Monthly Archives: March 2010
March 25, 2010Posted by on
A team of archaeologists have found the bone of a little finger while digging at Denisova Cave in the Altai Mountain, located in southern Siberia. The size of the bone suggests that it came from a child between five and seven years of age. It is difficult to distinguish between different species of humans based solely on the morphology of a single finger bone. However, the tentative dates put the age of the bone at between 30,000 and 50,000 years ago; a window of time when both Neandertals and modern humans coexisted in Eurasia.
In order to determine which species the little finger came from, Johannes Krause of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany sequenced the complete mitochondrial DNA (mtDNA) from the finger bone and compared its DNA with that of modern humans and Neandertals. What they found surprised everyone involved in the project. The mtDNA of Denisova did not match that of modern humans or Neandertals. In fact it last shared a common ancestor with us and Neandertals in Africa around a million years ago.
We know of three major hominin migrations out of Africa. The first occurred with Homo erectus around 1.9 million years ago, followed by the ancestors of Neandertals sometime between 500,000 and 300,000 years ago, and finally modern humans around 50,000 years ago. This makes the Denisova specimen too late to be part of the Homo erectus exodus and too early to part of the other two.
However, it may be a little premature to declare this a new species of human. Svante Pääbo’s team is already busy sequencing the nuclear DNA of the Denisova specimen. One, albeit unlikely, possibility is that this will turn out to be a representative of an outlier Neandertal population. Previous studies have found a wide diversity in both the morphology and mitochondria of geographically separated Neandertal populations. Until the nuclear DNA has been mapped it is not possible to definitively say if we are really dealing with a new species of human. However, if this does turn out to be the case, it would mean that we shared the globe with at least three other species of humans as late as 40,000 years ago.
March 22, 2010Posted by on
How long will it take mankind to learn that while they listen to “the speaking hundreds and units, who make the world ring” with the pretended triumphs they have witnessed, the “dumb millions” of deluded and injured victims are paying the daily forfeit of their misplaced confidence!
Almost 170 years after Oliver Wendell Holmes read these words to the Boston Society for the Diffusion of Useful Knowledge the pseudoscience of homeopathy continues to thrive. An EU commission statement estimates that some 30 million people in the EU use homeopathy, while the WHO estimates that around 500 million in the world use it.
Since Wendell Holmes’ time a colossal body of evidence has been amounted showing that homeopathy has no medicinal effect beyond the placebo effect. The core concepts of homeopathy fly in the face of science and logic. homeopathy uses highly dilute solutions of a substance to treat disease. Most homeopathic solutions are so dilute that there is almost no chance that they will contain even a single molecule of the original active agent. Counterintuitively, homeopathic practitioners claim that the more dilute the solution, the stronger the homeopathic remedy. This contradicts the well-known phenomenon of dose response, which says that the more of a chemical an organism is exposed to, the greater the effect. Take one sleeping pill and it will help you sleep; take two and the effect is even more powerful; take 100 sleeping pills and you are not likely to wake up … ever! On the other hand, homeopaths would suggest that the more dilute the solution, the more “powerful” the effect. But how could a solution of something that doesn’t contain even a single molecule of active ingredient have any effect? Here, things get even more bizarre. They suggest that water has memory. Seemingly, water has the ability to remember contact with certain substances, while at the same time being able to forget all the raw sewage and fecal matter that it has been in contact with. If homeopathy is nothing but water, why do so many people continue to believe it works?
Scientists and sceptics who engage with advocates of homeopathy usually end up throwing their hands up in the air in frustration. The reason is that most people who have come to believe in homeopathy do not do so based on scientific data or for particularly rational reasons. As such, it is unlikely that anyone who did not come to a particular position based on logic or reason will be argued out of that position using logic and reason. Indeed, no amount of rational argument will convince proponents of this modality that they are misguided. Holmes was well aware of the ineffectiveness such an exercise, stating that “… it is impossible not to realize the entire futility of attempting to silence this asserted science by the flattest and most peremptory results of experiment.”
