Anthropology posts

November 25, 2009
01:13 PM
2,035 views

The Most Super Eruption of a Supervolcano

About 73,000 years ago in what is now Sumatra, Indonesia, Mount Toba exploded in the largest eruption since the appearance of Homo sapiens. This enormous eruption (a supereruption of a supervolcano in the new parlance) spewed 2800 km3 of pyroclastic material from a 100 by 30 km caldera. That is a hell of a lot – almost three times more than Yellowstone 600,000 years ago and even more than the giant (super) Yellowstone Huckleberry Ridge eruption of 2 million years ago. Toba was probably the biggest single explosive eruption in tens of millions of years.Lake Toba, Sumatra. The white dashed line marks the extent of the 73 ka caldera, which is 100 km long and 30 km wide. Landsat image from NASA.Martin Williams of the University of Adelaide is the lead author of an upcoming paper on the eruption’s environmental impact. Stanley Ambrose of the University of Illinois at Urbana-Champaign, a co-author on the study, suggested in a 1998 paper that the eruption correlates to a catastrophic drop in human population. There is strong genetic evidence that such a bottleneck occurred and reduced the human population to perhaps 1,000-10,000 breeding pairs during the Middle Stone Age; the time constraints are broad but they allow the Toba eruption as a cause. From my reading of the literature, this idea is fairly well accepted, though there is by no means a consensus.The eruption covered much of the Indian subcontinent with 10-15 cm of ash and released huge amounts of aerosols like hydrogen sulfide and sulfur dioxide into the atmosphere. There’s good evidence from geochemical markers in ice cores that the eruption had the immediate short-term effect of causing a 6-year volcanic winter – a more extreme version of the years following the 1815 Tambora, 1883 Krakatau, and 1991 Pinatubo eruptions. This 6-year period marks the beginning of the coldest 1,800 years of the Pleistocene, although the relationship between the eruption and the longer term cooling is controversial.The main contribution of the Williams et al. (2009) study is that it directly demonstrates environmental changes from the eruption across the Indian subcontinent. By examining pollen in a marine core from the Bay of Bengal and the isotopic signature of soil carbonate minerals from across central India, they show a sudden and lasting cooling and drying coincident with the ashfall. The pollen counts from the core showed a reduction in trees and wet-adapted ferns. The ... Read more »

Williams, M., Ambrose, S., van der Kaars, S., Ruehlemann, C., Chattopadhyaya, U., Pal, J., & Chauhan, P. (2009) Environmental impact of the 73ka Toba super-eruption in South Asia. Palaeogeography, Palaeoclimatology, Palaeoecology. DOI: 10.1016/j.palaeo.2009.10.009

Ambrose, S. (1998) Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans. Journal of Human Evolution, 34(6), 623-651. DOI: 10.1006/jhev.1998.0219

November 25, 2009
08:04 AM
665 views

Mental Illness vs. Suicide

by Neuroskeptic in Neuroskeptic

Do countries with more mental illness have more suicides? At first glance, it seems as though the answer must be "yes". Although not all suicides are related to mental illness, unsurprisingly people with mental illness do have a much higher suicide rate than people without. So, all other things being equal, the rate of mental illness in a country should correlate with the suicide rate. Of course, all other things are not equal, and other factors might come into play such as the quality of mental health services. But it still seems as though there should be a correlation, albeit not a perfect one, between mental illness and suicide.I decided to see whether or not there is such a correlation. The World Health Organization (WHO) provides the relevant data here. There have only ever been three studies attempting to measure rates of common mental illnesses internationally (1,2,3), and all three were run by the WHO. The WHO also collates national suicide rates (here) for most countries, although a few are missing. No-one seems to have published anything looking for a correlation between these two sets of numbers of before, or if they did, I've failed to find it.So what's the story? Take a look - In short, there's no correlation. The Pearson correlation (unweighted) r = 0.102, which is extremely low. As you can see, both mental illness and suicide rates vary greatly around the world, but there's no relationship. Japan has the second highest suicide rate, but one of the lowest rates of mental illnesses. The USA has the highest rate of mental illness, but a fairly low suicide rate. Brazil has the second highest level of mental illness but the second lowest occurrence of suicide.*Some technical notes: Two of the three surveys, the ICPE (2000) and the WMHS (2004), sampled the whole population of each country. The other one, which was also the earliest, the PPGHC (1993), surveyed people attending family doctors. Because this is a slightly different approach, I'll focus on the ICPE and the WMHS, although the results are very similar (see below).The ICPE sampled 7 countries and the WMHS sampled 14, but 4 countries were included in both surveys, so there's a total of 17 countries. I've used the mean of the ICPE and the WMHS for those 4 countries where we have data from both, for the rest I've used whichever is available. For the suicide rates, the WHO gives data for various different years, so I've used 2002, or the nearest available year, since this is between 2000 and 2004. For two countries, Lebanon and Nigeria, the WHO do not report suicide rates. For China, rates of mental illness are given in both Beijing and Shanghai.The studies used structured diagnostic interviews to try to measure the percentage of people suffering from mental illness in the 12 months before the interview. As I've said previously, this -attempts to study a random sample of the population of a certain country. In order to establish whether each person is mentally ill or not, they use structured diagnostic interviews. These consists in asking the subject a fixed ("structured") series of questions, and declaring them to have a certain mental disorder if they answer "Yes" to a given number of them.In this case the structured question interview was called the CIDI and it used DSM-IV criteria. You can check it out here. Example question:You mentioned having periods that lasted several days or longer when you felt sad, empty, or depressed most of the day. During episodes of this sort, did you ever feel discouraged about how things were going in your life? (YES, NO, DON’T KNOW, REFUSED)*The rates from the population surveys (ICPE & WMHS) don't correlate with suicide but they do correlate with the rates from the PPGHC survey of people attending family doctors. The association here is very strong, with a correlation r = 0.693. The only outlier is the US. This is despite the fact that a decade elapsed between the first survey (1993) and the other two (2000, 2004).This is important because it shows that the mental illness surveys are measuring something about these countries, something which is stable over time. They're not just producing random junk results. But whatever they're measuring, it's not related to suicide.*What does this mean? You leave a comment and tell me. But here's my take. I've often expressed skepticism of population surveys and their (very high) estimates of mental illness, but even so, I was surprised to find no correlation at all with suicide. I'd say that any meaningful measure of mental illness should correlate with suicide. These surveys, using the CIDI, don't, so to me they're not meaningful.One thing to bear in mind about these numbers is that they deal with "common" mental illnesses like depression, substance abuse and anxiety. They leave out the most severe disorders such as schizophrenia. Also, people in psychiatric hospitals, in prison, and the homeless, will not have been included in the studies because they sample "households". That could be why there's no association with suicide, but if so then these surveys are missing a very important aspect of mental health.The surveys do seem to measure something, but I don't think it has much to do with mental illness. This is just a guess but I suspect they're measuring willingness to talk about your emotional life to strangers. At least stereotypically, the Chinese and the Japanese are known as more reserved in this regard than Brazilians and Americans. So it's no surprise that when you ask people a load of personal questions, the "rates of mental illness" seem to be lower in Japan than in America. This doesn't mean Americans are really more ill, just more open.I've been talking about surveys looking at differences between countries, but if these are flawed, then so are surveys looking at just one... Read more »

