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Doubled Gene Boosted Brain Power

Human-specific duplications of a gene involved in brain development may have contributed to our species’ unique intelligence.

By | May 7, 2012

image: Doubled Gene Boosted Brain Power Wellcome Images, Mark Lythgoe & Chloe Hutton

WELLCOME IMAGES, MARK LYTHGOE & CHLOE HUTTON

Duplications of a gene involved in development of the cortex may have boosted human brain power during early hominin evolution by enhancing neuronal connections, according to two Cell papers published online last week (May 3). The gene, SRGAP2, partially duplicated three times during the period when the human Homo lineage was emerging from Australopithecus about 2-3 million years ago.

The protein product of one duplication, dubbed SRGAP2C, appears to increase neuronal migration and connections. The duplicated gene encodes only a fragment of the original, to which SRGAP2C binds to inhibit its function. When SRGAP2C was expressed in mice, neurons migrated faster and produced more dendritic spines, protrusions that receive signals from neighboring neurons, potentially increasing the density of neural connections in the murine brains. This suggests that SRGAP2 duplications may have increased the processing power of our ancestor’s brains.

“If you’re increasing the total number of connections, you’re probably increasing the ability of this network to handle information,” Franck Polleux, who led the second study, told Nature. "It’s like increasing the number of processors in a computer."

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Avatar of: James Kohl

James Kohl

Posts: 53

May 8, 2012

 It’s been more than 20 years since the late Robert L. Moss et al.
published Gonadotropin-Releasing Hormone and Human Sexual Behavior
(Moss, Dudley, & Riskind, 1991). Vertebrate gonadotropin releasing
hormone (GnRH) neurons produce one of three different peptides,
presumably because three paralogous GnRH genes originated from gene
duplications (Oka, 2010).

The prenatal migration of GnRH neurons into the brain of humans is
responsible for the direct connection from olfactory/pheromonal input to
changes in hypothalamic GnRH pulse frequency, luteinizing hormone
secretion, and hippocampal neurogenesis, which links food odors and
social odors to learning and memory required for adaptive behaviors
based on nutrient chemical availability and the presence or absence of
conspecifics. It is likely that anything that alters GnRH pulse
frequency, whether it’s the gene or genes responsible for Kallmann’s
syndrome, or nutrient chemical availability that alters maturation of
the brain and behavior will alter learning and memory associated with
food acquisition and mate choice as preferences develop based on
prenatal chemical exchanges in placental mammals and the postnatal
effects of food odors and pheromones.

Thus, the epigenetic effects of chemicals from our sensory
environment on GnRH are probably essential to the development of an
evolved brain and behavior involved in seeking out proper nutrition and
reproductively “fitâ€쳌 mates. “Bobâ€쳌 Moss knew he would not be able to
prove the cause and effect relationship that continues to show up in the
newest literature on human brain development, but he also knew that
someone would prove the link from GnRH to nutrition dependent human
sexual behavior. Clearly, others are getting closer to that proof, as is
seen in this latest news on gene duplications and human brain
development. It may nevertheless be important to keep in mind that
evolved brain development is dependent on nutrient chemicals and
pheromones that alter receptor-mediated intracellular signaling and
stochastic gene expression in species from microbes to man, if only to
keep evolved brain development in its proper context.

References:

Moss, R. L., Dudley, C. A., & Riskind, P. N. (1991). Gonadotropin
releasing hormone and human sexual behavior. In C. B. Nemeroff (Ed.),
Neuropeptides and Psychiatric Disorders. Washington, D.C: American
Psychiatric Press.

Oka, Y. (2010). Electrophysiological Characteristics of
Gonadotrophin-Releasing Hormone 1-3 Neurones: Insights From a Study of
Fish Brains. Journal of Neuroendocrinology, 22(7), 659-663.

Avatar of: Guest

Anonymous

May 8, 2012

(A re-write of the original)

Has anyone in research considered asking a few of the world champion chess masters, or, better yet, repeat winners of the Jeopardy television game show to submit DNA samples for comparison of particular sequences?

Please don't dismiss the idea as trivial.  It's no joke.

Winning at chess is not nearly so complex a challenge as winning in a contest where the neuronal messages must sort through literally millions of nuances of meaning of words, as well as millions of samplings of fact, rather than processing game pieces of limited number and limited operational ranges of movement. 

Possibly what accounts for the Jeapordy game show winners' amazing feats of mind is savantism, and perhaps it is not. It would be useful to know. In savantism a portion of the brain normally applied to some other purposes is conscripted, as it were, leaving a short change elsewhere. Or, some other trade-off occurs, such that something such as less energy is available to another process than has historically been rationed to its access. Processing a pronouncedly greater amount of information, in the context of innumerable nuances of meaning for single terms (or data cluster types, at no compensatory cost would be almost magical, would it not. Arriving at correct responses in fractions of seconds, which others could not do except by directly consulting dictionaries, encyclopedias, data banks... awesome! But at no compensatory cost? Mega-awesome!