It is tempting to criticise such beliefs on the grounds that the people who hold them are somehow lacking basic cognitive skills. In fact, people who believe in all kinds of strange things are often very rational in other aspects of their life. I would instead argue that the faulty thinking that many engage in is a byproduct of our mind works. The human brain evolved not only to explain the world around us; it evolved to deal with an innumerable amount of tasks. Cultural transmission does not occur by downloading information, as was once believed, but rather is based on an inferential system. We classify things in our environment into ontological categories. Most things we encounter in our environment fall into one of the following groups: person, animal, natural object, tool and plant. Each ontological category has a set of characteristics that define it and set it apart from other categories. We make certain inferences about objects based on which ontological category it belongs to. For instance, we are not surprised when a dog walks down the street but would find it strange if we saw an oak tree doing so. Locomotion is part of our mental template for people and animals but not plants. We find certain counter-intuitive notions more memorable than blander ones, a prerequisite for a successful meme. Superstitious beliefs often combine ontological beliefs with a category violation. For instance, disembodied souls and inanimate statues that can cry, hear or bleed represent category violations for a person and a natural object respectively. However, not all superstitious beliefs are equally believable. While the belief in ghosts is widespread, the belief that ghosts cannot think and have desires is virtually non-existent. Violations must allow for further inferences, otherwise they result in cognitive dead ends. Although few of my readers literally believe in superheroes and zombies, that does not stop us from making inferences about what their needs, wants and limits would be if they did exist.
The idea that water has memory is a categorical violation. Memories are characteristic of a person or animal but not a natural object. Crucially, the belief that water has memory does not block further cognitive inferences. Conversely, we would find it much more difficult to believe that water remembers the substances that other water had been in contact with. This type of belief is rare since it prevents us from making further inferences. We have experience with the concept of remembering things that we have been in contact with but don’t have experience of what it is like to remember things other people have been in contact with. People I met when I was younger — people who I have not seen for many years – still have an influence on me now. Likewise, it is not such a large cognitive leap to believe that substances that came into contact with water still have an influence over it.
Another important component of homeopathy is vitalism. The idea that we are more than just the aggregate of chemical and mechanical processes is an appealing one. Vitalism appeals to our core intuitions. Vitalists believe that the laws of science are inadequate to explain life processes. There must be something more to it – a soul or some elan vital. All of us operationally view ourselves as both body and mind, even those of us who outright reject the idea of a disembodied self or soul. The self is not something that governs the brain, rather the self is the outcomes of brain processes. However, our brain does a wonderful job of convincing us otherwise. The father of homeopathy, Samuel Hahnemann, saw the vital force as a “spirit like” force that maintained life. He believed that the inner vital force maintained the body’s internal balance. When the body became ill it would push the illness outwardly, causing the symptoms of the disease or illness to manifest. Many homeopaths believe that all disease come down to one thing — the disturbance of the vital force. They believe that only homeopathic remedies stimulate the vital force into action.
Sympathetic or imitative magic is found in cultures the world over. Sympathetic magic is based on two related concepts: the law of similarity and the law of contagion. The former states that like things produce like effects, while the latter is the idea that items that have been in contact continue to affect each other. Perhaps the best known example of sympathetic magic is the use of voodoo dolls to place a curse on a specific person. Cargo cults would also engage in sympathetic magic by building landing strips and radio towers to encourage the airplanes that delivered them precious cargo during World War II to come back again. In the past, whooping cough and a sore throat were often treated by tying knots in a piece of string and hanging it around the ill person’s neck. The knots were supposed to symbolise the tightness in the person’s throat. Liverworts have been used for hundreds of years as a cure ailments of the liver, probably because of the plant’s resemblance to the liver. A cure for pneumonia was to tie the lungs of a sheep to the soles of the feet of a patient. Golden objects and butter were commonly used as cures for jaundice. It was believed that warts could be cured by rubbing them on a frog, most likely because of the frog’s warty appearance. The use of oysters, rhinoceros horns and tiger penises as aphrodisiacs are all examples of sympathetic thinking. The list goes on and on.
In a similar vein, homeopathy uses the concept of “like cures like.” It is based on the idea that substances which produce symptoms similar to those of a particular illness can treat that illness. For instance, homeopaths may treat a person suffering from hay fever with an onion extract, since both produce watery eyes and a runny nose. The idea that water can still remember things it was previously in contact with, is an example of the “law of contagion.” In this regard, homeopathy is similar to the concept of holy water that is common to many religions.
The brain processes that lead someone to believe in homeopathy exist in all of us. Our mental capacities evolved to aid in our survival, with erroneous beliefs an emergent property of our intuitive psychology. We are all prone to cognitive dissonance aversion, memory illusion, and confirmation bias. Such cognitive traps are probably adaptive and essential to mental well-being. The biologist Lewis Wolpert suggests that scientific thinking is in fact aberrant. Science is a conscious departure from intuition and common sense. Homeopathy is parasitic upon brain processes that originally evolved for other activities. If we want to understand why people believe in homeopathy, we must first understand how such beliefs enlist our evolved mental capacities.
