Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
You may remember this messed-up stray cat that reader Rik Gern decided to take under his wing. He was feeding it and petting it a bit, but I had urged him to get it vet care as it was clearly infested with pathogens and needed shots.
He was hesitant because he didn’t know how to go about conveying a semi-wild cat to the vet, but, thanks to the enormous outburst of good advice from the readers (63 comments!), Rik’s getting it to the vet this week. As he wrote me:
Well, I’ll be taking the kitty to a free clinic a week from Thursday! She’s got a new hair brush, which she loves, and Advantage, which she doesn’t love! She’s also been getting raw fish (catfish nuggets) and she’s crazy about that!!! I’m going to try to transition her to an indoor cat, but we’re both a little hesitant about having her in the house, so I’m letting that develop at whatever pace feels mutually comfortable.
Your readers have been very helpful–I’m touched!
Another reader—an artist—asked Rick for a high-res picture so he could paint the cat’s portrait!
Rik didn’t ask this, but maybe readers could suggest a name. At any rate, thanks to all the many people who, concerned with the fate of a single felid, wrote in with advice.
It would obviously be adaptive for some animals to be able to distinguish between natural phenomena, like wind, and phenomena that have similar effects but are caused by hidden agents like predators. One example (used in the paper below) is the rustling of trees in a tropical forest canopy. We know how to distinguish between the rustling caused by wind, which is general, and the rustling that is localized and moves slowly, like that caused by a troop of monkeys moving through the trees. (I experienced this myself on a recent trip to Costa Rica). If you’re liable to be disturbed (or eaten) by monkeys you need to pay attention to avoid the troop, but in the case of wind you don’t want to waste valuable foraging time looking up and getting nervous every time a leaf rustles.
This notion of “hidden causal agency,” of course, has been suggested as a pivotal factor in the origin of religion. If you’ve read Pascal Boyer’s provocative book Religion Explained, you’ll remember his thesis that before humans understood natural phenomena (e.g., thunder, lightning, or tree rustling), it was natural for them to impute them to causal agents—supernatural ones. This was, he thought, a “spandrel” piggybacking on our evolved notion to be alert, and to mentally ascribe natural phenomena to things that could either help us or hurt us. (For example, it’s better to think that a rustle in the bushes is a predator than to ignore it, even though there’s a “false positive” cost of interrupting your tasks because you’re hyper-alert. But better to be hyper-alert than to ignore a rustle that could kill you.) And that, says Boyer, ultimately led to religion: the ultimate belief in hidden causal agency.
So far the only animal shown to have the ability infer hidden causal agency is Homo sapiens. A dog lover told me that he’s absolutely sure that dogs can do it (caninophiles attribute all sorts of wisdom to dogs in the absence of any scientific evidence!), but so far there have been no studies demonstrating this.
Such tests are, however, possible. One was recently conducted in New Caledonian crows, Corvus moneduloides. These animals are awesomely smart, and in fact are the only non-human species known to modify non-natural materials in the lab to make tools for procuring food, and to use other tools in ways previously seen only in primates (go here for a good description of three kinds of crow tool-use). Here’s a video of one of these smart beasts figuring out how to retrieve food by bending the tip of a wire into a hook. It’s amazing:
At any rate, a group of researchers at the Universities of Auckland, Cambridge, and Vienna wanted to figure out if these crows had the notion of hidden causal agency. The method was, as the authors note, “to infer what caused an inanimate object to move.” The results, described in a new paper in the Proceedings of the National Academy of Sciences by Alex Taylor, Rachael Miller, and Russell Gray (free access and download at link), suggest that crows can indeed infer hidden causal agency.
The study involved using 8 crows trained to use a stick as a tool for retrieving food. The experimenters then put the food-retrieving apparatus on a table in front of a curtain. The curtain had a hole in it through which a stick could protrude.
