Neuroanthropology

For a greater understanding of the encultured brain and body…

Archive for the ‘Genetics’ Category

Your Great x 2360 Grandpa was a Neanderthal!

Posted by Paul Mason on October 26, 2010

Is your Dad the descendent of a Neanderthal? Visit our PLoS website to find out more. 

Recent evidence has shown that a small percentage of human DNA is Neanderthal. This Neanderthal DNA entered the human gene pool between 80,000 and 50,000 years ago.

While human DNA may contain traces of Neanderthal ancestors, mitochondrial DNA from Neanderthals has not been found in humans. Mitochondrial DNA comes uniquely from your mother. Is it plausible that male Neanderthals were able to mate with female humans, but that the reciprocal cross was unable to occur?

Analyses of the Y chromosome suggest that we share a common male ancestor 59,000 years ago. Could this male ancestor have possibly been Neanderthal?

If our common male ancestor is neanderthal, and considering that the Y chromosome is transmitted uniquely through the paternal line, could it mean that men are more closely related to Neanderthals than women? Have men and women truly come from two different species?

Visit the full post on our PLoS website for the full explanation of this intriguing hypothesis.

Posted in Evolution, general, Genetics, Human variation | 8 Comments »

My genome is not my self

Posted by dlende on January 16, 2009

pinker-hairBy Agustin Fuentes

We are not our genes and they are not us. Knowing what copies of genes we carry can tell us a little about getting sick and losing our hair, and maybe even add insight into our ancestry. But that does not tell us about how and why we do the things that we do.

Steven Pinker, in his recent New York Times Magazine article My Genome, My Self, argues that genes do have great influence on our behavior. As an anthropologist, evolutionary theorist, and a researcher of human and other primate behavior I am here to tell you that he is overshooting the mark. Human behavior is simultaneously biology, culture, experience and more.

Natural selection, one of the main drivers in evolutionary change, works on the whole body and behavior complex, not on single genes or even the genome itself. It is the dynamic product of genes, organs, bodies, behaviors, ecologies, and societies that eventually affects evolutionary patterns in humans. No gene or even set of genes can be held in isolation of the systems in which they exist.

Read the rest of this entry »

Posted in Evolution, Genetics, Human variation | 5 Comments »

The Flynn Effect: Troubles with Intelligence 2

Posted by gregdowney on December 16, 2008

James R. Flynn

James R. Flynn

Since I’m in Dunedin, New Zealand, I thought I’d write on one of the University of Otago’s most neuroanthropological philosophers, Prof. James Flynn, and dive back into the maelstrom around average IQ scores in different social groups. Prof. Flynn famously pointed out to people outside the standardized testing industry that IQ tests had to be periodically recalibrated because average IQ scores in industrialized countries steadily inflated, suggesting either that people were growing smarter or something else was up with these tests.

Flynn gathered tests from Europe, North America and Asia, around thirty countries in all, and discovered that, for as far back as we had data in any case, average IQ test scores had risen about 3 points per decade and in some cases more. Only recently, in some Scandanavian countries, to the gains appear to be levelling off (see, for example, Sundet 2004; Teasdale and Owen 2005).

We’ve been down this road before at Neuroanthropology before, delving into the murky depths of group averages and tests scores. Back in December 2007, Agustín offered neuroanthropology and race- getting it straight, following up on a discussion sparked by Daniel’s post, IQ, Environment & Anthropology. I put in my two cents, and caught an ear-full, for Girls closing math gap?: Troubles with intelligence #1 (the first ‘part’ of this post). I’ve been wanting to re-enter this particular body of hot water since I read a story on Science Daily, Plastic Brain Outsmarts Experts: Training Can Increase Fluid Intelligence, Once Thought To Be Fixed At Birth, so against my better instincts, my shoes are off and I’m poking my toes in.

Ironically, in spite of the fact that children spend longer on average in school than in previous decades, the Flynn Effect does not show up on the parts of standardized tests that measure school-related subjects. That is, tests of vocabulary, arithmetic, or general knowledge (such as the sorts of facts one learns in school) have showed little increase, but scores have increased markedly on tests thought to measure ‘general intelligence’ (or ‘g’), such as Raven’s Progressive Matrices which require mental manipulation of objects, logical inference, or other abstract reasoning.

