As we watch our bodies change, knowing that all cells are replaced every few years, we wonder, "Am I this body?". If pieces of "me" change that often, what does "me" mean?
There was however, the position of "well, at least "I" am this brain". This brain, we were told, doesn't change. The neurons we were born with are the ones we will die with, constant and unchanging throughout our lives. We have also been told that there is no possibility of genetic change making any difference as that stopped long ago.
As it turns out, none of this is true...
The "doctrine" during much of the 20th century was that brains did not change after childhood. However, new tools developed over the past 20 years to look at our brains in great detail, especially fMRI, demonstrated "neuroplasticity", or changes in neural pathways and connections, which occurs under different environments, behaviors and functions.
There are many, many, studies demonstrating neuroplasticity. R. A. Poldrak in (2002) and Berger, et. al. in "Multidisciplinary Perspectives on attention and development of self regulation" (2007) demonstrated that many forms of skill acquisition induce plastic changes. Work by R. Davidson and A. Lutz in "Buddha's Brain: Neuroplasticity and Meditation" (2008) and in much of their other work, demonstrated the ability to plastically modify the brain with meditation.
Surprisingly, now we find that new neurons are generated throughout life. This breakthrough started with Joseph Altman's work @ MIT in 1963. Altman demonstrated that "neurogenesis", or "birth of neurons" occurs in the hippocampus and subventricular zone of our brains.
There was great resistance to his work, however, until it was demonstrated in rats, birds, bunnies, other primates, and humans by many other researchers over the last 30 years. P. Rakic in "Neurogenesis in adult primate cortex: an evaluation of the evidence" (2002), and many others confirmed the theory. There have been several studies, esp by E. Gould, et. al in "Neurogenesis in the Neurocortex of Adult Primates" that demonstrate that neurons generated in the subventricular zone, and perhaps the neurocortex, are used in the neurocortex.
Another fundamental axiom is that our brains have not evolved over the last 200,000 years since "anatomically modern humans" appeared, or not since we left Africa about 50,000 years ago as "behaviorally modern humans" with symbolic culture, language, and stone tools. "Everyone" was certain that in the last 10,000 or 15,000 years, following the last Ice Age, after we developed agriculture, and mated with (yes, we DID..and got some really useful genes) and "outcompeted" larger-brained Neanderthals that there could be no genetic changes in humans, i.e.:
We cannot escape the conclusion that man's evolution towards manness suddenly came to a halt. Ernst Mayr, 1963.
There's been no biological change in humans in 40,000 or 50,000 years. Everything we call culture and civilization we've built with the same body and brain - Stephen Jay Gould, 2000.
However, "The 10,000 year explosion" by Gregory Cochran and Henry Harpending (2009), and their earlier PNAS paper in 2007 w/Hawks, Wang and Moyzsis question that axiom and even contend that genetic evolution is accelerating.
With agriculture, hunter gatherers became farmers with huge changes in diet, disease exposure, and social structure and a booming population. Modern humans went from a population of 200,000 about 100,000 years ago > 6,000,000 about 12,000 years ago, and then > 100X that by A.D. 1. This huge population allowed for many different forms of genes, called alleles, to arise.
A few alleles were important; most meaningless. Lactose tolerance, generated by lactase, makes lactose digestion possible. DNA from central/northern European skeletons of 7,000 yrs ago did not have the lactase allele. By 3,000 yrs ago, 25% of skeletons had the allele; today it is in 80%. Rapid "useful" genetic change.
Fulciparum malaria, the most lethal type, generated different protective genetic responses in different tropical regions. There are at least 6 different genetic variations of defenses, from sickle cell hemoglobin (HbS), to G6PD deficiency. Some come with serious side effects; sickle-cell anemia afflicts 250,000 children/yr; another 20,000 get Duchenne muscular dystropy. Fulciparum malaria is 4,000 yrs old; the defenses about 2,500 yrs. Dramatic genetic changes in a short period to deal with a critical problem, but w/serious side effects.