Sartorius N, Ustün TB, Costa e Silva JA, Goldberg D, Lecrubier Y, Ormel J, Von Korff M, & Wittchen HU. (1993) An international study of psychological problems in primary care. Preliminary report from the World Health Organization Collaborative Project on 'Psychological Problems in General Health Care'. Archives of general psychiatry, 50(10), 819-24. PMID: 8215805

WHO. (2000) Cross-national comparisons of the prevalences and correlates of mental disorders. WHO International Consortium in Psychiatric Epidemiology. Bulletin of the World Health Organization, 78(4), 413-26. PMID: 10885160

Demyttenaere K, & et Al. (2004) Prevalence, severity, and unmet need for treatment of mental disorders in the World Health Organization World Mental Health Surveys. JAMA, 291(21), 2581-90. PMID: 15173149

November 23, 2009
02:24 PM
914 views

Brain Damage, Pedophilia, and the Law

by Neuroskeptic in Neuroskeptic

An intriguing and tragic story of brain damage is reported in the latest issue of Neurocase: Klüver-Bucy syndrome, hypersexuality, and the law.The authors are Devinsky, Sacks, and Devinsky - Sacks being neurologist and author Dr. Oliver Sacks. Their anonymous patient, a 51 year old married American man, is currently serving a jail sentence for downloading child pornography. But he's not your average pedophile.The man's problems began at the age of 19 when he -first suffered attacks of déjà vu ... They became much more frequent – as many as 20 attacks a day – and much more complex, the déjà vu now being followed by a cascade of other symptoms: sharp pains in the chest and sensations of breathlessness; alterations of hearing; occasional musical hallucinations – he would always hear a particular song ‘as clearly as if it were being played in the next room’...Tests showed that he was suffering from epilepsy, and that the seizures originated in the right mesial temporal lobe, an area of the brain involved in memory and emotion. Temporal lobe epilepsy is relatively common, and it's a fascinating topic in itself, as the symptoms often include hallucinations and other strange experiences such as a powerful sense of déjà vu.Anticonvulsant drugs didn't help, so at age 33, the patient had surgery to remove the region where the seizures began. However, a few months later, the seizures returned, worse than before. So, at age 39, he had a second operation to remove even more of his right temporal lobe. That's when his real trouble started -Approximately a month after surgery, behavioral changes of irritability, hyperphagia [increased eating] and hypersexuality (including coprophilia) developed. He became more sexually active with his wife and masturbated more often. Compulsively, he began to watch adult pornographic images and videos on the internet when his wife slept.The unfortunate patient's symptoms are a rare example of Klüver-Bucy Syndrome (KBS) in man. Here's the very first account of it -He no longer clearly understands the meaning of the sounds, sights, and other impressions that reach him. His food is devoured greedily, the head being dipped into the dish, instead of the food being conveyed to the mouth by the hands. He reacts to all kinds of noises, even slight ones – such as the rustling of a piece of paper – but shows no consequent evidence of alarm or agitation and displays tyrannizing proclivities towards his mate.That's a description of a lab monkey, written in 1888 by British neuroscientists Sanger Brown and E. A. Schaefer. Compare it to the patient's own words about what happened to him -My appetite for food and sex increased dramatically. I had greater mood swings. I wanted sex constantly. Every day. I was very easily stimulated and began to touch myself regularly. I began to request sex daily from my wife. If I wasn’t having sex with my wife, I masturbated. This behavior increased over time. I became more emotionally labile, obsessive–compulsive... I become distracted so easily that I can’t get anything started or done.It's a classic example of KBS, although the patient only had his right temporal lobe damaged, whereas in monkeys KBS usually follows removal of both the left and the right temporal lobes. Also, it's interesting that the symptoms only started a month after the surgery.The patient's appetite for sex (and food) was insatiable, and this became his downfall -Some websites solicited him to view and purchase child pornography. He became obsessed with this and eventually purchased and downloaded pornographic images of prepubescent females engaged in sexual activities from the internet. He was ashamed and secretive about these activities, not discussing the pornography or masturbation with his wife or with anyone else.In 2006, he was arrested. A psychiatrist prescribed an antipsychotic, quetiapine, and an antidepressant, sertraline. His sexual obsessions disappeared, and according to his wife, "he became much warmer and loving but the medications shut off his libido... sex became non-existent."The patient was subsequently charged with 'knowingly and wilfully possessing material which contained at least three images of child pornography'. He plead guilty. Dr Devinsky told the court that the right temporal lobe damage was the "major contributing factor to the patient’s hypersexuality and viewing of child pornography" and that he was, therefore, not responsible for his actions. Oliver Sacks agreed, saying a letter that he was. . . a man of superior intelligence and of real moral delicacy and sensibility, who at one point was driven to act out of character under the spur of an irresistible physiological compulsion resulting from his brain injury. A recurrence of such behavior is extremely unlikely given his character and insight... He is strictly monogamous.The prosecution, however, argued that he was in control of actions, because he was able to avoid acting inappropriately in public, and they sought the maximum sentence possible - 20 years. They said thatthe patient’s hypersexual behavior in some situations but not others was evidence for volitionally controlled criminal behavior; that it was incompatible with a neurological cause. For example, he downloaded and viewed child pornography at home but not at work.The judge, however, accepted that the patient's medical condition was a mitigating factor in the case. He sentenced him to 26 months imprisonment, 25 months home confinement, and 5 years under supervision - the minimum punishment allowable by law.Should he have been punished at all? Devinsky, Sacks, and Devinsky don't think so: "Was he criminally responsible? Did his behavioral actions warrant imprisonment? We believe the answer is no to both questions."But the case raises difficult questions about free will and responsibility. At first glance, it seems as though the man's brain damage didn't directly make him download the child porn, but merely gave him an "urge" to do so. Don't we have the ability to choose whether or not to follow our urges? Isn't that what "free will" is?On the other hand, damage to the same parts of the brain causes strikingly similar symptoms in monkeys. An alien scientist observing life on earth might well conclude, from cases like this, that all the species of monkeys on this planet are very similar - including humans. You damage a certain part of their brains, and their behaviour changes in a predictable way. Most of us humans would say that other monkeys don't have "free will" - but then how are we so sure that we do?Links: I've previously blogged about drugs to increase libido and the question of free will. The Neurocritic has a great post on neurology and sex from a few weeks back. Finally, perhaps the most important question raised by this case is what would the Paedofinder General say?... Read more »

