Recently in Evolution Category

David MacMillan sent the following e-mail to me and a handful of others. He directed us to this article from the Sacramento Bee, which describes how a biologist, Michel Milinkovitch, discovered a bearded dragon that lacked both scales and beard. He bought the reptile from a breeder and, with his graduate student, Nicolas Di-Po, sequenced its genome and discovered that the same gene codes for scales in reptiles, feathers in birds, and hair in mammals. The only sensible conclusion that may be drawn is that reptiles, birds, and mammals share a common ancestor. Herewith, Mr. MacMillan’s e-mail, reproduced with permission:

A bearded dragon was born without any scales, leading to what may turn out to be one of the most exciting evolutionary discoveries of the decade.

Can’t wait to see how creationists – particularly the ones at Answers in Genesis – try to spin this.

This lizard was found by a biologist in a pet store. Curious, he decided to buy it and have its DNA sequenced. By comparing its DNA to “normal” bearded dragon DNA, they were able to locate the gene that is typically responsible for the formation of scales in reptiles. Big surprise: it’s the exact same gene responsible for the formation of feathers in birds and hair in mammals.

It was already known that the gene for feathers in birds matched the gene for hair in mammals. Because common descent requires that birds and mammals both evolved from reptiles, this commonality represented a major limitation on the origin of scales. If the gene for scales didn’t match, it would seriously challenge a major framework of common descent.

Not only did the discovery allow scientists to verify this prediction, but it also gave them the information they needed to find and observe scale development in reptile embryos. Sure enough, it too matched the time of hair development in mammals and feather development in birds. Well-informed readers will not that this is not embryonic recapitulation; rather, it is a common developmental cycle resulting from common ancestry. This product of evolutionary science enables new understanding of life in the here and now.

How will Answers in Genesis respond? I’m not sure – but I can make some educated guesses.

“This is a clear example that mutations are always harmful.”

“This lizard, rather than progressing upward, has lost information (an example of microevolution) and has not changed ‘kinds’ (as required by macroevolution).”

Of course these miss the point completely; this particular lizard’s mutation merely allowed for another discovery.

“The belief that this gene can be used to trace common origins of reptiles, birds, and mammals is an evolutionary assumption based on the naturalistic presuppositions of secular scientists.”

“Even if it is proven that this same gene does control scales, feathers, and hair, this would be a demonstration of common design within the Biblical worldview.”

These miss the point that this is a necessary prediction of the evolutionary model.

Any other possible answers?

Micropterus salmoides

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Micropterus salmoides – large mouth bass, Chester, N.Y. I am a little late with this picture, but 10 days ago I visited my brother Michael Gilman in New York. The upper picture is a large mouth bass guarding his eggs. Mike told me that they usually hatch on Father’s Day. Sure enough, he sent me the lower picture, the bass fingerlings, on June 19, Father’s Day. Fish, unfortunately, are not very bright, and (having guarded the nests for who knows how long) they eat their own offspring. Mike said that they saw a few fingerlings on Monday, and none since; presumably, some of the survivors are hiding. I have been a little slow on the uptake, and I decided to run these pictures on Sunday, one week after Father’s Day.

Photography Contest VIII

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Polish your lenses, dust off your tripods, search your archives (and, if you have entered before, remember that you are not limited to 3 good pictures per lifetime) – the eighth Panda’s Thumb photography contest, begins – now!

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Pierce extinction meter, still-camera version. They sold for $1.95 in 1946.

We will accept entries from 12:00 CST, Monday, June 20, through 12:00 CST, Monday, July 4. We encourage pictures of just about anything of scientific interest. If we get enough entries, consistently with Rules 11 and 12, we may assign entries to different categories and award additional prizes, presuming, of course, that we can find more prizes.

The first-place winner will receive a signed copy of Why Evolution Works (and Creationism Fails), which has been donated by one of the authors. The National Center for Science Education will donate copies of Sahotra Sarkar’s Doubting Darwin: Creationist Designs on Evolution and Barbara Forrest and Paul R. Gross’s Creationism’s Trojan Horse: The Wedge of Intelligent Design to the second- and third-place winners.

Chrysomela sp.

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Chrysomela sp. – leaf beetle. Thanks to a volunteer at BugGuide for the identification.

… June 20. That is, we will accept entries from noon, June 20, to noon, July 3, where noon is defined by the Panda’s Thumb server, which thinks it is still in Central Standard Time, or UTC(GMT) - 5 h. The rules will be essentially the same as previous years’. We have not chosen categories yet, but please be assured that they (or it) will be all-inclusive.

