A new fMRI study in PLoS reports Differential Brain Activation to Angry Faces by Elite Warfighters, the elite warfighters being US Navy SEALs.SEALs are indeed pretty elite. This being a British blog, I wouldn't want to say that they're the world's elitest naval special forces unit. That's the British Special Boat Service. But they could still kill you ten times before you knew they were there (unless you're in the Special Boat Service.)Anyway, San Diego researchers Paulus et al scanned 11 SEALs and 23 healthy civilian men during an emotional face matching (originally developed by Hariri et al) that involved seeing happy, angry, and fearful faces.Such tasks are very popular in neuroimaging at the moment because looking at faces of people expressing strong emotions reliably activates emotion-related brain areas, without needing to actually induce emotions in your volunteers which can cause practical problems, i.e. people getting scared and maybe panicking in the MRI scanner. Whether studying emotional-face-induced activation is a valid substitute for studying emotion-induced activation is an open question.What happened? fMRI being a sensitive way of measuring human brain activation, they found some differences between the two groups in neural responses to seeing the faces:elite warfighters relative to comparison subjects showed relatively greater right-sided insula, but attenuated left-sided insula, activation. Second, these individuals showed selectively greater activation to angry target faces relative to fearful or happy target faces bilaterally in the insula.OK. So what does that mean?These findings support the notion that elite warfighters... deploy greater neural processing resources toward potential threat-related facial expressions and reduced processing resources to non-threat-related facial expressions. This finding suggests that rather than expending more effort in general, elite warfighters show more focused neural and performance tuning, such that greater neural processing resources are directed toward threat stimuli and processing resources are conserved when facing a nonthreat stimulus situation.So the message is that SEALs are better at focusing on threats and don't get distracted by benign background stuff. Although apparently this is only true of their insula, not an area known for its role in attention, and the threat was an angry face on a screen. But that aside, this is not very surprising given that they're highly-trained soldiers.But the unsurprisingness of this result is a problem. We don't need neuroscience to tell us that elite soldiers are good at detecting and responding to threats. That's rather obvious. I'd guess that most of them were pretty good at it before they got selected, and then they got even better with training. This must have something to do with the brain, because your brain is what allows you to learn stuff.What we don't understand very well yet is how training (or other forms of learning) works, on a neural level, i.e. what the molecular and cellular mechanisms are. It would be really nice to find out. Unfortunately, fMRI studies like this are unable to tell us that, because they only study the very last stage in the process, the final product.This is in no way a problem with this paper alone, and it's no worse than many other articles. The same issue applies to many neuroimaging studies of abnormal states like depression or, as I've posted about previously, psychological trauma. Such results can form the basis for investigations into mechanisms, and as ways of testing theories, but on their own, finding that abnormal brains react in abnormal ways is not, in itself, very useful.Paulus, M., Simmons, A., Fitzpatrick, S., Potterat, E., Van Orden, K., Bauman, J., & Swain, J. (2010). Differential Brain Activation to Angry Faces by Elite Warfighters: Neural Processing Evidence for Enhanced Threat Detection PLoS ONE, 5 (4) DOI: 10.1371/journal.pone.0010096... Read more »
Paulus, M., Simmons, A., Fitzpatrick, S., Potterat, E., Van Orden, K., Bauman, J., & Swain, J. (2010) Differential Brain Activation to Angry Faces by Elite Warfighters: Neural Processing Evidence for Enhanced Threat Detection. PLoS ONE, 5(4). DOI: 10.1371/journal.pone.0010096
Everyone is familiar with the bow and arrow, but what on earth is an atlatl? Although this implement was once used all over the world and was an important part of life, in most areas it was replaced by other weapons so long ago that it is no longer remembered, and most people today have [...]... Read more »
