth of decay occuring in just days or months of time. Even at present rates, considerable heat is produced by radioactive nuclear decay. An acceleration of this process will multiply the heat output greatly. This heat, which is produced within rocks, must be removed, or it could melt or even vaporize the earth's crust. This clearly did not happen to the earth. In fact, the existence of zircons with helium, radiohalos, and fission tracks shows that the host rocks and minerals have not experienced excessive heating. These physical records of nuclear decay would rapidly disappear if temperatures increased to hundreds of degrees. Possible mechanisms have been explored that could safeguard the earth from severe overheating during accelerated decay events. One of these involves cosmological or volume cooling, the result of a rapid expansion of space. Many details remain to be filled in for this and other proposed processes of heat removal. (page 179)

So, their response to the problem of all this energy is to propose that the very fabric of space time itself expanded! You don't just have a functioning universe, expand space 20 fold, and then expect the universe to keep on functioning just like it was before. And unlike the Big Bang, there's no physical evidence at all for this expansion (and I'm curious just what type of scriptural evidence there is). The only reason they're proposing it is as a post hoc rationalization to maintain their preconceived notions.

More Info:

To tell the truth, with such a gaping hole in their hypothesis, I don't think there's any real need to even address the rest of the book. This is a fatal flaw if there ever was one.

Still, I have fun debunking bad science, and I suspect the type of people who read my blog have fun reading those debunkings, so I'll take a look at their other points. But for that, you'll have to wait for Part II.

Update Part II is now online.


Updated 2010-11-29 Added a link to the entry where I requested creationist literature, and slightly reworded the opening paragraph.

Friday, November 19, 2010

Book Review - The God Delusion

While reviewing unfinished blog entries, I came across this one. I'd originally intended to write a very in depth review of this book, but never quite got around to doing it, and it's now been years since I read the book. Still, what I'd already written wasn't bad, so I figured it was worth cleaning up a bit and posting on the blog.

After putting it off for over a year and a half, I finally read The God Delusion by Richard Dawkins. There were a couple reasons I put it off so long. First, when the book first came out, I was just coming to grips with non-belief, and I was still too embarassed to take the book to the cashier. Second, even as I did become more comfortable with atheism, I thought that the book would just be a lot of preaching to the choir. However, thanks to the urging of a few people, I decided to go pick up the book, and I'm glad I did.

To be honest, for me, a good portion of the book was preaching to the choir, but not quite as much as I'd feared. I anticipated 420 pages of dissecting arguments for the existence of gods, pointing out inconsistencies in religious doctrines, and reasons why non-belief is the more rational choice. And while a good part of the book does address those points, that's only about half of it. The rest of the book deals with different but related issues, such as the roots of religion, the basis for morality, and reasons for speaking out against religion.

I have read several unfounded complaints of the book. Just consider the first editorial review on the book's Amazon page by Publisher's Weekly.

For a scientist who criticizes religion for its intolerance, Dawkins has written a surprisingly intolerant book, full of scorn for religion and those who believe...

While Dawkins can be witty, even confirmed atheists who agree with his advocacy of science and vigorous rationalism may have trouble stomaching some of the rhetoric: the biblical Yahweh is "psychotic," Aquinas's proofs of God's existence are "fatuous" and religion generally is "nonsense..."

He insists that religion is a divisive and oppressive force, but he is less convincing in arguing that the world would be better and more peaceful without it.

Admittedly, some sections use strong language, particularly introductions to chapters, but I never read anything as scornful, nor particularly intolerant. Yes, Dawkins described Yahweh as "psychotic," but that was in the context of the atrocities of the Old Testament (such as Jephthah and his daughter from Judges 11). And after re-reading the section on Aquinas, I think Dawkins was justified in calling it like he saw it - Aquinas's arguments weren't all that good.

The last part of this review is something I've seen used as the sole argument of some reviews. It has nothing to do with the proposition of whether or not a god exists, only the consequences of belief in a god. And personally, I think Dawkins did address that aspect fairly well, though I guess that's a matter of personal opinion.

