Red-capped manakin moonwalk

February 20, 2009 • 1:27 pm

To continue the series of bizarre bird dances demonstrating the ways that sexual selection can mold behavior, I present a short film of the red-capped mankin “moonwalk”, taken in Costa Rica.  The species is Pipra mentalis, whose males shuffle down branches while courting. Stiles & Skutch (1989) in A Guide to the Birds of Costa Rica, describe this behaviour of the male as “backwards slides with legs stretched up and yellow thighs exposed.” There are other unique aspects to the courtship behavior as well, including swooping and wing-slapping.

Darwin proclaimed wrong AGAIN; we fight back!

February 19, 2009 • 2:13 pm

The January 24th issue of New Scientist had a garish cover showing the tree of life, with the words “DARWIN WAS WRONG” emblazoned over it.   An editorial bemoaned the phylogenetic errors of the old man, adding a few other buzzwords as well:

A particularly pertinent example is provided in this week’s cover story – the uprooting of the tree of life which Darwin used as an organising principle and which has been a central tenet of biology ever since (see “Axing Darwin’s tree”). Most biologists now accept that the tree is not a fact of nature – it is something we impose on nature in an attempt to make the task of understanding it more tractable. Other important bits of biology – notably development, ageing and sex – are similarly turning out to be much more involved than we ever imagined. As evolutionary biologist Michael Rose at the University of California, Irvine, told us: “The complexity of biology is comparable to quantum mechanics.”

The editors knew in fact that this sensationalistic cover would be appropriated by creationists (as it indeed was), but still said that a “revolution” in biology was in the offing:

As we celebrate the 200th anniversary of Darwin’s birth, we await a third revolution that will see biology changed and strengthened. None of this should give succour to creationists, whose blinkered universe is doubtless already buzzing with the news that “New Scientist has announced Darwin was wrong”. Expect to find excerpts ripped out of context and presented as evidence that biologists are deserting the theory of evolution en masse. They are not.

What is so wrong with the tree of life?  Well,  an article by Graham Lawton asserts that horizontal gene transfer (the movement of bits of DNA between species by “infection”), a phenomenon often seen in bacteria and some protists, and occasionally in complex metazoa, invalidates the whole idea of a tree with bifurcating branches.  This, of course, is nonsense.  Such gene transfer may fuzz out or even obscure genealogies in some prokaryotes, but nobody thinks it’s going to efface the genealogy of most other groups.  Can we expect to find that we’re really more closely related to gibbons than to chimpanzees, a truth that has been obscured by massive horizontal transfer from eating bush meat?  Don’t expect huge changes in the genealogy of life that we’ve already assembled from molecular data.

And chalk up another erroneous and irresponsible journalistic asssertion that Darwinism is dead.  Several of us, including Dan Dennett, P. Z. Myers, and Richard Dawkins, wrote a letter (“Darwin was Right”)  to the editor of New Scientist. You can find it here.  An excerpt:

Of course there’s a tree; it’s just more of a banyan than an oak at its single-celled-organism base. The problem of horizontal gene-transfer in most non-bacterial species is not serious enough to obscure the branches we find by sequencing their DNA. . . .

The accompanying editorial makes it clear that you knew perfectly well that your cover was handing the creationists a golden opportunity to mislead school boards, students and the general public about the status of evolutionary biology. Indeed, within hours of publication members of the Texas State Board of Education were citing the article as evidence that teachers needed to teach creationist-inspired “weaknesses of evolution”, claiming: “Darwin’s tree of life is wrong”.