Devinsky J, Sacks O, & Devinsky O. (2009) Kluver-Bucy syndrome, hypersexuality, and the law. Neurocase : case studies in neuropsychology, neuropsychiatry, and behavioural neurology, 1-6. PMID: 19927260

November 23, 2009
11:01 AM
683 views

Natural selection among us: The Kuru epidemic

by Brian Appleby in CJD Blogger

Kuru is an acquired prion disease, transmitted through ritualistic cannibalism, that reached epidemic proportions in the Fore tribe of Papua New Guinea. In a previous post, I presented an article by John Collinge’s group on the selection process of heterozygosity at codon 129 of the prion protein gene (PRNP). The research group has gone a step further by recently describing a new polymorphism of the PRNP gene, G129V. The authors performed PRNP genotyping of 3,000 individuals from the Eastern Highland population, which included 709 individuals who had participated in cannabalistic rituals. They looked specifically at the codons 127 and 129 among geographic regions and among individuals that were stratified by risk exposure (i.e., high, medium, and low risk). The G127V variant was only found in those regions where kuru was prevalent. 127V was present in half of the women who had the highest exposure to kuru and who were homozygous for methionine at codon 129 (MM). Interesting, although 129V was present in kuru exposed populations, it was not found in those who succumbed to kuru or in unexposed population groups around the world. 127V was also invariably linked to a 129M allele and predominately found in 129MM homozygotes in contrast to 129MV heterozygotes. Heterozygosity at codon 127 thus conveyed resistance to kuru in others susceptible 129MM homozygotes. Thus the newly described G127V polymorphism was naturally selected among populations exposed to kuru as a resistance factor. Both codon 129V and codon 127V are examples of natural selection that have occurred recently. Once again, prion diseases teach us a lot about biology in general…hence another important factor for studying them. Mead S, Whitfield J, Poulter M, Shah P, Uphill J, Campbell T, Al-Dujaily H, Hummerich H, Beck J, Mein CA, Verzilli C, Whittaker J, Alpers MP, & Collinge J (2009). A Novel Protective Prion Protein Variant that Colocalizes with Kuru Exposure. The New England journal of medicine, 361 (21), 2056-2065 PMID: 19923577 del.icio.us Tags: kuru,evolution,epidemiology,prion diseases,research,biology,genetics,risk ... Read more »

Mead S, Whitfield J, Poulter M, Shah P, Uphill J, Campbell T, Al-Dujaily H, Hummerich H, Beck J, Mein CA.... (2009) A Novel Protective Prion Protein Variant that Colocalizes with Kuru Exposure. The New England journal of medicine, 361(21), 2056-2065. PMID: 19923577

November 19, 2009
08:19 PM
533 views

What Does It Mean to Be Navajo?

by teofilo in Gambler's House

In the previous post I made a distinction between “affiliation” and “identity” that may not have been totally clear. In the context of Keith Kloor’s article on Navajo connections to Chaco, the basic point I want to make could be drastically oversimplified to something like this:

The Park Service’s finding that the Navajos are “affiliated” with [...]... Read more »

Warburton, M., & Begay, R. (2005) An Exploration of Navajo-Anasazi Relationships. Ethnohistory, 52(3), 533-561. DOI: 10.1215/00141801-52-3-533

November 19, 2009
08:11 AM
1,289 views

East is East?

by Alun in AlunSalt

I’m not planning to blog a lot on the Astronomical Orientation of Ancient Greek Temples as is openly accessible. Your comments are going to carry a lot more weight there than here. But I’ll try and keep track of what other people are saying elsewhere. I’m expecting this to be the first paper of a [...]... Read more »

Salt, A. (2009) The Astronomical Orientation of Ancient Greek Temples. PLoS ONE, 4(11). DOI: 10.1371/journal.pone.0007903

November 18, 2009
03:25 PM
662 views

Oh no! Ideophones are not response cries!

by Mark D. in The Ideophone

In their commentary on Evans & Levinson's recent hotly debated Myth of Language Universals paper, Pinker & Jackendoff briefly mention ideophones — and erroneously shelve them away as 'response cries'. It seems this error is a particularly easy one to make for speakers of SAE languages. In this post I flesh out why this might be so, and explain what's the difference between response cries (also known as interjections) and ideophones.... Read more »

Pinker, S., & Jackendoff, R. (2009) The reality of a universal language faculty. Behavioral and Brain Sciences, 32(05), 465. DOI: 10.1017/S0140525X09990720

