Recently in Evolution Category

Celithemis eponina


Photograph by Robin Lee-Thorp.

Photography contest, Honorable Mention.


Celithemis eponina – Halloween pennant.

Attacus atlas


Photograph by Diogenes.

Photography contest, Honorable Mention.


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

Metaconglomerate rock


Photograph by Dan Phelps.


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


Photograph by Robert Dullien.


Grus canadensis – sandhill crane.

Hirundo rustica


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

Solar corona Cloud iridescence


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.



Photograph by Debbie Garelick.


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.



Photograph by Gabrielle Hovinen.


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


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

Lenticular cloud


Lenticular clouds, Golden, Colorado, November, 2012. The camera was facing east, with its back toward the foothills of the Rocky Mountains. The clouds looked as if they may have formed on the leeward side of South Table Mountain.


Professor Steve Steve’s cousin, Dr. Steffi Steffi, a lesser giant panda (Ailuropoda melanoleuca minor), was in Peru on December 21, 2005, and she read about the previous day’s decision in the Times Digest. Here she looks with pleasure at the announcement by Wesley Elsberry in The Panda’s Thumb on December 20 and a longer article by Laurie Goodstein in the Times the following day.

Toxicodendron rydbergii


Toxicodendron rydbergii – western poison ivy, South Boulder Creek Trail, Boulder, Colorado, September, 2015. Poison ivy is red only in the fall.

Toxicodendron radicans rydbergii


Toxicodendron radicans rydbergii – western poison ivy, South Boulder Creek Trail, Boulder, Colorado, July, 2015. As I was taking the picture, a little voice approached me and asked, “Do you know —? Is that —? Could that be —? Poison ivy?” Yes, and it was one of the lushest fields of poison ivy I have seen this side of New Jersey, growing right along the trail. You can identify it because it has 3 leaflets, and often the outer ones are shaped like mittens, though not as distinctively as these. Poison ivy is red only in the fall; we will see that in 2 weeks.

Evolution finally winning?


Good article in Slate, Evolution Is Finally Winning Out Over Creationism, by Rachel Gross. I have not checked the surveys myself, but Gross reports,

The people responsible for this shift are the young. According to a recent Pew Research Center report, 73 percent of American adults younger than 30 expressed some sort of belief in evolution, a jump from 61 percent in 2009, the first year in which the question was asked. The number who believed in purely secular evolution (that is, not directed by any divine power) jumped from 40 percent to a majority of 51 percent. In other words, if you ask a younger American how humans arose, you’re likely to get an answer that has nothing to do with God.


The overall proportion of Americans who believe in secular evolution has doubled since 1999, from 9 percent to 19 percent, according to a 2014 Gallup poll.…[M]ost of that increase has been drawn from the pool of Americans who previously reported that they believed in evolution guided by God [theistic evolution], which simultaneously dropped from 40 percent to 31 percent.

Why? In part because evolution is “in the air” (thank the Internet!) and in part because evolution-deniers are older and dying off.

Acknowledgment. Thanks to Mike Antolin of the Colorado State University for the link.

Typha latifolia


Typha latifolia – broad-leaved cattail, South Boulder Creek trail, 2015. The upper picture was taken with a Sony α6000 camera and a 310-mm (35-mm equivalent) lens; the lower with a Canon SX280 point-and-shoot camera and a 600-mm (equivalent) lens. Consumer Reports rated the image quality of both cameras “Very Good,” but they cautioned that you cannot compare ratings across camera types.

So I decided to compare the 2 cameras myself. The 2 images are cropped to show the same areas and reveal individual pixels. The SX280 image shows some electronic noise and a bit of chromatic aberration. The α6000 image, though taken at half the focal length, is far better. The α6000 may show better gray scale, but that may be an artifact of the exposure, which I have not compared. Nevertheless, if you do not want to push the limit, the SX280 image is very serviceable indeed.

Last March Tom English and I posted an argument here here at Panda’s Thumb analyzing an argument by William Dembski, Winston Ewert, and Robert Marks. They had made an argument that evolutionary “search” would not do better than blind search; we proved that their argument showed no such thing.

