Jeff's Lunchbreak

This entry is part of a series. For a bit of an introduction and an index of all entries in the series, go here.

This installment covers Chapter 19, Evolution in a Muddle.

Biogeography is one of the greatest bits of evidence for evolution. It really is strange to see McCann try to twist it to cast doubt on evolution.

This we know: the American opossum is a form of marsupial life now found only in America. It exists in lonely isolation in the midst of a vast continent abounding in non-marsupial forms of mammalian life. All other marsupials live together in one mass in all but complete isolation from non-marsupial beasts, yet the American opossum singularly upsets all the inferences that the evolutionist who demands progress would draw, if he could, from these baffling facts of natural history. (McCann 235)

Immediately following, we see a strange jump (well, not so strange when you understand that pride is one of the reasons many creationists don't want to accept evolution) from marsupial evolution to human evolution.

Whence came the opossum? How did it get to North America? Why didn't it bring along the kangaroos and other marsupials of Australia? Why didn't the Australian marsupials include the American opossum in the general family? Who knows? Who will ever know? These questions are precisely like those which one must ever ask when examining the strange theories of man's ape-origin. (McCann 235 - 236)

After going on for a few pages about this problem with opossums, McCann answers his own question, although he doesn't seem to know it.

Why were Darwin, Huxley, Spencer, Haeckel and the rest so significantly silent with respect to the opossum? Why have the foremost evolutionists of this generation maintained similar silence? They have never lacked the knowledge that the marsupials, or pouched mammals, flourished during what is described as the Secondary epoch, and that the opossum, even though its first relics were found in the so-called Tertiary rocks under Paris, is really a true marsupial, and therefore originated with all the other marsupials in the Secondary epoch. (McCann 236)

The distribution of marsupials is a strong bit of evidence for evolution. First, recall that the history of life on this planet involves both time and place. Marsupials and placental mammals both evolved around the same time, but not in the same regions. Marsupials had a chance to colonize Australia before Australia split off from Asia and Antarctica, but placental mammals didn't. Therefore, for a very long time, the only mammals in Australia were marsupials and monotremes, monotremes being an even more ancient branch on the mammal family tree. Marsupials weren't limited to just Australia, however - they were living in other nearby parts of the world before Australia became isolated, and so had a chance to spread to the rest of the world.

For some reason, placental mammals fared better than marsupials wherever they came into contact, and most marsupials became extinct as placental mammals spread. But there's no rule saying that all marsupials had to go extinct - it was just the trend. So, it's not surprising to find some marsupials still surviving among placental mammals, such as opposums. But, because the placental mammals didn't have the chance to colonize Australia before it became isolated, Australia's marsupials flourished. The first placental mammals that did get a chance to colonize Australia were bats - blown in on the wind. Rats, surviving on driftwood, were the next placental colonists. But outside of bats and rats, no other placental mammals lived in Australia until the arrival of humans and their livestock.

The present distribution of marsupial and placental mammals makes perfect sense considering the evolutionary and geologic history.

Man, talk about arrogance.

Why does man alone make progress and why does such progress as he does make have nothing to do with his body? All beasts have bodies, yet if there is one beast-characteristic concerning which we are certain, it is that no beast makes progress of any kind whatsoever. (McCann 237)

I've already mentioned this in previous installments, but I wonder what McCann would have thought of current studies of chimps - their tool use and cultures.

This is either a case of gross ignorance, or deliberate misrepresentation, since I know archaeopteryx was known in McCann's time. After a whole discussion of bird evolution, and wondering what an intermediate form might have looked like, how could McCann have not even mentioned archaeopteryx, at least in an attempt to refute it?

What kind of a reptile could have been the ancestor of the turkey? Not a rattlesnake, of course, or any such reptile form. We must find something special, so we attempt to smooth out the difficulty by insisting that the line of descent from reptiles to birds has not been from ordinary reptiles, through pterodactyl-like forms, to ordinary birds, but to the birds without keels on the breast-bone from certain extinct reptiles such as the Dinosauria.

One of the best known of these Dinosauria is the Iguanodon of the Wealden formation. The skeletal characters of these Dinosauria are wholly unlike those of ordinary birds, but in certain points they manifest resemblances to the osseous structure of such birds as the ostrich, rhea, emeu, cassowary, apteryx, dinornis, etc. These resemblances are quite as marked toward each other as are the resemblances, heretofore referred to, between the skeleton of the horse and the skeleton of man. (McCann 238)

Actually, his last sentence was very telling. Horses and humans have very similar skeletons because we're both mammals. We're not the most closely related mammals, but our skeletons are still more similar to each other than, say, to a frog. The fact that a turkey and an iguanodon have very similar skeletons is a strong indication that birds are just another type of dinosaur. If you look at other types of dinosaurs, particularly the theropods, and narrowing it down further to the maniraptoran theropods, you see quite a few similarities. In fact, there are so many similarities, that it gets a bit murky trying to determine the whole genealogy. One archaeopteryx specimen was even originally mistaken for a Compsognathus theropod by the amateur collector who found it.

Book Review - Archaeopteryx: The Icon of Evolution

Now McCann has made it personal! (or, as personal as an attack can be by a dead man, directed at a person who wasn't even born when the attacker died, and at a field that was still in its infancy).

