Alfred Russel Wallace (1823-1913)

February 17, 2013 • 12:00 pm

by Greg Mayer

As ever-alert reader Dominic has reminded us, 2013 is the centenary of Alfred Russel Wallace’s death, and it is thus an appropriate time to reflect on the many contributions of this great scientist who was, along with Charles Darwin, the co-discoverer of natural selection.

Alfred Russel Wallace (1823-1913) in Singapore, 1862
Alfred Russel Wallace (1823-1913) in Singapore, 1862.

Like Darwin, who was his older contemporary, Wallace’s views on natural history were developed and brought to a head by extended travel and collecting, in Wallace’s case first to the Amazon, and then the Malay Archipelago. It was in Sarawak that Wallace wrote his first staunchly evolutionary paper, “On the Law which has regulated the Introduction of New Species”. In this paper he noted that new species arise adjacent in time and space to those to which they bear closest affinity, similar to Darwin’s observations on the former and current organic inhabitants of South America. Three years later he wrote the “Ternate paper”, in which he introduced a concept of natural selection very close to Darwin’s, the receipt of which by Darwin led to the joint publication in 1858 of Wallace’s paper along with extracts from Darwin’s unpublished works.

Wallace went on to make important contributions in selection theory, adaptive coloration, behavior, systematics, and, especially, biogeography. He was also a devoted socialist and, later in life, a spiritulaist. One of his least known efforts is his involvement in the life on Mars debate: he was a strong opponent of Percival Lowell‘s views, and wrote a book arguing against life existing on Mars, especially that Lowell’s “canals” were evidence for it. (Wallace was right about the canals, though Lowell may turn out to be right about life.)

One of the most important events surrounding the centenary has already occurred, and Matthew noted it here on WEIT at the time: the launch of Wallace Online, a wonderful website modeled on Darwin Online, and, like the latter, directed by John van Wyhe of the National University of Singapore. We have long been fans of John and Darwin Online here at WEIT. I urge all of you to go right this minute to Wallace Online and begin exploring the many astounding and amazing resources available there. The place to start is John’s brief but pithy biography of Wallace. Among John’s chief collaborators are Kees Rookmaaker, who has also contributed much to the Darwin project, and Charles Smith of Western Kentucky University. We have had occasion a number of times to link to Smith’s very valuable website, the Alfred Russel Wallace Page, and I am very glad to see such accomplished Wallaceophiles collaborating on this new project.

The Natural History Museum in London (or, as we systematists with a memory know it, the BM(NH)) also has a fantastic website devoted to the centenary, with links to many documents and images, all superintended by George Beccaloni, another noted Wallaceophile, who is also keeping a “blog” on the subject. We hope to have a number of Wallaceocentric items here at WEIT in the coming year.

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Darwin, C. R. and A. R. Wallace. 1858. On the tendency of species to form varieties; and on the perpetuation of varieties and species by natural means of selection. Journal of the Proceedings of the Linnean Society of London. Zoology 3 (20 August): 46-50. (pdf)

Wallace, A.R. 1855. On the law which has regulated the introduction of new species. Annals and Magazine of Natural History (ser. 2) 16 (93): 184-196. (pdf)

Wallace, A. R. 1907. Is Mars Habitable? A Critical Examination of Professor Percival Lowell’s Book “Mars and its Canals,” with an Aternative Explanation. London: Macmillan. (full text, including page imagespdf)

Results: the Teddy Experiment

February 17, 2013 • 8:33 am

Yesterday I described an experiment I conducted with my late tomcat Teddy.  When he trotted from the hallway of my apartment (where he greeted me in front of the elevator), into the apartment itself, his tail changed from the wary horizontal position to the happy vertical position.  At what point during the transit from hallway to safehouse did Teddy’s tail go vertical?

I mentioned two hypotheses: when his head crossed the doorway (which would suggest that perception of the brain being inside was sufficient to induce happiness) or when his entire body had passed through the doorway, indicating that Teddy knew when his whole self was safe inside the apartment.

Most people voted for the latter, but a few suggested “head alone”

The answer: the tail went vertical only when Teddy’s whole body was inside.