The number of entries has gone down monotonically or almost so since the first contest in 2009. Thus, we want to dispel the rumor that each person gets only 3 decent pictures per lifetime and encourage our readers to submit up to 3 photographs per person, even if you have already submitted several in past contests and think that you have used up your allocation: There is no Law of Conservation of Complex Specified Photographic Quality!

So wipe your lenses, grease your shutters, check your archives, and be ready!

Hardground with borings

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Photograph by Dan Phelps.

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Hardground with borings from the Grant Lake Limestone (Upper Ordovician, Maysvillian), Maysville, Kentucky. Mr. Phelps explains, “Hardgrounds are surfaces in the geologic record that lithified on the sea floor and then were bored into and encrusted by marine invertebrates, followed by the deposition of more sediments. They are common in Ordovician carbonates of Kentucky.” And adds, “The creationist explanations for hardgrounds can be hilarious. Especially look at the diagram with gas emissions lifting antediluvian hardgrounds to be redeposited in the Flood.”

Recurvirostra americana

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Recurvirostra americana – American avocet, Cottonwood Lake, Boulder, Colorado, 3 days ago.

A retired European geneticist, Wolf-Ekkehard Lönnig, has made a point that he feels is devastating to population genetic arguments about the effectiveness of natural selection. In a post at the Discovery Institute’s blog Evolution News and Views. He pointed to an argument he made in 2001 in an encyclopedia article. The essence of his criticism is that many organisms produce very large numbers of gametes, or of newborn offspring. Most of those must die. Then

If only a few out of millions and even billions of individuals are to survive and reproduce, then there is some difficulty believing that it should really be the fittest who would do so.

In addition, he was interviewed two days ago by Paul Nelson, in a podcast posted very recently by the Center for Science and Culture of the Discovery Institute, on their blog Evolution News and Views. You will find it here. He makes the same point (while Nelson misunderstands him and keeps raising an unrelated point about protein spaces).

It is a stunning thought that evolutionary biologists have ignored this issue. Have they? Have population geneticists ever thought about this? Well, actually they have, starting nearly 90 years ago. And the calculations that they made do not offer support to Dr. Lönnig. Let me explain …

Dan Phelps just sent us an editorial in the Lexington Herald-Leader. The editorial accuses Kentucky of seeking science jobs while at the same time denying science: not just evolution but also global warming, alternative energy sources, and conservation. The editorial notes that Kentucky is “perennially short of money,” in part because of tax breaks like that for the Ark Park, and concludes,

Kentucky forgoes tax revenue to help deny science while telling students they need to learn it. In homage to coal, Kentucky dumbly stints on alternative energy technologies, or even conservation, while telling young people they need to prepare to work in advanced manufacturing.

The messages aren’t just mixed, they’re in open conflict.

That about sums it up.

Celithemis eponina

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Photograph by Robin Lee-Thorp.

Photography contest, Honorable Mention.

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Celithemis eponina – Halloween pennant.

Attacus atlas

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Photograph by Diogenes.

Photography contest, Honorable Mention.

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Attacus atlas – Atlas moth. This specimen is a captive male at the Museum of the Academy of Natural History of Pennsylvania, Philadelphia.

Metaconglomerate rock

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Photograph by Dan Phelps.

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Metaconglomerate rock (commercially known as marinace; if anyone knows why, please comment below).

Mr. Phelps writes:

I originally became interested in this rock after reading this blog post. The material was hard to find in small quantities, but I found a company that sells interesting rock slabs to use as cutting boards. If you notice, my slab has handles, which I will probably remove.

The rock is actually a metaconglomerate from Brazil and may represent a metamorphosed Proterozoic glacial tillite.

It is relatively easy to construct an entire series of events that led to the formation of this interesting and beautiful rock. Specimens of this rock might be useful for educators to show basic geologic concepts, including geologic time, to both students and the public.

Note that individual cobbles and pebbles are made of quartzite, gneiss, and what is either a migmatite or a metamorphosed pinkish orthoclase feldspar-rich granite. The greenish black matrix is rich in the mineral chlorite.

I came up with the following steps to form this rock slab. Please comment below or e-mail me at [Enable javascript to see this email address.] if you think I have missed anything.

1. Deposition of the sediments that make up the precursors of the cobbles/pebbles.

2. Lithification of sedimentary rocks that were the precursors of the cobbles/pebbles. These include sandstone, and shales and siltstones (protoliths of the metamorphic rocks in Step 3).

3. Metamorphism of the sedimentary rocks in Step 2 by heat and pressure, resulting in quartzite and gneiss. Some of the gneiss may have partially melted then crystallized to form a pinkish orthoclase-rich migmatite.