“Revolutionary” sentiments are rife  in evolutionary biology, but let’s be a little careful before we throw away a paradigm which has, after all, proved to be largely correct for a century and a half.  I didn’t anticipate that Darwin Year would bring the neo-Kuhnians out of the woodwork to clamor for an Extended Evolutionary Synthesis. I still can’t see what’s wrong with the old one!

new-scientist

Chicken head tracking: a marvel of evolution

February 19, 2009 • 8:19 am

Many birds can keep their heads absolutely stationary while their bodies move around. (Think, for example, of a hummingbird sipping nectar from a flower while its body moves all around.)  This is an adaptation to keep the bird’s perception of the environment constant despite other gyrations of the body (such as the bobbing motion of a walking pigeon).  One of my friends called my attention to this YouTube video of the phenomenon, involving a guy holding a chicken.  It’s absolutely amazing–so much so that I wanted to try it myself. When I was in North Carolina this weekend, I visited a friend who has a pet chicken, and we tried out this maneuver with the bird.  Sure enough, the head remained stationary.  I am informed that a reputable journal will soon have a short article about bird head tracking, and I’ll post a linke to it here when it’s published in a month.

Addendum: the same guy demonstrates the phenomenon with a lovely purple martin.

Two articles about animal morality

February 17, 2009 • 5:30 am

Re the most recent discussion about whether the rudiments of morality may be found in our relatives, an alert reader has called my attention to two articles in today’s (UK) Telegraph, here and here, that briefly describe Frans de Waal’s work on chimps and monkeys, indicating that they show the building blocks of morality. I am really not an expert on this topic, but it seems to have arisen spontaneously. From the first article:

Although morality has always been viewed as a human trait that sets us apart from the animals, it now appears our closest ancestors share the same scruples.

Scientists have that discovered monkeys and apes can make judgements about fairness, offer sympathy and help and remember obligations.

Researchers say the findings may demonstrate morality developed through evolution, a view that is likely to antagonise the devoutly religious, who see it as God-given.

Professor Frans de Waal, who led the study at Emory University in Georgia, US, said: “I am not arguing that non-human primates are moral beings but there is enough evidence for the following of social rules to agree that some of the stepping stones towards human morality can be found in other animals.”

Are we ready for an “extended evolutionary synthesis”?

February 16, 2009 • 3:30 pm

Over at Time magazine, Carl Zimmer has a good essay, “The Ever Evolving Theories of Darwin”, about Darwin’s contributions and what has happened in evolutionary biology since 1859. The essay was kind of spoiled for me, though, by the ending, in which Zimmer seems to buy into something he calls the “extended evolutionary synthesis”. To quote Zimmer:

In the mid-1900s, biologists succeeded in merging the newest biological developments at the time into a new vision of evolution known as the Modern Synthesis. Today a number of biologists argue that it’s time for a new understanding of evolution, one that Pigliucci has called the Extended Evolutionary Synthesis. For now, they are fiercely debating every aspect of that synthesis–how important gene-swapping is to the course of evolution, for instance, and how gene networks get rewired to produce new traits.

Some researchers argue that many patterns of nature–such as the large number of species in the tropics–cannot be reduced to the effect of natural selection on individuals. They may be following rules of their own. “Which of these ideas is going to actually survive and prove fruitful is anybody’s guess,” says Pigliucci. “I don’t see things coalescing for at least a decade or more.”

It seems to me that a science journalist should do more than simply tell their readers that something new is in the air: a journalist should EVALUATE these new claims. If all one did was say “some evolutionists think. . .”, and then describe their thoughts, any old claim could get press.

It just isn’t true to say that every aspect of the Modern Synthesis is fiercely debated. Richard Goldschmidt, the most distinguished contemporary opponent of the Modern Synthesis, was wrong about speciation, about mutation, about genetics, about the origin of higher taxa, among other things; the Synthesis got all of these pretty much right. Much of WEIT summarizes general conclusions originating in the Modern Synthesis (and the abundant evidence that supports them), about which consensus in evolutionary biology is both broad and deep (WEIT is the 250-page version; for a two-page version of the conclusions, see pp. 10 and 11 of Doug Futuyma’s Evolution, Sinauer, 2005).

And who ever said that the pattern of greater species diversity in the tropics could be completely explained by natural selection? There is the little matter of differences in climate, habitat, and geological history. We already know pretty much that gene-swapping is unlikely to be important in the evolution of many species, like vertebrates (it may play some role, but surely not a major one!), and nobody has suggested that gene networks get rewired by any means other than natural selection.