I don't entirely agree with all of Dawkins' arguments, but I still recommend this book.


Added 2010-11-23 Thinking about The God Delusion again, I recall a certain passage that I found really funny (just about the only humorous passage from the book). As luck would have it, it was one of the parts available from Google Books. I'll included the lead in for context. So, here's the passge, from page 86:

More recently, the physicist Russell Stannard (one of Britain's three well-known religious scientists, as we shall see) has thrown his weight behind an inititiative, funded by - of course - the Templeton Foundation, to test experimentally the proposition that praying for sick patients improves their health.

Such experiments, if done properly, have to be double blind, and this standard was strictly observed. The patients were assigned, strictly at random, to an experimental group (received prayers) or a control group (received no prayers). Neither the patients, nor their doctors or caregivers, nor the experimenters were allowed to know which patients were being prayed for and which patients were controls. Those who did the experimental praying had to know the names of the individuals for whom they were praying - otherwise, in what sense would they be praying for them rather than for somebody else? But care was taken to tell them only the first name and initial letter of the surname. Apparently thta would be enough to enable God to pinpoint the right hospital bed.

The very idea of doing such experiments is open to a generous amount of ridicule, and the project duly received it. As far as I know, Bob Newhart didn't do a sketch about it, but I can distinctly hear his voice:

What's that you say, Lord? You can't cure me because I'm a member of the control group?... Oh I see, my aunt's prayers aren't enough. But Lord, Mr Evans in the next-door bed... What as that, Lord?... Mr Evans received a thousand prayers per day? But Lord, Mr Evans doesn't know a thousand people... Oh, they just referred to him as John E. But Lord, how did you know they didn't mean John Ellsworthy?... Oh, right, you used your omniscience to work out with John E they meant. But Lord...

Monday, November 15, 2010

Books, A Year in Review - 2010, Part II

Old Book Bindings, from Wikimedia Commons Here is the second part of my review of the books I read in the last year. Part I was an analysis of my reading habits, while this entry will give a brief review for each book.

I've always tried to point out my favorite books in these posts. Like last year, though, I had quite a few favorites this year. From kids fiction, it would be Treasure Island and The Higher Power of Lucky (with Night of the Twisters being borderline for making the favorites list). In adult fiction, it would be The Count of Monte Cristo and Flat Land. In non-fiction, it would be Guns, Germs, and Steel, Misquoting Jesus, The Tangled Bank, and Archaeopteryx: The Icon of Evolution. So, out of 20 books read, 8 are my favorites (with a 9th almost making it).

Continue reading "Books, A Year in Review - 2010, Part II" »

Monday, November 8, 2010

Books, A Year in Review - 2010, Part I

Old Book Bindings, from Wikimedia CommonsWell, it's that time of year again, when I look back over my reading habits for the past 12 months*. I've been doing this for several years, now (see previous reviews for 2007, 2008, and 2009). It all started with an article about an AP-Ipsos poll on people's reading habits. Among other things, it pointed out that around 1 in 4 adults in this country hadn't read any books at all in the previous year, and that among those that had, the average number of books read was 6. (Yes, this is the second time I've copied that sentence verbatim).

Like in the past two years, I'm breaking this up into two entries. In the first, I'll reflect on my reading habits (which means it probably won't interest many people), and in the second, I'll give a brief review of each book.

So, here are all the books I read in the last year, sorted by topic instead of by the order in which I read them.

Children's & Young Adult Fiction

  1. Treasure Island
  2. The Higher Power of Lucky
  3. When Zachary Beaver Came to Town
  4. Night of the Twisters
  5. Firegirl
  6. Lyra's Oxford
  7. The Tale of Despereaux: Being the Story of a Mouse, a Princess, Some Soup and a Spool of Thread
  8. The Demigod Files (A Percy Jackson and the Olympians Guide)

Adult Fiction

  1. The Count of Monte Cristo
  2. Flatland/Sphereland (Everyday Handbook)
  3. The Secret Diary of Adrian Mole, Aged 13 3/4
  4. Animal Farm: Centennial Edition
  5. The Android's Dream
  6. Pride and Prejudice and Zombies: The Classic Regency Romance - Now with Ultraviolent Zombie Mayhem!