Then, each crow was given three sequential “hidden causal agent” (HCA) trials: a human walked into the room behind the curtain (in all trials there was also another human standing in the corner of the room), and then the stick was pushed through the hole, protruding near the food apparatus, 15 times. (The movement was controlled by pulling strings, usually by someone outside the room, so the stick always moved the same way.) After the crow saw this, the human (and the person in the corner) then left the room, so that the crows could go back to their food-retrieving setup. (They don’t do that when the stick is moving because it could hit them in the head.)
Here’s what the experimental setup looked like (figure 1 from the paper):
After the crows had experienced causal agency, and saw that the stick stopped moving when the observer left the room, each was given three trials with an “unknown causal agent” (UCA). A person came in and stood in the corner of the room, as before, but nobody came in and went behind the curtain. The stick was again moved 15 times in and out of the hole by the person outside the room. Then the stick stopped moving, and the observer outside the curtain also left the room, as he did before:
To see whether the crows were worried that the stick would move, and attribute that to the man behind the curtain, the experimenters measured how often the crows “inspected” the hole, that is, how often they looked toward it and abandoned their probing for food, seeing if the stick might come out and poke them. The definition of “inspection” is in the paper, and the behavior is clear in the video below. Here’s their predictions, which differ based on whether or not the crows habituate to a causal agent:
If the crows could attribute the stick’s movement to the hidden human, they could infer that when the human left the room, the stick would not move again. In contrast, in the second, unknown condition, if the crows were capable of causal reasoning, they would predict that the stick might move again because they had not observed a potential causal agent leave the hide. This “causal reasoning hypothesis,” therefore, made the opposite prediction from the “habituation hypothesis” outlined above. In the hidden agent condition, the crows should show similar levels of caution to those in the final trial of habituation to the hide. In the unknown condition, the crows should show a high level of caution, despite the movement of the stick no longer being a novel stimulus.
Here are the results, which graph the number of crow “inspections” (i.e., when they abandoned probing to look at the hole). The results are divided up for the initial “habituation trial” (with no stick moving), and sequentially for the three HCA trials and then the three UCA trials:
Fig. 1. Inspection rate across conditions. Final habituation trial before testing is indicated by 20cm hab. (Upper Left ) Diagram of the HCA condition. (Upper Right) Diagram of the UCA condition. In the HCA condition, one human walked into the hide and one stood in the corner of the room. A wooden stick was then probed from the hide. The agent then exited the hide. Both humans then left the room. In the UCA condition, one human entered the cage and stood in the corner. The tool was then probed through the hole. The human then left.
What you see is that when the human was behind the curtain and then was observed to leave, the rate of inspection after the crow goes back to its food-box is low, and remains low. (It is in fact equal to the “habituation” trial when there was no stick poking out.) But when the stick moves and a human wasn‘t in the room (UCA trial), the rate of inspection is significantly higher than in the HCA trials, at least for the first two of the three UCA trials (there appears to be some habituation in the latter trials). The higher inspection rate is presumably because since the crows didn’t see a human come in and then leave the curtain, they were worried that somebody was still behind the curtain moving the stick, and they remained nervous that they might get poked. As the authors say,
These results show that New Caledonian crows, like humans, can attribute an observable event to a hidden causal agent. When the stick moved while a potential agent was in the hide, and that agent then departed, the crows had a relatively low inspection rate. All of the crows we tested, however, increased their inspection rates after observing the stick move when no potential causal agent was present. In fact, inspection rates were far higher in the first trial of the unknown agent condition than in the first human agent trial. This was despite the human trial being the first time the crows had observed the novel stimuli of a stick emerging from the hide and a human entering and exiting the hide. Similarly, no crows abandoned probing and left the table when the stick emerged from the hide for the first time, but some did when the stick’s movement could not be attributed to a causal agent. Given the probing stick was a novel, aversive stimulus to the crows, a purely associative account would struggle to explain why the crows reacted to this stimulus in the unknown causal condition but not in the human condition. This pattern of results is, however, predicted by a causal account of the crows’ actions: the crows attributed the movement of the stick in the human condition to the agent inside the hide and, so, inferred that the stick was unlikely to be probed again once the human had left the hide. In the unknown condition, there was no recently departed causal agent to attribute the movement of the stick to, so the crows reasoned the stick could be probed again.
