Category Archives: Evolution

Evolution: Education and Outreach, vol. 2 issue 1.

Posted on by

This year, Evolution: Education and Outreach will have a special (but not exclusive) focus on Darwin in celebration of the 200th anniversary of his birth and the 150th anniversary of the Origin of Species.

The first issue in volume 2 is now available, once again free online.

Evolution: Education and Outreach
Volume 2, Issue 1

Editorial: Darwin’s Year
Niles Eldredge and Gregory Eldredge
1

Why Darwin?
Niles Eldredge
2-4

Artificial Selection and Domestication: Modern Lessons from Darwin’s Enduring Analogy
T. Ryan Gregory
5-27

Charles Darwin and Human Evolution
Ian Tattersall
28-34

Experimenting with Transmutation: Darwin, the Beagle, and Evolution
Niles Eldredge
35-54

Studying Cultural Evolution at the Tips: Human Cross-cultural Ecology
Lauren W. McCall
55-62

Industrial Melanism in the Peppered Moth, Biston betularia: An Excellent Teaching Example of Darwinian Evolution in Action
Michael E. N. Majerus
63-74

Assessment of Biology Majors’ Versus Nonmajors’ Views on Evolution, Creationism, and Intelligent Design
Guillermo Paz-y-Miño C. and Avelina Espinosa
75-83

Darwin’s “Extreme” Imperfection?
Anastasia Thanukos
84-89

Don’t Call it “Darwinism”
Eugenie C. Scott and Glenn Branch
90-94

Educational Malpractice: The Impact of Including Creationism in High School Biology Courses
Randy Moore and Sehoya Cotner
95-100

Scholar’s Dilemma: “Green Darwin” vs. “Paper Darwin,” An Interview with David Kohn
Mick Wycoff
101-106

The “Popular Press” Responds to Charles Darwin, The Origin of Species and His Other Works
Sidney Horenstein
107-116

Paleontology and Evolution in the News
Sidney Horenstein
117-121

Charles Darwin’s Manuscripts and Publications on the World Wide Web
Adam M. Goldstein
122-135

Teaching Evolution in Primary Schools: An Example in French Classrooms
Bruno Chanet and François Lusignan
136-140

Why Why Darwin Matters Matters
Why Darwin Matters: The Case Against Intelligent Design, by Michael Shermer. New York: Henry Holt, 2006.
Tania Lombrozo
141-143

DeSalle’s and Tattersall’s Human Origins: A Companion to The Museum of Natural History’s Hall of Human Origins and More
Human Origins: What Bones and Genomes Tell Us about Ourselves, by Rob DeSalle and Ian Tattersall. College Station: Texas A & M University Press, 2008. Pp. 216. H/b $ 29.95
Robert Wald Sussman
144-147

I am not certain whether the dedication we wrote to the late Dr. Majerus will appear online, but I am hoping it will be included in the print issue. Here it is, just in case.

This issue of Evolution: Education and Outreach includes a paper by Prof. Michael Majerus of Cambridge University, a world expert on industrial melanism and a champion of the peppered moth as an excellent example of natural selection in the wild. In it, Prof. Majerus describes the controversy surrounding the peppered moth, much of it based on misrepresentations and misunderstandings. He also describes, with extraordinary modesty, his own widely respected research which has refuted the misplaced criticism of the peppered moth example.

We consider the paper a testament to Prof. Majerus’s patience and dedication to settling debates in science as they should be settled – with evidence rather than rhetoric. In this regard, Prof. Majerus’s paper not only highlights an exquisite example of evolution in action, but also serves to illustrate how careful scientific study generates outstanding results.

It is with deep regret that we note that Prof. Majerus passed away peacefully during the night of January 26/27 from a brief but severe illness. As Prof. David Summers, Head of the Department of Genetics at Cambridge, wrote

“Mike Majerus was a traditional Cambridge scientist; a charismatic individual for whom the boundaries between life and work, and teaching and research, were very hard to discern. He was a world authority in his field, a tireless advocate of evolution and an enthusiastic educator of graduate and undergraduate students.”

