Peppered moths, evidence for natural selection and evolution

September 20, 2014

In 2007, as part of the continuing series explaining evolution and how it should be taught in public schools, I wrote this piece on the controversy over peppered moths as part of the basic information pages for this blog.  With modest edits, I repeat it here, both to re-emphasize the importance of the examples, and to make it easier for internet search engines to index the material.

Among creationists, in the past decade or so it has become popular to claim that much of evolution is less than sound science. In order to support that claim, specific points of evolution theory are often distorted, and specific evidence that strongly supports the theory are questioned and denied.

In a famous hoax, Jonathan Wells wrote a book, Icons of Evolution, in which he claimed ten popular stories about evolution were false.

Wells spent a chapter denying the work of H. B. Kettlewell — the famous peppered moth research, in which Kettlewell discovered a classic case of natural selection at work over a 150-year period in England. When air pollution darkened the bark of trees, peppered moths in industrialized areas with the darkened trunks, also darkened. Kettlewell ran several experiments to see whether predation by birds might be a driver of this selection event, and concluded that the lighter moths stood out on darkened tree bark, and that it was likely that predation by birds or other moth predators pushed the rise of the darker moths.

Kettlewell’s conclusions were spectacularly borne out when cleaner air lightened the trunks of the trees, and lighter moths reappeared. The selective pressure ran back toward lighter moths.

The two most common variants of the peppered moth, the one on the left showing how it got is name, and the one on the right showing the variant that became more common when air pollution darkened the bark on trees where the moth rests.  BBC image

The two most common variants of the peppered moth, the one on the left showing how it got is name, and the one on the right showing the variant that became more common when air pollution darkened the bark on trees where the moth rests. BBC image

Kettlewell’s research was groundbreaking in its pioneering of new ways to study evolution in the wild. But because he was at the cutting edge, questions arose about the exact nature of his conclusions. Kettlewell tried several different methods to count moth predation, finally settling on a system of release and recapture, and counting the moths that were not recaptured as casualties to the predator. Kettlewell released moths in the presence of English titmice, who promptly found moths colored wrongly to hide, and ate them. Tits are not the chief predators of these moths, some argue, and critics wondered whether Kettlewell could accurately conclude what the predator was. Ultimately, it has become clear that Kettlewell’s conclusions are accurate regardless the predator. Scientists like Majerus and Jerry Coyne — fierce rivals now, showing the unanimity of science support for Kettlewell’s conclusions across the spectrum of science views — urge more research to refine what we know about the moths.

Critics claimed some of the steps in some of the experiments as faulty, and extrapolated that the entire conclusions are faulty. In reality, because Kettlewell got similar results with different methods, his conclusions are more robust.

When I took Wells’ chapter on moths and tracked down the citations, I discovered that each person he cited disputed Wells’ conclusions — some quite violently.  The hoax, it turns out, is Wells’s claim that the story is false.

Over the past decade, while Wells and the Discovery Institute have continued their assault on science, some of the refutations of his work have fallen by the wayside.

In this page, I hope to preserve the arguments showing Wells’ work’s problems, and preserve some of the publications that have become difficult to find.

Creationism controversy in Pratt, Kansas

In 1999 the school board in Pratt, Kansas, considered biology curriculum and book changes. In what now appears to be practice for future fights, the Discovery Institute of Seattle, Washington, descended on Pratt with Jonathan Wells and others , urging the school board to dilute evolution in the curriculum or eliminate it, and using a variety of unusual arguments on the science to buttress their claims that the science of evolution was somehow in question.

Specifically, Wells introduced his claims on Kettlewell’s work. When they heard of the incident, some researchers scrambled to present the view of science. Bruce Grant of William and Mary College, and Jerry Coyne of the University of Chicago, wrote letters to the local newspaper, The Pratt Tribune, defending Kettlewell’s work and questioning Wells’ tactics and conclusions. Evolution is solid science, they said, and should be taught undiluted to students.

These letters were available on the internet at the time, but have recently become difficult to find. I reproduce them here:

Dr. Jerry Coyne is professor of ecology and evolution at the University of Chicago.