Yet, who is to say it cannot happen. We need to know.

Possibly there are factors other than would be found in DNA that account for it.  But, were no DNA-based variation found, that would be informative in an Edisonian way (i.e., would add to our repository of things we know do not solve the goal of subject inquiry). 

We know that trying to spot just any DNA change to account for an anomaly by (good, bad or indifferent) would compare to looking for a needle in a haystack, on a by-hand-and-eye basis. However data, in a super computer, is processable at near light speed. So the work would be sped up (at a dollar cost for the computer and program and date fed into it. But looking for a change in a narrow band of DNA, such as implied by the subject article, rather than generally, might make practical even a hand-eye mode of observing (given an advanced familiarity with DNA norms in that narrow band, and a precocious individuals DNA chart... would it not?

If an additional duplication were to be found in the subject sequence, great. If not, back to the drawing board.

Surely somewhere, someone is building a comparative DNA data bank enabling comparison of parameters peculiar in cases of zero sum precocity (that is, precocity not attained as a trade off in which a portion of the brain needed for other purposes is not compromised in the offing).  Downstream of identifying DNA factors in purely advantaged precocity, we might seek to identify any undesirable physiological-psychological trade-offs that might account for it; and if we find none, classify the benefit as having occurred in a non-zero sum dynamic, in which benefit comes without cost or, veritably so. (This is, is it not, what has had to occur in the evolution of the human brain. Compensations have had to occur at every step upward. For example, the food/energy requirements of a larger brained members of the species would not have survived times of limited food supply, such as droughts, and thence would not have been conserved, unless, of course, some gain were provided, such that the larger brain enabled finding food sources a smaller one would not have) where the compensatory cost is survival-quotient expendable.

In evolution, I would surmise, many scenarios surely occur in which the game is zero zero sum, and there is no free lunch. However, if millions more neuron connections could occur that provide a high ratio of benefit to cost, perhaps that is as good as it gets. And some deletions (such as loss of acuity of ability to smell as keenly as dogs do, might have bought something more valuable by way of an ability to gain in some other way.

But let us just assume that, once in a great while, along comes a duplication of the subject type in the subject article, that is not zero sum, and some humans get an enormous boost in ability to store, retrieve and utilize coping-benefit-wise... information and voluminous nuances of subtle meanings in an "intelligent" way.

What a marvelous thing it would be to propagate that benefit broadly throughout the species expeditiously. The very least we might expect to see, as a result, might be long waiting lines at sperm banks.

Avatar of:

Posts: 0

May 8, 2012

 It’s been more than 20 years since the late Robert L. Moss et al.
published Gonadotropin-Releasing Hormone and Human Sexual Behavior
(Moss, Dudley, & Riskind, 1991). Vertebrate gonadotropin releasing
hormone (GnRH) neurons produce one of three different peptides,
presumably because three paralogous GnRH genes originated from gene
duplications (Oka, 2010).

The prenatal migration of GnRH neurons into the brain of humans is
responsible for the direct connection from olfactory/pheromonal input to
changes in hypothalamic GnRH pulse frequency, luteinizing hormone
secretion, and hippocampal neurogenesis, which links food odors and
social odors to learning and memory required for adaptive behaviors
based on nutrient chemical availability and the presence or absence of
conspecifics. It is likely that anything that alters GnRH pulse
frequency, whether it’s the gene or genes responsible for Kallmann’s
syndrome, or nutrient chemical availability that alters maturation of
the brain and behavior will alter learning and memory associated with
food acquisition and mate choice as preferences develop based on
prenatal chemical exchanges in placental mammals and the postnatal
effects of food odors and pheromones.

Thus, the epigenetic effects of chemicals from our sensory
environment on GnRH are probably essential to the development of an
evolved brain and behavior involved in seeking out proper nutrition and
reproductively “fitâ€쳌 mates. “Bobâ€쳌 Moss knew he would not be able to
prove the cause and effect relationship that continues to show up in the
newest literature on human brain development, but he also knew that
someone would prove the link from GnRH to nutrition dependent human
sexual behavior. Clearly, others are getting closer to that proof, as is
seen in this latest news on gene duplications and human brain
development. It may nevertheless be important to keep in mind that
evolved brain development is dependent on nutrient chemicals and
pheromones that alter receptor-mediated intracellular signaling and
stochastic gene expression in species from microbes to man, if only to
keep evolved brain development in its proper context.