We are proud to present Prof. Majerus’s article on the peppered moth and are grateful for his contribution to the journal, for his important and diligent research, and for his dedication to defending and enhancing science education. We extend our deepest condolences to his family, friends, and colleagues. He will be missed.

T. Ryan Gregory
Associate Editor

Niles Eldredge
Editor-in-Chief

Forbes on Darwin.

Posted on by

Well, I certainly don’t agree with their full selection of authors (see Pharyngula and NeuroLogica), but anyway here is the set of papers in Forbes on evolution.

The Evolution Of Evolution

By Hana R. Alberts

Surveying a landscape of cognition–and controversy.


What We See When We Look In The Mirror

By Lionel Tiger

Humankind’s epic search for existential answers.


In Praise Of A Beautiful Theory

By Michael Ruse

Why evolution matters today more than ever.

The Self-Made Species

By Denis Dutton

We fail to realize just how much evolution shapes our personalities.

You Should Believe In Love At First Sight

By Helen Fisher

Charles Darwin knew about romance.


Keeping Pace With Change

By Owen D. Jones

Why it matters that behaviors evolve.

Survival Of The (Financially) Fittest

By Leo M. Tilman

Evolutionary pressures and economic fate.

We Are The Moral Animals

By Larry Arnhart

Fear of a Darwinian, animalistic hedonism is unfounded.


From Evolution Comes Literature

By Joseph Carroll

Can we prove what we read and write is rooted in biology?


Why Evolution Doesn’t Matter

By Matt Woolsey

Forget century-old debates. Biology should inspire technology for the future.

The Reticent Abolitionist

By Adrian Desmond

Slavery is hard to justify if all species–animal, black and white–share a common ancestor.


Darwin The Dog Lover

By David Allan Feller

Canine companionship inspired evolutionary observations.

A Life In 14,500 Letters

By Paul White

Glimpses of the earnest passions behind the beard.


The Debate Over Intelligent Design

By Kathryn Tabb

What would Darwin say?


Darwinian Dangers

By Ken Ham

The Creation Museum’s founder fears moral collapse and racism.


There Is No ‘Politically Correct’ Science

By John G. West

It’s impossible to isolate Darwinian theories from their societal consequences.


A Neurosurgeon, Not A Darwinist

By Michael Egnor

Why I don’t believe in atheism’s creation myth.


The Problem Of Evidence

By Jonathan Wells

If it isn’t testable, it isn’t science.

The Man In Darwin’s Shadow

By Michael Shermer

Did Alfred Russel Wallace think up evolution first?


Alfred Russel Wallace

By Michael A. Flannery

The proponent of intelligent design in Darwin’s day.

On the Origin of Species – Chapter 2

Posted on by

Once again, this is just a repost of what I wrote in my book club discussion forum.

Chapter 2 – Variation Under Nature

This is a fairly short chapter, with much less information than the discussion of variation under domestication. In part, this is because a lot more was known about variation in domesticated animals and plants than in natural species. However, it wasn’t considered by everyone to be a good approach — Wallace always thought Darwin’s argument was weakened by relying so much on domestication as an analogy with natural processes.

Some things I found interesting in this chapter:

1) Species are hard to define. We talked in class about how there is no clear definition of species and how this causes problems in biology. Well, Darwin recognized the difficulty very early (p.67).

“Nor shall I here discuss the various definitions which have been given of the term species. No one definition has as yet satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species.”

2) Darwin begins to suggest that the variation within species (e.g., varieties) is the same stuff that turns into differences among species. He introduces the term “incipient species” to indicate this. However, not all incipient species will become species — some may go exinct and some may not change further (p.76).

“Hence I believe a well-marked variety may be justly called an incipient species; but whether this belief be justifiable must be judged of by the general weight of the several facts and views given throughout this work.