Read the rest of this entry »

Posted in Education, general, Genetics, Inequality, Learning | 12 Comments »

Andy Clark & Michael Wheeler: Embodied cognition and cultural evolution

Posted by gregdowney on November 23, 2008

The Cognition and Culture website has posted a link to the new edition of the Philosophical Transactions of the Royal Society B on ‘cultural transmission and evolution of human behaviour.’ I wanted to comment on just one piece on embodied cognition and cultural evolution, by philosophers Michael Wheeler and Andy Clark (unfortunately, Philosophical Transactions B is behind a subscription wall, although there’s a one-page ‘free preview’ [ouch] here). The Cognition and Culture website has the table of contents posted here. I was vaguely familiar with Michael Wheeler’s work before this piece, but Andy Clark (it’s not much of a profile) has written some of the work that’s most influenced my thinking about the effects of varied skill acquisition on cognition, especially his remarkable book, Being There: Putting Brain, Body and World Together Again (Amazon listing).

A ream of Clark’s papers can be found here. A review of Michael Wheeler’s book, Reconstructing the cognitive world: The next step, written by Leslie Marsh can be downloaded here. We’ll come back to Andy Clark’s work again in later posts.

I must admit a certain morbid fascination with how one of my favorite streams of thought — embodied cognition — would fare combined with cultural evolution — an area of scholarship that, well, to put it nicely, is uneven (before you get all defensive, let me just stop you with one word: mimetics). It’s sort of like watching one of your good friends get hit on by a sleazy guy at a bar. She looks happy, but you’re sort of cringing at the chance that she might actually take him home. In spite of this instinctual cringe, this special edition of Philosophical Transactions has some really interesting work on cultural evolution, especially because many of the pieces focus tightly on the enormously problematic issue of cultural transmission.

Read the rest of this entry »

Posted in Embodiment, Evolution, general, Genetics, Human variation, Philosophy | Tagged: , , , , , , , , | 4 Comments »

Nova: Ghost in Your Genes

Posted by gregdowney on August 23, 2008

The vertebrae in which hoxc-6 is active (marked purple) in both a chick embryo and garter snake embryo.

The vertebrae in which hoxc-6 is active (marked purple) in both a chick embryo and garter snake embryo.

Although the title of the special made me think of ‘Party in Your Pants’ (juvenile, I’m well aware), I thought I’d post a link to the website for the Nova special, ‘Ghost in Your Genes.’

The special explores epigenetics and the complex network of regulatory mechanisms that affect gene expression, including a nice little slideshow on Hox genes. We’ve explored the topic before here at Neuroanthropology (see Pharyngula on epigenetics) in part because a better understanding of the molecular mechanisms of organic development tends to undermine the overly simplistic notion that there are two forces shaping any organism — genes and environment or ‘nature’ and ‘nurture.’ With the epigenetic material, it’s painfully obvious that genes are not some kind of organic destiny writ in DNA, as some popular understandings tend to have it (and that popular understanding is often mobilized in simplistic accounts of subjects like behavioural genetics, as we will know).

We’ve already discussed some of the quirks about twins’ genes here (at Identical twins not… err… identical?), and there’s a nice example of genetically identical twin mice looking anything but identical (and having significant differences in health). The story, ‘A Tale of Two Mice,’ has a sobering subtext about the effects on gene expression of BPA (Bisphenol A), an organic chemical known to leach out of plastics (see Wikipedia for a brief overview of the issues). However, I’m still not convinced that calling this complex interaction ‘the epigenome’ or ‘the second genome’ is moving in the right direction. Even with this reservation, the visual aids for thinking about epigenetic processes are excellent.

Thanks to Dr. Jovan Maud (from Macquarie University and Culture Matters) for pointing this piece out to me. Unfortunately, I just gave my lecture on this stuff a week and a half ago — I’m afraid that I confused my audience a lot more than the people at Nova. It’s a nice site though for getting a bit of a feel for the sorts of factors that affect gene expression.

Credits
The brilliant graphic accompanied a reprint of Sean B. Carroll’s article, ‘The Origins of Form: Ancient genes, recycled and repurposed, control embryonic development in organisms of striking diversity,’ originally published in Natural History, November 2005. Carroll’s article can be accessed here, and it’s a great entry-level piece on hox genes and basic ‘evo-devo’ thought, but the author of Endless Forms Most Beautiful.

Posted in general, Genetics, Links | Tagged: , , , | 1 Comment »

Pharyngula on epigenetics

Posted by gregdowney on July 23, 2008

P. Z. Myers of Pharyngula, when he isn’t driving creationists into paroxysms, can write some great translations of biological concepts for the average reader. He does this in the post, Epigenetics, where he points out some of the problems with textbook definitions of the term. I really recommend checking this post out, but get a cup of coffee and a comfortable seat before you do — the post is not lite fare.