References and further reading
Boyer, P (2001): Religion Explained. Evolutionary Origins of Religious Thought. New York: Basic Books.
Holmes OW (1842). Homœopathy, and its kindred delusions; two lectures delivered before the Boston society for the diffusion of useful knowledge, Boston: William D. Ticknor.
Wolpert, L (1993). The unnatural nature of science. Cambridge, MA: Harvard University Press.
Above photo “Hot Raw Sewage” by Stuck in Customs is used under creative commons license.
March 17, 2010Posted by on
Welcome to the St. Patrick’s Day special edition of Four Stone Hearth 88. Four Stone Hearth is a fortnightly anthropology blog carnival. Topics covered span the four major fields of anthropology: archaeology, socio-cultural anthropology, bio-physical anthropology and linguistic anthropology. If you would like to host the carnival, please write to Martin Rundkvist. The next issue will be hosted at the Greg Laden’s blog on 31 March.
Online Degrees.net has posted their 100 best blogs for anthropology students. It is a wonderful resource that I recommend checking out. Now on with this round of carnival posts.
Luis over at the blog Leherensuge reports on the alleged archaeological forgery at Glozel. The controversy revolves around a hoard of objects that appear to date from different time periods. The death of the principle protagonist, Emile Fradin, has renewed interest in these alleged artefacts. Are these the genuine article or just another Piltdown. Decide for yourself.
Over at Testimony of the spade, Magnus Reuterdahl reflects on how extant abbeys can give us a greater appreciation for those which over time have falling into ruin.
Martin Rundkvist over at Aardvarchaeology, has mixed feelings about his Magnum opus entitled “Domed oblong brooches of Vendel Period Scandinavia.” Martin relays how sticking to your “scholarly ideals” is not always the easiest road to career advancement.
In a recent post, I discuss the trend towards decreased head size starting around 30,000 years ago, which continues today.
Carl Feagans at ahotcupofjoe looks at the dispersal of early Homo out of Africa.
Last year, amidst much media fanfare everybody came to know about our 47 million year old purported ancestor “Ida”. This was indeed a spectacularly preserved fossil specimen, which preserved the outline of the body as well as the stomach contents. However, the scientific community at the time aired scepticism about the claim that it was on the evolutionary line that led to us. Many palaeontologists and primatologists were quick to point out that this primate looked more lemur-like. Well, it turns out that they were right. In a paper published in the Journal of Human Evolution shows that this species, Darwinius masillae, belonged to an extinct branch of primates, most closely related to lemurs and lorises. Brian Switek of the Laelaps gives a synopsis of the paper, while Eric Michael Johnson at Primate Diaries gives a very accessible account of the whole affair.
John Hawks is a fly on the wall at a symposium on genetics and genealogy of the African Diaspora. He reports on Fatimah Jackson’s genetic work in Africa and African-Americans, in particular the idea of “ethnogenetic layering”.
Raymond Ho at the Prancing Papio blog has a review of a paper on the changing mating systems in Sichuan snub-nosed monkeys. The pieces offers some plausible evolutionary reasons for the shift from polygynous to polygamous mating systems.
Valerie Williamson writes about Siberian languages, which are on the verge of extinction. The race is on for linguists to document these languages before they disappear completely.
In the spirit of the occasion, anthropologyworks has compiled a bibliography of social anthropology articles on Ireland and the Irish.
Krystal, over at Anthropology in Practice, talks about a street vendor in her city that has started to take coffee orders via text message. Is this merely a fad or society simply adapting to our greater reliance on digital media?
Ronald Kephart a.k.a. the Cranky Linguist reports on the educational malpractice of teaching religion as science at Liberty University.
Eric Michael Johnson reports on the Itineraries of Exchange symposium. This piece gives us an insight how indigenous groups have managed to maintain traditions and self-determination in the face persecution, racism, and exploitation.
Also check out Eric’s article on Coca Cola’s over-exploitation of water resources in India. It seems that the slogan “Good Till the Last Drop” has a more pernicious meaning.
A Very Remote Period Indeed has a wonderfully titled piece “Mad Neanderthals, peer review and scholarly publication”. Controversy has surrounded the journal Medical Hypotheses since its very conception. This journal is unique in that it doesn’t have a peer review system, while promoting controversial and thought-provoking ideas. However, Julien Riel-Salvatore tells of the comment he published in this journal in response to an article that proposed that Spongiform Encephalopathies may have led to the demise of the Neanderthals. Julien does not think the biggest problem is with the journal’s incredibly low standards but rather with the academic publishing house Elsevier, who by purchasing Medical Hypotheses has given it an air of legitimacy.
