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eeyonkee
Trad climber
Golden, CO
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Topic Author's Reply - Feb 13, 2013 - 09:31pm PT
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In affluent families, about 0-20% of the variance in intelligence is due to home environment and other shared environments (and most of the variation is explained by genetics), but in the context of poverty 0-20% of variance in intelligence is explained by genetics and the rest is explained by environments like the home. Why would this be? Most believe it is because in the context of socioeconomic deprivation, parenting really matters (e.g., the value of having a good parent is magnified by facing danger and disadvantage), but in the context of abundant resources most variation in parenting is functionally equivalent.
Interesting as hell. As a software developer, I see this kind of thing thing all of the time. The "thing" being that if you didn't include a particular variable, in this case relative socioeconomic deprivation, you would miss a big part of the real world that you are trying to model.
This might be a good metaphor for group selection. Perhaps in certain species, say ants, some variable has exceeded a threshold and group selection IS the dominant selection pressure. In most other species, that variable does not reach the threshold required for group selection to succeed. Presumeably, below that threshold. the cheaters overwhelm the slight advantage that group altruism affords. With respect to my original topic number 2, I'd still have to go with selection at the gene level (Dawkins) over selection at the group level (the Wilsons) in humans.
With respect to epigenetics in its broadest sense, I'm beginning to suspect that it might play a big part in distinguishing you from your identical twin. The only other option you have is "the environment" based on the math behind the twin studies. It's not hard for me to see that this could be true and, at the same time, for epigenetics to play only a small role in the evolution of humans.
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High Fructose Corn Spirit
Gym climber
-A race of corn eaters
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Feb 14, 2013 - 07:21pm PT
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re: favorite stories, films, documentaries concerning evolution
A few I can think of...
(1) Distant Origin, Star Trek Voyager (still!)
(2) Creation (2009)
(3) Planet of the Apes
(4) The Chase, Star Trek Next Generation
(5) Darwin's Darkest Hour
(6) Jurassic Park
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My impression is that natural selection works across all levels, most potently at the replicator level; and then on up.
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Jan
Mountain climber
Okinawa, Japan
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Feb 15, 2013 - 05:37am PT
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I've posted this synopsis on the God vs Science thread also since most of our arguments there boil down to the question of consciousness. In any case, a study of Einstein's brain It certainly makes it look to me like Genetics was all important. What we can't answer is whether all of those unusual characteristics would have gone to waste if Einstein had grown up in a deprived background.
The brain of celebrated physicist Albert Einstein has been a subject of much research and speculation. It was removed within seven and a half hours of his death. The brain has attracted attention because of Einstein's reputation for being one of the foremost geniuses of the 20th century, and apparent regularities or irregularities in the brain have been used to support various ideas about correlations in neuroanatomy with general or mathematical intelligence. Scientific studies have suggested that regions involved in speech and language are smaller, while regions involved with numerical and spatial processing are larger. [Einstein's inferior parietal lobe (which is responsible for mathematical thought, visuospatial cognition, and imagery of movement) was 15% larger than average.] Other studies have suggested an increased number of glial cells in Einstein's brain.[1]
Harvey had reported that Einstein had no parietal operculum in either hemisphere.,[8] but this finding has been disputed.[9] Photographs of the brain show an enlarged Sylvian fissure. In 1999, further analysis by a team at McMaster University in Hamilton, Canada revealed that his parietal operculum region in the inferior frontal gyrus in the frontal lobe of the brain was vacant. Also absent was part of a bordering region called the lateral sulcus (Sylvian fissure). Researchers at McMaster University speculated that the vacancy may have enabled neurons in this part of his brain to communicate better.
Einstein himself claimed that he thought visually rather than verbally.
A study, "The cerebral cortex of Albert Einstein: a description and preliminary analysis of unpublished photographs",[9] was published on November 16, 2012, in the journal Brain. Dean Falk, an evolutionary anthropologist at Florida State University, led the study - which analysed 14 recently discovered photographs - and described the brain: "Although the overall size and asymmetrical shape of Einstein’s brain were normal, the prefrontal, somatosensory, primary motor, parietal, temporal and occipital cortices were extraordinary."[13]
Preserving the brains of geniuses was not a new phenomenon—another brain to be preserved and discussed in a similar manner was that of the German mathematician Carl Friedrich Gauss almost a hundred years earlier. His brain was studied by Rudolf Wagner who found its weight to be 1,492 grams and the cerebral area equal to 219,588 square millimeters.[14] Also found were highly developed convolutions, which was suggested as the explanation of his genius.