4. Weathering of the metamorphic rocks in Step 3.

5. Erosion of these metamorphic rocks into well-rounded pebbles/cobbles.

6. Deposition of these pebbles/cobbles in a fine-grained mud.

7. Lithification of the sediment from Step 6. This results in a rock type of pebble/cobble sized fragments in a fine-grained mudstone matrix and is called a diamictite. Diamictites often represent lithified glacial till.

8. Metamorphism of the rock formed in Step 7 forming a metaconglomerate. This occurred deep enough underground to change the mudstone matrix into greenish black chlorite.

9. An orogeny (mountain building) event stretched many of the pebbles and cobbles giving the rock a foliation.

10. Pressure solution causes some of the pebbles/cobbles to erode at boundaries where they touch each other.

11. Weathering and erosion bring the metaconglomerate to the surface.

12. Human quarrying followed by cutting and polishing of the slab.

Interesting video, Proof of evolution that you can find on your own body, deals with several vestigial organs in the human body. It is certainly hard to see why a god might have included such organs if she had created humans by any method other than evolution. The video is only 4 min long; watch it!

The Sensuous Curmudgeon informs us today that the Tri-State Freethinkers of Newport, Kentucky, will launch a billboard campaign that, as they put it, intends to “counter” the grand opening of the Ark Park in July. They have launched an IndieGoGo campaign with an intended goal of $2000; when I checked a moment ago, it looked as though they had raised nearly $3100 in a single day.

The billboard will read

Genocide and Incest Park
Celebrating 2000 Years of Myths

Yes, I know, that may be a bit over the top and, except for the picture, does not obviously refer to the Ark Park. But, dammit, the Ark Park is well over the top, and I intend to contribute $18* right away.
______

* A bit of numerology; even strict materialists can have traditions.

Grus canadensis

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Photograph by Robert Dullien.

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Grus canadensis – sandhill crane.

Hirundo rustica

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Hirundo rustica - barn swallow, Goose Creek, Boulder, Colorado.

Solar corona Cloud iridescence

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I am afraid that this is not a very good picture, first because the colors are not very well defined and second because I could not find a single, smallish object with which to block the sun, so I had to settle for this tree.

I could not immediately find a halfway decent explanation of cloud iridescence. Wikipedia says it is a diffraction phenomenon, with no elaboration. Here is what I think is going on.

I do not feel like drawing any cartoons, so please have a look at the Wikipedia article on the Airy disk. About 2/3 of the way down, you will see a plot of intensity as a function of angle. This plot represents the diffraction pattern of a circular aperture. The pattern shows a series of secondary maxima at various angles off axis. The first secondary maximum has an intensity of approximately 2 % of the intensity at 0.

What has the Airy disk to do with iridescence? Oddly, the diffraction pattern of a circular obstacle is the same as that of a circular aperture, except near 0. If the cloud cover is thin enough and the droplets are all approximately the same diameter, we may see colored fringes, because we are standing at the location of the first secondary maximum of a particular wavelength. The angle 0 in the Wikipedia figure is the line between the sun and a droplet; it is not directly in line with the sun from our point of view. We may see several different colors because the secondary maxima of different wavelengths appear at different angles.

In the picture above, we do not see colors very clearly, most probably because the droplets do not have the same diameter. However, because the cloud is between us and the sun, we see a circular halo all the way around the sun, which suggests to me that the droplets are spherical and (I would guess) liquid water rather than ice crystals. (Ice crystals like to be snowflakes, hexagonal cylinders, or flat hexagonal plates. These are oriented by viscous forces, so the scattering pattern would not demonstrate circular symmetry.)

Finally, if you look to the right of the first ring of colored fringes, you will see a second partial ring, which represents the second secondary maximum of the diffraction pattern.

Rainbow

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Photograph by Debbie Garelick.

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Rainbow. The rainbow is formed from relatively nearby raindrops. It is evidently raining lightly, because you can see a light cloud cover behind the rainbow. Direct backscatter from the clouds probably accounts for much of the brightness of the sky inside the arc and helps make a dramatic picture. See also here.

Rainbow

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Photograph by Gabrielle Hovinen.

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Rainbow, showing a primary and a secondary rainbow, plus a bevy of Hovinens. The primary rainbow is overexposed, but the photograph clearly shows how the sky is brighter inside the primary rainbow and outside the secondary rainbow. See Figure 6 here.

Iridescence with wave clouds

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Iridescence with wave clouds, Boulder, Colorado, December, 2015.

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