At first blush grooming among primates might seem to strictly serve hygienic purposes. After all, primates are furry little mammals crawling with ectoparasites like lice, ticks, and other icky arthropods. Despite this, primates seem to allocate more time to grooming than necessary for basic hygiene. Primates groom each other to strengthen social bonds and reduce [...]... Read more »
Noe, R., & Hammerstein, P. (1994) Biological markets: supply and demand determine the effect of partner choice in cooperation, mutualism and mating. Behavioral Ecology and Sociobiology, 35(1), 1-11. DOI: 10.1007/s002650050063
Port, M., Clough, D., & Kappeler, P. (2009) Market effects offset the reciprocation of grooming in free-ranging redfronted lemurs, Eulemur fulvus rufus. Animal Behaviour, 77(1), 29-36. DOI: 10.1016/j.anbehav.2008.08.032
Most research on human-environment interactions focuses on large-scale changes in environmental conditions over long periods of time (by human standards, at least). There are good reasons for this, especially when applied to prehistory, most importantly that there are a lot of potential data sources for environmental conditions that can be correlated with cultural chronologies to [...]... Read more »
Recently there’s been a television promotional advertisement that really bugs me. It shows a man watching events appearing before his eyes and has a voice-over that says something to the effect of “When you look back on your life are you going to see a life filled with interesting people and excitement?” and when is [...]... Read more »
Jeremy Freese. (2003) Imaginary imaginary friends? Television viewing and satisfaction with friends. Evolution and Human Behavior, 24(1), 65-69. DOI: 10.1016/S1090-5138(02)00109-5
Each week, Research Bloggers Kevin Zelnio, Razib Khan, and I will choose a journal article to discuss in podcast form. We’ll make sure it’s an article that we or someone else has covered on their blog, so ideally, you’ll read the blog post first to get a general understanding of the research, then listen to [...]... Read more »
Malmstrom, H., Linderholm, A., Liden, K., Stora, J., Molnar, P., Holmlund, G., Jakobsson, M., & Gotherstrom, A. (2010) High frequency of lactose intolerance in a prehistoric hunter-gatherer population in northern Europe. BMC Evolutionary Biology, 10(1), 89. DOI: 10.1186/1471-2148-10-89
I’ve talked a bit about Jane Hill’s theory that agriculture was introduced to the Southwest by a migration of speakers of Uto-Aztecan languages from Mesoamerica, which she supports mostly through somewhat unconvincing linguistic evidence. A recent paper in, yes, PNAS offers a strong set of counterarguments to Hill’s theory, and offers an alternative theory in [...]... Read more »
Merrill, W., Hard, R., Mabry, J., Fritz, G., Adams, K., Roney, J., & MacWilliams, A. (2009) The diffusion of maize to the southwestern United States and its impact. Proceedings of the National Academy of Sciences, 106(50), 21019-21026. DOI: 10.1073/pnas.0906075106
Non-English speakers’ access to emergency services in Australia is in the news again as a Melbourne man has been convicted of the murder of his wife. What makes the case particularly shocking is the fact that the victim, who was originally from Afghanistan, tried to call police a few days before the murder but couldn’t [...]... Read more »
Piller, Ingrid, & Takahashi, Kimie. (2010) Language, Migration, and Human Rights. Wodak, Ruth, Paul Kerswill and Barbara Johnstone. Eds. Handbook of Sociolinguistics. London: Sage. info:/
Earlier I mentioned recent research suggesting that the heartland of Mesoamerican agriculture was in western Mexico, which has important implications for the place of that region in Mesoamerica as a whole and in areas, like the Southwest, subject to Mesoamerican influence in prehistory. The main research I was talking about is contained in two papers [...]... Read more »
Piperno, D., Ranere, A., Holst, I., Iriarte, J., & Dickau, R. (2009) Starch grain and phytolith evidence for early ninth millennium B.P. maize from the Central Balsas River Valley, Mexico. Proceedings of the National Academy of Sciences, 106(13), 5019-5024. DOI: 10.1073/pnas.0812525106
Ranere, A., Piperno, D., Holst, I., Dickau, R., & Iriarte, J. (2009) The cultural and chronological context of early Holocene maize and squash domestication in the Central Balsas River Valley, Mexico. Proceedings of the National Academy of Sciences, 106(13), 5014-5018. DOI: 10.1073/pnas.0812590106
Zizumbo-Villarreal, D., & Colunga-GarcíaMarín, P. (2010) Origin of agriculture and plant domestication in West Mesoamerica. Genetic Resources and Crop Evolution. DOI: 10.1007/s10722-009-9521-4
“Abyssinia is, apparently, the native land of donkeys,” Vavilov states flatly. well, maybe.