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cowpoke
climber
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Mar 18, 2013 - 09:33am PT
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An interesting article in the last issue of Child Development that is relevant to the discussions of epigenetics: Epigenetic Vestiges of Early Developmental Adversity: Childhood Stress Exposure and DNA Methylation in Adolescence (Essex et al., 2013; Volume 84, Pages 58–75)
Abstract: "Fifteen-year-old adolescents (N= 109) in a longitudinal study of child development were recruited to examine differences in DNA methylation in relation to parent reports of adversity during the adolescents’ infancy and preschool periods. Microarray technology applied to 28,000 cytosine–guanine dinucleotide sites within DNA derived from buccal epithelial cells showed differential methylation among adolescents whose parents reported high levels of stress during their children’s early lives. Maternal stressors in infancy and paternal stressors in the preschool years were most strongly predictive of differential methylation, and the patterning of such epige- netic marks varied by children’s gender. To the authors’ knowledge, this is the first report of prospective associations between adversities in early childhood and the epigenetic conformation of adolescents’ genomic DNA."
From the discussion section of the paper (pp. 69-70):
"Taken together, these findings offer novel evidence for a biological embedding of early experience, or more specifically, the temporally remote correlates of early adverse experiences on the human epigenome and its regulatory role in the expression of specific genes, including genes that guide neurodevelopment. Both relative increases and decreases in promoter region methylation were detected in the genomes of adolescents whose par-
ents had reported significant adversity in past years. Although DNA methylation is generally associated with a down-regulation in gene expression, the epigenetic control of differential transcription is almost certainly far more complex and involves a broad and diverse array of chromatin modifications (see, e.g., Mehler, 2008). As a consequence, discerning a coherent and functional ‘‘meaning’’ of the reported findings lies beyond the present state of epigenetic science. We note, however, that to our knowledge these data constitute only the second report of altered DNA methylation in buccal epithelial cells associated with environmental exposure, following a recent study that reported DNA methylation marks in such cells from 5-year-old children associated with maternal smoking during the intrauterine period (Breton et al., 2009).
Importantly, our findings may be correctly viewed as an instantiation of ‘‘gene–environment interplay’’ and the capacity for experience and genomic variation—allelic or epigenetic—to conjointly influence salient developmental endpoints (Gilbert & Epel, 2009; Rutter, Moffitt, & Caspi, 2006). One variety of such interplay is the moderation of early experiential effects by single nucleotide polymorphisms within genes affecting key neural circuitry and neurotransmission pathways (Caspi et al., 2002). The most broadly recognized examples of epigenetic regulatory processes are those described within the caregiving behavior of the mother rat and within the dietary influences on coat color in mice. Studies by Meaney, Szyf, and colleagues (Meaney & Szyf, 2005; Weaver, Cervoni, et al., 2004) have shown how phenotypic differences in the reactivity of the HPA system arise from the mother rat’s licking and grooming behavior in her pups’ first several postnatal days. Such behavior changes reactivity phenotypes by demethylating the binding site for transcription factor Egr1 in the enhancer region of the pups’ GR gene. Waterland and Jirtle (2003) supplemented the diets of pregnant, viable yellow Agouti mice with methyl-donors, such as folate, choline, and betaine, and created dramatic differences in offspring coat color. Pups of mothers fed methyl-donor supplements had increased methylation of the Agouti allele that guides yellow fur development, resulting in suppressed gene expression and phenotypic reversion to a brown coat color."
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bc
climber
Prescott, AZ
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Mar 18, 2013 - 10:16am PT
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I got a chance to see the famous Lucy (Australopithecus afarensis) fossil at the Bowers Museum in Santa Ana, CA. Worth a quick visit if you're in the area. It'll be there until April 28th.