References:

Moss, R. L., Dudley, C. A., & Riskind, P. N. (1991). Gonadotropin
releasing hormone and human sexual behavior. In C. B. Nemeroff (Ed.),
Neuropeptides and Psychiatric Disorders. Washington, D.C: American
Psychiatric Press.

Oka, Y. (2010). Electrophysiological Characteristics of
Gonadotrophin-Releasing Hormone 1-3 Neurones: Insights From a Study of
Fish Brains. Journal of Neuroendocrinology, 22(7), 659-663.

Avatar of:

Posts: 0

May 8, 2012

(A re-write of the original)

Has anyone in research considered asking a few of the world champion chess masters, or, better yet, repeat winners of the Jeopardy television game show to submit DNA samples for comparison of particular sequences?

Please don't dismiss the idea as trivial.  It's no joke.

Winning at chess is not nearly so complex a challenge as winning in a contest where the neuronal messages must sort through literally millions of nuances of meaning of words, as well as millions of samplings of fact, rather than processing game pieces of limited number and limited operational ranges of movement. 

Possibly what accounts for the Jeapordy game show winners' amazing feats of mind is savantism, and perhaps it is not. It would be useful to know. In savantism a portion of the brain normally applied to some other purposes is conscripted, as it were, leaving a short change elsewhere. Or, some other trade-off occurs, such that something such as less energy is available to another process than has historically been rationed to its access. Processing a pronouncedly greater amount of information, in the context of innumerable nuances of meaning for single terms (or data cluster types, at no compensatory cost would be almost magical, would it not. Arriving at correct responses in fractions of seconds, which others could not do except by directly consulting dictionaries, encyclopedias, data banks... awesome! But at no compensatory cost? Mega-awesome!

Yet, who is to say it cannot happen. We need to know.

Possibly there are factors other than would be found in DNA that account for it.  But, were no DNA-based variation found, that would be informative in an Edisonian way (i.e., would add to our repository of things we know do not solve the goal of subject inquiry). 

We know that trying to spot just any DNA change to account for an anomaly by (good, bad or indifferent) would compare to looking for a needle in a haystack, on a by-hand-and-eye basis. However data, in a super computer, is processable at near light speed. So the work would be sped up (at a dollar cost for the computer and program and date fed into it. But looking for a change in a narrow band of DNA, such as implied by the subject article, rather than generally, might make practical even a hand-eye mode of observing (given an advanced familiarity with DNA norms in that narrow band, and a precocious individuals DNA chart... would it not?

If an additional duplication were to be found in the subject sequence, great. If not, back to the drawing board.

Surely somewhere, someone is building a comparative DNA data bank enabling comparison of parameters peculiar in cases of zero sum precocity (that is, precocity not attained as a trade off in which a portion of the brain needed for other purposes is not compromised in the offing).  Downstream of identifying DNA factors in purely advantaged precocity, we might seek to identify any undesirable physiological-psychological trade-offs that might account for it; and if we find none, classify the benefit as having occurred in a non-zero sum dynamic, in which benefit comes without cost or, veritably so. (This is, is it not, what has had to occur in the evolution of the human brain. Compensations have had to occur at every step upward. For example, the food/energy requirements of a larger brained members of the species would not have survived times of limited food supply, such as droughts, and thence would not have been conserved, unless, of course, some gain were provided, such that the larger brain enabled finding food sources a smaller one would not have) where the compensatory cost is survival-quotient expendable.

In evolution, I would surmise, many scenarios surely occur in which the game is zero zero sum, and there is no free lunch. However, if millions more neuron connections could occur that provide a high ratio of benefit to cost, perhaps that is as good as it gets. And some deletions (such as loss of acuity of ability to smell as keenly as dogs do, might have bought something more valuable by way of an ability to gain in some other way.

But let us just assume that, once in a great while, along comes a duplication of the subject type in the subject article, that is not zero sum, and some humans get an enormous boost in ability to store, retrieve and utilize coping-benefit-wise... information and voluminous nuances of subtle meanings in an "intelligent" way.

What a marvelous thing it would be to propagate that benefit broadly throughout the species expeditiously. The very least we might expect to see, as a result, might be long waiting lines at sperm banks.

Avatar of:

Posts: 0

May 9, 2012

Again and again, if I told you once I told you a million times:
It's NOT genetics that modifies culture, It's culture that modifies genetics !!!

Dov Henis (Comments From 22nd Century)
Seed of Human-Chimp Genomes Diversity
http://dovhenis.wordpress.com/...

Avatar of: Dov

Dov

Posts: 1457

May 9, 2012

Again and again, if I told you once I told you a million times:
It's NOT genetics that modifies culture, It's culture that modifies genetics !!!

Dov Henis (Comments From 22nd Century)
Seed of Human-Chimp Genomes Diversity
http://dovhenis.wordpress.com/...

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