In response to our analysis here of the Dembski-Ewert-Marks paper, Winston Ewert has replied at Evolution News and Views. As that site does not allow comments, I have finally gotten around to posting a response here (six months late). Tom has now put up a related thread at The Skeptical Zone; I will try to comment in both discussions.

Ewert rather dramatically reveals that Tom and I do not actually disagree with any of the theorems in their paper. And he’s right about that. How did they discover this remarkable fact? Perhaps it was by reading our post, where we said

We’re not going to argue with the details of their mathematics, but instead concentrate on what in evolutionary biology corresponds to such a choice of a search.

or by reading a comment in that thread where I also said:

As theorems they may be mathematically true, but the average poor performance of searches is true only because so many irrelevant and downright crazy searches are included among the set of possible searches.

Ewert is right that we did not question their theorems. Instead we concentrated on what would follow from their theorems. We showed in a simple model that once there are organisms that reproduce, with genotypes that have phenotypes and fitnesses, that evolution will find higher fitnesses much more effectively than random guessing. So is it true that having what they call Active Information, embodied in a fitness surface and in a reproducing organism whose genotypes have those fitnesses, requires that there be Design Intervention to set up that system?

The issue is not the correctness of their theorems but, given that they are correct, what flows from them. Dembski, Ewert, and Marks (DEM) may object that they did not say anything about that in their paper.

We don’t think that it is a stretch to say that DEM want their audience to conclude that Design is needed.

Let’s look at what conclusions Dembski, Ewert, and Marks draw from their theorems. There is little or no discussion of this in their paper. Are they trying to persuade us that a Designer has “frontloaded” the Universe with instructions to make our present forms of life? Let’s look at what Dembski and Marks have said about that (below the fold) …


| 1 Comment

Conjunction by Darren Insko.

Photography contest, Finalist.

Fascinating article by Rhitu Chatterjee in Science this past week. I am not a specialist in physiological optics, but I have always understood that you cannot give sight to someone who is blind from birth and is older than, perhaps, a teenager. According to Chatterjee’s article, most ophthalmologists understood the same thing. It is not true.

Chatterjee describes a project to perform cataract operations on people who are congenitally blind. Some of these are teenagers or young adults, and they learn to see – not as well as you and I, possibly because part of their visual cortex has been used for touch or hearing, but they learn to see. In consequence, a neuroscientist, Pawan Sinha, launched Project Prakash as a humanitarian effort to give sight to people who have blindness that would be preventable in the developed nations.

What interested me more, in a way, was that newly sighted people fell for precisely the same optical illusions that normally sighted people fall for. For example, the two bars across the railroad tracks in Figure 1, the Ponzo illusion, are the same length, as you can verify with a ruler. The dashed lines on the right side of Figure 1 are parallel and show that the two bars are the same length – except that the illusion persists, and the dashed lines do not look parallel.


Figure 1. Ponzo illusion. The “more distant” bar appears longer than the “closer” bar. The usual explanation, that we learn to see perspective in drawings, is apparently falsified by the fact that newly sighted people also fall for the Ponzo illusion.

Probably most readers are familiar with the Ponzo illusion. The usual explanation is that we learn over time to recognize 2-dimensional drawings of 3-dimensional objects, and we think that the upper bar is farther away than the lower bar and so must be longer.

Amazingly, 9 newly sighted children fell for the Ponzo illusion.

Likewise, Figure 2 shows the Müller-Lyer illusion. Here, (a) the line segment with the arrows pointing out always looks shorter than (b) that with the arrows pointing in. The illusion persists, even when we provide a ruler to show that the lines are the same length. (See also here for a slightly different view of the Müller-Lyer illusion.)


Figure 2. Müller-Lyer illusion. (a) The line segment with the arrows pointing out looks shorter than (b) the line segment with the arrows pointing in. The illusion persists even when we provide a ruler for reference. Newly sighted people also fall for the Müller-Lyer illusion. From M. Young, No Sense of Obligation, Science and Religion in an Impersonal Universe (2001).

Once again, the 9 newly sighted children fell for the illusion.

No one Chatterjee spoke to has a good explanation, but it seems that we must be hardwired to perceive and interpret much more than is commonly thought.

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