I repeatedly observed that the moment Teddy’s butt (“bum” for you Brits) passed over the threshold of my place, his tail would rise up instantly.

Conclusion: Teddy became mentally secure only when he knew that his entire body was out of harm’s way, safe in my crib.

Now there’s a paper for Nature! (One would, of course, have to test many cats.)

Uncle Eric goes all anti-scientistic, argues for “ways of knowing” other than science

February 17, 2013 • 7:02 am

I am a big fan of the avuncular Eric MacDonald, our Official Website Uncle™, not only because he abandoned a position as an Anglican priest to become a “strident” atheist, but also because he fights for the right to commit assisted suicide, argues forcefully against the stupidities of theology, and, not the least, has been gracious and helpful in guiding me through my readings in theology.  It is thus with some trepidation that I must take issue, as I have before, with Eric’s arguments against the sin of “scientism.”

In his latest post at Choice in Dying, “Getting things into perspective,” Eric warns against the dangers of scientism, which he defines as “the view that scientific knowledge, and scientific knowledge are all-encompassing and exhaustive of the entire scope of human knowledge.”  He argues, as he has in the past, that there are “ways of knowing” beyond those used by science.

What areas involve those ways of knowing? Eric, arguing first that religion is not one of them, nevertheless sees two:

1. History. I quote:

it is commonly objected that historical knowledge is, in the requisite sense, scientific, since it depends upon evidence, and may even make predictions as to what we will find in the public record or in archaeological digs. For several reasons this does not seem satisfactory to me, since it is clear that our historical understanding of events changes over time. Gibbon’s history of The Decline and Fall of the Roman Empire, for example, with its wealth of often reliable detail, is also quite clearly a product of its time. No one, while they might use and even confirm much of the factual material that is contained in Gibbon’s volumes, would write a history of the fall of Rome in quite the way that Gibbon does, with his particular social and political emphases. Histories of the First World War often, according to Hew Strachan’s The First World War, by failing to take into consideration the time and circumstances in which the Great War took place, also fail to understand why, at the time, this was considered to be, not an absurd and monstrous waste of life, but of the first importance for the future of civilisation; and he points out the paradox that results from this assessment of the Great War’s meaninglessness. . .

It is important to note that whether we look at the world in one way rather than another does not obviously depend on the factual evidence that can be brought to bear on the question of the correct interpretation or understanding of the events in question.

The question that arises for me on the basis of considerations such as this. . . is whether we have, then, in history, a “way of knowing” which is distinct from that of science? My own view is that it is the notion of “ways of knowing” that is the problem here, not the fact that there are different types of knowledge, all of which, to some degree, depend upon evidence, but none of which can be simply subsumed under science as the paradigm case of what we understand when we speak about knowledge or truth.

I think Eric is conflating here the facts of history with the interpretation of history.  And yes, those facts can change with time, but so can scientific facts. Facts of history and science are both provisional, depending on the current state of knowledge and new evidence that arises. But this says nothing about whether empirical evidence, reason, doubt, and consensus about the evidence—in other words, the tools of science—aren’t the way to find out what happened in history.

Yes, I am construing science broadly here, as a “methodology for finding out truths about the universe,” and that methodology is pretty much the same whether one is a historian or a scientist. If you construe “science” more narrowly, as “the body of knowledge accumulated by scientists,” then yes, historical facts don’t come from science. But that misses the point. The way one finds out that Julius Caesar existed is pretty much the same way we find out that the supercontinent Pangaea existed—through historical reconstruction and tangible evidence.

Really, it matters to me very little whether one argues that history is a branch of science or not. What matters to me is that they use the same methods to establish what really happened in our universe. And of course how one views the relative importance of various factors in history is often not something subject to empirical adjudication, but is simply a philosophy or worldview. It is interpretation, not fact. So what?