I’ve heard that there are criticisms of this experiment on the internet, though I haven’t looked for them (alert readers might try). But it looks at least suggestive to me, especially in light of the known intelligence and reasoning ability of these birds.
Here’s a new video in which one of the authors, Alex Taylor, explains the experiment and shows the setup (it also shows what they mean by a crow’s “inspection”). Maybe I wasted my time writing all that stuff above!
As the authors note, they’re not the first to speculate that some species can impute agency. As the authors note, Darwin conjectured this in The Descent of Man:
Darwin himself speculated that a dog barking at a parasol moving slightly in a breeze might be because the dog reasoned that “movement without any apparent cause indicated the presence of some strange living agent.”
Well, I’m not convinced that dogs have the notion of causal agency, or are even as smart as crows (dog-lovers, don’t attack me, but wait for experiments before you assert your pet has a concept of agency!). But it’s possible that this notion is far more widespread in animals than we think, and experiments like the one above are the way to show it. They’re not that hard, actually, and I suspect more will be done soon.
In the meantime, when you see a crow—because they’re all smart—give it a wink in recognition of a fellow intelligent being.
Alert reader B. D. Wilson (who ran the eBay auction for Doctors Without Borders) took it upon himself to edit my talk on the evidence for evolution from the 2009 Atheists Alliance International conference, omitting needless material and speeding up my speech. It’s now twenty minutes long—a third of its original length.
This is a condensed version of Jerry Coyne’s excellent lecture on some of broad lines of evidence for evolution. Starting as a one hour lecture I edited out introductions, pauses, jokes, gaffes and the Q & A, then did some compression to fit it into a tidy, information-dense 20 minute packet. If someone you know does not believe in evolution, point them to this short video so they can become familiar with some of the evidence.
I can’t bear to listen to more than a minute or so, because my speech has been accelerated so much that I sound like Alvin the Chipmunk. But several readers have written in (how did they locate this?) to say that they found it informative, not jarring, and useful as a short talk for those who really want to know the evidence for evolution. So here it is; listen at your own risk.
I almost expect David Seville to yell at the end of this talk, “JerrEEEEEEEEEEEEE!!!”
In what he calls a “global disaster” now unfolding in northern latitudes as the sea area that freezes and melts each year shrinks to its lowest extent ever recorded, Prof Peter Wadhams of Cambridge University calls for “urgent” consideration of new ideas to reduce global temperatures.
In an email to the Guardian he says: “Climate change is no longer something we can aim to do something about in a few decades’ time, and that we must not only urgently reduce CO2 emissions but must urgently examine other ways of slowing global warming, such as the various geoengineering ideas that have been put forward.”
. . . Wadhams has spent many years collecting ice thickness data from submarines passing below the arctic ocean. He predicted the imminent break-up of sea ice in summer months in 2007, when the previous lowest extent of 4.17 million square kilometres was set. This year, it has unexpectedly plunged a further 500,000 sq km to less than 3.5m sq km. “I have been predicting [the collapse of sea ice in summer months] for many years. The main cause is simply global warming: as the climate has warmed there has been less ice growth during the winter and more ice melt during the summer.
“At first this didn’t [get] noticed; the summer ice limits slowly shrank back, at a rate which suggested that the ice would last another 50 years or so. But in the end the summer melt overtook the winter growth such that the entire ice sheet melts or breaks up during the summer months.
“This collapse, I predicted would occur in 2015-16 at which time the summer Arctic (August to September) would become ice-free. The final collapse towards that state is now happening and will probably be complete by those dates”.
And then things just get worse:
“As the sea ice retreats in summer the ocean warms up (to 7C in 2011) and this warms the seabed too. The continental shelves of the Arctic are composed of offshore permafrost, frozen sediment left over from the last ice age. As the water warms the permafrost melts and releases huge quantities of trapped methane, a very powerful greenhouse gas so this will give a big boost to global warming.”