It need not be supposed that all varieties or incipient species necessarily attain the rank of species. They may whilst in this incipient state become extinct, or they may endure as varieties for very long periods.”

3) Sometimes daughter species can co-exist with parental species — it is not always a gradual change of one species into another. In other words, Darwin recognizes cladogenesis (indeed, something compatible with punctuated equilibria) and not only anagenesis (p.76) .

“If a variety were to flourish so as to exceed in numbers the parent species, it would then rank as the species, and the species as the variety; or it might come to supplant and exterminate the parent species; or both might co-exist, and both rank as independent species.”

4) Nevertheless, Darwin does not think that species are real. They are just convenient constructs (p.76).

“From these remarks it will be seen that I look at the term species, as one arbitrarily given for the sake of convenience to a set of individuals closely resembling each other, and that it does not essentially differ from the term variety, which is given to less distinct and more fluctuating forms. The term variety, again, in comparison with mere individual differences, is also applied arbitrarily, and for mere convenience sake.”

UPDATE: John Wilkins does not think that this and similar passages indicate that Darwin considered species as mere conveniences, only that he considered the distinction between varieties (which he called “incipient species”) and species to be mainly arbitrary. He may have a point.

5) Darwin suggests that widespread, numerous species are likely to produce more daughter species (p.77). This would seem to contradict later models of speciation involving geographic isolation, especially ones based on drift in small isolates.

“Hence it is the most flourishing, or, as they may be called, the dominant species,— those which range widely over the world, are the most diffused in their own country, and are the most numerous in individuals,—which oftenest produce well-marked varieties, or, as I consider them, incipient species.”

6) Darwin has compiled a series of data (he doesn’t show them here) comparing genera that are diverse (lots of species) and those that are not, and argues that larger genera include species that themselves include more varieties. He argues on this basis that dominant lineages will become more dominant, since these varieties are incipient species. However, he also notes that this does not continue indefinitely because some previously dominant lineages disappear and some small genera can expand.

On the Origin of Species – Chapter 1

Posted on by

I am not planning any official blogging of the Origin (cf. Blogging the Origin), but I am currently reading it with a few students from my evolution course just for fun. We’re discussing it online and will be meeting to talk about it every week or two. I’m posting below what I posted in our discussion forum.

Chapter 1 – Variation Under Domestication

Darwin spends a lot of time discussing the fact that domestic breeds vary. This may seem pretty obvious to us, but it was an important set up for the idea that variation is common. Remember– no variation, no selection.

He also goes to pains to convince readers that domestic breeds (e.g., of pigeons) were all descended from a common ancestor. Again, this may seem obvious to us, but as he notes (p. 50), almost all breeders assumed that each breed was descended from a different wild ancestor. So, he is using these examples to establish common descent and branching.

Several important ideas already appear in the chapter:

1) Although he didn’t know how heredity works he knew it is crucial for his mechanism (p.33).

“Any variation which is not inherited is not important for us.”

2) Differences between modern organisms may be so great that it is difficult to imagine that they share common ancestors — he used the example of pigeons, which would be classified as different species if a taxonomist didn’t know they were domestic breeds because they look so different (p.44). And yet, all the information indicates that they are descended from the same ancestor species.

“Altogether at least a score of pigeons might be chosen, which if shown to an ornithologist, and he were told that they were wild birds, would certainly, I think, be ranked by him as well-defined species. Moreover, I do not believe that any ornithologist would place he English carrier, the short-faced tumbler, the runt, the barb, pouter, and fantail in the same genus”.

3) Selection is the main mechanism of change. Not crossing, not effects of environment, and so on (p.66).

“Over all these causes of Change I am convinced that the accumulative action of Selection, whether applied methodically and more quickly, or unconsciously and more slowly, but more efficiently, is by far the predominant Power.”

4) Selection is about the accumulation over many generations of almost imperceptibly slight changes (p.52-53). The emergence of breeds is gradual, probably too much to notice as it is occurring (p.62).