Non-Fiction

  1. Guns, Germs, and Steel: The Fates of Human Societies
  2. Myths and Legends From Ancient Greece and Around the World
  3. Catholicism for Dummies, Pocket Edition**
  4. Misquoting Jesus: The Story Behind Who Changed the Bible and Why
  5. The Year of Living Biblically: One Man's Humble Quest to Follow the Bible as Literally as Possible
  6. The Tangled Bank: An Introduction to Evolution
  7. Archaeopteryx: The Icon of Evolution

So, that's 21 books altogether - pretty close to what I've read the past two years.

I guess I might as well get used to it - I like kids books. Three of those kids books I read because my daughter read them and recommended them to me, but the other five I read entirely of my own volition.

I did read a bit more adult fiction this year than in years past. I've got a few books I want to read next year that should continue that trend.

I have to admit to not reading the full version of The Count of Monte Cristo. It was a paper back we had laying around the house, and I never took a close look at the cover. I was halfway into the book before I actually studied the cover and read "Translated and Abridged by Lowell Bair". At that point, I was too caught up in the story to put it down and wait until I had the full version. So, I went online and read about the translations. Many of the 'abridged' versions of The Count of Monte Cristo were actually censored versions - they left out parts that were unbecoming to Victorian sensibilities. The book I read included those parts, at least, but I have no idea how it compares to the full unabridged story.

My non-fiction books weren't so heavily biased towards biology this year. I only read two books on evolution. The first, The Tangled Bank: An Introduction to Evolution), was one that I'd specifically mentioned last year as being on my wish list. The other, Archaeopteryx: The Icon of Evolution, fulfilled one of my stated goals from last year, of getting "away from general evolutionary books, and more into those on specific topics." I still want to read Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom) and Why Evolution Is True. Maybe I'll get to them next year.

I did get into religious books a bit more this year than other years, although the pocket edition of Catholicism for Dummies hardly counts as a book (I almost left it off this list). I'll try to read at least one or two books on religion each year, but I don't know if I'll keep on reading as many as I did this year.

I'm still working on knocking out this list. I knocked out a few more this year, which only leaves 89 left to go.

All in all, I think my reading was pretty balanced this year, but I could probably add a little more history and philosophy in there.

Stay tuned for Part II, where I'll post my reviews for each book.

Update 2010-11-15 Part II is now online.


* Okay, I'm a little late this year. I usually do this post in October. To keep the comparison fair, I only included the books I read up until around the middle of October, and left off the books I've read since then.

** I found the pocket edition of Catholicism for Dummies in the dollar rack at Target. I haven't been able to find it online, yet, but I'll link to it if I ever do.

Updated 2010-11-10 I completely forgot about one of the books I'd read last year, The Demigod Files (A Percy Jackson and the Olympians Guide), so I added it, and updated the counts.

Friday, September 10, 2010

Book Review - Archaeopteryx: The Icon of Evolution

On a recent trip to the Houston Museum of Natural Science, I bought a ticket to see the the exhibit, Archaeopteryx: Icon of Evolution (related link). The exhibit was a fascinating collection of fossils from the Solnhofen region of Germany, with an archaeopteryx known as the Thermopolis specimen as the centerpiece. The archaeopteryx fossil was very interesting, but there were two things about it, in particular, that I was struck by. First was the size. For some reason, in my mind's eye, archaeopteryx had always been a big bird, something along the lines of an eagle. The archaeopteryx fossil at the museum was about the size of a crow (more on this below). Second was the level of detail in the feather imprints, which photos just don't do justice to. It's not that the feathers were imprinted perfectly in their entirety, but in the regions where the preservation was best, it was very obvious that you were looking at an actual feather.

Thermopolis Specimen
The Thermopolis Archaeopteryx, With a Hand for Comparison to Show Size

So, after I left the exhibit, I went to the museum gift shop to find a souvenir. About the only thing they had that was appropriate for an adult was the book, Archaeopteryx: The Icon of Evolution, by Peter Wellnhofer*.

