Prozac and suicide: what's going on?Many people think that SSRI antidepressants do indeed cause suicide, and in recent years this idea has gained a huge amount of attention. My opinion is that, well, it's all rather complicated...At first glance, it seems as though it should be easy to discover the truth. SSRIs are some of the most studied drugs in the world. We have data from several hundred randomized placebo-controlled trials, totaling tens of thousands of patients. Let's just look and see whether people given SSRIs are more likely to die by suicide than people given placebo.Unfortunately, that doesn't really work. Actual suicides are extremely rare in antidepressant trials. This is partly because most trials only last 4 to 6 weeks, but also because anyone showing evidence of suicidal tendencies is excluded from the studies at the outset. There just aren't enough suicides to be able to study.What you can do is to look at attempted suicide, and at "suicidality", meaning suicidal thoughts and self-harming behaviours. Suicidality is more common than actual suicide, so it's easier to research. Here's the bad news: the evidence from a huge number of trials is that compared to placebo, antidepressants do raise the risk of suffering suicidality(1) and of suicide attempts(1) (from 1.1 per 1000 to 2.7 per 1000), when given to people with psychiatric disorders.There's no good evidence that SSRIs are any worse or any better than other antidepressants, or that any one SSRI stands out as particularly bad(1,2). The risk seems to be worst in younger people: compared to placebo, SSRIs raised suicidality in people below age 25, had no effect in most adults, and lowered it in the oldest age groups(1). This is why SSRIs (and all other antidepressants) now carry a "black box" in the USA, warning about the risk of suicide in young people.*This is very troubling. Hang on though. I mentioned that suicidality is an exclusion criterion from pretty much all antidepressant trials. This is for ethical as well as practical reasons: it's considered unethical to give a suicidal person an experimental drug, and it's really impractical to have patients dying during your trial.Indeed the recorded rate of suicidality in these trials is incredibly tiny: only 0.5% of the psychiatric patients experienced any suicidal ideation or behaviour at all(1). The other 99.5% never so much as thought about it, apparently. If that were representative of the real world it would be great; unfortunately it isn't. Yet what this all means is that antidepressants could not possibly reduce suicidality in these trials, because there's just nothing there to reduce. Even if, in the real world, they prevent loads of suicides, these trials wouldn't show it.How do you investigate the effects of drugs "in the real world"? By observational studies - instead of recruiting people for a trial, you just look to see what happens to people who are prescribed a certain drug by their doctor. Observational studies have strengths and weaknesses. They're not placebo controlled, but they can be much larger than trials, and they can study the full spectrum of patients.Observational studies have found very little evidence suggesting that antidepressants cause suicide. Most strikingly, since 1990 when SSRIs were introduced, antidepressant sales have increased enormously, and the suicide rate has fallen steadily; this is true of all Western countries.More detailed analyses of antidepressant sales vs. suicide rates across time and location have generally either found either no effect, or a small protective effect, of antidepressant sales(1,2,3, many others). In the past few years, concern over suicidality has led to a fall in antidepressant use in adolescents in many countries: but there is no evidence that this reduced the adolescent suicide rate(1,2).Another observational approach is to see whether people who have actually died by suicide were taking SSRIs at the time of death. Australian psychiatrists Dudley et al have just published a review of the evidence on this question, and they found that out of a total of 574 adolescent suicide victims from the USA, Britain, and Scandinavia, only 9 (1.5%) were taking an SSRI when they died. In other words, the vast majority of youth suicides occur in non-SSRI users. This sets a very low upper limit on the number of suicides that could be caused by SSRIs.*So what does all this mean? As I said, it's very controversial, but here's my take, with the standard caveat that I'm just some guy on the internet.The evidence from randomized controlled trials is clear: SSRIs can cause suicidality, including suicide attempts, in some people, namely some people below age 25. The chance of this happening is below 1% according to the trials, but this is still worrying given that lots of people take antidepressants. However, the use of antidepressants on a truly massive scale has not led to any rise in the suicide rate in any age group. This implies that overall, antidepressants prevent at least as many suicides as they cause.My conclusion is that the clinical trials are not much use when it comes to knowing what will happen to any individual patient. The evidence is that antidepressants could worsen suicidality, or they could reduce it. This is hardly a satisfactory conclusion for people who want neat and tidy answers, but there aren't many of those in psychiatry. For patients, the implication is, boringly, that we should follow the instructions on the packet - be vigilant for suicidality, but don't stop taking them except on a doctor's orders.Dudley, M., Goldney, R., & Hadzi-Pavlovic, D. (2010). Are adolescents dying by suicide taking SSRI antidepressants? A review of observational studies Australasian Psychiatry, 18 (3), 242-245 DOI: 10.3109/10398561003681319... Read more »