“We cannot suppose that all the breeds were suddenly produced as perfect and as useful as we now see them; indeed, in several cases, we know that this has not been their history. The key is man’s power of accumulative selection: nature gives successive variations; man adds them up in certain directions useful to him. In this sense he may be said to make for himself useful breeds.”

“But, in fact, a breed, like a dialect of a language, can hardly be said to have had a definite origin. A man preserves and breeds from an individual with some slight deviation of structure, or takes more care than usual in matching his best animals and thus improves them, and the improved individuals slowly spread in the immediate neighbourhood. But as yet they will hardly have a distinct name, and from being only slightly valued, their history will be disregarded. When further improved by the same slow and gradual process, they will spread more widely, and will get recognised as something distinct and valuable, and will then probably first receive a provincial name.

…

But the chance will be infinitely small of any record having been preserved of such slow, varying, and insensible changes.”

5) Selection is known to occur, at least with breeding (p.52, p.55).

“The great power of this principle of selection is not hypothetical.”

6) Most changes are ignored (neutral) or detrimental, but some are noticed and selected (p.61).

“Nor let it be thought that some great deviation of structure would be necessary to catch the fancier’s eye: he perceives extremely small differences, and it is in human nature to value any novelty, however slight, in one’s own possession. Nor must the value which would formerly be set on any slight differences in the individuals of the same species, be judged of by the value which would now be set on them, after several breeds have once fairly been established. Many slight differences might, and indeed do now, arise amongst pigeons, which are rejected as faults or deviations from the standard of perfection of each breed.”

7) Selection doesn’t require conscious effort. It can be unconscious (p.56).

“…a kind of Selection, which may be called Unconscious, and which results from every one trying to possess and breed from the best individual animals, is more important. Thus, a man who intends keeping pointers naturally tries to get as good dogs as he can, and afterwards breeds from his own best dogs, but he has no wish or expectation of permanently altering the breed.”

8) Large populations are best for selection (p.63).

“But as variations manifestly useful or pleasing to man appear only occasionally, the chance of their appearance will be much increased by a large number of individuals being kept; and hence this comes to be of the highest importance to success.

…

When the individuals of any species are scanty, all the individuals, whatever their quality may be, will generally be allowed to breed, and this will effectually prevent selection.”

9) If breeds are going to diverge, they must not interbreed (i.e., what we would now say means blocking gene flow) (p.64).

“In the case of animals with separate sexes, facility in preventing crosses is an important element of success in the formation of new races,—at least, in a country which is already stocked with other races. In this respect enclosure of the land plays a part.

…

On the other hand, cats, from their nocturnal rambling habits, cannot be matched, and, although so much valued by women and children, we hardly ever see a distinct breed kept up; such breeds as we do sometimes see are almost always imported from some other country, often from islands.”

The accurate language challenge, part II.

Posted on by

Once again, the challenge is to translate sloppy shorthand into technically accurate explanations for what is going on…

As microbes evolve, they adapt to their environment. If something stops them from growing and spreading—such as an antimicrobial—they evolve new mechanisms to resist the antimicrobials by changing their genetic structure. Changing the genetic structure ensures that the offspring of the resistant microbes are also resistant.

http://www3.niaid.nih.gov/topics/antimicrobialResistance/Understanding/history.htm

________________________
Get your Darwin Year gear here.

The accurate language challenge, part I.

Posted on by

Here is a little exercise I use in my evolution class. I post a segment of a news story that describes an evolutionary process in sloppy terms and then ask the students to translate it into language that accurately describes what is going on.

Here’s one from today’s Discovery News.

Lizards Evolved Quickly to Avoid Death by Ants

It takes some effort for fire ants to get under the hard scales of an unsuspecting lizard. When the insects finally penetrate the reptile’s fleshy core, the attackers inject a toxin that paralyzes their victim. Then, they tear the lizard to pieces, which they carry back to their nest.