November 17, 2009
02:57 AM
945 views

The somniloquy hypothesis: How the immature brain learns facts

by William Lu in The Quantum Lobe Chronicles

A while back I wrote about the possible adaptive function of somnambulism or sleep-walking. Well...I've come up with yet another hypothesis addressing a behavior falling under the category of parasomnias. Somniloquy or sleep-talking happens during stages of NREM sleep, the time declarative memory (i.e. factual knowledge) is consolidated. This seemingly bizarre behavior typically occurs in childhood and is outgrown by puberty. Presentation can vary from rhythmic nonsense words to long coherent speeches. No one really knows where it comes from. The most popular answer seems to be because of stress.We could just leave it at that, but it doesn't really explain why it came about in the first place. I have a hard time simply writing-off weird behaviors that have managed to stick around for long periods of time. In my head I'm thinking "there's just gotta be a functional purpose"!Here's what I think NREM sleep-talking is all about. Somniloquy is just behavioral evidence of the maturing brain consolidating syntactical and semantical aspects of language. It's also important to note that the calm quality of NREM sleep-talk is very different compared to the loud and emotional sleep-talk found during rapid eye movement behavior disorder. This makes a lot of sense. REM sleep is known to process emotional memory so of course you'd see this kind of late night emotionally charged verbal diarrhea. Some have postulated that this irratic unconscious behavior protected the stressed out sleep deprived caveman from hungry predators looking for some easy eats. On the flip side, factual bits of data like "Paris is the capital of France" isn't emotional at all (unless you're strangely disturbed by this bit of info) and that's why you hear the flat affect during NREM somniloquy.So there you go. I've laid out a tentative explanation for NREM somniloquy. I haven't seen anything else around to explain this more pleasant form of sleep-talking. If you spot any let me know. It'd be cool if we could figure out a way to induce somniloquy in different stages of sleep and observe what the brain was doing.In the meantime, I wouldn't fret too much over your kids mumbling something about world domination as they nap. They're probably just learning how to orate more effectively. Gais S, & Born J (2004). Declarative memory consolidation: mechanisms acting during human sleep. Learning & memory (Cold Spring Harbor, N.Y.), 11 (6), 679-85 PMID: 15576885... Read more »

Gais S, & Born J. (2004) Declarative memory consolidation: mechanisms acting during human sleep. Learning , 11(6), 679-85. PMID: 15576885

November 12, 2009
05:50 AM
593 views

Adaptations for the visual assessment of formadibility: Part II

by Michael Meadon in Ionian Enchantment

In Part I of this series, I summarized the experiments and findings of Aaron Sell and colleagues' paper "Human adaptations for the visual assessment of strength and fighting ability from the body and face". In Part II, I evaluate their claims.

This evidence Sell et. al. present seems compelling with regards to proposition (i): adults appear to be able to make remarkably accurate estimates of upper-body strength from even degraded cues such as static images of faces. As I noted in Part I, however, the truth of propositions (ii) (that this ability is an adaptation) and (iii) (that upper-body strength determines formidability) are more doubtful. I will assess the evidence for each of these claims, starting with the latter.

Concluding that the truth of (i) implies people can visually estimate fighting ability – the likelihood of an individual prevailing in combat – requires us to assume (iii): that upper-body strength is a good proxy for formidability. Unfortunately, Sell and his colleagues provide only indirect, theoretical, reasons for supposing this is true: namely, the greater sexual dimorphism between upper-body and lower-body strength and the fact that the driving force of certain weapons is largely a function of upper-body strength (p. 576). , These considerations, however, seem far from decisive and while it is certainly plausible that upper-body strength is a very (or the most) important component of fighting ability, rigour clearly requires direct empirical evidence. Other likely components of formidability – speed, stealth, skill, bravery, etc. – are either orthogonal to, or even negatively correlated with, high upper-body strength. There are doubtlessly multiple complex tradeoffs between the different components of fighting ability and thus there are likely multiple local-optima in ‘formidability space’. The point of this argument is that without an empirical determination of the magnitude of the correlation between formidability and strength, Sell et. al.’s conclusion rests on an (admittedly plausible) assumption. More importantly, however, it is at least possible that uncontrolled-for components of formidability may introduce confounds or complications that could influence the correlation between perceived and actual strength in either direction. For example, there may be a semi-independent ability to estimate fighting skill, and, depending on the direction of the correlation between upper-body strength and this skill, it may lead us to under- or overestimate the accuracy of visual assessment of fighting ability. The problems around claim (iii), however, are comparatively minor; the major weakness of Sell et. al.’s paper lies with their claim that the ability to visually estimate formidability evolved by natural selection.

An adaptationist claim like (ii) is significantly more complex than other types of propositions because it entails assertions about the past and about design (Symons, 1992: 140-141). As Richard Burian has explained, when one asserts some trait is an adaptation, “one is claiming not only that the feature was brought about by differential reproduction among alternative forms, but also that the relative advantage of this feature vis-à-vis its alternatives played a significant causal role in its production” (1983: 294). In other words, the assertion that the ability to estimate formidability is an adaptation entails that it evolved over deep time by natural selection, and that the ‘function’ of this psychological trait and its neurological substrate is to detect formidability. To say some feature is an adaptation, then, is a compound claim involving multiple independent propositions, each of which requires substantiation. Sell et. al., it seems to me, fall short of this evidentiary standard, not least because they never mount an explicit defense of (ii), despite the fact that they have the onus and that it is a crucial aspect of their paper. There are, nonetheless, a number of arguments that can be extracted from the paper (or advanced on behalf of the authors). In rough order from least to most persuasive, these are (a) that (i) was previously unknown and that Sell et. al. predicted its existence from evolutionary considerations, (b) that comparative data indicates that such assessments are widespread and perhaps even homologous across taxa, (c) that accurate visual formidability assessment is at a minimum not highly culturally bound, and perhaps universal, and (d) the functional goodness-of-fit between the ‘design problem’ and its ‘solution’.