The Pratt Tribune, December 06, 2000

Original:
http://www.pratttribune.com/archives/index.inn?loc=detail&doc=/2000/December/06-663-news91.txt Accessed in 2003

Jerry A. Coyne: Criticism of moth study no challenge to evolution

I have learned that the Pratt school board, apparently responding to creationist pressure, has recently revised its tenth-grade biology curriculum to include material that encourages students to question the theory of evolution. In reading the standards, I see that one of my articles – an article constantly misrepresented by creationists – is included as a supplementary reading used to cast doubt on evolution.

Dr. Jerry Coyne's Skeptic Trump card.  He is a professor at the University of Chicago.

Dr. Jerry Coyne’s Skeptic Trump card. He is a professor at the University of Chicago.

Except for a few creationist dissenters, the community of professional biologists has long accepted evolution as an essential theory supported by innumerable pieces of evidence. To make students think otherwise is as harmful as urging them to question the value of antibiotics because there are a few people who believe in spiritual healing.

My article appended to the Pratt standards is a re-evaluation of a classic evolutionary story in which rapid changes in the proportions of color forms of peppered moths occurred in only about 100 years. This evolutionary change is thought to be a response to air pollution, changes in the colors of trees, and increased bird predation. My only problem with the peppered-moth story is that I am not certain whether scientists have identified the precise agent causing the natural selection and evolutionary change. It may well be bird predators, but the experiments leave room for doubt.

Creationists such as Jonathan Wells claim that my criticism of these experiments casts strong doubt on Darwinism. But this characterization is false. All of us in the peppered moth debate agree that the moth story is a sound example of evolution produced by natural selection. My call for additional research on the moths has been wrongly characterized by creationists as revealing some fatal flaw in the theory of evolution.

In reality, the debate over what causes natural selection on moths is absolutely normal in our field. It is not uncommon for scientists to reexamine previous work and find it incomplete, or even wrong. This is the normal self-correcting mechanism of science. Textbook examples may be altered as additional data are found. Creationists, on the other hand, neither air their disagreements in public or admit that they were wrong. This is because their goal is not to achieve scientific truth, but to expel evolution from the public schools.

It is a classic creationist tactic (as exemplified in Wells’ book, “Icons of Evolution”) to assert that healthy scientific debate is really a sign that evolutionists are either committing fraud or buttressing a crumbling theory. In reality, evolution and natural selection are alive and well, with new supporting evidence arriving daily.

I strongly object to the use of my article by the Pratt school board to cast doubt on Darwinism. And I feel sorry for the students who are being misled by creationists into doubting one of the most vigorous and well-supported theories in biology.

Jerry A. Coyne
Professor of Ecology & Evolution
The University of Chicago

Dr. Bruce Grant was professor of biology at William and Mary University, now emeritus.

The Pratt Tribune, December 13, 2000
Original:

http://www.pratttribune.com/archives/index.inn?loc=detail&doc=/2000/December/13-653-news92.txt

Accessed 2003

Bruce Grant: Charges of fraud misleading

In recent weeks your newspaper has printed letters debating revisions in high school biology curricula. Some of the correspondents have leveled charges of fraud directed at evolutionists for attributing changes in the colors of peppered moths to natural selection. As I am one of the evolutionary biologists who study peppered moths, I feel obliged to comment. Charges of fraud cannot be left unchallenged.

Some background about peppered moths is necessary. The common form of this moth species is pale gray. About 150 years ago, a black specimen was discovered near an industrial city in England. Over the years, the black (melanic) form became ever more common as the pale form became rare. By 1900 the black form exceeded 90 percent in peppered moth populations throughout the industrialized regions of England. The phenomenon was dubbed industrial melanism.