2. Morality. I quote Eric again:

I do want to deny that religion, for instance, has anything resembling knowledge of the things about which it speaks. But I also want to claim, contrary to those who hold that science is the paradigm case of knowledge, that we can also have moral knowledge, and that, in terms of our knowledge about morality, it is morally wrong that people should be prevented by the state or any other organisation from asking for help to die when their suffering has become intolerable. I think that is an offence against the good, just as I believe that torture or deliberate cruelty in war are opposed both to duty, and to the rights of others, whether innocents or combatants, not to be subject to cruel and unusual treatment. But I do not think there is a “way of knowing” associated with those convictions, if by that is meant a particular methodology which is uniquely distinct from the methodological naturalism of science. Nevertheless, it is vital to understand that, notwithstanding morality’s relating to a domain of knowledge which is not simply continuous with science, or subject to the canons of scientific truth, it does not follow that rational grounds for accepting moral claims are not required by those who hold that something is or is not the right or the wrong thing to do.

None of us argue that rationality and evidence can’t inform moral claims. If you think abortion is wrong because fetuses feel pain, science can in principle investigate that. If you think that torture is wrong because in no case can the suffering of one individual prevent the suffering of many, that’s amenable to investigation, too.  But what is not amenable to empirical investigation is the claim that “it is objectively wrong to allow people to commit suicide in certain circumstances.” To make that claim, you have to add another proviso, one that explains the “objective wrong”—and that is a claim that involves preferences that can’t be decided objectively.

For example, Eric may argue that assisted suicide is good because it relieves people’s suffering and has no down side for society, so in the main it is a social good. That’s a rational argument—and one I happen to agree with—but it still depends on defining “relief of suffering without detrimental social effects” as a “moral good.”  Now the effects of allowing assisted suicide can be observed empirically, but the decision that what is “moral” depends on nonempirical considerations. Like Eric, Sam Harris takes it to be an objective question; for Sam, what is “moral” is “what increases well being.” But that itself is a subjective decision, and I can imagine some situations in which what we feel is moral actually decreases overall well being. (Because I generally agree with Sam, though, I think that in such situations one should reassess one’s idea of what is moral.).  And then there is the thorny problem of agreeing what represents well being: how to weigh off the various and conflicting effects that an act has on society.  That, too, may be a purely subjective matter, not capable of being adjudicated by empirical reason. How do you trade, for example, wealth against health?

I am starting to think that we should dispense with the idea of “moral” and “immoral” acts for two reasons. The first is because the notion of morality is implicitly connected with free choice, that is, with “free will” in the dualistic sense. I don’t think we have that kind of free will. And if one can’t choose one’s acts freely, then one can’t decide to be “moral” or “immoral.” Rather, as a consequentialist, I’d replace “morality” with what it really means for most people, “the overall effects of an act on an individual or society.” Thus an “immoral act” might better be seen as “an act that reduces societal well being.” There are some problems with that, too (two are mentioned above), but I won’t go into that now.

What disturbs me most about Eric’s piece comes near the end, where he levels the accusation that scientists can resemble ideologues, and science an ideology. This comes perilously close to what creationists say. I quote Eric again:

I take Steven Weinberg’s saying very seriously, that

“[w]ith or without religion, good people can behave well and bad people can do evil; but for good people to do evil — that takes religion”. [see Wikiquote]

However, I would add: “or any other absolute ideology.” It seems to me that what people are calling and defending as scientism might itself be prone to being used in such ways. Indeed, anything which tries to draw a fence around truth, and to corral and confine it in ways that cannot be justified without contradicting the truth so defined, is in danger of creating an ideological view of the world which, in time, might well lead to inhumanity and evil.

And that is what worries me about the term that is so often heard from the defenders of science as the only source or domain of truth, that that claim itself is not a scientific one, and, as such, already takes the first step towards an ideological (dare I say?) idolisation of science. That is one of the reasons why idolatry has often been considered the original sin of religion, that it takes the limited human understanding of the object of its worship and obedience, absolutises that, and allows such an absolute to guide its beliefs and actions without qualification. Many people have said that Hitler’s social Darwinist ideal of the survival of the fittest, and the eugenic policies and racial theories that stemmed from that — and which led, in the end, to so many and such unimaginable atrocities – was perverted science, but, if so, it was perverted science of which scientists themselves were not entirely free, for scientists are as prone to quasi-religious absolutism as any other human being, for whom certainty or near certainty is always a temptation and a danger.