That’s it for another edition of Four Stone Hearth. Happy St. Patrick’s Day to one and all!
Golden snub nosed monkey from artsonearth,
CocaColaIndia by Carlos Latuff under the Wikimedia Commons licence.
Marilyn Monroe reading James Joyce. Flickr creative commons licensed content by user I, Puzzled.
March 15, 2010Posted by on
The Times Online recently ran a story about a French team that have made an endocast by digitally scanning inside the skull of Cro-Magnon 1, perhaps the most famous of all Upper Palaeolithic skulls. The mould of Cro-Magnon highlights what has been long known about these European early modern humans since their first discovery in 1868 – they had bigger brains than us. In fact, average human brain size has been decreasing during the last 30,000 or so years. This revelation was rather troubling for nineteenth-century anthropologists who sought to link brain size with intelligence. Not only did these early modern humans have a larger brain volume than us, but so too did the Neanderthals, who were regarded by many at the time as “a barbarous and savage race” (Schaaffhausen 1858). To add injury to insult, the decrease in head size coincides with some of the greatest cultural innovations in human history.
The Times article forwards a number of the various hypotheses about why brain size has decreased. Antoine Balzeau reasons that “the cerebellum — a brain structure linked to language and concentration — appears to take up a larger proportion of the head now than in the time of Cro Magnon 1.” While it is true that the cerebellum is proportionally larger in modern humans, it is proportionally smaller than in apes, by around 20%. We still don’t know enough about brain function to be able to say what advantage, if any, a larger cerebellum would give us.
Second up, is the suggestion that big heads are somehow an adaptation to cold climate. There are a number of problems with this idea. If having a large skull is an adaptation to cold environments we would expect to see such traits peaking in the aftermath of the Last Glacial Maximum around 20,000 years ago, many millennia after Cro-Magnon walked the earth. As a general rule people living in Arctic regions tend to have more rounded heads, unlike the long headed Cro-Magnon. What’s more, the limbs of Cro-Magnon and their kin are quite long, contradicting Allen’s Rule which predicts that species will evolve smaller appendages as an adaptation to colder climes. Their body type also differs markedly from that of Neandertals, for whom there is a better case to made of being cold-adapted.
The article goes on to suggest diet as a driving force behind the decrease in head size. Cranial robusticity has indeed been shown to correlate with diet. It is important, however, to make the distinction between cranial size and robusticity. While the two are related they do not necessarily go hand in hand. While the Gravettian populations were undoubtedly more robust than most modern-day populations, they are not especially robust when compared to the Mesolithic populations of Téviec and Hoëdic or modern Aboriginal Australian or Fuegian populations. It is also unclear what dietary innovation could account for the decrease in head size. We have unambiguous evidence for the control of fire at around 250,000 years ago, while agriculture did not appear until around 10,000 years ago. The dates just don’t add up.
The article suggest one more hypothesis for the downsizing of the brain: “… with high infant mortality, only the toughest survived — and the toughest tended to have big heads.” Infant mortality is an ever-present problem for humans because bipedalism has constrained the size of the birth canal. If anything, giving birth to a larger headed children is going to lead to increased mortality for both the mother and child. Indeed, natural selection has restricted in utero brain growth in humans, with a large proportion of brain development occurring outside of the womb. In most non-human primates, the brain is close to adult size by the first year of life. In humans, on the other hand, near-adult brain size is not reached until about ten years of age.
Perhaps, the best explanation for the larger head size of our ancestors is one that the authors failed to mention – allometry. Bigger animals have bigger brains. While the cranial capacity for modern humans is large for a primate of our size, it is still only about a quarter of the size of that of an elephant. The decrease in brain size during the late Pleistocene was also accompanied by a decrease in body size. In other primates that show a decrease in brain size, there is an accompanying decrease in body size. Having a larger brain comes at a cost. The brain is a greedy glucose-guzzling tissue. The is possible that our smaller brain has allowed us to reallocate energy for other bodily functions.
References and further reading
Henneberg M. Evolution of the human brain: is bigger better?. Clin Exp Pharmacol Physiol 1998, 25:745-749.
Schaaffhausen H. On the crania of the most Ancient Races of Man. Müllers Archiv 1858:453.
March 13, 2010Posted by on
I will be hosting a St. Patrick’s Day special edition of Four Stone Hearth on Wednesday, March 17th. Four Stone Hearth is a fortnightly anthropology blog carnival. If you have read or written any interesting blog posts on archaeology, socio-cultural anthropology, bio-physical anthropology or linguistic anthropology in the last few weeks, please email me a link and I’ll be sure to include them.