Bruce Grant, Professor of Biology, Emeritus, College of William and Mary

Bruce Grant, Professor of Biology, Emeritus, College of William and Mary

Because people knew that birds eat insects, scientists as early as 1896 suspected that birds were eating the different color forms of peppered moths selectively based on their degree of conspicuousness in habitats variously blackened by industrial soot. Extensive experimental work supports this view, although questions remain. Other scientists proposed that moths responded to the presence of pollutants by developing darker body colors. We now know from genetic analysis that the colors of adult peppered moths are determined by genes; thus, the changes in the percentages of pale to black moths over generations reflect changes in the genetic makeup of moth populations.

As industrial practices have changed in many regions, we have observed black moths plummet from 90 percent to 10 percent in the just the past few decades. Once again, we have observed significant genetic changes occur in moth populations. Evolution is defined at the operational level as genetic change over time, so this is evolution. Of the several factors known to produce evolutionary change, only natural selection is consistent with the patterns of the changes we see occurring in moth populations. Evolution examined at this level is as well established as any fact in science.

We still have work to do. We do not all agree about the relative roles of contributing factors, such as the flow of genes between moth populations in different regions, the importance of lichens on trees, where on trees moths might hide from predators, how important is differential predation, and so on. As in any branch of science, participants endlessly debate interpretations. Such wrangling is the norm, and it stimulates additional research. That is how we make progress.

Our debates have never been secret. For recent overviews of the controversies, please see http://www.wm.edu/biology/melanism.pdf [now at http://bsgran.people.wm.edu/melanism.pdf] or www.els.net/elsonline/html/A0001788.html [ now http://mrw.interscience.wiley.com/emrw/9780470015902/els/article/a0001788/current/abstract, subscription required]. Yet, unwarranted charges of fraud, fakery and cover-ups repeatedly appear in letters printed in newspapers. In your paper, Ms. Katrina Rider “asserts” the peppered moth story is a hoax. She conveys the impression that dead moths were glued to trees as part of a conspiracy of deception. She seems unaware that moths were glued to trees in an experiment to assess the effect of the density (numbers) of moths on the foraging practices of birds. Taken out of the context of the purpose of the experiment, the procedure does sound ludicrous.

But, should we blame Ms. Rider for her outrage upon learning that moths were glued to trees? No. Instead, I blame Dr. Jonathan Wells, who wrote the article she cites as her source of information. While he has done no work on industrial melanism, he has written opinion about the work. To one outside the field, he passes as a scholar, complete with Ph.D. Unfortunately, Dr. Wells is intellectually dishonest. When I first encountered his attempts at journalism, I thought he might be a woefully deficient scholar because his critiques about peppered moth research were full of errors, but soon it became clear that he was intentionally distorting the literature in my field. He lavishly dresses his essays in quotations from experts (including some from me) which are generally taken out of context, and he systematically omits relevant details to make our conclusions seem ill founded, flawed, or fraudulent. Why does he do this? Is his goal to correct science through constructive criticism, or does he a have a different agenda? He never mentions creationism in any form. To be sure, he sticks to the scientific literature, but he misrepresents it. Perhaps it might be kinder to suggest that Wells is simply incompetent, but I think his errors are by intelligent design.

Bruce Grant
Professor of Biology
College of William and Mary
Williamsburg, Virginia

_____________

Update, September 2012: Creationists appear never to learn. The hoaxed “controversy” on peppered moths continued well after these exchanges back in 2000, which I collected when creationists tried to block science in textbooks in the great Texas State Board of Education Wars of 2003. Even after losing that fight, creationists continued to carp.

Publication of Of Moths and Men, nominally a history of Kettlewell and his experiments, revived the creationist claims of error — without evidence, as the author of the book noted, but since when have creationists ever changed course because of evidence?

In the midst of the flap, Michael Majerus went back to basics. He re-ran Kettlewell’s experiments, essentially. Of course, he discovered Kettlewell was right. I blogged about it earlier, but I failed to update this post. See these other posts at Millard Fillmore’s Bathtub:

Also, WordPress has improved since 2007; it finds relevant links, and related stories through Zemanta. I’ve added links above, and related articles below.