It seems highly significant, firstly, that Sell and his colleagues predicted the existence of a previously unknown trait – i.e. (i) – from general comparative and evolutionarily psychological considerations. It is important to be careful here, though, because it is entirely possible for (i) to be true but for (ii) to be false (but obviously not vice versa). Some philosophy of science should clarify the situation. Hans Reichenbach (1938) usefully distinguished between the “context of discovery” (the creative process of using background knowledge to invent new hypotheses and theories) and the “context of justification” (the evidence-driven process of testing hypotheses and subjecting them to peer evaluation). For example, Friedrich Kekulé von Stradonitz reportedly first imagined the six-carbon ring structure of benzene after having a dream of an ouroboros (the context of discovery). It does not follow from this, however, that benzene actually had anything to do with snakes, or that testing the idea (the context of justification) involved an ancient symbol. Similarly, even if Sell et. al. predicted the existence of an ability to make formidability estimates from evolutionary theory, it does not necessarily follow that the trait evolved. Propositions (i) and (ii) are logically and epistemically independent, and each needs to be tested against related but different sets of evidence. The fact that (i) was predicted rather than retrodicted from evolution gives as no more than prima facie reason to think it evolved and (a) is thus weak evidence for (ii).

Sell et. al. cite a large and growing body of literature that documents parallels between human and non-human conflict, including, importantly, evidence that non-human animals can visually detect formidability. If this trait is homologous across species, including humans – and that is a gargantuan if – we can be confident (ii) is true since homology suggests that the emergence and persistence of the trait is due to natural selection. It should be clear, however, that building a convincing phylogenetic case for such a widespread homology would be a mammoth undertaking, and no one, as far as I know, has yet done so. The fact that there seems to be a preliminary case for homology is at best suggestive, no conclusions can reasonably be drawn until much more science is done. In other words, were (b) true we could reasonably infer (ii), but we simply do not have enough evidence to conclude (b) is in fact true so, on current evidence, it provides minimal support.

The logic of argument (c) is the following: given that traits that reliably emerge in developmentally normal individuals are likely (though not necessarily) adaptations, de... Read more »

Sell, A., Cosmides, L., Tooby, J., Sznycer, D., von Rueden, C., & Gurven, M. (2009) Human adaptations for the visual assessment of strength and fighting ability from the body and face. Proceedings of the Royal Society B: Biological Sciences, 276(1656), 575-584. DOI: 10.1098/rspb.2008.1177

November 10, 2009
02:58 PM
1,109 views

New Virtual Issue of Cultural Anthropology on "Security"

by Kevin Karpiak in Anthropoliteia: the anthropology of policing

special online virtual issue of Cultural Anthropology on the topic of "Security"... Read more »

WELKER, M. (2009) “CORPORATE SECURITY BEGINS IN THE COMMUNITY”: Mining, the Corporate Social Responsibility Industry, and Environmental Advocacy in Indonesia. Cultural Anthropology, 24(1), 142-179. DOI: 10.1111/j.1548-1360.2009.00029.x

LAKOFF, A. (2008) THE GENERIC BIOTHREAT, OR, HOW WE BECAME UNPREPARED. Cultural Anthropology, 23(3), 399-428. DOI: 10.1111/j.1548-1360.2008.00013.x

MASCO, J. (2008) “SURVIVAL IS YOUR BUSINESS”: Engineering Ruins and Affect in Nuclear America. Cultural Anthropology, 23(2), 361-398. DOI: 10.1111/j.1548-1360.2008.00012.x

FELDMAN, I. (2007) DIFFICULT DISTINCTIONS: Refugee Law, Humanitarian Practice, and Political Identification in Gaza. Cultural Anthropology, 22(1), 129-169. DOI: 10.1525/can.2007.22.1.129

Fassin, D. (2005) Compassion and Repression: The Moral Economy of Immigration Policies in France. Cultural Anthropology, 20(3), 362-387. DOI: 10.1525/can.2005.20.3.362

November 10, 2009
06:12 AM
696 views

Adaptations for the visual assessment of formidability: Part I

by Michael Meadon in Ionian Enchantment

In the last couple of years there has been an explosion in research on faces and what can be inferred from them. It turns out, for example, that you can predict electoral outcomes from rapid and unreflective facial judgments, that women can (partially) determine a man's level of interest in infants from his face alone, that the facial expression of fear enhances sensory acquisition, and much, much else. A particularly interesting addition to this literature is Aaron Sell et. al.'s paper, "Human adaptations for the visual assessment of strength and fighting ability from the body and face". Sell and his colleagues hypothesized that human beings possess evolved psychological mechanisms 'designed' to estimate the fighting ability (or physical formidability) of conspecifics - i.e. other Homo sapiens sapiens - from minimal visual information. An ancillary, but important, claim the authors also make is that formidability is largely a function of upper-body strength and thus the latter is a suitable proxy for the former. To summarize for clarity, Sell et. al. claim that:

(i) people can estimate the formidability of others from visual cues of their bodies and faces,

(ii) this ability is an adaptation, and thus evolved by natural selection, and

(iii) upper-body strength is the single most important determining factor of fighting ability.

The authors’ rationale for the first two hypotheses stems from the observation that in social species such as humans, ‘the magnitude of the costs an individual can inflict on competitors largely determines its negotiating position’ (p. 575). That is, formidability is often an important component of an organism’s ability to compete in zero-sum games (notably, access to limiting resources). Given the dangers of physical confrontation, a rapid visual assessment of the formidability of an opponent could be extremely beneficial because it would allow an individual to weigh up its chances of success, and thus choose to fight only when there is a reasonable prospect of victory. Indeed, Sell et. al. note that the widespread so-called ritualized animal contests are best interpreted as joint demonstrations and assessments of formidability, with physical violence usually ensuing only when individuals are closely matched. If the ability to visually estimate a competitor’s formidability was indeed adaptive, and if violence was frequent and recurrent throughout human evolutionary history (as is likely the case), it is not unreasonable to expect natural selection to have forged mechanisms to make such estimates. Sell and his colleagues tested hypothesis (i) empirically in a number of studies and the evidence seems to bear it out overall. While the truth of (ii) is more doubtful, I will argue that, pending further research, it is reasonable to accept it preliminarily for a number of reasons. Finally, I will argue the lack of empirical evidence in the study for (iii) is problematic but not decisively so: it is clear that there is a correlation between upper-body strength and formidability, but we do not know how strong this correlation is so it is difficult to judge how good a proxy the one is for the other.

After the jump, I summarize Sell et. al.'s primary findings (though I leave out one of their experiments). In Part II - coming later in the week - I evaluate their paper.

