This link has been bookmarked by 13 people . It was first bookmarked on 26 Jun 2008, by Rudy Garns.
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09 Oct 12
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One of these is that the development of increased cognitive capacity is related to increased brain size over evolutionary time. This was the view held by Charles Darwin, who wrote “the difference between man and the higher animals, great as it is, is certainly one of degree and not of kind”
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However, Ralph Holloway
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suggested that evolutionary changes in cognitive capacity are the result of brain reorganization, rather than changes in size alone
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Is this assumption about quantity correct? It would appear not. Many mammals have larger brains than humans. This is known as absolute brain size. The blue whale has a brain that is five times larger than a human brain.[vi] Is it five times smarter?
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a whale in his place with a brain size that is only .01% of his body weight as compared to a human brain that is 2%. At the same time consider the pocket mouse’s brain, which is 10% of its body weight
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What can be said for human brains is they are four to five times larger than would be expected for an average mammal of its size
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The other problem with the big brain theory is that Homo sapiens’ brain size has decreased about 150cc over the species’ history, while their culture and social structures have become more complex.
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While not all genes’ functions are known, there are many genes that are involved with the development of the brain that are different from other mammals, and specifically from other primates.
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There is not much difference between species in the genes that do routine “house-keeping” in the nervous system, which are those that are involved in the most basic cellular functions such as metabolism and protein synthesis.
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two genes have been identified—the story of which is fascinating in itself--that are specific regulators of brain size: microcephalin[xvi] and ASPM (abnormal spindle-like microcephaly associated.)
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Recent research from Bruce Lahn, a professor of genetics at the University of Chicago and The Howard Hughs Medical Institute, and his lab has shown that both of these genes have undergone significant changes under the pressure of natural selection during the evolution of Homo sapiens.
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implicating these genes as the cause of the rapidly exploding brain size of our ancestors.
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they found evidence that some of these genes are experiencing ongoing positive selection in humans. They calculated that one genetic variant of microcephalin arose approximately 37,000 years ago, which coincides with the emergence of culturally modern humans, and it increased in frequency too rapidly to be compatible with random genetic drift or population migration. This suggests that it underwent positive selection.[xxi] An ASPM variant arose about 5800 years ago, coincident with the spread of agriculture, cities and the first record of written language. It too is found in such high frequencies in the population, that it indicates strong positive selection.
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05 Jul 11
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I have decided something like a phase shift has occurred in becoming human. There simply is no one thing that will ever account for our spectacular abilities, aspirations and capacity to travel mentally in time to almost the infinite world beyond our present existence
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Even though we have all of these connections with the biologic world from which we came, and we have in some instances similar mental structures, we are hugely different. While most of our genes and brain architecture are held in common with animals, there are always differences to be found
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while we can use lathes to mill fine jewelry, and chimps can use stones to crack open nuts, the differences are light years apart. And while, the family dog may appear empathetic, no pet understands the difference between sorrow and pity.
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psychologist David Premack once lamented, “Why is it that the (equally great) biologist E.O Wilson can spot the difference between two different kinds of ants at a hundred yards, but can’t see the difference between an ant and a human?” The quip underlines strong differences of opinion on the issue of human uniqueness. It seems that half of the scientific world sees the human animal as on a continuum with other animals and others see a sharp break between animals and humans, see two distinct groups. The argument has been raging for years and it surely won’t be settled in the near future. After all, we humans are either lumpers or splitters. We either see the similarities or prefer to note the differences.
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I want to begin by simply recognizing the huge differences between the human mind and brain and other minds and brains and see what structures, processes, and capacities are uniquely huma
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A cell is a cell is a cell. It's a universal unit of processing that only scales in size between the bee and the human.
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Humans are unique. It is the “how” and the “why” that have been intriguing scientists, philosophers and even lawyers for centuries
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How unique are we and how are we unique?
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17 May 10
James Choate"...Scientists compared the genetic sequences of ethnically and geographically diverse people from around the world and found that the genes which code for the nervous systems, had some sequence differences (known as polymorphisms) among individuals. By a
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26 Sep 08
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18 Aug 08
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26 Jun 08
Rudy Garns"Scientists compared the genetic sequences of ethnically and geographically diverse people from around the world and found that the genes which code for the nervous systems, had some sequence differences (known as polymorphisms) among individuals. By analyzing human and chimpanzee polymorphism patterns, genetic probabilities and various other genetic tools, and geographical distributions, they found evidence that some of these genes are experiencing ongoing positive selection in humans. They calculated that one genetic variant of microcephalin arose approximately 37,000 years ago, which coincides with the emergence of culturally modern humans, and it increased in frequency too rapidly to be compatible with random genetic drift or population migration. This suggests that it underwent positive selection.[xxi] An ASPM variant arose about 5800 years ago, coincident with the spread of agriculture, cities and the first record of written language. It too is found in such high frequencies in the population, that it indicates strong positive selection."
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15 May 08
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21 Apr 08
Social AtaxiaExcerpt from the Prologue and First Chapter of Human: The Science Behind What Makes Us Unique, by Michael Gazzaniga.
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12 Apr 08
"What we don’t know is if the genetic changes caused the cultural changes or were synergistic, and even if they did, what exactly is going on in those big brains and how is it happening? Is it just happening in ours or is it happening but just to a less
michael_gazzaniga neuroscience edge consciousness cognition evolution genetics delicious_import
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11 Apr 08
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