I would ask Uncle Eric here: do you really believe that? If so, could you name some of the scientists who are guilty of “quasi-religious absolutism”? Am I (or Richard Dawkins) one of them?

Eric is dead wrong here. Those scientists whom he views as scientistic absolutists have a love of art, music, and are prone to all kinds of emotional experiences that, for the nonce, don’t fall in the purview of science. I could not for a minute explain to you, using reason and observation, why I think “The Dead” is the greatest thing ever written in the English language.  What we (or I) maintain is that the only way to find out what is real in the universe is to use the methods formalized by science: reason, observation, doubt, replication, and consensus.

And it is a base canard (duck + OH) for Eric to bring up Hitler in this connection.  Eric really needs to read Gary Hill’s essay, “Fundamental flaws underlie the myth that Darwin influenced Hitler.” Had Darwin not existed, I am absolutely sure that the Holocaust would still have happened. All it took was antisemitism (that’s from religion, Eric) and politial ideology. The notion of genocide also is deeply religious (viz.,the Old Testament). If you want, you can throw in selective breeding as a “scientific” rationale for exterminating a supposedly inferior group, but artificial selection came long before Darwin.  If Eric wants to maintain that scientists are ideologues who resemble the faithful, let him give examples, and not just a few, either! I deny that accusation, and think that the notion that “scientists are as prone to quasi-religious absolutism as any other human being” is a vile and baseless claim. Are we just as absolutist as, say, Southern Baptists?

At any rate, at the end Eric explains why he wants to include morality as a “way of knowing”:

. . . I sometimes fear that in the ready acceptance of a near apotheosis of science, some contemporary nonbelievers, including myself, are in danger of overestimating the reach of their thought, and are therefore in danger of establishing a form of dogmatism that it is essential that we avoid. One of my primary concerns is that this dogmatism is quickly adopting a form of moral relativism that will make it impossible with any integrity to continue to speak even of the moral importance of truth, let alone of anything else. If science is, as some people have begun to say, not only paradigmatic of knowledge, but its only domain, then our concern for the moral failures of the religions, which are, I believe, many, is only a point of view amongst many points of view, with no more authority than the power needed to enforce it. This would be an unparalleled disaster both for humanism, as a world view, and for humanity itself, which will seek moral guidance, and if it cannot receive it from nonbelievers, will find it in the religions that have already wreaked such moral havoc in the world. While, in my view, religion is epistemologically weak, it obviously continues to wield a degree of influence over the minds and hearts of billions that unbelief can only dream of. To throw away our greatest advantage, by overselling the value of science, as awesome as science’s accomplishments are, would be, to my mind, not only a great pity, but, more importantly, a betrayal of all that those who have surrendered religious belief have hoped for.

In other words, by denying that morality can be subject to the same empirical standards that determine truth in science, we scientists are enabling religion. In the end, if there aren’t objective moral truths, why not just turn to religion for guidance?  (After all, religion does give the pretense of purveying objective morality.) But there is an alternative: secular philosophy informed by reason and empiricism. By arguing that morality is objective, Eric is adopting an insupportable position in the admirable cause of attacking the moral authority of religion. But you don’t have to go after science to deny that authority. The Euthyphro argument does just fine. We should just admit that, in the end, morality rests on certain propositions about what it is good to achieve, and those propositions can’t be decided using empirical evidence.

I am, frankly, disturbed that Eric is taking the tactic of many religious accommodationists by arguing that “science does bad stuff, too” (e.g., Hitler) and that “science, like religion, can be a faith.” Those arguments are quite familiar to me, but only coming from people like Jeffrey SmallPaul Davies, and John Polkinghorne. In the interest of overthrowing religion, Eric is adopting the same tactic that accommodationists and the faithful use to support faith: making arguments that drag science down to the level of religion.

Without a doubt: the world’s cutest frog

February 16, 2013 • 12:53 pm

From Tastefully Offensive via Matthew Cobb, we have a video of the Namaqua Rain Frog (Breviceps namaquensis). If you don’t think frogs can induce squee, think again. It’s not only unbearably cute, but makes adorable squeaking sounds.

The inflation of the body, shown above and below, is a defense mechanism, as is the squeaking.