Dudley, M., Goldney, R., & Hadzi-Pavlovic, D. (2010) Are adolescents dying by suicide taking SSRI antidepressants? A review of observational studies. Australasian Psychiatry, 18(3), 242-245. DOI: 10.3109/10398561003681319
It is well documented that Thomas Robert Malthus’ An Essay on the Principle of Population greatly influenced both Charles Darwin and Alfred Russell Wallace’s independent conception of their theory of natural selection. In it, Malthus puts forward his observation that the finite nature of resources is in conflict with the potentially exponential rate of reproduction, [...]... Read more »
For some time now, evolutionary biologists have used phylogenetics. It is a well-established, powerful set of tools that allow us to test evolutionary hypotheses. More recently, however, these methods are being imported to analyse linguistic and cultural phenomena. For instance, the use of phylogenetics has led to observations that languages evolve in punctuational bursts, explored [...]... Read more »
Lycett SJ, Collard M, & McGrew WC. (2009) Cladistic analyses of behavioural variation in wild Pan troglodytes: exploring the chimpanzee culture hypothesis. Journal of human evolution, 57(4), 337-49. PMID: 19762070
Greenhill, S., Currie, T., & Gray, R. (2009) Does horizontal transmission invalidate cultural phylogenies?. Proceedings of the Royal Society B: Biological Sciences, 276(1665), 2299-2306. DOI: 10.1098/rspb.2008.1944
A new study interestingly implies that human activities may not always be bad for biodiversity. Long before the colonizers arrived in South America, indigenous farmers, belonging to the Arauquinoid cultures, had already interfered with the Amazonian biodiversity. Their novel agricultural engineering methods had changed the savannah ecosystem, resulting in increased biodiversity. Thus states the solid paper, on 'Pre-Columbian agricultural landscapes, ecosystem engineers, and self-organized patchiness in Amazonia', published in Proceedings of the National Academy of Sciences (online before print, April 12th 2010), by Doyle McKey (Université de Montpellier II, France), Stéphen Rostain, José Iriarte, Bruno Glaser, Jago Jonathan Birk, Irene Holst, and Delphine Renard. The savannahs of coastal Guyana tend to flood during the rains and are dry during the summer. However, strange complexes of mounds are seen in the terrain of these plains, running for 360 miles from Berbice River to Cayenne. Due to their perfect symmetry, the mounds were deduced to be man-made. The mounds drained well during the rains and floods (their drainage capacity was nine times as high as the seasonally flooded savannah). The authors deduce that these are large raised beds/fields, made out of the surrounding topsoil, for cultivating crops (a theory further substantiated by soil samples containing microfossils of maize, cassava, and squash), constructed by the pre-Columbian farmers, around 1000-700 years ago. The interesting point is that this farming was practiced in wastelands considered to be unsuitable for agriculture- a feat achieved due to their effective agricultural engineering. When these fields were abandoned, the mounds were colonised by flora and fauna, thus creating a new ecosystem. These 'ecosystem engineers' (viz., ants such as Acromyrmex octospinosus and Ectatomma brunneum, termites such as Nasutitermitinae, and earthworms) built their nests on the raised beds so that the colonies wouldn't be flooded. Their burrowing aerated it further, helping in accumulating sufficient rainfall. Moreover, the mounds were fertilised as a result of them congregating organic matter into their nests and accumulating minerals such as nitrogen, potassium, and calcium. As a result, the perennial plants on the mounds flourished and their strong roots prevented the erosion of the mound. All of these alterations initiated by humans have resulted in a higher biodiversity than seen in the normal savannahs. This study would give additional impetus to the debate over whether most of the Amazon rainforest and savannahs (commonly considered to be pristine) are sites of significant human occupation, especially during the pre-Columbian times. The authors suggest that this agricultural system could be a model for modern farming, especially considering the beneficial ecological changes. Although this is a perfect example of a terrain modified by humans and maintained by Nature, it must be noted the increase in biodiversity was a result of 400-800 years of no/minimal human intervention. Secondly, the ‘punja’ technique of rice/paddy cultivation has a very similar methodology and is followed in parts of Kerala. link: http://www.pnas.org/content/early/2010/04/07/0908925107.abstract?sid=93317154-3ce6-43c8-9a1e-456e24272c2bMcKey D, Rostain S, Iriarte J, Glaser B, Birk JJ, Holst I, & Renard D (2010). Pre-Columbian agricultural landscapes, ecosystem engineers, and self-organized patchiness in Amazonia. Proceedings of the National Academy of Sciences of the United States of America, 107 (17), 7823-8 PMID: 20385814... Read more »