The increasing population density of farming people living in proximity to animals generated a host of lethal "Old World" diseases like smallpox, measles, diptheria, whooping cough, etc.; "adaptive selection" resulted. When the surviving Europeans encountered New World hunter-gatherer societies with no such developed genetic resistance, the results were catastrophic. Pizarro's 168 soldiers conquered the entire Incan Empire of millions because of the smallpox they transmitted.
There are many examples in Cochran and Harpending, et al.'s work of other major genetic changes that have occurred as we adapted to famines, plague, climatic changes, relocation, new diseases, cultures, religions and technical innovations. As our DNA data bases become increasingly sophisticated, many more big surprises will certainly arise.
There is also now an explosion in "epigenetics", the study of "heritable" changes in what genes actually express, or what effect they have on the subsequent functional gene product, w/o there having been a change in the underlying DNA sequence. There is conclusive evidence that epigenetic mechanisms can enable the effects of parents' experiences to be passed down to subsequent generations.
Epigenetics changes the "ball game" in many areas. Am on the same Research Advisory Group as the leader of the recent work @ King's College, London covered in this BBC piece, "Study Links Womb Environment to Childhood Obesity", which is how epigenetics may well cause childhood obesity.
Dogs also demonstrate how rapidly dramatic genetic change can manifest. Dogs were domesticated 15,000 years ago; all dog genes are from wolves - there is no dog behavior that does not exist in wolves to some degree. In this relatively short time, we have dogs of great variety in intelligence and aggressiveness.
A Border Collie can learn a new command after 5 repetitions and respond correctly 95% of the time; a basset hound takes 80 repetitions to achieve 25% accuracy. Border collies were in one biting attack between 1982 and 2006; pit bull terriers were in 1,110.
How much variation is there in our own brains?
Zoran Josipovic, et al. in his paper "The Influence of Meditation in Anti-correlated Networks In The Brain", was discussed in an earlier blog "Does non-dual meditation change our "interior" and our "exterior"?". Zoran, et al. described how they generated the exact position and size of critical Regions of Interest (ROIs) for their fMRI analysis, including the key posterior cingulate cortex (PCC), and precuneus.
As the chart shows, there is significant variation in location and active volume of key centers in the brains of the 24 experienced Tibetan Buddhist meditators. Would all of these different brains respond in exactly the same way for all different functions?
So, what is that "awakens"? What is that is running this process? Is there anything that is constant amid all of these changes?
There was however, the position of "well, at least "I" am this brain". This brain, we were told, doesn't change. The neurons we were born with are the ones we will die with, constant and unchanging throughout our lives. We have also been told that there is no possibility of genetic change making any difference as that stopped long ago.
As it turns out, none of this is true...
 |
| Richie Davidson Univ. of Wisconsin - Madison |
The "doctrine" during much of the 20th century was that brains did not change after childhood. However, new tools developed over the past 20 years to look at our brains in great detail, especially fMRI, demonstrated "neuroplasticity", or changes in neural pathways and connections, which occurs under different environments, behaviors and functions.
There are many, many, studies demonstrating neuroplasticity. R. A. Poldrak in (2002) and Berger, et. al. in "Multidisciplinary Perspectives on attention and development of self regulation" (2007) demonstrated that many forms of skill acquisition induce plastic changes. Work by R. Davidson and A. Lutz in "Buddha's Brain: Neuroplasticity and Meditation" (2008) and in much of their other work, demonstrated the ability to plastically modify the brain with meditation.
Surprisingly, now we find that new neurons are generated throughout life. This breakthrough started with Joseph Altman's work @ MIT in 1963. Altman demonstrated that "neurogenesis", or "birth of neurons" occurs in the hippocampus and subventricular zone of our brains.
 |
| Elizabeth Gould Princeton University |
There was great resistance to his work, however, until it was demonstrated in rats, birds, bunnies, other primates, and humans by many other researchers over the last 30 years. P. Rakic in "Neurogenesis in adult primate cortex: an evaluation of the evidence" (2002), and many others confirmed the theory. There have been several studies, esp by E. Gould, et. al in "Neurogenesis in the Neurocortex of Adult Primates" that demonstrate that neurons generated in the subventricular zone, and perhaps the neurocortex, are used in the neurocortex.