Nothing could be so inefficient as the aerial navigation of 1921. There is more power in a 1921 airplane than was in the sails of a whole flotilla of frigates a hundred years ago. The stupendous power of the aerial motor has given us sensational results quickly, so that the problems of flight have been actually disregarded. Man's flight depends upon freak devices in which an aviator has at his command a howling volcano. The bird's wing fans the air with a slow motion, three strokes to the second. This slow motion produces high speed in flight, whereas the airplane's propeller has the speed of a rifle bullet with comparatively slow speed of flight. (McCann 243)

Birds do have a few advantages over us human aircraft builders. Their nerves provide them with feedback about the airflow over their entire body, and they can then use their muscles to move their feathers to tweak the airflow. This type of thing would be very difficult to do on an airplane made out of metal, or even with newer composite materials.

Bird also have the advantage, through evolution, of being able to customize the shape of their payload (i.e. their internal organs). Aircraft must be sized to have hollow interiors that can accommodate us humans and our bags.

Aside from those advantages, airplanes are pretty damned good. For example, at cruise speeds, propellers are around 90% efficient at converting energy from the engine into thrust. 90%! I don't care if McCann doesn't like how fast they spin to do it - that's pretty good. Lift to drag ratios of aircraft compare quite well to birds, as well. According to this site, American black vultures have an L/D of 22 (that's the highest I found for a bird in a quick google search). That's just about the same as the B-52, which has an L/D of around 21. More extreme aircraft can do even better than that. The U-2 has an L/D of around 28, and the Virgin Atlantic Global Flyer has one of about 37. If you want to get really extreme, sailplanes (i.e. gliders) have lift to drag ratios of around 70.

http://en.wikipedia.org/wiki/Lift-to-drag_ratio

I know I discussed modern planes above, but even those from the '20s were pretty good. The fact of the matter is that air is so sparse that it makes flying a challenge. You can go to one extreme and be supremely efficient, such as sail planes or albatrosses, or go to the other extreme and expend a lot of energy, such as helicopters or hummingbirds. Most birds and man made flying machines fall somewhere in between, but flight is always more demanding than other forms of travel.

McCann then went on to wax poetic about birds, which I can certainly appreciate. Unfortunately, he went on to show once again, that he doesn't really understand the whole concept of common descent.

As no such thing as a feather is possessed by any other creature except birds, the turkey, which possesses feathers, must be a bird. But birds, we are told, stand midway between reptiles and beasts. All reptiles possess cold blood. All beasts possess warm blood. A reptile's blood may be as low as 60 degrees or 40 degrees Fahrenheit. The blood of beasts approximates 100 degrees Fahrenheit. The blood of birds should come between them, yet the temperature of the turkey is 107 degrees Fahrenheit. Thus the turkey, which comes between the reptile and the beast, puts the beast between the reptile and the turkey. For that matter so does the barnyard fowl. (McCann 244)

First of all, we now know of other animals besides birds which possessed feathers - dinosaurs. So, possession of feathers is not unique to birds, and can't be used to define an animal as a bird.

'Beast' is not an evolutionary relevant term, but I think we can assume that McCann meant mammals. Still, birds did not evolve from, nor into, mammals, so there's no reason to use mammals as any type of comparison to what you'd expect birds to be like.

This following quote is wrong on a couple levels.

The limbs of beasts and reptiles are variously constructed. There is no resemblance between the structure of the wings of the bat and the scoop of the mole; the paddles of the whale and the foot of the horse, but in birds the hind-limbs are always "walking" legs and the fore-limbs are always wings. (McCann 244)

No resemblance between bat wings and mole legs? What is he talking about? Here are images of the skeletons of both a mole and a bat (stolen from Meriam Webster's 's Visual Dictionary Online).

source

source

Now, they're both highly specialized limbs, but the similarities are obvious. Both have a humerus that starts at the shoulder, a radius and ulna that go from the elbow to the wrist (the ulna is extremely reduced in the bat), several carpal bones in the hand, and then five fingers going out from there. Obviously, from looking at birds and insects, there's no reason wings have to look like bat wings. The reason is that because of evolution, they're limited by their ancestry.

Regarding his last sentence, hasn't McCann ever heard of Kiwis, penguins, or ostriches? They have 'wings' in the same sense that whales have arms. It's obvious from the homology, but it's also obvious that they no longer serve the same function.

Ah, I see McCann has heard of archaeopteryx, but I'm not sure if he's really studied it. Just consider these two paragraphs, with nothing omitted.

Is the turkey reptile, beast or bird? All beasts and reptiles have teeth except ant-eaters, turtles and terrapins, yet no bird has teeth. The many thousands of species of animals, with three lonely exceptions, have teeth, yet of the twelve thousand species of birds not one has teeth. How comes it that these toothless birds have descended from toothed reptiles?

In Miocene times, although the parrot lived in Europe, the turkey did not. The evidence indicates that it was confined to America. The Archeopteryx, found, 1861, in oolitic strata in Bavaria, is generally looked upon as the oldest of all the extinct birds. It, too, differed from all other birds. Instead of having a stubby, fleshy, nosey pad of bone and flesh for a tail, it possessed a real tail containing twenty bones, from each of which two long feathers projected. (McCann 245)

How can he make the categorical statement that no birds have teeth, and then in the very next paragraph discuss archaeopteryx? Did he even look at the fossil?

Again, with the arrogance.

The broad indisputable fact stands out beyond dispute that no species of animal, save man only, makes progress. Progress results from the exercise of a rational intelligence, free choice and free will. Man alone possesses these attributes of man. (McCann 246)

We may be the most technological animal, but we're not the only one who makes tools. Once again, I'll direct readers to Frans de Waal's article in the New York Times.

Proceed to Chapter 20