More, and Further Reading:


Every polling station should have this sign

September 18, 2014

Polling station, in unnamed location in Scotland, for the referendum on Scotland independence.  From @standrewsradio

Polling station, in unnamed location in Scotland (?) posted on Twitter during the referendum on Scotland independence, but around since at least April 2014. From @standrewsradio

“Please do not sit on the fence.”

It would work in Texas elections this year, too.  97% of eligible Scot voters registered to vote; as I write this, it looks like about 90% of those people voted in the election.

Ain’t democracy grand?

“Vote: It’s what citizens do.”

Update:  Seems to be at the Plaistow Youth Center, in England.

From BBC:

BBC caption:  After four weeks of campaigning the polls are closed, we now await the result of the general election. Quentin Gadd spotted these signs at a polling station, he says,

BBC caption: After four weeks of campaigning the polls are closed, we now await the result of the general election. Quentin Gadd spotted these signs at a polling station, he says, “Is this proof positive that the organisers of the Plaistow Youth Centre are taking a stand against those who choose to abstain?”

The photo may be from 2010, from this site, which identifies the photo location further, with a different photo:  “Sign at the polling station in Plaistow, West Sussex, on Local Council Polling Day.”


This guy is really lit! So are his bagpipes!

September 18, 2014

From the voting festivities in Scotland today, a very graphic demonstration of why one should never, never, never drink and play bagpipes.

From Twitter, Wall Street Journal's account:  Photos: Scotland votes in independence referendum | http://on.wsj.com/1ubZMTH

From Twitter, Wall Street Journal’s account: Photos: Scotland votes in independence referendum | http://on.wsj.com/1ubZMTH

In every other way, this vote should be closely watched.  Two nations pushed together by force of arms hundreds of years ago, discussing whether and how to split up.  No guns.  No tanks.  Lots of discussion, lots of fun, lots of ballots.  97% of eligible voters registered to vote, and indications are at least 90% of them turned out.

Can you imagine what would happen in U.S. elections if 90% of registered voters showed up at the polls, instead of 40%, or 30%?  Can you imagine if 97% of U.S. eligible voters bothered to register, instead of the less-than-50% we have now?

You bagpipes would flame, too.


227 years ago today, in this room

September 17, 2014

Independence Hall, Philadelphia; room where the Constitution was created and signed; Dept of Interior photo

Caption from Department of Interior’s Tumblr site: 225 years ago today, the Constitution of the United States was signed in Independence Hall. Today, you can tour the Hall and see where the Declaration of Independence and Constitution were both signed, and you can also view the Liberty Bell [close by]. This is a site not to miss while visiting Philadelphia.
Photo: National Park Service

Does this room look a little familiar?  You’ve probably seen Howard Chandler Christy’s painting of the event we celebrate today.

Howard Chandler Christy’s “Signing of the Constitution,” 1940

Howard Chandler Christy’s “Signing of the Constitution,” 1940; Architect of the Capitol image. This massive, 20′ x 30′ painting hangs in the House Wing of the U.S. Capitol, in the east stairway — a location where, alas, most people cannot get to without a guide anymore.

Click to the Architect of the Capitol’s site for the story of the painting, intended by Congress to fill a gap in the story of America told by art in the Rotunda and throughout the halls of the building.

Dr. Gordon Lloyd, Pepperdine University, creator of the interactive

Dr. Gordon Lloyd, Pepperdine University’s School of Public Policy, and expert in the Constitution and its history.  I met Lloyd almost a decade ago, in programs for history teachers, sponsored by the Bill of Rights Institute, Liberty Fund, and National Endowment for the Humanities.

My old friend Dr. Gordon Lloyd of Pepperdine University, working with the Ashbrook Center for Public Affairs, created a study tool from the Christy painting which should be used a lot more in classrooms.  Click over to the Edsitement site, and see for yourself.

Every year there are a few more tools on the internet to study the Constitution with, for teachers to use in the classroom on Constitution Day and every day.  I wonder what will be the effects in another decade.

How important is it that students learn the Constitution, what it says, and how it affects our daily lives?  How important is it that students learn the history of the creation of the Constitution, and does that history reverberate for those students as they venture out into their roles as citizens in the republic created by the document?