We have surely gone way beyond Darwin in our understanding of the pattern and process of evolution. But I am irritated by the constant appearance of what I call “BIS”–the Big Idea Syndrome. An evolutionist finds a new phenomenon, say transposable elements, or epigenetics, or “modularity,” and suddenly that one phenomenon becomes the centerpiece of a claim that modern evolutionary theory is ripe for a revolution. Yet when you look for the beef, it isn’t there. Where are all the examples of genetic assimilation, a phenomenon that was said to completely overturn our views?

I may sound curmudgeonly here, but it behooves all of us—especially journalists—to think twice before proclaiming that evolutionary biology is about to experience the equivalent of quantum mechanics.

Note added:  Over at his blog, Rationally Speaking, Massimo Pigliucci has taken issue with my characterization of the “extended synthesis” debate, and I recommend that people read his  case for this synthesis.  I don’t want to get into squabbling, but want to make one point. Massimo says the following:

Jerry is “irritated” by what he calls “BIS–the Big Idea Syndrome,” where any new idea that comes about, be it modularity, evolvability, evolutionary capacitors, epigenetic inheritance, phenotypic plasticity, genetic accommodation, species selection, cis-regulatory evolution, and so on and so forth, “becomes the centerpiece of a claim that modern evolutionary theory is ripe for a revolution.” Again, nobody I know is calling for a revolution, but the above mentioned ideas and empirical evidence cannot simply be filed away as “more of the same.”

Well, I beg to differ, and I think anyone who has read the literature on evo devo, genetic assimilation, modularity, and the like will realize that some of their proponents (I don’t want to name names here) are self-consciously claiming that neoDarwinism is incomplete in very important ways, and that some new viewpoints (not just new data or phenomena) are needed.  Let’s look at part of the invitation to the Altenberg 16 conference:

As you know because you have been involved in this to some extent, for some time now there have been persistent rumors that the Modern Synthesis (MS) in evolutionary biology is incomplete, and may be about to be completed. Such suggestions have been received with skepticism by a number of biologists, including some of the very originators of the MS.

The challenge seems clear to us: how do we make sense, conceptually, of the astounding advances in biology since the 1940s, when the MS was taking shape? Not only we have witnessed the molecular revolution, from the discovery of the structure of DNA to the genomic era, we are also grappling with the increasing feeling – for example as reflected by an almost comical proliferation of “-omics,” that we just don’t have the theoretical and analytical tools necessary to make sense of the bewildering diversity and complexity of living organisms.

This implies, at least to me, that we cannot grasp “the bewildering diversity and complexity of living organisms” without some new tools and insights.  I am not yet willing to sign onto this, because I think the theoretical tools–the idea of natural selection and mathematical population genetics–are already at hand, and although we may get new analytical tools (such as genomics!), the rest is just hard grinding work trying to understand speciation and natural selection in the wild.  I may be wrong, but I don’t scent revolution in the wind yet.

I close with a statement by my old mentor, Dick Lewontin, who of course as an old Marxist would be in favor of revolutions:

“The so-called evolutionary synthesis – these are all very vague terms. . . . That’s what I tried to say about Steve Gould is that scientists are always looking to find some theory or idea that they can push as something that nobody else ever thought of because that’s the way they get their prestige. . . .they have an idea which will overturn our whole view of evolution because otherwise they’re just workers in the factory, so to speak. And the factory was designed by Charles Darwin.”

Do animals have morality? A response: “For I will consider my cat Peyton”

February 16, 2009 • 1:18 pm

peyton1

A moral cat?

An alert reader, my friend and colleague Dr. Greg Mayer from The University of Wisconsin, Parkside, read Steven Pinker’s thoughts on the evolution of morality (posted below) and informed me that he saw the rudiments of morality in his cat Peyton (pictured above). I asked him why, and he responded with an answer so cogent that I thought it deserved posting. To wit:

My cat's morality

In his post on the material mind, Steve Pinker mentions the rudimentary moral sentiments-- "sympathy, trust, retribution, gratitude, guilt". I’m pretty sure my cat, Peyton, has some of them. Gratitude and guilt– maybe; retribution– probably not; but sympathy and trust– absolutely.