Before I get started with my own review, let me note that the publisher has a great section for the book. Perhaps best for someone considering buying the book is the section of sample pages. The pages shown are not anomalous - nearly every page had many illustrations, which was great. Also note the small text size and amount of text per page. Even though the book was only 208 pages, it was an information packed 208 pages.

The book was divided into several sections. The first was a short description of the locale where the fossils were found, the Solnhofen region of Bavaria, in Germany. It was the sort of description you'd expect from a chamber of commerce.

Next came a brief description of the geology of the Solnhofen region, and what this tells us about the ancient environment of the area. All of the archaeopteryx specimens found so far have come from Solnhofen Jurassic limestone deposits. It turns out that these deposits were from lagoons in shallow seas. The water was apparently fairly calm, and formed stratified regions with very low oxygen levels at the sea floor - no multicellular life could survive in those anoxic conditions. The mainland was not very close, but it's possible there were islands nearby. So, the limestone deposits were necessarily not the native habitats of any of the terrestrial animals found there. It's possible that the archaeopteryx were blown out to sea during storms, and didn't have the strength to fly back to land (the fact that all archaeopteryx found thus far are juveniles supports this idea).

Horseshoe Crab Death March
Death March of a Horseshoe Crab, Which Died after Wandering into an Anoxic Lagoon

After that came a discussion of the history of fossil discovery in the Solnhofen. Obviously, being a marine environment, most of the fossils from the region are from sea creatures, with the fossils of terrestrial animals being very rare. Because of the way the fossils were formed, the preservation is excellent, and Solnhofen fossils have been prized for centuries. They were regular inclusions in the curiosity cabinets of medieval Europe, which emerged in the 16th century (some of the best collections served as the start of modern museums).

Next came the heart of the book - 83 pages discussing the known archaeopteryx specimens in detail. If you think 83 pages of discussion sounds like a lot - it was, and it was a bit dry. I think of myself as a fairly knowledgeable layperson when it comes to evolution and biology, but much this section was a bit advanced for me. The fossils were described in technical terms (radius, ulna, meta carpal, flexor tubercle, pneumatic foramina), which would have made a firm grounding in anatomy useful in understanding this chapter.

This section started with a discussion of how the urvogels (a common name for archaeopteryx from German, meaning proto bird) likely became fossils - they floated in the sea for a few days before sinking to the sea floor, where they were covered with a microbial film before being covered by sediment. One fact I found interesting is that the feathers formed an imprint in the sediment before decomposing, and then this imprint was transferred to the adjacent layer of sediment after the feather decomposed. So, when a slab containing an archaeopteryx is split, both new slabs show only one side of the feathers.

After discussing fossilization, this section moved on to the controversy in the nomenclature and taxonomy of archaeopteryx. The rules of taxonomy state if a species is named twice, the first description has precedence, even if it was obscure and few people heard of it, or if the type specimen wasn't as complete as the later one. (This, for example, is why brontosaurus is now referred to as apatosaurus, since apatosaurus was the first name used, even if it wasn't as widely known). An early archaeopteryx specimen, not being recognized as a bird, was named Pterodactylus crassipes, so crassipes should be the species name. But before that specimen was recognized as a bird, a fossil feather was discovered and used as the original type specimen for Archaeopteryx lithographica. Once subsequent archaeopteryx were discovered, they were named after the feather, even though it's not certain if the feather is actually from the same animal. Another ealy genus name was Griphosaurus. In the end, most people referred to the animals as archaeopteryx, so a special petition was made to the International Commission on Zoological Nomenclature in 1977 to make the London specimen the type specimen, and to make Archaeopteryx lithographica the official genus and species names.

There is, however, some controversy as to whether the archaeopteryx specimens found so far are actually all from the same species. Most notable is the size difference between the specimens, but there are also differences among the details of the anatomy. The size and some of these differences could be explained by the urvogels being different ages at their times of death, along with individual variability, or even sex differences. But, it's possible that the fossils represent more than one species.