Epigenetics, although devilishly difficult, is absolutely essential for breaking with the common conception of DNA as ‘blueprint’ or marching orders for biological processes. In biological developmental processes, the expression of DNA is quite a bit more interesting than just ‘genes made it happen.’ Myers lays out a host of good examples, such as the variable degree to which histones permit or inhibit DNA transcription, the inactivation of parts of DNA when methylated, how chromosome geometric arrangement might affect gene expression, and other factors. He also discusses X chromosome inactivation in females (because they have two, one has to shut down), genomic imprinting on non-sex chromosomes (Myers discusses chromosome 15 and some of the disorders that can result), and disease changes in genetic expression (such as liver cirrhosis and retroviral insertions, which I touched on in an earlier posts on ‘identical’ twins).

Grunt Doc joked in the last Grand Rounds blog carnival that he hoped our post on psychiatric genetics ‘wouldn’t be on the test’; that goes double for the material Myers is covering. Fascinating, but, wow, tough to wrap the head around. But it’s already making me look at our calico cats in a new light…

Stumble It!

Graphic: Originally from Nature 441, 143-145 (11 May 2006); downloaded from UNSW Embryology, h/t to Pharyngula.

Posted in general, Genetics | 1 Comment »

Bench and couch: genetics and psychiatry

Posted by gregdowney on July 19, 2008

Vaughn at Mind Hacks has a nice piece on recent research, reported in Nature, on psychiatric genetics: Mental illness: in with the intron crowd. The original article, Psychiatric genetics: The brains of the family, appeared in Nature on 10 July (but it’s behind a subscription wall if you want to see the original — sorry). Daniel linked to Vaughn’s article in the last Wednesday Round Up (#20), but I wanted to make a further brief comment. Vaughn does a really nice job of laying out the key issues, so I’d recommend jumping over there if this brief discussion whets your appetite.

The problem for neuropsychiatry is that genetic links to psychiatric disorders are proving difficult to clearly define. Abbott explains the situation really well:

Finding genes involved in psychiatric conditions is proving to be particularly intractable because it is still unclear whether the various diagnoses are actually separate diseases with distinct underlying genetics or whether… they will dissolve under the genetic spotlight into one biological continuum. Indeed, some researchers suggest that it would be better to abandon conventional clinical definitions and focus instead on ‘intermediate phenotypes’, quantifiable characteristics such as brain structure, wiring and function that are midway between the risk genes involved and the psychopathology displayed.

Read the rest of this entry »

Posted in Genetics, Mental Illness | Tagged: , , , , , , | 3 Comments »

Relax your genes

Posted by gregdowney on July 5, 2008

Image from Good Karma Flags

Image from Good Karma Flags

Relax — it can affect your genes.

A recent article on PLoS One by a research team from the Benson-Henry Institute for Mind/Body Medicine at Massachusetts General Hospital (MGH) and the Genomics Center at Beth Israel Deaconess Medical Center (BIDMC) discusses the genetic effects of the relaxation response, a widespread bodily state induced by different mind-body techniques (such as meditation).

The original piece, Genomic Counter-Stress Changes Induced by the Relaxation Response, was published at PLoS One, and the findings are also discussed on ScienceDaily, Relaxation Response Can Influence Expression Of Stress-related Genes. It’s starting to be a bit of a refrain from genetics research, but it still bears repeating: the team is exploring a way that ‘changing the activity of the mind can alter the way basic genetic instructions are implemented,’ as Dr. Herbert Benson explained (in ScienceDaily).

The relaxation response is a bodily state, found in a variety of contexts, characterized by ‘decreased oxygen consumption, increased exhaled nitric oxide, and reduced psychological distress.’ Long-term effects of relaxation exercises include decreased oxygen intake and carbon dioxide elimination; reductions in blood pressure, heart and respiration rate; prominent low frequency heart rate oscillations; and some changes in cortical and subcortical brain regions, including increased thickness of the cortex (see NeuroReport and here also on the effect of meditation on aging).