And, HuffPo being what it is, they include dogs on the page. It’s the same thing they do on the “science” page, putting in irrelevant things that might catch the attention of someone passing by.
How can I stay away, though? They included this awesome Russian video of a cat and a dog battling over a cheeseburger.
But more bad news: the outcome is completely unrealistic.
Oh, and there’s a new video of everyone’s favorite tubby tabby, Maru, wedging himself into another too-small box:
And more cognitive dissonance: over at the “Religion” section, HuffPo has an article by one Professor Sahar Aziz of The Texas Wesleyan School of Law, taking Americans to task for anti-Islamic gestures like the Qur’an burning of Pastor Terry Jones, and calling for condemnation of such bigotry. As I mentioned yesterday, one can attack a religion without attacking all of its adherents. I, like many atheist writers, have already condemned Terry Jones, but I strongly defend his right to burn Qur’ans. Further, I agree with Aziz that Americans should counter attempts to suppress religion or erode the rights of those whose faiths we dislike.
But in her whole article she completely fails to condemn the murderous thugs who have not only attacked people and embassies because of some badly-made film, and previously flew planes into buildings, bombed nightclubs, and engaged in other attempts to murder innocent people in the name of the Religon of Peace. Whose fault is that? According to Azia, ours:
Many Americans fail to appreciate that this inflammatory video is not viewed by Muslims abroad in a vacuum. Indeed, it follows on the heels of a Quran-burning by a radical Christian pastor in Florida, urination on Qurans by U.S. troops, opposition to mosque building across the United States, police surveillance of Muslim students and mosque-goers across the East Coast, and offensive campaign rhetoric accusing American Muslims en masse of disloyalty — all of which contradict America’s proclaimed values of religious freedom, equal protection, and respect for diversity.
Religious freedom, of course, includes the freedom to criticize religion, no matter how vile or strident that criticism may be. Aziz continues:
Thus, Muslims abroad do not view the American-made hate film as merely an expressive act by a lone actor protected by the First Amendment. Rather it is part of a broader American assault on the Islamic faith wherein Muslims are expected to take it on the chin and smile.
Coupled with the dearth of videos, speeches, and public acts by average Americans proclaiming their respect for Islam and their acceptance of Muslims as equal compatriots, Muslims abroad are left questioning whether defense of free speech is pretext for condoning bigotry. For if all you hear and see from America is hateful speech, selective targeting and counterterrorism enforcement against Muslims, and shameless Muslim-bashing by politicians, then calls to protect freedom of speech unsurprisingly fall on deaf ears.
No, Muslims don’t have to take it on the chin and smile. They can counter anti-Islamic speech with their own speech, and match Qur’an burnings with American flag burnings. And I don’t care whether Muslims question whether defense of free speech is pretext for condoning bigotry. Free speech can indeed be a blanket for bigotry, but if we don’t protect the rights of bigots, we can’t protect the rights of anyone. Besides, Muslims don’t object when their own countries regularly portray Jews as money-grubbing killers of Christians. That is government-sponsored condoning of bigotry. No problem with that in the Middle East!
And it’s one thing to have deaf ears, another thing entirely to sever someone’s head with a knife. Aziz doesn’t seem to recognize this distinction when she piles all the blame on people like Terry Jones. In her haste to blame Muslim anger on America, she says only one brief sentence about the violence engendered by that anger:
When a Muslim terrorist attempts to harm Americans or burns an American flag, should Muslims in America publicly condemn such acts or can they assume that the guilt of one will not be imputed onto the entire religion?
Attempts to harm Americans? Attempts? No, they’re not just attempts, they’re successful attempts, and offended Muslims are not just killing Americans. Have a look (scroll down) at this list of Islamic terrorist attacks, and note the variety of nations that have been victimized.
Frankly, I don’t care about Muslims burning American flags. Let a million flags burn, and let Americans burn them too. It’s only a piece of cloth, and that’s not the same thing as a piece of flesh. When you destroy a flag, there is not a network of friends and family left to mourn the loss.