B. namaquensis is from South Africa, locally abundant, and, thankfully, not threatened. The one in the video above is covered with sand, so here are two pictures of its normal appearance:

From SA Reptiles; http://www.sareptiles.co.za/forum/viewtopic.php?f=30&t=12228
From SA Reptiles; http://www.sareptiles.co.za/forum/viewtopic.php?f=30&t=12228

They are fossorial (i.e., live underground) and the color pattern is, as you see, variable. They are not associated with water, and so the frog doesn’t produce tadpoles: the babies are produced by “direct development” in the adult.

Image from SA Reptiles, http://www.sareptiles.co.za/forum/viewtopic.php?f=142&t=29576
Image from SA Reptiles, http://www.sareptiles.co.za/forum/viewtopic.php?f=142&t=29576

Is this a case of convergent evolution involving felids and anurans?

Tard
Tard

BioLogos announces grants to reconcile Christianity and evolution

February 16, 2013 • 10:16 am

Reader “Sigmund” (Martin Corcoran), who is this site’s Official BioLogos Watchdog™, just noticed that the accommodationist organization has awarded a series of large grants addressing the relationship between evolution and Christianity. I asked him to write a brief post about the awards, which contain the usual signs of Templetonian nepotism and some unintentional LOLs.

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BioLogos announces winners of its Evolution and Christian Faith grants.

by Sigmund

This past week BioLogos announced the chosen projects from amongst the applicants for its ‘Evolution and Christian Faith’ grant program.  This involves 3 million dollars of Templeton Foundation funds to be distributed to groups or individuals working to “address theological and philosophical concerns which certain branches of Christianity have about evolutionary creation.”

According to BioLogos the applicants had to to fulfill certain criteria:

“All projects will explore consonance between evolution and Christian faith. Proposals were not considered if they rejected (or at least did not helpfully inform) historic, creedal Christianity (e.g. historical Resurrection, high view of Scripture, etc.) or if they rejected the conclusions of mainstream science (e.g. old earth, common descent, etc.). Please note that this does not mean all grantees are necessarily ardent supporters of evolutionary creation.”

In other words, applicants need to be believing Christians who accept an old-earth timescale and some—although not necessarily all—elements of evolutionary theory.

The grants, ranging from $23,000 to $300,000, were awarded to 37 individuals or groups.

The projects funded fit into two main categories. First, the vexatious question of how to reconcile scientific data on human origins with the biblical account of Adam and Eve. No fewer than eight of the projects directly tackle this issue.

Most of these seem to be desperate attempts to contrive a plausible interpretation of Genesis that somehow encompasses the current scientific consensus on human evolution. Only one: “Adam, Paul and Evolution: what Evangelicals need to know”, run by a team from Trinity Western University, appears to include a strong scientific input from Dennis Venema, a geneticist who is frequent contributor to BioLogos on subjects dealing with human evolution. The rest are content to play the evangelical horses and men, bravely trying to put the Humpty Dumpty of Adam and Eve together again after it was cruelly pushed from the wall (by science.)   

The other major theme, with 18 of the grants in this category, is the promotion of theistic evolution in various Christian communities, including those in the Spanish- and French-speaking world, amongst Evangelicals in Holland and Korea, and amongst high school students.

 Of the rest of the grantees, only one provides a hope of producing meaningful data, namely that run by Dr Jonathan Hill of Calvin College, whose proposal involves a longitudinal survey of 3000 members of  the US population, designed to “profile how faith commitments and social context influence beliefs about human origins.”

As can be expected with BioLogos, there is abundant evidence of the standard Templeton Foundation gravy-training: quite a few of the ‘winners’ are BioLogos contributors, including the newly appointed BioLogos scholar Jeffrey Schloss as well as Loren Haarsma, the husband of newly appointed BioLogos president Deborah Haarsma.

There is also some unintentional hilarity. This section, from the abstract of Dr Adam Johnson of Bethel University, explains why evangelicals might have problems accepting evolution.