McKey D, Rostain S, Iriarte J, Glaser B, Birk JJ, Holst I, & Renard D. (2010) Pre-Columbian agricultural landscapes, ecosystem engineers, and self-organized patchiness in Amazonia. Proceedings of the National Academy of Sciences of the United States of America, 107(17), 7823-8. PMID: 20385814
When examining the dispersal of Pleistocene hominins, one of the more fascinating debates concern the patterns of biological and technological evolution in East Asia and other regions of the Old World. One suggestion emerging from palaeoanthropological research places a demarcation between these two regions in the form of a geographical division known as the Movius Line. Specifically, the suggestions that initially led to the Movius Line were based on observations of differing technological patterns, namely: the lack of Acheulean handaxes and the Levallois core traditions in East Asia.... Read more »
Lycett, S., & Norton, C. (2010) A demographic model for Palaeolithic technological evolution: The case of East Asia and the Movius Line. Quaternary International, 211(1-2), 55-65. DOI: 10.1016/j.quaint.2008.12.001
When examining the dispersal of Pleistocene hominins, one of the more fascinating debates concern the patterns of biological and technological evolution in East Asia and other regions of the Old World. One suggestion emerging from palaeoanthropological research places a demarcation between these two regions in the form of a geographical division known as the Movius [...]... Read more »
Lycett, S., & Norton, C. (2010) A demographic model for Palaeolithic technological evolution: The case of East Asia and the Movius Line. Quaternary International, 211(1-2), 55-65. DOI: 10.1016/j.quaint.2008.12.001
The recent technical comments on Ardipithecus has left some of us scratching our heads and thinking about how to define a meaningful phylogenetic trait. Drew Rendall and Tony DiFiore wrote one of my favorite papers on the subject, which deals specifically with the perceived “special” status of behavior in human and primate evolution. I think [...]... Read more »
Rook, L. (1999) Oreopithecus was a bipedal ape after all: Evidence from the iliac cancellous architecture. Proceedings of the National Academy of Sciences, 96(15), 8795-8799. DOI: 10.1073/pnas.96.15.8795
Lovejoy, C., Suwa, G., Spurlock, L., Asfaw, B., & White, T. (2009) The Pelvis and Femur of Ardipithecus ramidus: The Emergence of Upright Walking. Science, 326(5949), 71-71. DOI: 10.1126/science.1175831
Rendall D, & Di Fiore A. (2007) Homoplasy, homology, and the perceived special status of behavior in evolution. Journal of human evolution, 52(5), 504-21. PMID: 17383711
An upcoming study Personality and Individual Differences links eye color to perceived dominance ratings. But there's more to the study than immediately reaches the eye...... Read more »
Kleisner, K., Kočnar, T., Rubešová, A., & Flegr, J. (2010) Eye color predicts but does not directly influence perceived dominance in men. Personality and Individual Differences, 49(1), 59-64. DOI: 10.1016/j.paid.2010.03.011
Ooooo, is there some Ardi drama today! Two technical comments were published in science which question the conclusions reached by Tim White and his team in last September’s Ardi blitz. The comment by Esteban Sarmiento was particularly interesting, particularly this quote: In contrast to what the authors describe in other papers, the LCA character conditions [...]... Read more »
Sarmiento, E. (2010) Comment on the Paleobiology and Classification of Ardipithecus ramidus. Science, 328(5982), 1105-1105. DOI: 10.1126/science.1184148
White, T., Suwa, G., & Lovejoy, C. (2010) Response to Comment on the Paleobiology and Classification of Ardipithecus ramidus. Science, 328(5982), 1105-1105. DOI: 10.1126/science.1185462
A new study in PLoS ONE by Victoria Horner, Darby Proctor, Kristin E. Bonnie, Andrew Whiten, and Frans de Waal suggests that prestige is an important factor in other primates besides humans. By employing a simple behavioral experiment these researchers demonstrated that chimpanzees, when given a choice between two nearly identical tasks, will choose the one they previously witnessed a high-ranking member of the troop perform. ... Read more »
The perspective that whales, dolphins, and other such marine mammals should be afforded "human rights" has surfaced again.