Two relatively recent studies shed light on the domestication of the donkey. A 2004 paper by Albano Beja-Pereira and his colleagues, published in Science, looked at the molecular evidence. The researchers conclude that the donkey was domesticated twice, once from the Nubian sub-species [...]... Read more »
Beja-Pereira A, England PR, Ferrand N, Jordan S, Bakhiet AO, Abdalla MA, Mashkour M, Jordana J, Taberlet P, & Luikart G. (2004) African origins of the domestic donkey. Science (New York, N.Y.), 304(5678), 1781. PMID: 15205528
Rossel, S., Marshall, F., Peters, J., Pilgram, T., Adams, M., & O'Connor, D. (2008) Domestication of the donkey: Timing, processes, and indicators. Proceedings of the National Academy of Sciences, 105(10), 3715-3720. DOI: 10.1073/pnas.0709692105
Lee Berger’s son, Matthew, found the ~1.9 million year old hominin remains of female adult and a juvenile male in cave deposits at Malapa, South Africa. The remains have been analyzed and been published in Science today, and so far this finding is the big fossil hominid of 2010. The skull of the juvenile is the [...]... Read more »
Berger, L., de Ruiter, D., Churchill, S., Schmid, P., Carlson, K., Dirks, P., & Kibii, J. (2010) Australopithecus sediba: A New Species of Homo-Like Australopith from South Africa. Science, 328(5975), 195-204. DOI: 10.1126/science.1184944
Dirks, P., Kibii, J., Kuhn, B., Steininger, C., Churchill, S., Kramers, J., Pickering, R., Farber, D., Meriaux, A., Herries, A.... (2010) Geological Setting and Age of Australopithecus sediba from Southern Africa. Science, 328(5975), 205-208. DOI: 10.1126/science.1184950
Anyone who has seriously studied an empirical or mathematical science knows there is something very special about how those studies affect the way we view the world. There is something very profound feeling in the way our minds works after we’ve been exposed to logical and testable systems, and it enters into almost [...]... Read more »
A diagram of how the skeletons of Australopithecus sediba came to be preserved in the Malapa cave deposit. From Dirks et al, 2010.
A little less than two million years ago, in what is now South Africa, a torrential downpour washed the bodies of two humans into the deep recesses of a cave. Just how their remains came to be in the cave in the first place is a mystery. Perhaps they fell in through the gaping hole in the cave roof just as hyenas, saber-toothed cats, horses, and other animals had, but, however the humans entered the cave, their bones ultimately came to rest in a natural bowl carved into the rock. This mode of preservation would keep their remains in good condition until their discovery in 2008, and today in the journal Science a team of researchers has described them as the latest addition to our family tree, Australopithecus sediba. Read the rest of this post... | Read the comments on this post...... Read more »
Lee R. Berger, Darryl J. de Ruiter, Steven E. Churchill, Peter Schmid, Kristian J. Carlson, Paul H. G. M. Dirks, Job M. Kibii1. (2010) Australopithecus sediba: A New Species of Homo-Like Australopith from South Africa. Science, 195-204. info:/10.1126/science.1184944
Paul H. G. M. Dirks, Job M. Kibii, Brian F. Kuhn, Christine Steininger,, Steven E. Churchill, Jan D. Kramers, Robyn Pickering, Daniel L. Farber,, & Anne-Sophie Mériaux, Andy I. R. Herries, Geoffrey C. P. King, Lee R. Berger. (2010) Geological Setting and Age of Australopithecus sediba from Southern Africa. Science, 205-208. info:/10.1126/science.1184950
When a leopard eats a baboon, what is left behind? This question is not only relevant to primatologists and zoologists. Even though instances of predation on humans is relatively rare, big cats still kill and consume people, and when they do they can virtually obliterate a body. Yet, just like a human criminal, the dining habits of big cats leave tell-tale clues, and in 2004 researchers Travis Pickering and Kristian Carlson fed two captive leopards eight complete baboon carcasses each in order catalog the most useful ways to identify the victim of a big cat kill. Read the rest of this post... | Read the comments on this post...... Read more »
PICKERING, T., & CARLSON, K. (2004) Baboon taphonomy and its relevance to the investigation of large felid involvement in human forensic cases. Forensic Science International, 144(1), 37-44. DOI: 10.1016/j.forsciint.2004.03.003
