Interesting Topics on Evolution

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cowpoke

climber
Feb 11, 2013 - 05:46pm PT
the chapter on parenting in this book is the one I remember best, and the one that I thought flew in the face of conventional thinking. His thesis was that, based on evidence from twin studies and the like, 50% of what makes you you is genetic but, of the other 50%, only 0 to 10 percent could be correlated with your family. He speculates that who you hang with (peers) might account for a big part of that remaining 50%.
eeyonkee, this was first proposed by Judith Rich Harris based on the behavioral genetics data, but it has fallen under scrutiny because of the increasing documenting of gene-environment interactions in human development (based on ideas originally proposed by Sandra Scarr, who argued that much of the variation in parenting is functionally equivalent within enriched environments). The classic empirical example is the work of Erik Turkheiver (behavior genetists at UVA), who demonstrated that the heritability of intelligence is moderated by poverty. 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.
go-B

climber
Hebrews 1:3
Feb 11, 2013 - 08:45pm PT
That's cool Jan,
photo not found
Missing photo ID#289240
see these every year!
High Fructose Corn Spirit

Gym climber
-A race of corn eaters
Feb 12, 2013 - 09:44am PT
It's Darwin Day.

Darwin Day is a global celebration of science and reason held on or around Feb. 12, the birthday anniversary of evolutionary biologist Charles Darwin.

Evolve. :)
cowpoke

climber
Feb 12, 2013 - 10:22am PT
As an addition to my previous post, it might be interesting, to some of you, to see the data on the moderating effects of SES for the heritability of intelligence. The following figure is taken from Socioeconomic Status Modifies Heritability of IQ in Young Children Turkheimer, Haley, Waldron, D'Onofrio & Gottesman (2003), Psychological Science, Vol. 14, pp. 623-628. Underneath the figure, I explain the meaning of the letters A, C, and E for those not familiar with heritability analyses of behavioral genetic data.
moderating effects of SES for heritability of IQ &#40;low SES is at th...
moderating effects of SES for heritability of IQ (low SES is at the far left hand of horizontal axis and high SES at the far right hand of horizontal axis)
Credit: cowpoke
In this figure, A is the portion of IQ explained by genetics, C is the portion of IQ explained by "shared environments" (i.e., environments that twins in the same family share such as their home environment and parenting that is common to the two twins), and E is the portion of variance explained by non-shared environments (this is where environmental experiences that are unique to individuals within families fall, things like experiences with peers; technically, however, it is the error term in the model, which means anything not explained by genetics and shared environment).
eeyonkee

Trad climber
Golden, CO
Topic Author's Reply - Feb 13, 2013 - 09:31pm PT
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.
High Fructose Corn Spirit

Gym climber
-A race of corn eaters
Feb 14, 2013 - 07:21pm PT
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

.....

My impression is that natural selection works across all levels, most potently at the replicator level; and then on up.

.....

Jan

Mountain climber
Okinawa, Japan
Feb 15, 2013 - 05:37am PT
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.
High Fructose Corn Spirit

Gym climber
-A race of corn eaters
Feb 17, 2013 - 12:05pm PT
This morning's adorable squeaking sound...


http://www.youtube.com/watch?feature=player_embedded&v=cBkWhkAZ9ds

.....

The Evolutionary Epic in two minutes....



http://www.youtube.com/watch?feature=player_embedded&v=MrqqD_Tsy4Q
High Fructose Corn Spirit

Gym climber
-A race of corn eaters
Feb 25, 2013 - 05:05pm PT
re: directed evolution
re: the National Medal of Technology and Innovation

Could isobutanol created by 'directed evolution' solve the worldwide oil crisis?

http://www.huffingtonpost.com/2013/02/25/directed-evolution-frances-arnold_n_2743308.html?utm_hp_ref=talk-nerdy-to-me&ncid=edlinkusaolp00000008
cowpoke

climber
Mar 18, 2013 - 09:33am PT
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."
bc

climber
Prescott, AZ
Mar 18, 2013 - 10:16am PT
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.
Lucy fossil
Lucy fossil
Credit: bc
Lucy reconstruction
Lucy reconstruction
Credit: bc

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.
Jan

Mountain climber
Okinawa, Japan
Mar 18, 2013 - 11:33am PT
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.
Phantom X

Trad climber
Honeycomb Hideout
Mar 18, 2013 - 12:19pm PT
Did you say Cameroon? Your up Grug.
Jeremy Ross

Gym climber
Mar 18, 2013 - 01:01pm PT
That's an interesting abstract and discussion, cowpoke. I can't access the paper via google....any chance you could post the methods and possibly the results sections? Pretty please...DNA regulation and differential gene expression have always fascinated me.



-JR
cowpoke

climber
Mar 18, 2013 - 01:40pm PT
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
Don Paul

Big Wall climber
Colombia, South America
Mar 18, 2013 - 01:52pm PT
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?
Jeremy Ross

Gym climber
Mar 18, 2013 - 01:56pm PT
Thanks, Cowpoke. I understand it's a pain in the ass to copy/paste. I'll email the author.



-JR
High Fructose Corn Spirit

Gym climber
Potemkin Village
Jul 8, 2013 - 02:33pm PT
re: "sneaky f*#ker" strategy
re: how "wising up" in evolutionary theory might benefit you

http://blogs.smh.com.au/lifestyle/allmenareliars/archives/2007/02/sneaky_f*#ker_t.html

http://www.newstatesman.com/society/2011/05/males-social-sex-idea-alpha

"The late John Maynard Smith took red deer as an example of where things go wrong. While the powerful males are busy rutting, many of the females slope off to have sex with the less macho males of the herd (Maynard Smith labelled them the "**sneaky f*#kers**").

Not to be missed...

http://www.youtube.com/watch?v=t1SX4KYpelQ

Do you know any sneaky f*#kers?
Ed Hartouni

Trad climber
Livermore, CA
Jul 8, 2013 - 03:56pm PT
Candyman...

High Fructose Corn Spirit

Gym climber
Potemkin Village
Nov 1, 2013 - 11:04pm PT
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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