I thought I'd revisit a post I wrote about this several months ago, from the archives, when this first hit the news after the AAAS conference in San Diego. So here's a modified, updated version of the original post.
The blogosphere is all a-twitter with talk of the recent commentary in Science that dolphins should be considered people. Well, sort of people. Non-human people.
On the heels of the incident at SeaWorld in Florida in which a trainer was killed by one of the killer whales, this is especially an important issue to consider.
Frequent commenter Daniel Bassett writes at his blog, Fishschooled:
The first argument of course is the extreme intelligence of dolphins. They (1) have larger brains than humans, (2) have a brain to body weight ratio greater than great apes, and (3) they are the second most encephalized beings on the planet. Encephalisation is the folding of the brain and increases volume and surface area, which has been shown to correlate with intelligence. But intelligence is just one part of the argument. The neocortex of dolphins is very advanced and allows them to problem solve and be self aware, and even have a form of intellect or rational thought. They also have spindle neurons that are involved in emotions, social cognition, and the ability to sense what others are thinking.
Thomas White, a philosopher at Loyola Marymount University, argues that these characteristics makes the dolphin a person, but a non-human person. They are alive, aware of their environment, have emotions, have distinct personalities, exhibit self control, and treat others with respect or ethical consideration. White argues that dolphins tick off all the boxes of what it is to be human. Research on intelligence is still in it's infancy with a lot to discover. But, based on these ideas can we justify putting dolphins in places like Seaworld for our own amusement?
Figure 1: A non-human person? Read the rest of this post... | Read the comments on this post...... Read more »
According to popular thought, Charles Darwin’s Origin of the Species was heavily influenced by his grandfather Erasmus Darwin (1). The impact that a grandparent can have upon an impressionable child should never be underestimated. To what extent do you think that Dana Carvey was influenced by his grandfather?
Dana Carvey is “DARWIN” – watch more funny [...]... Read more »
C. U. M. Smith, . (2010) Like Grandfather, Like Grandson: Erasmus and Charles Darwin on evolution. Perspectives in Biology and Medicine, 53(2), 186-199. DOI: 10.1353/pbm.0.0152
Human beings give their attention readily to people who already have it. It doesn't matter if a guy won fame for his action movies, people will listen to his advice on carbon sequestration, and go out an buy his brand of shoe. That's not logical, but it does follow a predictable rule, which is that being famous, "cool" and/or prestigious gives you ready access to the minds of others. That bias may have evolved a very long time ago, according to this paper in the journal PLoS One last week. Prestige, it reports, sways chimpanzees the same way it does people.
The authors—Victoria Horner, Darby Proctor, Kristin E. Bonnie, Andrew Whiten and Frans de Waal—taught a novel game to members of two chimpanzee troops that live at the Yerkes Primate Research Center near Atlanta. In one troop, Georgia, a high-ranking female, was taught to put plastic tokens into a polka-dotted receptacle to win a treat; the same routine, except with a striped receptacle, was taught to Tara, an ape nobody, who was low on the totem pole of social rank. (Chimp troops, like military units or Condé Nast magazines, operate with a very clear, harshly enforced pecking order.) In the other group, the learners were high-ranking Ericka and low-ranking Julianne.
As each one went through her routine, others watched and soon learned it. Many decided to get in on the action. Practically, there was no difference between imitating Georgia and imitating Tara, as the tasks and reward were identical. But the chimps much preferred to follow the high-ranking Georgia: 70 percent of the tokens they collected went into her bin. The difference between high and low status was even more marked in the second group, where 90 percent of the tokens went where Ericka was putting hers.
In a social animal, the authors conclude, learning depends on prestige. Among chimps in the wild, they write, innovations probably won't spread unless they have the equivalent of a celebrity endorsement—that is, unless they are introduced by someone high in rank.
So perhaps celebrity influence isn't a peculiarity of our times, but rather a trick evolution has played on us. For eons, imitating the "cool" guy was probably a very good bet for a social primate, because "cool" meant he was doing something right (being the best tracker, being the son of the top female) and therefore getting more food, sex and protection than the average schlub.
Civilization makes fine distinctions between kinds of prestige—we don't expect Nobel-winning physicists to be good at basketball, or Tiger Woods to play like Sonny Rollins—but elsewhere in the mind, all prestige is still the same.