More:

This is an encore post.

This is an edited encore post.


President Obama on Constitution Day 2014

September 17, 2014

President Barack Obama literally standing with the Constitution, at the National Archives. (source of photo?)

President Barack Obama literally standing with the Constitution, at the National Archives. (source of photo?)

Your flag is up. You’ve already read the Constitution and all 27 amendments.

Time to pass on greetings to others:  Happy Constitution Day!

From the President of the United States:

CONSTITUTION DAY AND CITIZENSHIP DAY, CONSTITUTION WEEK, 2014

- – – – – – -

BY THE PRESIDENT OF THE UNITED STATES OF AMERICA

A PROCLAMATION

Eleven years after a small band of patriots declared the independence of our new Nation, our Framers set out to refine the promise of liberty and codify the principles of our Republic.  Though the topics were contentious and the debate fierce, the delegates’ shared ideals and commitment to a more perfect Union yielded compromise.  Signed on September 17, 1787, our Constitution enshrined — in parchment and in the heart of our young country — the foundation of justice, equality, dignity, and fairness, and became the cornerstone of the world’s oldest constitutional democracy.

For more than two centuries, our founding charter has guided our progress and defined us as a people.  It has endured as a society of farmers and merchants advanced to form the most dynamic economy on earth; as a small army of militias grew to the finest military the world has ever known; and as a Nation of 13 original States expanded to 50, from sea to shining sea.  Our Founders could not have foreseen the challenges our country has faced, but they crafted an extraordinary document.  It allowed for protest and new ideas that would broaden democracy’s reach.  And it stood the test of a civil war, after which it provided the framework to usher in a new birth of freedom through the 13th, 14th, and 15th Amendments.

America’s revolutionary experiment in democracy has, from its first moments, been a beacon of hope and opportunity for people around the world, inspiring some to call for freedom in their own land and others to seek the blessings of liberty in ours.  The United States has always been a nation of immigrants.  We are strengthened by our diversity and united by our fidelity to a set of tenets.  We know it is not only our bloodlines or an accident of birth that make us Americans.  It is our firm belief that out of many we are one; that we are united by our convictions and our unalienable rights.  Each year on Citizenship Day, we recognize our newest citizens whose journeys have been made possible by our founding documents and whose contributions have given meaning to our charter’s simple words.

Our Constitution reflects the values we cherish as a people and the ideals we strive for as a society.  It secures the privileges we enjoy as citizens, but also demands participation, responsibility, and service to our country and to one another.  As we celebrate our Nation’s strong and durable framework, we are reminded that our work is never truly done.  Let us renew our commitment to these sacred principles and resolve to advance their spirit in our time.

In remembrance of the signing of the Constitution and in recognition of the Americans who strive to uphold the duties and responsibilities of citizenship, the Congress, by joint resolution of February 29, 1952 (36 U.S.C. 106), designated September 17 as “Constitution Day and Citizenship Day,” and by joint resolution of August 2, 1956 (36 U.S.C. 108), requested that the President proclaim the week beginning September 17 and ending September 23 of each year as “Constitution Week.”

NOW, THEREFORE, I, BARACK OBAMA, President of the United States of America, do hereby proclaim September 17, 2014, as Constitution Day and Citizenship Day, and September 17 through September 23, 2014, as Constitution Week.  I encourage Federal, State, and local officials, as well as leaders of civic, social, and educational organizations, to conduct ceremonies and programs that bring together community members to reflect on the importance of active citizenship, recognize the enduring strength of our Constitution, and reaffirm our commitment to the rights and obligations of citizenship in this great Nation.

IN WITNESS WHEREOF, I have hereunto set my hand this sixteenth day of September, in the year of our Lord two thousand fourteen, and of the Independence of the United States of America the two hundred and thirty-ninth.

BARACK OBAMA

In that case, Happy Constitution Week!

What should we do tomorrow?


2014’s Constitution Day – Fly your flag

September 17, 2014

Happy Constitution day!  (Remember to fly your flag today.)