Another fundamental axiom is that our brains have not evolved over the last 200,000 years since "anatomically modern humans" appeared, or not since we left Africa about 50,000 years ago as "behaviorally modern humans" with symbolic culture, language, and stone tools. "Everyone" was certain that in the last 10,000 or 15,000 years, following the last Ice Age, after we developed agriculture, and mated with (yes, we DID..and got some really useful genes) and "outcompeted" larger-brained Neanderthals that there could be no genetic changes in humans, i.e.:
 |
| Stephen Jay Gould Harvard University |
There's been no biological change in humans in 40,000 or 50,000 years. Everything we call culture and civilization we've built with the same body and brain - Stephen Jay Gould, 2000.
However, "The 10,000 year explosion" by Gregory Cochran and Henry Harpending (2009), and their earlier PNAS paper in 2007 w/Hawks, Wang and Moyzsis question that axiom and even contend that genetic evolution is accelerating.
With agriculture, hunter gatherers became farmers with huge changes in diet, disease exposure, and social structure and a booming population. Modern humans went from a population of 200,000 about 100,000 years ago > 6,000,000 about 12,000 years ago, and then > 100X that by A.D. 1. This huge population allowed for many different forms of genes, called alleles, to arise.
 |
| Henry Harpending University of Utah |
A few alleles were important; most meaningless. Lactose tolerance, generated by lactase, makes lactose digestion possible. DNA from central/northern European skeletons of 7,000 yrs ago did not have the lactase allele. By 3,000 yrs ago, 25% of skeletons had the allele; today it is in 80%. Rapid "useful" genetic change.
Fulciparum malaria, the most lethal type, generated different protective genetic responses in different tropical regions. There are at least 6 different genetic variations of defenses, from sickle cell hemoglobin (HbS), to G6PD deficiency. Some come with serious side effects; sickle-cell anemia afflicts 250,000 children/yr; another 20,000 get Duchenne muscular dystropy. Fulciparum malaria is 4,000 yrs old; the defenses about 2,500 yrs. Dramatic genetic changes in a short period to deal with a critical problem, but w/serious side effects.
The increasing population density of farming people living in proximity to animals generated a host of lethal "Old World" diseases like smallpox, measles, diptheria, whooping cough, etc.; "adaptive selection" resulted. When the surviving Europeans encountered New World hunter-gatherer societies with no such developed genetic resistance, the results were catastrophic. Pizarro's 168 soldiers conquered the entire Incan Empire of millions because of the smallpox they transmitted.
There are many examples in Cochran and Harpending, et al.'s work of other major genetic changes that have occurred as we adapted to famines, plague, climatic changes, relocation, new diseases, cultures, religions and technical innovations. As our DNA data bases become increasingly sophisticated, many more big surprises will certainly arise.
There is also now an explosion in "epigenetics", the study of "heritable" changes in what genes actually express, or what effect they have on the subsequent functional gene product, w/o there having been a change in the underlying DNA sequence. There is conclusive evidence that epigenetic mechanisms can enable the effects of parents' experiences to be passed down to subsequent generations.
Epigenetics changes the "ball game" in many areas. Am on the same Research Advisory Group as the leader of the recent work @ King's College, London covered in this BBC piece, "Study Links Womb Environment to Childhood Obesity", which is how epigenetics may well cause childhood obesity.
Dogs also demonstrate how rapidly dramatic genetic change can manifest. Dogs were domesticated 15,000 years ago; all dog genes are from wolves - there is no dog behavior that does not exist in wolves to some degree. In this relatively short time, we have dogs of great variety in intelligence and aggressiveness.
 |
| Border Collie |
How much variation is there in our own brains?
 |
| Variations in location and size of critical brain centers Josipovic, et. al. |
As the chart shows, there is significant variation in location and active volume of key centers in the brains of the 24 experienced Tibetan Buddhist meditators. Would all of these different brains respond in exactly the same way for all different functions?
So, what is that "awakens"? What is that is running this process? Is there anything that is constant amid all of these changes?
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