For about three decades, dependable clinical studies have shown that relaxation response-producing exercises have a range of positive health benefits. What makes the current research distinctive (at least in my reading) is that the team traced this metabolic process to its genetic effects. As the authors write:

This study provides the first compelling evidence that the RR elicits specific gene expression changes in short-term and long-term practitioners. Our results suggest consistent and constitutive changes in gene expression resulting from RR may relate to long term physiological effects. Our study may stimulate new investigations into applying transcriptional profiling for accurately measuring RR and stress related responses in multiple disease settings.

Read the rest of this entry »

Posted in Genetics, Meditation, Psychological anthropology, Stress | Tagged: , , , , | 4 Comments »

Live healthy, turn on your genes

Posted by gregdowney on June 17, 2008

For all those out there who still think that ‘it’s all in the genes,’ here’s a recent news story on the way that changes in lifestyle can affect genetic activity. Will Dunham at ABC News brings us, Healthy Lifestyle Triggers Genetic Changes: Study (I also pulled it off the Reuters feed). The study was small, and I doubt that it was nearly as rigorous as really necessary, but the findings are interesting.

In a small study, the researchers tracked 30 men with low-risk prostate cancer who decided against conventional medical treatment such as surgery and radiation or hormone therapy.

The men underwent three months of major lifestyle changes, including eating a diet rich in fruits, vegetables, whole grains, legumes and soy products, moderate exercise such as walking for half an hour a day, and an hour of daily stress management methods such as meditation.

As expected, they lost weight, lowered their blood pressure and saw other health improvements. But the researchers found more profound changes when they compared prostate biopsies taken before and after the lifestyle changes.

After the three months, the men had changes in activity in about 500 genes — including 48 that were turned on and 453 genes that were turned off.

Read the rest of this entry »

Posted in Food & Eating, general, Genetics, Medical anthropology | Tagged: , | 2 Comments »

Genomics and ‘Post-Neo-Darwinism’

Posted by gregdowney on June 17, 2008

Blogging on Peer-Reviewed ResearchI’ve been trying to put together my reader for a new unit (class) on human evolution at Macquarie University that I’ll be doing next semester. As usual, I’m doing this at the 11th hour, but this should be my last completely new, never-before-taught-at-my-university class for at least a year (I hope). In the process of checking out the most recent edition of my favorite human evolution journals, I happened across an odd and really thoughtful piece by Prof. Kenneth Weiss, who’s at Penn State. In the past, I’ve remarked about ‘post-neo-Darwinism,’ a term that I’m sure causes grimaces and eye-rolling, but that I think is worth discussing (I can’t take credit for the term; I think I heard it from Prof. Emily Schultz of St. Cloud State University at the last meeting of the American Anthropology Association).

By the way, Daniel posted a great ‘Evolution Round Up’ just recently with a whole lot of interesting material (I especially enjoyed Mo’s piece at Neurophilosophy on ‘Synapse proteomics & brain evolution’). We’re not really an evolution theme website, but it’s obvious how important it is to locate brain development in frameworks consistent with evolution. (I’ll come back to why being overly persuaded by evolutionary frameworks can be pernicious in a second, and it’s broader than my recent rant about memetics.)

Unfortunately, because the Weiss piece is more of an essay, in his recurring column entitled ‘Crotchets & Quiddities,’ there’s really no abstract of it, so I can’t link through to a nice concise summary of the piece. So, more than usual, I’m going to copy blocks of text from his essay, ‘All Roads Lead to… Everywhere?: Is the genetic basis of interesting traits so complex that it loses much of its traditional evolutionary meaning?’, before I get into my own commentary. Obviously, if you have access through a good research library, you should be able to get your hands on the original article. (More on Weiss’s columns can be found here – they’re quite good.)

The set-up for Weiss’s discussion is the idea that it doesn’t make sense to talk about ‘THE road’ to any particular place in a complex systems of highways and secondary roads because there are many routes:

With such choices, it doesn’t make much sense to ask, ‘‘What is the road to Rome?’’ In a somewhat similar way, rapidly growing knowledge about the nature of genomes and what they do suggests that what’s good for the Romans is good for biology as well. Instead of a gene for this and a gene for that, we face the possibility that all genes lead to everywhere, which may have important
implications with regard to our understanding of the genetic basis or evolution of traits like the shape of the skull, a skull, or this skull. If all real roads lead to the Circus Maximus, do all our craniofacial genetic roads lead to the foramen magnum?

Read the rest of this entry »

Posted in Evolution, general, Genetics, Human variation | Tagged: , , | Leave a Comment »

 
Follow

Get every new post delivered to your Inbox.

Join 323 other followers