Have you read the U.S. Constitution lately?

Contrary to what your local Tea Party claims, it hasn’t changed.  But most people need a refresher from time to time.

First page of the U.S. Constitution, National Archives and Records Administration photo

First page of the U.S. Constitution, National Archives and Records Administration photo

Okay, maybe that’s a little tough to read.  Check out the on-line display of the National Archives and Records Administration in the Charters of Freedom section:

More:

 

Rotunda for the charters of Freedom at Nationa...

Rotunda for the charters of Freedom at National Archives (NARA) building in Washington, D.C. Here displayed are the Declaration of Independence, the Bill of Rights, and the U.S. Constitution. (Photo credit: Wikipedia)

This is an encore post.

This is an encore post.

 


U.N. General Assembly notes progress against malaria

September 16, 2014

In Ghana:  Community members perform a scene to educate others on how and why to use bednets. (USAID/Kasia McCormick) 2012. USAID Africa Bureau

In Ghana: Community members perform a scene to educate others on how and why to use bednets. (USAID/Kasia McCormick) 2012. USAID Africa Bureau, via Wikimedia

In stark contrast to the usual hoax stories we get in the U.S. about malaria and DDT, the United Nations General Assembly this past week passed a resolution noting progress made in fighting the parasitic disease.

Quoting wholesale from Ghana Web:

The United Nations General Assembly at its 68th Session, adopted Resolution A/68/L.60, “Consolidating Gains and Accelerating Efforts to Control and Eliminate Malaria in Developing Countries, Particularly in Africa, by 2015” by consensus.

Recognising progress made through political leadership and a broad range of national and international actions to scale-up malaria control interventions, this annual resolution urges governments, United Nations agencies, and all stakeholders to work together to meet the targets set out in the Roll Back Malaria Partnership’s Global Malaria Action Plan (GMAP) and the UN’s Millennium Development Goals (MDGs).

An official statement issued in Accra and copied the Ghana News Agency said with just less than 500 days until the 2015 deadline of the MDGs, the adoption of this resolution by the General Assembly reiterates the commitment of UN Member States to keep malaria high on the international development agenda.

“We have seen tremendous progress against this killer disease in recent years, but continued success will require increased political and financial commitment from donor and endemic governments alike. Together we can scale-up efforts and continue saving lives,” it said.

The statement said since 2001, the World Health Organisation (WHO) estimated that malaria death rates have decreased by nearly 50 per cent in Africa alone, where 90 per cent of all malaria-related deaths still occur – contributing to a 20 per cent reduction in global child mortality and helping drive progress towards UN MDG 4.

“Between 2001 and 2012, collective efforts helped avert an estimated 3.3 million deaths (69 per cent) of which were in the 10 countries with the highest malaria burden in 2000 and more than half of the 103 countries that had ongoing malaria transmission in 2000 are meeting the MDG of reversing malaria incidence by 2015.

“Despite these advances, almost half of the world’s population remains at risk from malaria, with an estimated 207 million cases of infection around the world each year and 627,000 deaths. Around the world, a child still dies from malaria every minute.

“The resolution calls for donor and endemic governments alike to support global malaria control efforts, including the secretariat of the Roll Back Malaria Partnership, and to intensify efforts to secure the political commitment, partnerships and funds needed to continue saving lives.

“Increased financing will be critical to further advancements, as current international and domestic financing for malaria of US 2.5 billion dollars in 2012 amounts to less than half of the US 5.1 billion dollars estimates to be needed annually through 2020 to achieve universal coverage of malaria control interventions,” the statement said.

In 2012, United Nations Secretary-General Ban Ki-moon named malaria as a top priority of his second mandate. Malaria control has consistently proven to be a strong global health investment, generating high return on low investments.

Impacting all eight of the United Nations MDGs, malaria prevention and treatment serves as an entry point to help advance progress against other health and development targets across the board by reducing school absenteeism, fighting poverty, and improving maternal and child health.

Did you see that report in your local newspapers, or on radio or television?

More:


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