That might explain why "cool" isn't a quality the authorities can control (a fact that greatly irritates the sort of people who put themselves in charge of others' morals). In her fascinating book Outcasts, for instance, Ruth Mellinkoff quotes a sermon preached in Germany in 1272: "You are not satisfied that almighty God has given you a choice of colors such as red, blue, white, green, yellow, and black for your clothing. No, in your arrogance you have cut your clothes into pieces—here putting red in the white, there yellow in the green, another is striped; this one motley, that dark brown ... This arrogance never ends, for as soon as someone discovers a new fashion, all of you must try it!"
At the time, it was soldiers who slashed up their sleeves and wore multiple patches—"pied" clothing, like the "Pied Piper" sported. In other words, while respectable burghers talked up examples of responsibility and piety, their children were more impressed by the medieval European equivalent of "gangstas."
Chimps live with a single social hierarchy, but people live with two. One is civilization's official pecking order, which values the mathlete valedictorian more highly than the studly dropout. The other pecking order gives top status to whoever is getting attention, sex and other goodies right now—never mind how. As most of us remember from high school, this intuitive hierarchy is hard to resist. If you had to choose, who would you follow around collecting tokens to win a banana—Angelina Jolie or Carol W. Greider?
Horner, V., Proctor, D., Bonnie, K., Whiten, A., & de Waal, F. (2010). Prestige Affects Cultural Learning in Chimpanzees PLoS ONE, 5 (5) DOI: 10.1371/journal.pone.0010625
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Cooperation is seen not only in humans, but in societies formed by organisms from ants to baboons. But in many cases, it’s difficult to figure out why any individual would want to cooperate. Wouldn’t it be easier just to take what you want without doing any work? While cooperation is good for the group, why [...]... Read more »
Boyd, R., Gintis, H., & Bowles, S. (2010) Coordinated Punishment of Defectors Sustains Cooperation and Can Proliferate When Rare. Science, 328(5978), 617-620. DOI: 10.1126/science.1183665
Following my discussion on bullying and cyberbullying, the NYT featured an article discussing the ways "antagonistic relationships can often enhance social and emotional development more than they impede it." The article suggests that when someone dislikes you, "it may be adaptive to dislike them back." This two part post will explore the following questions:Are there documented benefits to
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Dodge KA, Lansford JE, Burks VS, Bates JE, Pettit GS, Fontaine R, & Price JM. (2003) Peer rejection and social information-processing factors in the development of aggressive behavior problems in children. Child development, 74(2), 374-93. PMID: 12705561
Haselager, G., Hartup, W., Lieshout, C., & Riksen-Walraven, J. (1998) Similarities between Friends and Nonfriends in Middle Childhood. Child Development, 69(4), 1198-1208. DOI: 10.1111/j.1467-8624.1998.tb06167.x
Snyder, J., Brooker, M., Patrick, M., Snyder, A., Schrepferman, L., & Stoolmiller, M. (2003) Observed Peer Victimization During Early Elementary School: Continuity, Growth, and Relation to Risk for Child Antisocial and Depressive Behavior. Child Development, 74(6), 1881-1898. DOI: 10.1046/j.1467-8624.2003.00644.x
Installment #7 in the mini-series on multilingual signage
When I lived in Basel in Switzerland, my then-preschool child was just learning to make sense of the alphabet and to sound out words – a development I obviously encouraged as much as I could by seizing every literacy opportunity. Generally speaking, pretty much everything can be a [...]... Read more »
A Cuban crocodile (Crocodylus rhombifer), photographed at the National Zoo in Washington, D.C.
Outside of the trash-grubbing black bears I occasionally come across when driving to hikes in northern New Jersey, I never encounter large predators near my home. The imposing carnivores which once roamed the "garden state" were extirpated long ago. This is a very unusual thing. For the majority of the past six million years or so hominins have lived alongside, and have regularly been hunted by, an array of large carnivorous animals, but humans have not been entirely helpless. Rather than a one-sided war, our relationship with large predators is a deeply-rooted and complex exchange in which we have eventually come to fret over the survival of the animals we have traditionally feared.
The contents of a cave in Sierra de Atapuerca, Spain emphasize the long-running tensions between our species and large carnivores. Described in the Journal of Archaeological Science by Ruth Blasco, Jordi Rosell, Juan Luis Arsuaga, José M. Bermúdez de Castro, and Eudald Carbonell, the Middle-Pleistocene-age level TD10-1 of the Gran Dolina cave preserves a moment in time in which the hunted may have become the hunters. Along with stone tools, level TD10-1 contains the remains of bears, wolves, horses, elk, bison, lions, and other animals. Many of the herbivore bones bear cutmarks made by stone tools, but, interestingly enough, so do a lion fingerbone and rib. The additional presence of a lion lower arm bone (a radius) fractured as if it was slammed against something or whacked with a stone hammer suggests that the humans occupying the cave ate just about everything on the lion that was edible, from meat to marrow, and after they left small carnivores entered the cave to gnaw on the scraps still clinging to the carcass.