Comparison of the Size of Various Archaeopteryx Specimens
Size Comparison of Archaeopteryx Specimens

Next came the discussion of each fossil. For each fossil, Wellnhofer gave a brief overview of how the fossil was discovered and brought into public light, followed by a detailed physical description, which as I already mentioned, was rather technical when it came to anatomy. Besides the feather (which may or may not be from an archaeopteryx), there have been 10 archaeopteryx specimens discovered so far, of differing levels of completeness and preservation. Most are now housed in museums, and are known by the city in which they're permanently located. In order of discovery (though not necessarily public knowledge), the specimens are the feather, London, Berlin, Maxberg, Haarlem, Eichstatt, Solnhofen, Munich, Burgermeister-Muller, the 9th, and Thermopolis specimens.

The first, and one of the most complete, was what is now known as the London specimen. It was discovered in 1861, just two years after Darwin published On the Origin of Species, and made quite a stir being such an obvious transitional form. Also notable is the Maxberg Specimen, which has gone missing since its owner's death. Luckily, casts were made of the fossil before it was lost, but casts are not as useful as the real thing.

Once all the fossils had been described, the next section was a sort of synthesis, describing as much as we can know about archaeopteryx from the fossils we've found. Wellnhofer started with the subject with the most certainty, the skeleton, and moved on from there through less certainty and more conjecture - plumage, physiology, then lifestyle.

The remaining four chapters were all related - discussing early bird evolution, and the role of archaeopteryx in understanding that story. Archaeopteryx is, after all, the oldest bird yet known (though not the first bird, as is too often mistakenly said). Wellnhofer discussed some of the leading hypotheses on the ancestor of birds, including the thecodont hypothesis and the crocodile hypothesis, along with a few more 'imaginative' theories. But the leading hypothesis, which is pretty much certain, is that birds are a lineage of dinosaurs, closely related to the maniraptoran theropods. They're so similar, actually, that there's some discussion as to whether some animals traditionally classified as non-avian dinosaurs are in fact birds that have secondarily lost the ability to fly (in the same manner as ostriches, but back when birds still had teeth and clawed hands).

One of the things that struck me is just how much more dinosaur-like than bird-like archaeopteryx was (yeah, yeah, I know - birds are dinosaurs, but I think my meaning is clear enough). In fact, the Solnhofen Specimen was originally mistaken for a Compsognathus theropod by an amateur collector. I've included two pictures from the book below to dramatically illustrate this (I apologize for the quality of the scans, but like I said in another review, I wasn't about to ruin the binding on my book just to make it lay flat in the scanner).

Comparison of Bambiraptor, Archaeopteryx, and a Modern Chicken
Comparison of Bambiraptor, Archaeopteryx, and a Modern Chicken - not to scale

Comparison of Archaeopteryx to a Modern Eagle
Comparison of Archaeopteryx to a Modern Eagle - not to scale

Take a close look at those skeletons. If you had to pick which other animal archaeopteryx was most closely related to, it seems pretty obvious that it would be the bambiraptor. Archaeopteryx still had clawed hands, a hyperextensible 'killer' claw on its foot (though not shown in the above reconstruction), a long bondy tail, gastralia (the bones under the stomach), a more theropod pubis, and teeth in its mouth. Just as important is what archaeopteryx didn't have - a pygostyle, a keratinous beak, a large keeled sternum, fused hand bones, a fused tibiotarsus, or a fused tarsometatarsus. It also seems pretty likely that archaeopteryx lacked a bastard wing. And those are just some of the differences between archaeopteryx and modern birds.

I hadn't realized just how many ancient birds have been discovered that are younger than archaeopteryx. There are quite a few. In fact, the evolutionary story of birds following archaeopteryx is pretty well understood. The family tree below illustrates this. Note that archaeopteryx is most likely not actually the ancestor of today's birds. Like most animals, it was in a lineage that went extinct, which means it had a few traits it had evolved that set it apart from the surviving avian lineage. However, it's still a very valuable specimen for understanding what early birds were like.