Apologists like Aziz make me ill. The first commenter on her piece is right:
Given the disrespect paid to Judaism and its symbols throughout the Islamic world day in day out, I think Muslims should do some introspection and change from within before demanding anyone else make any changes.
There aren’t too many occurrences of Christians and Jews burning down the embassies and consulates of Muslim countries.
Has Aziz forgotten about “the broader Islamic assault on the Jewish and Christian faiths wherein Jews and Christians are expected to take it on the chin and smile”? We respond with words, Muslims with swords.
In February of last year I reported on a study by Ceci and Williams showing that, at least according to the authors’ methodology, there was little evidence of gender bias against women in academia for getting grants, being hired as a faculty member, or getting papers published. Although women still occupy faculty positions disproportionately less often compared to their acquisition of degrees, I found this result heartening. It was, however, a meta-analysis of many other studies, and these can be problematic.
I was therefore disheartened to see a new study, by Corinne Moss-Racusin et al. in the same journal—the Proceedings of the National Academy of Sciences (download free at link, I think; if you’re unable, email me for the pdf)—showing bias against women of a different kind: the hiring of students to be laboratory managers. This is not a meta-analysis, but a single sociological study, and—though I’m not an expert in the field—the results look sound to me.
The authors did a simple thing: they sent a group of application materials from a fictitious undergraduate looking a lab-manager job to 127 American biology, chemistry, and physics professors of both sexes. The applications were not for jobs in the professors’ own labs, but simply applications that the faculty were asked to evaluate for the student’s competence and hireability, as well as to decide what salary and how much mentoring the applicant could expect to get from them.
The applications were identical except for one thing: they had the name of either a male ( “John”, n = 63 applications) or a female (“Jennifer”, n = 64 applicants). As the study states, “Faculty participants believed that their feedback would be shared with the student they had rated . . ”
The applications were designed to be good but not perfect: that is, the applicant had a few flaws. This was done to ensure that there would be discernible variation in how the applications were judged. If the applicant was perfect in every respect, it would be harder to judge any bias on the part of the raters.
The results are disappointing, for they show a substantial disparity between males and females in all categories, with women at the bottom. Surprisingly, female faculty were as biased as male faculty. All of the male-female differences in perceived quality were statistically significant.
This graph tells the tale for perceived competence, hireability, and mentoring; women are lower on all counts:
Fig. 1. Competence, hireability, and mentoring by student gender condition (collapsed across faculty gender). All student gender differences are significant (P < 0.001). Scales range from 1 to 7, with higher numbers reflecting a greater extent of each variable. Error bars represent SEs. n(male student condition) = 63, n(female student condition) = 64.
And here are the means, grouped by sex, for perceived competence, hireability, mentoring, and the salary that was deemed appropriate for the candidate. Note that the gender of the faculty member evaluating the application is also given.
In the part of the table below, the categories—”competence” through “salary” are in the same order as above, but this time the applicant was Jennifer instead of John:
The caption from the paper: Scales for competence, hireability, and mentoring range from 1 to 7, with higher numbers reflecting a greater extent of each variable. The scale for salary conferral ranges from $15,000 to $50,000. Means with different subscripts within each row differ significantly (P < 0.05). Effect sizes (Cohen’s d) represent target student gender differences (no faculty gender differences were significant, all P > 0.14). Positive effect sizes favor male students. Conventional small, medium, and large effect sizes for d are 0.20, 0.50, and 0.80, respectively (51). n(male student condition) = 63, n(female student condition) = 64. ***P < 0.001.
Oy vey! The ratings of the female applicant were substantially lower than those of the male in every respect. Means with different subscripts between the tables (e.g., a vs. b) are significantly different, while those with identical subscripts don’t differ significantly.
The salient results:
For competence hireability, and willingness to mentor the applicant, women were ranked roughly 25% lower then men.