…

It’s an unpleasant way to die, and one that at least one species of lizard is rapidly evolving to avoid. In just 70 years, according to a new study, eastern fence lizards in parts of the United States have developed longer hind limbs and new behaviors that help them escape the clutches of the venomous ants.

Have at it!

(Hint: Start your answer with “Within a population of lizards…”)

________________________
Get your Darwin Year gear here.

Darwin’s note on higher and lower.

Posted on by

Here is a page from Darwin’s 1837 notebook. (Click for larger image)

In case you can’t read his handwriting (few can), it says

It is absurd to talk of one animal being higher than another. We consider those, when the cerebral structure / intellectual faculties most developed, as highest. A bee doubtless would when the instincts were.

________________________
Get your Darwin Year gear here.

Worse than lower and basal.

Posted on by

Why can’t reports in the media accurately convey the basics of evolution? And why can’t scientists make a dedicated effort to clarify things whenever they give an interview? What hope is there for clarifying the most fundamental concepts when every story seems to reinforce misconceptions?

From the Discovery Channel:

Ancestor For All Animals Identified

A sperm-looking creature called monosiga is the closest living surrogate to the ancestor of all animals, according to new research that also determined animal evolution may not always follow a trajectory from simple to complex.

Yet another find of the study, published in the latest PLoS Biology, is that Earth may have given rise to two distinct groups of animals: bilaterians — animals with bilateral symmetry, like humans — and non-bilaterians, which include corals, jelly fish, hydra, unusual, often poisonous, creatures known as cubozoans, and other organisms.

Free-living, unicellular organisms called choanoflagellates, however, could be on every person’s family tree, so long as it was a gigantic one.

…

They determined that so-called “simple” and “lower” tier animals, such as corals and jellyfish, evolved in parallel to “higher” animals, like seemingly more complex insects and even humans. On the tree of life, monosiga then currently holds the root position for the latter group.

Please, let’s try to get this right from now on. No study reconstructing phylogenetic relationships between modern taxa tells you what the ancestor of those taxa was. It may provide some clues, but all species being examined are derived in some ways and primitive in others.

Trichoplax is not your ancestor.
You share a common ancestor with it.

No biologist who knows anything about evolution would suggest that evolution “always follow[s] a trajectory from simple to complex”. There is no such thing as “higher” and “lower”, though this pre-evolutionary idea apparently is hard to abandon.

And not every rearrangement of proposed evolutionary relationships is a revolution. Many of the deep nodes have been enigmatic for a long time, so it’s not a surprise when they move around based on improved information. Here is how I, an evolutionary biologist, react to each new molecular phylogeny that moves animal branches around:

“Neat. I wonder if it will hold up. It will be interesting to think about what this means in terms of major patterns.”

For a much better take on this new phylogeny written by someone with expertise, see Todd Oakley’s latest post. If we could just get more scientists to write blogs…

(Incidentally, the idea that the ancestors of animals were choanoflagellate-like organisms dates to the 19th century. I even parodied this well-known idea on a shirt).

________________________
Get your Darwin Year gear here.

Lower and basal.

Posted on by

The story:

New Tree Of Life Divides All Lower Metazoans From Higher Animals, Molecular Research Confirms

The response:

“It is absurd to talk of one animal being higher than another” (Charles Darwin, 1837)

More information:

Understanding evolutionary trees

(By the way, Rob DeSalle, who is quoted in the story, was one of my postdoc advisors and he definitely understands phylogenies — but the story is pretty sloppy nonetheless)

Don’t call it Darwinism

Posted on by

For those of you who still are not reading Evolution: Education and Outreach, here’s another reason to check it out.

Eugenie Scott and Glenn Branch of the National Center for Science Education have a nice article coming out in the next issue entitled “Don’t call it Darwinism“. It is already free to access in preprint.

While you’re at it, you can have a look at the special issue on eye evolution, and my first contribution to a series entitled “Evolutionary Concepts” on artificial selection.