Avian Family Tree
Avian Family Tree

This discussion also helped to put into perspective the K-T mass extinction. You often hear that birds were the only lineage of dinosaurs to survive that event, which makes it seem like there must have been something extra special about birds. But look at that phylogenetic tree. Most birds died at the end of the Cretaceous along with their non-flying relatives. There may have been some advantage that the surviving lineage of birds possessed, or they may have just gotten lucky (similarly, most mammals also died out at the end of the Cretaceous).

Despite there not being any known birds older than archaeopteryx, in recent years, paleontologists have discovered quite a few feathered dinosaurs. The book discussed a few of those dinosaurs, and compared the structure of their feathers to those of archaeopteryx and birds. The dinosaur feathers are more primitive. Some are just a downy covering, but some more advanced feathers do resemble the flight feathers of birds, only lacking the asymmetry. While the downy feathers were likely used for insulation, the function of those flight-like feathers is still uncertain.

Wellnhofer also covered the ground up versus trees down debate on the origin of flight. Up until I heard of this debate a few years ago, I'd always assumed that avian flight must have evolved from the trees down. It didn't seem plausible that it would have developed any other way. But many people have made compelling arguments for how it could have evolved from the ground up, where the wings would initially have been used for balance, and then maybe flapped for extra thrust to increase running speed, before fully developing flight. It's interesting that the flapping motion of a bird wing is very similar to the motion possible in a maniraptoran arm (most likely used to capture prey).

Perhaps the best evidence for the ground up hypothesis is that archaeopteryx very strongly appears to be a fully terrestrial animal, with no special adaptations for an arboreal lifestyle. Since archaeopteryx wasn't the first bird, it's possible that archaeopteryx secondarily evolved a terrestrial lifestyle, but given its similarities to the theropods, this seems unlikely. One proposed evolutionary stage in the ground up scenario, wing-assisted incline running, is supported by observation of living birds. The idea has also been proposed that flight may have evolved from jumping and parachuting from cliffs or other elevated points, followed later by gliding, as a sort of reconciliation between the trees down and ground up hypotheses, but eliminating the trees.

The ground up hypothesis certainly seems to be the more likely at this point, but as Wellnhofer pointed out, all ideas on this are speculative for the time being, since we haven't found the fossils of earlier birds.

Archaeopteryx: The Icon of Evolution was a very interesting book. It's very informative and detailed, and I learned quite a bit from it. I wouldn't recommend it for everybody, though. The target audience is quite a bit higher than the general layperson. Although some sections would probably be interesting to many people, if you only have a passing interest in archaeopteryx, maybe Wikipedia is a better choice. But if you happen to have a really strong interest in avian evolution, and don't mind reading technical jargon, then this is the book for you.


Update 2011-08-02 - A new fossil, xiaotingia zhengi, has been found that sheds further light on the evolution of archaeopteryx like animals. A cladistics analysis using this fossil suggests that archaeopteryx might not be quite as closely related to birds as previously thought. You can read more about it in a new entry, Is Archaeopteryx Still a Bird?

Update 2010-09-28 - I reworded several sections to make them more clear, particularly the section on the origin of flight. I also added a bit of information to the section on the origin of feathers.

* Although I commonly buy books as souvenirs from museums, this one was a little more expensive that I was willing to pay, so I walked out of the museum without it. However, my wife and daughter, seeing how interested I was in it, bought it without me noticing, and gave it to me later as a Father's Day present. Actually, it was my daughter's girl scout troop leader who bought the book, who then gave it to my wife when I wasn't looking. The full story is that we were at the museum as part of a girl scout trip. My wife was an official full time chaperon for the trip, and although I helped with chaperoning duties for most of the time, since I wasn't officially one, I was free to go off and do my own thing if I wanted to. Since the tickets to the archaeopteryx exhibit cost extra, it was out of the budget for the girls, so I went through the exhibit by myself. I would have liked to have taken the girls, but to be honest, I think they were all fossiled out after the museum's main exhibits. At the least, they definitely wouldn't have taken as much time as I had.

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