There's a brief report at Discovery News that provides some detail about an artificial stone structure that appears to have been built at the entrance of Theopetra Cave (Greece) to protect its inhabitants from the elements. That, in and of itself is not news; what is news is the age of the thing: 23,000 years BP, obtained by optically stimulate luminescence (OSL)The structure is a stone wall that blocked two-thirds of the entrance to the Theopetra cave near Kalambaka on the north edge of the Thessalian plain. It was constructed 23,000 years ago, probably as a barrier to cold winds.“An optical dating test, known as Optically Stimulated Luminescence, was applied on quartz grains nested within the stones. We dated four different samples from the sediment and soil materials, and all provided identical dates,” Nikolaos Zacharias, director of the laboratory of archaeometry at the University of Peloponnese, told Discovery News. This is definitely cool, as there are not very many such structures known from the Paleolithic. One possible, though somewhat shaky, comparable example is that of "two low, roughly linear wall-like piles of cobbles, each about 50m long [that] border a portion of the scatter" of the scatter of mostly Upper Paleolithic stone tools recovered at site MAC064, Iran (Rosenberg 1984:83). I was surprised, though, that the report refers to the Theopetra structure as the oldest 'man-made' (sic) structure. This is because I can think of at least one other stone structure, at Ucagizli Cave in Turkey (Kuhn et al 2003: 114-116 - available as a free pdf here), that dates to slightly older than ca. 30,000 BP. Here's what it looks like:And though it appears at first glance to be perhaps less impressive than the Theopetra wall (though the picture in the DN report is a bit unclear as to what the exact boundaries of the wall are), Kuhn et al. (2003: 114) describe the Ucagizli wall as a feature consisting "of a single arched course of limestone blocks, each 20-40cm in length. The blocks form a 'wall' running roughly parallel to the back wall of the cave at a distance of 1.5 to 2m from it. The alignment is clearly artifical: it corresponds with neither the cave's dripline nor any obvious fault or crack in the roof , and there were no blocks of comparable size in the surrounding sediments. Moreover, several of the blocks were set on edge rather than resting on their broad face." By analogy to ethnographic observations, they interpret it as most likely demarcating the edges of "a bedding area in the back of the cave."So yes, the Theopetra wall is old, but not necessarily the oldest evidence of an artificial stone structure that we have for the Upper Paleolithic. In any case, it'll be very interesting to see what other material is associated with this wall at Theopetra, to see whether or not its interpretation as a windbreak is borne out. As I've discussed before with the case of La Folie, the correlation between features and other aspects of the archaeological record is critical in inferring their ultimate function.ReferencesKuhn, S. L., Stiner, M. C., Kerry, K. W., and Güleç, E. 2003. The early Upper Paleolithic at Üçağızlı Cave (Hatay, Turkey): preliminary results. In Goring-Morris, N., and Belfer-Cohen, A. (eds.) More Than Meets the Eye: Studies on Upper Palaeolithic Diversity in the Near East, Oxbow Books, Oxford, pp. 106-117. Rosenberg, Michael (1990). Stone "Walls" and Paleolithic Tools: The MAC064 Site Iran, 28, 83-88... Read more »
Rosenberg, Michael. (1990) Stone "Walls" and Paleolithic Tools: The MAC064 Site . Iran, 83-88. info:/
A few months ago, I asked Why Do We Sleep?That post was about sleep researcher Jerry Siegel, who argues that sleep evolved as a state of "adaptive inactivity". According to this idea, animals sleep because otherwise we'd always be active, and constant activity is a waste of energy. Sleeping for a proportion of the time conserves calories, and also keeps us safe from nocturnal predators etc.Siegel's theory in what we might call minimalist. That's in contrast to other hypotheses which claim that sleep serves some kind of vital restorative biological function, or that it's important for memory formation, or whatever. It's a hotly debated topic.But Siegel wasn't the first sleep minimalist. J. Allan Hobson and Robert McCarley created a storm in 1977 with The Brain As A Dream State Generator; I read somewhere that it provoked more letters to the Editor in the American Journal of Psychiatry than any other paper in that journal.Hobson and McCarley's article was so controversial because they argued that dreams are essentially side-effects of brain activation. This was a direct attack on the Freudian view that we dream as a result of our subconscious desires, and that dreams have hidden meanings. Freudian psychoanalysis was incredibly influential in American psychiatry in the 1970s.Freud believed that dreams exist to fulfil our fantasies, often though not always sexual ones. We dream about what we'd like to do - except we don't dream about it directly, because we find much of our desires shameful, so our minds disguise the wishes behind layers of