Constructing a coherent account of human origins requires vast memory resources and comprehension– more than most people freely have available in our busy world. We hypothesize that the cognitive burden embedded within human origins discussions produce a variety of emotional responses that influence origins discussions. Overly complicated discussions produce negative emotions such as exhaustion, frustration and cognitive dissonance. We tend to avoid ideas and explanations that produce such negative emotions. As a result, it’s often less cognitively and emotionally burdensome to neglect theological commitments – as in atheistic evolutionary accounts – or philosophical and scientific commitments – as in biblically literalist accounts. The cognitive perspective suggests that theistic evolutionary accounts frequently pose a variety of cognitive and emotional burdens that atheistic evolutionary and biblical literalist accounts do not pose.

 In other words, knowing scientific facts tends to make it difficult to accept biblical stories as literal truth.

You know, I think I can relate to this.

I had a similar issue around the age of seven when I learned the truth about the aeronautical abilities of reindeer.

Finally, it is worth viewing the image that BioLogos uses on its website to promote the program:

Picture 1

Two praying Charles Darwins? That’s one more than Lady Hope claimed!

Caturday felid: an experiment with my late cat

February 16, 2013 • 6:12 am

This is Teddy, my last cat: a beloved white tom who arrived unceremoniously at my old digs by walking through the catflap about 15 years ago. He was of indeterminate age when he arrived, and had clearly lived through several Chicago winters outdoors—a remarkable achievement. It is cold here!

Teddy was snow white, but was in fact yellow and black when he arrived, having obviously spent a lot of time lurking under cars. It took several baths and nearly a year to get the oil out of his fur and discern his true color.  After shots and neutering, and a short period of acclimation, he became a very sweet pet.  And he never went outdoors again, obviously completely traumatized by his years in the Chicago streets.

Teddy  copy

Teddy was so sweet and docile that I could carry him to the vet (a 20-minute walk) in my arms. Actually, the walk often took longer, as many people would stop me on the street to admire and pet him. At the vet’s, he’d sit patiently in my lap while waiting to be called. He would never flinch or show the least distress, even when the needle went in: he was the most sanguine of cats and I loved him dearly.

Sadly, Teddy was FIV-positive and I had to watch him carefully, taking special care of his teeth and gums, which could become infected. I had him about five years, and the FIV eventually did him in: he died about nine years ago of lymphoma.

He preferred to drink water from a cup, and not just any cup, but a ceramic mug I kept by the bed:

teddy_drinking

But on to the experiment I did with Teddy, an observational study whose results I’ll reveal tomorrow.

It all stemmed from an observation I made every night when I came home from work. I live on the eleventh floor of a high-rise building, and take the elevator up to my crib. Teddy would always be waiting inside my door when I arrived, and when he heard the elevator stop on the floor, he would meow plaintively from behind the door. I would open the door and Teddy would rush into the hall, rubbing against my legs and demanding fusses. He would then precede me into my place.

I noticed that when Teddy was out in the hall, his tail was lowered to the horizontal position, but when he was inside his tail would be proudly elevated.  And I had heard—I’m not sure if this is true, but I think it is—that cats who are wary or distressed lower their tails, but raise them when happy or content.

Obviously, sometime during the transition from the hallway into the secure confines of my apartment, Teddy’s tail would go vertical.  And that raised a question: at what point during the transit from hallway to apartment would he raise his tail?

I had two hypotheses.

a. He raised his tail when his head first came through the doorway, indicating that his brain perceived that he was safe, and therefore he felt more secure.

b. He raised his tail only when his entire body was inside the doorway, indicating that he had a sense of when his whole body was safe.

The results of this experiment, involving only observation (though many repeated observations), proved unequivocal. I will leave it to readers to guess what they were, and will reveal them tomorrow.

A visit to Hitch

February 16, 2013 • 5:21 am

As I promised yesterday, the first reader who visited the new bar Hitch, located in downtown Toronto, and quaffed Hitchens’s favorite tipple, would receive an autographed version of WEIT. Well, it didn’t take long.  One reader, who didn’t look at my post too carefully, even poured himself a shot of Mr. Walker’s amber restorative at home—in the morning.