The cat I had as a child used to catch small mammals in the yard, and then bring them back to the house. Many cats do this, and some interpret this as the cat sharing its prey with its (human) family, which might be gratitude. Peyton is an indoor cat, and so has no opportunity to share what she’s caught. But it might be that the sympathy and trust she shows to us can be seen as an expression of gratitude. Guilt I’m not sure about. She knows when we disapprove strongly of something she's done (as long as the disapproval is expressed immediately– you can't remonstrate with her over things that are over and done with), and she'll behave in a particular way (slink off), but what her mental state is like is hard to know.

But about sympathy and trust, I’m sure. She lets us do things with her (like playing Spidercat– this involves holding her upside down near the ceiling) that she would not tolerate from other creatures or people. She routinely exposes her belly and throat for scratching in a way that goes beyond mere pleasure seeking, because it makes her vulnerable, and thus trust must accompany the seeking of tactile pleasure. And in various forms of play, she holds back from scratching and biting strongly. Scratching and biting are key elements of cat play– what makes them play, instead of fighting or predation, is the cat's withholding of its effort so as not to injure the playmate. It's easiest to demonstrate the existence of sympathy and trust by seeing what happens when they're removed. We have to put her in a travel case to take her to the vet. She resists going in, because her trust is reduced by the odd circumstances, which she experiences very infrequently (ca. once per year). On leaving the vet's office, she more fully understands that the case and a trip in the car (which she doesn't like) are coming. She has now lost sympathy with us, and claws in ways designed to prevent her from going into the case, and she draws blood if the people are not careful. Thus the many incidents of play are revealed to be not some inability of the cat to fight effectively with people, but as a voluntary withholding of the full force of her defenses– sympathy.

I may seem like a raving anthropomorphizer here, but the differences in cognitive state, when you live in close contact with them (or observe them carefully in the wild) among amphibians, reptiles, and mammals (especially predatory mammals) are astounding. Darwin, of course, lived most of his life in the country, raised pigeons, and always had dogs which he studied carefully (see especially The Expression of the Emotions in Man and Animals), and I think this helped him to see the continuity of behavior, especially social, and even moral, between man and the animal kingdom. It's a little harder to notice with mice and hamsters (which, when kept as pets, tend not to be handled as much as cats and dogs), but the cognitive advance of Peyton over my turtle (who has a gentle disposition, and is noticeably brighter than my giant toad) is striking.

Thanks to Greg for this, and of course to the highly ethical Peyton as well.

Times of London reviews WEIT, and a Darwin MOVIE

February 15, 2009 • 7:30 pm

An alert reader has called my attention to a (very nice) review of my book in the Times of London on Feb. 12. It also reviews three other Darwin books (including Desmond & Morris’s book and one by the old man himself), and also calls attention to an upcoming Darwin movie that will be called “Creation”:

A fictionalised version of the great naturalist appeared in Tarsem Singh’s eccentric fantasy The Fall in 2006. Clad in a furry red coat and riding boots, Darwin found himself in the company of an African prince and Alexander The Great. But film fans will have to wait until later this year for a meaty, historically accurate exploration of his life. Adapted from Annie’s Box, an acclaimed book by Randall Keynes, Darwin’s great-great-grandson, Creation will link the death of Darwin’s daughter, Annie, to the writing of On the Origin of Species.

Male long-tailed manakins display in pairs to a female

February 15, 2009 • 3:02 pm

A way cool movie on the BBC website, highlights a new finding that these neotropical birds display in pairs, and are presumably unrelated, ruling out kin selection (they don’t talk about this in the article). How this evolved, if it’s not due to kin selection, is unclear, but the authors hypothesize that while the alpha male gets the female, the beta male eventually inherits the mating site. I don’t get it unless the alpha male is always older, or later finds another site, which doesn’t make sense. But anyway, the movie is great . . .

Note, a direct link, with better resolution, is here.