Read the rest of this post... | Read the comments on this post...... Read more »
Blasco, R., Rosell, J., Arsuaga, J., Bermúdez de Castro, J., & Carbonell, E. (2010) The hunted hunter: the capture of a lion (Panthera leo fossilis) at the Gran Dolina site, Sierra de Atapuerca, Spain. Journal of Archaeological Science. DOI: 10.1016/j.jas.2010.03.010
Dunham, K., Ghiurghi, A., Cumbi, R., & Urbano, F. (2010) Human–wildlife conflict in Mozambique: a national perspective, with emphasis on wildlife attacks on humans. Oryx, 44(02), 185. DOI: 10.1017/S003060530999086X
Caldicott DG, Croser D, Manolis C, Webb G, & Britton A. (2005) Crocodile attack in Australia: an analysis of its incidence and review of the pathology and management of crocodilian attacks in general. Wilderness , 16(3), 143-59. PMID: 16209470
SciCurious has written a review of an interesting paper suggesting a correlation between obesity and city vs. non-city life. As usual, the review by Sci is excellent, but I have a comment or two to add.
Having read the review and then the paper, I had to ask if it might be possible to conclude based on the data presentation that "race" (and thus "genetics") underlies the observed effect. This is because of this graph: Read the rest of this post... | Read the comments on this post...... Read more »
FRANK, L. (2004) Obesity relationships with community design, physical activity, and time spent in cars. American Journal of Preventive Medicine, 27(2), 87-96. DOI: 10.1016/j.amepre.2004.04.011
Regular readers of this blog know that while I think studying animal cognition, behavior, and communication is (sometimes) fun and (always) interesting, the real importance - the why should I care about this - is because by understanding animals, we can attempt to learn more about ourselves.
I've written about this before. Here are the relevant excerpts:
When human adults show complex, possibly culture-specific skills, they emerge from a set of psychological (and thus neural) mechanisms which have two properties:
(1) they evolved early in the timecourse of evolution and are shared with other animals, and,
(2) they emerge early in human development, and can be found in infants and children, as well as adults.
Three questions necessitate a comparative evolutionary approach (or, minimally, are enriched by such an approach):
(1) Is a given trait unique to humans?
(2) Does the acquisition of a given trait depend on uniquely human abilities?
(3) What functional problem does a given trait solve, and did it evolve for this particular function?
That the first question necessitates a comparative approach should be obvious. If comparative data indicate that even only one other species possesses the trait in question, then the question shifts a bit, and we have to determine whether the trait is homologous (depending on the same mechanisms), or homoplastic (depending on distinct mechanisms that presumably evolved independently). How can we distinguish homology from homoplasy? We look for signatures, or common features. For example, face processing in humans shows behavioral signatures (e.g. degradation when faces are inverted) and neural signatures (localized cortical activations). Those same features have been found in various monkey species that have been tested in face processing tasks, and this provides one piece of evidence for homology.
The third question distinguishes among the original function of a trait and the way it is currently used. Language, for example, allows us to recombine a finite set of elements in essentially infinite patterns to create meaning. Did this capacity evolve to facilitate communication, or for some other purpose? Assume that chimpanzees, for example, do not show evidence of this mechanism in their communication, but DO exhibit this mechanism for arithmetic computation. This might suggest that this ability evolved for number, and was then "re-purposed" by humans for communication. Of course, it is also possible that this capacity evolved independently in chimpanzees and in humans, but this seems less likely given the relatedness of our two species.
I used cognitive examples above, but of course these questions and methods of investigation apply to behavior more generally (especially since cognition and behavior are only different by virtue of different levels of analysis).
If oral sex offends you, the time to click away is now. Otherwise, read on. Read the rest of this post... | Read the comments on this post...... Read more »
Sometime in the early 1950s a wooden object was dredged from the mouth of the Skagit River, north of Seattle. It ended up in the possession of Mr. and Mrs. Edwin Johnson, residents of the nearby town of La Conner. In 1952 the Johnsons showed it to two local archaeologists, Herbert Taylor of Western Washington [...]... Read more »
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