Broadly speaking, Sell et. al. divided their subjects into two groups: the stimulus subjects (who provided the target photographs and strength measurements) and the judgement subjects (who rated the strength of the men in the target photos). The first group filled out a questionnaire, posed for photographs, had their body measurements taken (e.g. weight, height) and then had their strength measured in a number of ways. The photographs were then standardized and edited, and the target individuals’ upper-body strength measurements were combined to create a composite score for each. The judgement group was then presented with various versions of the photographs and asked to rate the physical strength of the target individuals. Specifically, these subjects were asked to: “Please rate the following [men/bodies/faces] on how physically strong you think the man is compared to other men of his age” on a 7-point Likert scale (1 = very weak, 7 = very strong). In the first study, 59 male undergraduates at the University of California Santa Barbara (UCSB) were recruited at a campus gym, their photos were taken and so on as described above. Each participant’s upper-body strength was then measured on four weight-lifting machines in random order (arm curl, abdominal crunch, chest press, and super long pull) and his lower-body strength was measured with a leg-press. The subjects also posed for two colour photographs: (a) full-person, without a shirt, standing next to a male experimenter for scale, and (b) face-only. (Dress was standardized and subjects were asked to keep a neutral expression). The images were then edited to create three sets of photographs: face-only, cropped below the jaw-line (as in the top row of picture below), full-person (not pictured), and body-only with the face removed (as in the bottom row).

After these stimulus materials were created, an additional 142 UCSB undergraduates (59 female) were asked to rate one set of 59 images (full person, body only or face only). The findings robustly supported the authors’ hypothesis: the average ratings of the men’s strength correlated with their actual upper-body strength at r=0.71 (p=10-10) for photographs of the whole person, at r=0.66 (p=10-8) for the body alone, and at r=0.45 (p=0.0003) for the face alone. These results, though, relate to perceived strength, not to perceived formidability itself. So to test whether judgments of strength track judgments of fighting ability, the researchers asked another group of 37 subjects (25 female) to “Please look at the following photographs of men and rate them on how tough each would be in a physical fight – how likely he would be to beat his opponent”. The correlation was nearly perfect: r=0.96 (p = 10-32).

Using hierarchical linear modelling (HLM) Sell et. al. further established that upper-body strength specifically, and not lower-body strength or other features such as height or age, largely determined perceived strength. In the first HLM, the target variable was rated strength and the predictor variables were upper-body strength and leg strength as measured on the leg press. Again, the results supported the authors’ hypothesis: in all cases, the predictive contribution of upper-body strength was large and highly significant, whereas the contribution of lower-body strength was equivocal, modest and of mixed significance. For face only photographs, upper-body strength was γ=0.31 (p=10-11) but leg strength γ=-0.09 (p=0.003); for body only, upper-body strength was γ=0.44 (p=10-19) but leg strength γ=0.007 (p=0.81); and for full person photos, upper-body strength was γ=0.41 (p=10-12) but leg strength γ=0.06 (p=0.03). Clearly, then, perceived strength is more a function of upper-body than lower body str... Read more »

Sell, A., Cosmides, L., Tooby, J., Sznycer, D., von Rueden, C., & Gurven, M. (2009) Human adaptations for the visual assessment of strength and fighting ability from the body and face. Proceedings of the Royal Society B: Biological Sciences, 276(1656), 575-584. DOI: 10.1098/rspb.2008.1177

November 9, 2009
11:30 AM
1,541 views

Reciprocity and the Anthropology of Organ Transplants

by Eric Michael Johnson in The Primate Diaries

Reciprocity is an intrinsic feature of human beings as well as most species of ape. Chimpanzees and bonobos regularly engage in granting gifts of food and expect a return on their generosity (those who don't reciprocate are less likely to receive such gifts in the future) (de Waal and Brosnan 2006). This "tit-for-tat" basis of exchange exists in all human societies and becomes ritualized based on the cultural norms that are present. One of the most well known descriptions of reciprocity among indigenous societies is that of the Kula among the Trobriand Islanders near Papua New Guinea that was documented by anthropologist Bronislaw Malinowski.

The Kula was a ritualized gift exchange in which a shell necklace or armband is given to a member of a neighboring tribe, at which time the receiver reciprocates by offering the other item in return. This exchange is then repeated between societies around the archipelago connecting thousands of individuals. Each person has therefore been the receiver from one direction and the giver in another. This ritualized obligation cemented lifelong connections between neighboring tribes and served as a basis for economic cooperation between peoples. Read the rest of this post... | Read the comments on this post...... Read more »

Margaret Lock. (2002) Twice Dead: Organ Transplants and the Reinvention of Death. California Series in Public Anthropology, no. 1. . info:/

November 4, 2009
07:23 AM
1,587 views

Long Toes & Short Ankles Help Sprinters Accelerate Faster

by Anthropology.net in Anthropology.net

The Journal of Experimental Biology has published an interesting paper about some unique features in sprinters: longer toes and shorter ankle joints. The only one flaw is that their sample size is limited, they only compared 12 collegiate sprinters with 12 non-athletes of the same height. Regardless, from a physical anthropological point of view, this [...]... Read more »

Knight, K. (2009) SHORT HEELS GIVE ELITE SPRINTERS THE EDGE. Journal of Experimental Biology, 212(22). DOI: 10.1242/jeb.039735

Lee, S., & Piazza, S. (2009) Built for speed: musculoskeletal structure and sprinting ability. Journal of Experimental Biology, 212(22), 3700-3707. DOI: 10.1242/jeb.031096

November 3, 2009
11:21 PM
715 views

Building a Religion: The Rock Art Evidence

by teofilo in Gambler's House

The idea that the kachina cult was not an indigenous development among the Pueblos but was instead introduced from the south seems to have originated with a 1974 article by Polly and Curtis Schaafsma. As they note, while some previous scholars had noted some elements of the cult that suggested Mesoamerican influence, the general consensus [...]... Read more »

Schaafsma, P., & Schaafsma, C. (1974) Evidence for the Origins of the Pueblo Katchina Cult as Suggested by Southwestern Rock Art. American Antiquity, 39(4), 535. DOI: 10.2307/278903

November 3, 2009
02:34 PM
1,035 views

Anime film characters: Do we perceive the intended race, or our own?

by Dave Munger in Cognitive Daily

One of my favorite cartoons as a child was "Speed Racer." It featured an all-American boy (first name, "Speed," last name, "Racer") engaging in that most American of pastimes: driving fast cars. Except that "Speed Racer" wasn't really American; it was made in Japan, and the original Japanese voices were crudely overdubbed in English. Perhaps I can be excused for not noticing the Japanese origins of the show -- I was only 10 years old. Even now, as an adult looking back at those cartoons, the characters do seem awfully American-looking. Or perhaps that's just my Caucasian bias.