This ranking did not depend on whether the professor who did the rating was male or female, so whatever bias is reflected here is shown by faculty of both genders. To me that is surprising.
Male faculty offered female applicants only 88% of the salary offered to males. The disparity was even greater for female professors, who were willing to offer the female applicants only 85% the salary of male applicants.
When they did a path analysis, combining “competence” and “salary” into one “composite competence variable,” the authors found that the strongest cause for all the disparities was this: “the female student was less likely to be hired than the identical male because she was viewed as less competent overall.”
A separate analysis of the faculty members’ views using something called the Modern Sexism Scale showed that the assessments of female (but not male) competence reflected “preexisting subtle bias” against women. This supported the authors’ a priori hypothesis that “subtle bias against women would be negatively related to evaluations of the female student, but unrelated to evaluations of the male student.”
The conclusions?
There is gender bias against women—and it’s pretty substantial—at this level of hiring. This is, of course, in conflict with the results of the Ceci and Williams study mentioned above. It’s possible that once women get past being hired as a faculty member, discrimination lessens substantially, but I am not sure the Ceci and Williams study, being a meta-analysis, is sound. In addition, every woman I know who is a faculty member in biology, and has discussed the issue with me, says she perceives sexism in the community at some level. Granted, those are anecdotes, but I know a lot of female faculty.
Because the bias is evinced at the student rather than postdoc/faculty stage (if you accept the results of Ceci and Williams), interventions promoting female advancement in science should take place early in the academic career, while one is still an undergraduate. This could involve, among other things, education of undergraduate advisers about the problem. As the authors note, “Because most students depend on feedback from their environments to calibrate their own worth, faculty’s assessments of students’ competence likely contribute to students’ self-efficacy and goal setting as scientists. which may influence decisions much later in their careers.” This suggests that women may abandon careers in academic science not because of bias manifested after they’re hired, but bias they perceive early in their careers.
The bias against women was manifested equally by both male and female faculty. This surprised me, but I’ve also been told by women that women are often harder on women than on men (again, anecdotes).
The authors’ conclusion is clear:
The dearth of women within academic science reflects a significant wasted opportunity to benefit from the capabilities of our best potential scientists, whether male or female. Although women have begun to enter some science fields in greater numbers, their mere increased presence is not evidence of the absence of bias. Rather, some women may persist in academic science despite the damaging effects of unintended gender bias on the part of faculty. Similarly, it is not yet possible to conclude that the preferences for other fields and lifestyle choices that lead many women to leave academic science (even after obtaining advanced degrees) are not themselves influenced by experiences of bias, at least to some degree. To the extent that faculty gender bias impedes women’s full participation in science, it may undercut not only academic meritocracy, but also the expansion of the scientific workforce needed for the next decade’s advancement of national competitiveness.
I have only one beef with this. I don’t give a hoot whether the USA beats all other nations in the quality and output of its scientists. That, to me, is a form of chauvinism, and science, being an international venture, should be promoted everywhere. A rising tide lifts all boats. We should try to eliminate gender bias not because it will make the U.S. more competitive, but simply because it’s the right thing to do.
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Moss-Racusin, C. A., J. F. Dovidio, V. L. Brescoll, M. J. Graham, and J. Handelsman. 2012. Science faculty’s subtle gender biases favor male students. Proc. Nat. Acad. Sci. USA, published online before print September 17, 2012, doi: 10.1073/pnas.1211286109
Somehow readers Dan McPeek and Ben Goren dug up and posted this YouTube video in the DWB/book comments on Sept. 19, when it had just gone up and accrued only a few comments. I immediately saw that it was funny enough to merit status as a Caturday Felid, and scheduled a post for today. In the last three days, elebenty gazillion other readers have sent it to me, and the YouTube views have shot up from about 300 to over 380,000. I don’t know how people find these things so quickly, but I’m glad they’re brought to my attention.
Herewith: the definitive proof that cats pwn dogs.
And, of course, even dogs are better than squids, a spineless beast that makes its living from suckers.