metaphor etc. "Steep inclines, ladders and stairs, and going up or down them, are symbolic representations of the sexual act..." Interpreting the symbolism of dreams can therefore shed light on the depths of the mind.Hobson and McCarley argued that during REM sleep, our brains are active in a similar way to when we are awake; many of the systems responsible for alertness are switched on, unlike during deep, dreamless, non-REM sleep. But of course during REM there is no sensory input (our eyes are closed), and also, we are paralysed: an inhibitory pathway blocks the spinal cord, preventing us from moving, except for our eyes - hence why it's Rapid Eye Movement sleep.Dreams are simply a result of the "awake-like" forebrain - the "higher" perceptual, cognitive and emotional areas - trying to make sense of the input that it's receiving as a result of waves of activation arising from the brainstem. A dream is the forebrain's "best guess" at making a meaningful story out of the assortment of sensations (mostly visual) and concepts activated by these periodic waves. There's no attempt to disguise the shameful parts; the bizarreness of dreams simply reflects the fact that the input is pretty much random.Hobson and McCarley proposed a complex physiological model in which the activation is driven by the giant cells of the pontine tegmentum. These cells fire in bursts according to a genetically hard-wired rhythm of excitation and inhibition.The details of this model are rather less important than the fact that it reduces dreaming to a neurological side effect. This doesn't mean that the REM state has no function; maybe it does, but whatever it is, the subjective experience of dreams serves no purpose.A lot has changed since 1977, but Hobson seems to have stuck by the basic tenets of this theory. A good recent review came out in Nature Neuroscience last year, REM sleep and dreaming. In this paper Hobson proposes that the function of REM sleep is to act as a kind of training system for the developing brain.The internally-generated signals that arise from the brainstem (now called PGO waves) during REM help the forebrain to learn how to process information. This explains why we spend more time in REM early in life; newborns have much more REM than adults; in the womb, we are in REM almost all the time. However, these are not dreams per se because children don't start reporting experiencing dreams until about the age of 5.Protoconscious REM sleep could therefore provide a virtual world model, complete with an emergent imaginary agent (the protoself) that moves (via fixed action patterns) through a fictive space (the internally engendered environment) and experiences strong emotion as it does so.This is a fascinating hypothesis, although very difficult to test, and it begs the question of how useful "training" based on random, meaningless input is.While Hobson's theory is minimalist in that it reduces dreams, at any rate in adulthood, to the status of a by-product, it doesn't leave them uninteresting. Freudian dream re-interpretation is probably ruled out ("That train represents your penis and that cat was your mother", etc.), but if dreams are our brains processing random noise, then they still provide an insight into how our brains process information. Dreams are our brains working away on their own, with the real world temporarily removed.Of course most dreams are not going to give up life-changing insights. A few months back I had a dream which was essentially a scene-for-scene replay of the horror movie Cloverfield. It was a good dream, scarier than the movie itself, because I didn't know it was a movie. But I think all it tells me is that I was paying attention when I watched Cloverfield.On the other hand, I have had several dreams that have made me realize important things about myself and my situation at the time. By paying attention to your dreams, you can work out how you really think, and feel, about things, what your preconceptions and preoccupations are. Sometimes.Hobson JA, & McCarley RW (1977). The brain as a dream state generator: an activation-synthesis hypothesis of the dream process. The American journal of psychiatry, 134 (12), 1335-48 PMID: 21570Hobson, J. (2009). REM sleep and dreaming: towards a theory of protoconsciousness Nature Reviews Neuroscience, 10 (11), 803-813 DOI: 10.1038/nrn2716... Read more »
Hobson JA, & McCarley RW. (1977) The brain as a dream state generator: an activation-synthesis hypothesis of the dream process. The American journal of psychiatry, 134(12), 1335-48. PMID: 21570
Hobson, J. (2009) REM sleep and dreaming: towards a theory of protoconsciousness. Nature Reviews Neuroscience, 10(11), 803-813. DOI: 10.1038/nrn2716
A leopard (Panthera pardus). Image from Wikipedia.