Edit: There's a lot of other cool stuff to see at this museum. You might want to give yourself about 3 hours or so.
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Jan
Mountain climber
Okinawa, Japan
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Mar 18, 2013 - 11:33am PT
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Recently we got a surprise about the evolution of Homo sapiens when a South Carolina African American man's DNA was found to have a common ancestor with other Homo sapiens, much further back than anticipated.
Homo sapiens as a distinct species only goes back 200,000 years and we only left Africa 50-60,000 years ago according to all previous DNA studies. However, this man's DNA showed his most recent common ancestor was 340,000 years ago. It was then discovered that there were 7 others from Cameroon.
All this is interesting because it means that this branch of the family tree departed during the time of Homo erectus or one of his direct descendants that we don't know about yet. Obviously these descendants mixed with generations of Homo sapiens in subsequent years, but some of the old Y-DNA remains.
So far now, we have discovered that Homo erectus evolved into neanderthal in Europe, denosovan in central Asia, floresiensis in Indonesia, Homo sapiens in East Africa and now the ancestor of the small group in Cameroon. The family tree was quite diverse.
This recent finding also establishes that there was a whole lot more cross species mating going on than we had previously imagined. Today about 2-3 % of Europeans have some neanderthal DNA and 6% of some north Asians have denisovan. And now from Africa more indications.
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Phantom X
Trad climber
Honeycomb Hideout
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Mar 18, 2013 - 12:19pm PT
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Did you say Cameroon? Your up Grug.
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cowpoke
climber
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Mar 18, 2013 - 01:40pm PT
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JR,
I have access to the pdf via my university, but for some reason it is not a version that can be saved (and it is a pain to cut and paste because the text is in narrow columns in the pub). I'd bet the first author would gladly email a reprint of the pdf, however. From the author note: Marilyn J. Essex, Department of Psychiatry, University of Wisconsin School of Medicine and Public Health, 6001 Research Park Boulevard, Madison, WI 53719. Electronic mail may be sent to mjessex@wisc.edu
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Don Paul
Big Wall climber
Colombia, South America
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Mar 18, 2013 - 01:52pm PT
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Hmm, the bottom of the US socioeconomic level is far more affluent than the middle class in most parts of the world. I wonder what you'd see in places that have refugee camps and starving people?
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High Fructose Corn Spirit
Gym climber
Potemkin Village
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Student Questioner: "I wanted to know if (1) you thought the society we are creating slows (undermines) the process of natural selection and (2) if you think that is a good or bad thing for our species."
Richard Dawkins: "To the extent that people are born who would not have been born under natural wild conditions, to the extent that medical science enables people to grow up and reproduce, to that extent genes are being put into the gene pool which would have been removed by natural selection in a wild state. I think that's pretty much inevitable. I don't think it's a bad thing. I like doctors, I like hospitals. I like the fact that, for children, it's quite difficult to die young nowadays and therefore if you want to reproduce you probably can. There was a time in the 1920s and 1930s when everybody was very worried about the dysgenic effects of modern medicine. I think it's something that we live with, and I am, on balance, happy to live with it. I would not like to live in a world in which children were dying of diseases which could be cured, so I'm not in favor of worrying about the dysgenic effects of modern medicine."
Michael Shermer Richard Dawkins Interview
An Appetite for Wonder, Cal Tech 2013
http://www.youtube.com/watch?v=lQ0cRIrOOiA
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High Fructose Corn Spirit
Gym climber
Potemkin Village
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re: dysgenic effects on gene pool resulting from use of technology
Is there now something of a race between ever increasing dysgenic effects and ever improving technology?
Audience Question: This is on the interplay between technology and evolution. Do you think our adaptability or survivability are at risk from our use of technology? What do you think of technology that may some day entrap us? like by permitting bad genes in increasing numbers of people. How do we reverse that or deal with that? Is there any alternative?