Does everyone see a little bit of themselves in animated cartoon characters? Or do the artists actually draw the characters to look more generic, less racially distinctive? There have been few studies about the perceived race and ethnicity of animated cartoon characters, and none focusing on the unique Japanese anime style.

So Amy Shirong Lu randomly selected 341 main characters out of 3,098 anime films made between 1958 and 2005. Each image was carefully edited to depict only a head-on, facial portrait-style picture. All clothing and background images were edited out, like this:

The character depicted here is Asuka Langley Soryu, from the movie Neon Genesis Evangelion, and of mixed Japanese and German descent. Lu recruited 1,046 people to view a randomly-selected set of 90 of the pictures and judge the characters' race based on the features depicted in the pictures. The animators' intended race of each character was judged based on the promotional materials for the film, or watching the movie itself. Still, in 125 of the cases, it was either impossible to determine the character's race or the character was of mixed ancestry. About half of all the characters were intended to be Asian, while only about 10 percent were Caucasian. Did the viewers responses match the actual race of the characters? Here are the results: Read the rest of this post... | Read the comments on this post...... Read more »

Lu, A.S. (2009) What Race Do They Represent and Does Mine Have Anything to Do with It? Perceived Racial Categories of Anime Characters. Animation, 4(2), 169-190. DOI: 10.1177/1746847709104647

November 2, 2009
12:52 PM
703 views

Real vs Placebo Coffee

by Neuroskeptic in Neuroskeptic

Coffee contains caffeine, and as everyone knows, caffeine is a stimulant. We all know how a good cup of coffee wakes you up, makes you more alert, and helps you concentrate - thanks to caffeine.Or does it? Are the benefits of coffee really due to the caffeine, or are there placebo effects at work? Numerous experiments have tried to answer this question, but a paper published today goes into more detail than most. (It caught my eye just as I was taking my first sip this morning, so I had to blog about it.)The authors took 60 coffee-loving and gave them either placebo decaffeinated coffee, or coffee containing 280 mg caffeine. That's quite a lot, roughly equivalent to three normal cups. 30 minutes later, they a difficult button-pressing task requiring concentration and sustained effort, plus a task involving mashing buttons as fast as possible for a minute.The catch was that the experimenters lied to the volunteers. Everyone was told that they were getting real coffee. Half of them were told that the coffee would enhance their performance on the tasks, while the other half were told it would impair it. If the placebo effect was at work, these misleading instructions should have affected how the volunteers felt and acted.Several interesting things happened. First, the caffeine enhanced performance on the cognitive tasks - it wasn't just a placebo effect. Bear in mind, though, that these people were all regular coffee drinkers who hadn't drunk any caffeine that day. The benefit could have been a reversal of caffeine withdrawl symptoms.Second, there was a small effect of expectancy on task performance - but it worked in reverse. People who were told that the coffee would make them do worse actually did better than those who expected the coffee to help them. Presumably, this is because they put in extra effort to try to overcome the supposedly negative effects. This paradoxical placebo response reminds us that there's more to "the placebo effect" than meets the eye.Finally, no-one who got the decaf noticed that it didn't actually contain caffeine, and the volunteer's ratings of their alertness and mood didn't differ between the caffeine and placebo groups. So, this suggests that if you were to secretly someone's favorite blend with decaf, they wouldn't notice - although their performance would nevertheless decline. Bear that in mind when considering pranks to play on colleagues or flatmates.It looks like science has just confirmed another piece of The Wisdom of Seinfeld:Elaine: Jerry likes Morning Thunder.George: Jerry drinks Morning Thunder? Morning Thunder has caffeine in it. Jerry doesn't drink caffeine.Elaine: Jerry doesn't know Morning Thunder has caffeine in it.George: You don't tell him?Elaine: No. And you should see him. Man, he gets all hyper, he doesn't even know why! He loves it. He walks around going, "God, I feel great!"- Seinfeld, "The Dog"Harrell PT, & Juliano LM (2009). Caffeine expectancies influence the subjective and behavioral effects of caffeine. Psychopharmacology PMID: 19760283... Read more »

Harrell PT, & Juliano LM. (2009) Caffeine expectancies influence the subjective and behavioral effects of caffeine. Psychopharmacology. PMID: 19760283