SK-54 is a curious fossil. The 1.5 million year old skullcap represents a juvenile Paranthropus robustus, one of the heavy-jawed hominins which lived in prehistoric South Africa, but there is something that makes this skull fragment particularly special. Near one of the sutures along the back of the skull are two neat puncture marks, the hallmark of a leopard.
Even though it was initially proposed that SK-54 had been murdered by another australopithecine wielding a weapon of bone or horn, in the late 1960's the paleontologist C.K. Brain was able to demonstrate that the holes almost precisely fitted with the lower canine teeth of a leopard. What's more, Brain determined that many of the accumulations of bones found in the South African cave deposits were attributable to the activities of predators, meaning that for a long span of time our ancient relatives (particularly juveniles) may have regularly been cat food. Nor were hominins the only primate fossils to be found in these accumulations. It seems that the prehistoric leopards had a taste for primates, just as some living leopards do.
In the Tai Forest of Cote d'Ivoire, leopards frequently kill and consume primate prey. It is rare that scientists observe an attack in progress, but the primate remains in big cat scat confirm that primates are a major part of the leopard diet in this forest. Along with what we know from the fossil record, these prey preferences have raised an interesting question. Have the hunting habits of leopards influenced primate evolution? Read the rest of this post... | Read the comments on this post...... Read more »
I saw this Op-Ed piece earlier this month about the decline of the RSVP, and it resonated strongly. It reminded me of my own experience last year when I organized my sister-in-law's (husband's sister) bridal shower. Apparently, I came very close to alienating the guest list, which contained mostly family members, because of the way my invitation was delivered.
The gathering was limited to "
... Read more »
Abu-Zahra, N. (1974) Material Power, Honour, Friendship, and the Etiquette of Visiting. Anthropological Quarterly, 47(1), 120. DOI: 10.2307/3317030
Finally, some commentaries on Evans & Levinson 2009 — a recent BBS paper that argues for linguistic diversity and against Universal Grammar— are trickling down the blogosphere. Nigel Duffield's "Roll up for the mystery tour" argues that "Universal Grammar ... walks free from the courtroom", based on the crucial point that "facts about attained, endstate grammars bear only tangentially on theories of UG". Which leads me to wonder: is it grammar?... Read more »
Evans, N., & Levinson, S. (2009) The myth of language universals: Language diversity and its importance for cognitive science. Behavioral and Brain Sciences, 32(05), 429. DOI: 10.1017/S0140525X0999094X
About five years ago Kari Stefansson published an interesting paper, A common inversion under selection in Europeans. The basic thrust of the results was that a particular genomic region in Europeans exhibited a pattern of variation whereby there was one variant which was inverted in relation to the modal type. They labelled them “H2″ and [...]... Read more »
Donnelly, M., Paschou, P., Grigorenko, E., Gurwitz, D., Mehdi, S., Kajuna, S., Barta, C., Kungulilo, S., Karoma, N., & Lu, R. (2010) The Distribution and Most Recent Common Ancestor of the 17q21 Inversion in Humans. The American Journal of Human Genetics, 86(2), 161-171. DOI: 10.1016/j.ajhg.2010.01.007
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