Richard Dawkins: Medical science is allowing bad genes to propagate in the population. Yes it is. But on balance, I don't deplore it. I think it's worth it. In the case of eyesight and eyeglasses, as long as we have the technology to go on making glasses, it will probably be okay. It's true that if that were wiped out then that would be serious. Imagine getting rid of spectacles. Anybody over the age of about 45 would no longer be able to read. They wouldn't be able to play a part in civilized life. So we do indeed depend on technology. But it's getting better. I was talking only yesterday to an eye surgeon who was telling me about the wonderful techniques of using laser surgery to reshape the cornea so you don't need eyeglasses at all. We are getting better at those sorts of things. So technology is at present keeping up with the dysgenic effects of modern medicine.
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In my view this is going to be one of the gravest problems future generations are going to face.
Damn you Second Law of Thermodynamics.
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Cruel Scenario: Fossil fuels crash. Energy-dependent high technologies collapse. Finely-tuned complex societies collapse. Natural Selection hits gene pool with vengeance.
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Paul Martzen
Trad climber
Fresno
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The thing about evolution and natural selection is that you don't know ahead of time, which genes will be most beneficial in the future. Some dimwit with bad eyesight might have the only gene that allows human survival of some future virus or germ.
Was there not a link earlier in this thread to studies indicating that increased population was accelerating human evolution/human variation? More population survival means more potential for genetic variation.
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High Fructose Corn Spirit
Gym climber
Potemkin Village
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On the evolution of tenacity in mice...
[Click to View YouTube Video]
http://www.youtube.com/watch?v=QM6MNw7i6Ng
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Paul,
yeah, as you know, evolution of extremely large populations esp with a lot of variation to begin with (e.g., our anthropic one) would present with countless aspects, many being adaptive.
Still, the plight of dysgenic effects, due to rising of technology and the undermining of natural selection in ever softening climates, is real.
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WBraun
climber
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God is the original gene ......
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Paul Martzen
Trad climber
Fresno
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Hey Fructos,
That is a very persistent mouse in that video.
Which dysgenic effects do you think are real? I have not studied this at all, but a quick search seems to show mostly speculation. I see that Richard Lynn documents that childbirth rates are lower for highly intelligent people as compared to criminals and low intelligent populations.
This may be, and it may have social repercussions, but my question is, what genetic issues does this raise? How is this genetically harmful? Myself, I don't see the problem from a long term genetic aspect. Perhaps you can elaborate your thoughts on this.
Your cartoon points out that many people are becoming fatter as our TVs get skinnier, but you don't think this is a genetic issue do you? In a sense, it is a genetic issue with the TVs, since they are fundamentally changed from the older TVs, but the fat guy is just eating too much.
Are there any multigenerational studies of some animal, or plant population where providing a too easy environment leads to genetic changes that endangers the long term survival of that population?
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High Fructose Corn Spirit
Gym climber
Potemkin Village
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Hey, I loved Logan's Run. A couple years ago, last time I watched, I googled the brunette, was happy to see she's aged well. If you have the dvd, York gives an excellent commentary of the film, btw.
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Paul, interspersing that cartoon in the text was probably confusing, sorry. Cartoon was just funny. Regarding dysgenic effects, I used the term because Dawkins used it - so i'm not sure how google-worthy or precise it is or how often it's used by evolutionary scholars in e theory. There might be a better term, or terms, out there to describe the process or phenom. I think it's also used to counterpoint "eugenic." I think it's interesting what is deemed eugenic or dysgenic depends on pov. If it could talk, the ancestor of the eyeless cave salamander might say its progeny suffered "dysgenic effects" when they lost their eyes eking out existence in darkness. However, on the other hand, the progeny might not agree as the eyes in darkness weren't needed; they might counter with the argument, "We're not dysgenic at all, just more streamlined and efficient now!" lol.
Same with dodo bird. Its gene pool got soft in the flight department in the absence of selection pressure for flight (predators). (Same with the extinct solitaire, too, apparently.)
In our case, the human case, poor eyesight to hernias, eg, to perhaps autism associated disorders, might be examples.
In any case, I liked Dawkins' reply - it was certainly thought-provoking - that the interplay between easy softer environment, natural selection and technology was inevitable, is inevitable, in addition to unpredictable, something we have to live with, on balance a good thing (at least for us), and not really something to worry about on those grounds. A day at a time, or a generation at a time, and do your best and hope for the best. Much like our situation with global warming, I guess.
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