Sadly, that didn’t cut the mustard. But alert reader George Benedik hied himself to the Hitch within hours, got his tipple (picture of bottle was required), and sent it with a brief report:

Okay, here I am, reporting from the Hitch, having a Johnnie Walker Black. Not my first choice of a drink, but as you already said, “Them’s the roolz!” The place looks nice and cozy, and the absence of a TV is certainly a plus. It doesn’t seem busy at the time (it’s only 5:15 p.m. now), but supposedly that’ll change later on. Ladies and gentlemen, brothers and sisters, comrades and friends: Cheers!

Hitch

He adds that, as befits a bar of that name, there’s a library, and sent a picture of the books along with another note:

Here is a (bad) photo of their “library.” Your book is not in it, unfortunately. The owner said he’ll make sure to add it.

image 4

He’d better!

And I expect that the Canadian Atheist group in Toronto will henceforth foregather at Hitch.

The assassin bug: aggressive mimicry of prey

February 15, 2013 • 1:35 pm

I’m shamelessly stealing this story from Alex Wild’s great Scientific American website, Compound Eye. His latest post describes a paper from the Proceedings of the Royal Society B (link below) by Wignali and Taylor, who show that assassin bugs from Australia (Stenolemus bituberus; these are true bugs in the order Hemiptera) kill spiders by entering their webs and producing vibrations that lure the spider by mimicking either the vibrations made by normal prey trapped in the web.  This shows that the evolution of mimicry need not involve any change in appearance but simply a change in behavior: in this case natural selection has favored those assassin bugs who are able to vibrate spider webs with the proper frequency.

Assassin bugs are usually called “thread-legged bugs” for obvious reasons:

Reduviidae: Emesinae (Belize); not the species used in the study but a related one. Photo used with permission.
Reduviidae: Emesinae (Belize); not the species used in the study but a related one. Photo used with permission.

They’re cryptic, too; as Alex notes: “In the field the insect looked like so little I thought it merely debris in a disorganized spider’s web. I didn’t see the faint outline of a young assassin bug until the debris shuddered, ever so slightly.” (Remember that some spiders, and of course bug-hunting birds, have keen vision.)

I hope my readers are now biology-savvy enough to understand the paper’s abstract:

Assassin bugs (Stenolemus bituberus) hunt web-building spiders by invading the web and plucking the silk to generate vibrations that lure the resident spider into striking range. To test whether vibrations generated by bugs aggressively mimic the vibrations generated by insect prey, we compared the responses of spiders to bugs with how they responded to prey, courting male spiders and leaves falling into the web. We also analysed the associated vibrations. Similar spider orientation and approach behaviours were observed in response to vibrations from bugs and prey, whereas different behaviours were observed in response to vibrations from male spiders and leaves. Peak frequency and duration of vibrations generated by bugs were similar to those generated by prey and courting males. Further, vibrations from bugs had a temporal structure and amplitude that were similar to vibrations generated by leg and body movements of prey and distinctly different to vibrations from courting males or leaves, or prey beating their wings. To be an effective predator, bugs do not need to mimic the full range of prey vibrations. Instead bugs are general mimics of a subset of prey vibrations that fall within the range of vibrations classified by spiders as ‘prey’.

Here’s another photo showing the bug entering a spider’s web for nefarious purposes:

Picture 2

Finally, a video (taken from the original paper via Alex) showing an assassin bug luring a spider to its death:

Some assassin bugs also kill spiders not by mimicking prey vibrations, but by sneaking up on them and stabbing them with their mouthparts (ergo their name). An earlier BBC report notes that, when using this latter tactic, assassin bugs are most likely to move toward their spider prey when the wind is blowing, masking any vibrations produced by their movement. They’re like ninja cats! This was demonstrated in clever experiments using fans to mimic the vibrations of spider webs produced by wind.

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Wignali, A. E. and P. W. Taylor. 2013. Assassin bug uses aggressive mimicry to lure spider prey. Proc. R. Soc. B 7 May 2011 vol. 278 no. 1710 1427-143, Published online October 27, 2010 doi: 10.1098/rspb.2010.2060

See also: Wignall, A.E. . & Taylor, P.W. (2008). Biology and life history of the araneophagic assassin bug Stenolemus bituberus including a morphometric analysis of the instars (Heteroptera, Reduviidae).. Journal of Natural History 42: 59-76. (pdf here)