October 31, 2009
11:17 PM
605 views

Werewolves of London, Ontario

by The Neurocritic in The Neurocritic

An American Werewolf in LondonIn the last post, we learned about the Psychopharmacology of Lycanthropy (and "endogenous lycanthropogens") from the April 1, 1992 issue of the Canadian Medical Association Journal (Davis et al., 1992). In a more serious review on clinical lycanthropy in the British Journal of Psychiatry Coll, O'Sullivan, and Browne (1985; PDF) began by stating:Lycanthropy is the delusion in which an individual believes he has been transformed into an animal, traditionally a wolf. Descriptions of this syndrome are found in the earliest medical writings such as those of the Greek Paulus Aegineta in the seventh century A.D. (Adams, 1844). There is also a biblical description of the syndrome in the Book of Daniel. Nebuchadnezzar (605-562 B.C.), the king who rebuilt Babylon, succumbed to a lycanthropic state after suffering from an apparent depressive illness for seven years.Nebuchadnezzar, by William BlakeIn his 1621 magnum opus, The Anatomy of Melancholy, Robert Burton (aka Democritus Junior) explained it thusly (in Part 1):Lycanthropia, which Avicenna calls cucubuth, others lupinam insaniam, or wolf-madness, when men run howling about graves and fields in the night, and will not be persuaded but that they are wolves, or some such beasts. Aetius and Paulus call it a kind of melancholy; but I should rather refer it to madness, as most do. Some make a doubt of it whether there be any such disease. Donat ab Altomari saith, that he saw two of them in his time: Wierus tells a story of such a one at Padua 1541, that would not believe to the contrary, but that he was a wolf... And Nebuchadnezzar in Daniel, as some interpreters hold, was only troubled with this kind of madness. This disease perhaps gave occasion to that bold assertion of Pliny, some men were turned into wolves in his time, and from wolves to men again: and to that fable of Pausanias, of a man that was ten years a wolf, and afterwards turned to his former shape: to Ovid's tale of Lycaon, &c. Not surprisingly, the modern-day diagnosis given to individuals afflicted with this delusion is usually a psychotic disorder in the context of schizophrenia (Fahy, 1989), severe depression (Coll et al., 1985; Rao et al., 1999; Younis & Moselhy, 2009), or bipolar disorder (Verdoux & Bourgeois, 1993).Benicio del Toro stars in The Wolfman, to be released in Feb. 2010.However, imaginary transmogrification isn't restricted to the lupine variety. A comprehensive review of the literature between 1966–2002 (Garlipp et al., 2004) identified 21 articles, primarily case studies:In the current medical literature man–animal metamorphoses were described concerning the following animals: wolf/werewolf, dog, gerbil, rabbit, horse, tiger, cat, bird, unspecified animal species, frog and bee. In Asia, Africa and South America, metamorphoses in tiger, hyena, crocodile and shark were observed.The authors mention that the specifics can be influenced by cultural factors. But then they deliver the psychodynamic perspective promised in the review's title (and a bit of condescension):The symptomatology can be seen as a continuity spectrum of developmental and culture dependent normal behaviour via transitional – a fantasy of an artist – and partial forms to the whole picture of lycanthropy described by Keck et al. (1988). The length of transformation is usually short, symptomatology has mostly disappeared in a week's time. People who live in preindustrial societies and people living on isolated countrysides are predisposed. Other precipitating factors seem to be subconscious sexual conflicts.Finally, they end with precipitating psychopathology:Lycanthropic symptomatology can be seen in different mental diseases. Most of the patients suffer from an affective disorder or from schizophrenia. Furthermore, the man–animal metamorphosis can be seen after the intake of psychotropic substances including cannabinoids as well as alcohol abuse. Rarely, lycanthropy is reported in personality disorders. Case reports can be found concerning organic psychosyndromes, dementia and epilepsy. We'll end with an article from the Canadian Journal of Psychiatry, on two unusual case reports (Gödecke-Koch et al., 2001):Case Report 1A 34-year old woman suffering from schizophrenia came to the emergency department. At first, she was mutistic; later she seemed agitated and tense. Suddenly, she started moving like a frog, jumping around, making frog-like noises, and showing her tongue as though in tend ing to catch a fly. We found out that she had taken part in a workshop about fairy tales prior to becoming symptomatic. An organic cause was excluded, and no drug intake was found.Case report 2A 24-year-old woman suffering from schizophrenia ... Read more »

Garlipp, P., Gödecke-Koch, T., Dietrich, D., & Haltenhof, H. (2004) Lycanthropy - psychopathological and psychodynamical aspects. Acta Psychiatrica Scandinavica, 109(1), 19-22. DOI: 10.1046/j.1600-0447.2003.00243.x

October 30, 2009
08:40 PM
732 views

Replication

by teofilo in Gambler's House

When I was working at Chaco, we would often get visitors who would complain about how hard it was to get there. They usually focused on the road in and asked why there wasn’t more effort to pave it and make it more accessible to the American public. After all, isn’t that what national parks [...]... Read more »

Pepper, G. (1905) Ceremonial Objects and Ornaments from Pueblo Bonito, New Mexico. American Anthropologist, 7(2), 183-197. DOI: 10.1525/aa.1905.7.2.02a00010

October 26, 2009
04:24 PM
762 views

Barack Obama Boosts Testosterone

by Neuroskeptic in Neuroskeptic

But only if you voted for him, and only if you're a man. That's according to a PLoS One paper called Dominance, Politics, and Physiology.It's already known that in males, winning competitions - achieving "dominance" - causes a rapid rise in testosterone release, whilst losing does the opposite. That's true in humans, as well as in other mammals. The authors wondered whether the same thing happens when men "win" vicariously - i.e. when someone we identify with triumphs.What better way of testing this than the U.S. Presidential Election? The authors took 163 American voters, and got them to provide saliva samples before, during and after the results came in on the night of the 4th November. Here's what happened -In Obama supporters (the blue line, natch), salivary testosterone levels stayed flat throughout the crucial hours. But supporters of John McCain or Libertarian candidate Bob Barr, suffered a testosterone crash after Obama's victory became apparent. That was only true in men, though; in women, there was no change.Heh. Of course, we hardly needed biology to tell us that people often identify strongly with their preferred political parties, and the fact that social events cause hormonal changes shouldn't surprise anyone - the brain controls the secretion of most hormones.The gender difference is interesting, though. Does this mean that men identify closer with politicians? Or maybe only with male ones - what would have happened if Hilary had won... or Palin? It could be that the testosterone surge accompanying success is strictly a man thing, although it's been shown to occur in women in some studies, but not consistently.Finally, I should mention that this paper contains some excellent quotes, such as "...Robert Barr, who arguably did not have a chance of winning...", "In retrospective reports of their affective state upon the announcement of Obama as the president-elect, McCain and Barr voters felt significantly more unhappy" and my favourite, "men who voted for John McCain or Bob Barr (losers)". That last one may be taken slightly out of context.Stanton, S., Beehner, J., Saini, E., Kuhn, C., & LaBar, K. (2009). Dominance, Politics, and Physiology: Voters' Testosterone Changes on the Night of the 2008 United States Presidential Election PLoS ONE, 4 (10) DOI: 10.1371/journal.pone.0007543... Read more »

Stanton, S., Beehner, J., Saini, E., Kuhn, C., & LaBar, K. (2009) Dominance, Politics, and Physiology: Voters' Testosterone Changes on the Night of the 2008 United States Presidential Election. PLoS ONE, 4(10). DOI: 10.1371/journal.pone.0007543

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