Mitochondrial Mutations May Have Aided Brain Evolution

From: Rich Travsky (_at_hotmMOVEail.com)
Date: 11/27/04 

Date: Fri, 26 Nov 2004 22:22:31 -0700

 http://www.nature.com/news/2004/041122/full/041122-5.html
 Published online: 23 November 2004; | doi:10.1038/news041122-5
 Energetic cells may have boosted the brain
 Did rapid mutation of cell powerhouses guide our neural evolution?

 A good brain needs lots of energy in order to function, and human
 brains are exceptionally good. Now geneticists have found that
 humans may also be exceptional in terms of the energy output of
 our cells, and are wondering whether this is linked to our
 intellectual prowess.

 Brains use more energy than one might expect. In humans this organ
 makes up only 2% of a person's body weight, on average. But it is
 estimated to account for about 20% of the energy used by the body
 at rest.

 One solution to providing more energy is simply to have more cells.
 In the development of the human brain, "the obvious difference that
 everyone talks about is the huge increase in size," says John Kaas,
 a neuroscientist at Vanderbilt University in Nashville, Tennessee.

 But there are limits to how much more power size can provide. Bigger
 brains come with additional overhead costs and problems with heat
 exchange. Something else must have helped to improve our brains.

 Within each cell, tiny structures called mitochondria are responsible
 for producing the energy-carrying molecules known as adenosine
 triphosphate or ATP. ...

 One solution to generating more energy in a single cell, therefore,
 is to increase its numbers of mitochondria. But in the brain, cells
 have long, thin arms called axons for connecting to other cells, and
 scientists suspect that these cannot physically accommodate ever
 larger numbers of mitochondria.

 So where did our brain cells get the power they needed? Lawrence
 Grossman, a biologist at the Wayne State University School of Medicine
 in Detroit, and his colleagues think it may have come from improvements
 inside the mitochondria themselves.

 Grossman and his team studied the genes for a protein in the electron
 transport chain known as complex IV, or COX. They compared the genetic
 sequence across many different mammalian species and found that the
 human lineage has undergone an exceptional number of changes.

 For example, there have been 11 changes in the part of the DNA that
 codes for a certain protein subunit in the past 58 million years,
 compared with just one change in the 25 million years before that. None
 of the rodents, lemurs or other mammals that they examined showed more
 than two or three changes in the same time period.
 ...
 He suggests that these changes could have given human brain cells a
 serious evolutionary boost, by increasing the amount of energy available
 to them. He and his team describe their theory in Trends in Genetics1.

 The group's findings fit with a growing body of evidence that our brains
 evolved with the help of a better energy supply. Research in modern
 primates has shown that there is a strong correlation between quality of
 diet and relative brain size, says Bill Leonard, who studies energetics
 at Northwestern University in Evanston, Illinois.

 "Humans are an extreme example of this: they have very large brains and a
 high quality, energy-dense diet," he says.
 ...

Relevant Pages

  • In the News: Brains Darwin Machine
    ... Alysson Muotri was looking for brain cells that glow ... Some neurons fire only when they perceive a straight vertical line, ... DNA sequence had altered brain cells. ...
    (talk.origins)
  • A GLOBAL DIGITAL NERVOUS SYSTEM - Gaia
    ... Erdekes elmelet, tamogatja a Gaia elmeletet, amit mar 15 eve tartok a fejemben. ... That's the essence of the ideas described by Peter Russell, a Cambridge University physicist, computer scientist, and futurist, in his book The Global Brain Awakens. ... In the next phase, the billions of isolated nerve cells start communicating with one another, growing fibers to connect with cells on other sides of the brain. ... This complex linking -- made more possible by software and communications technologies -- parallels the evolution of large-scale mental functions. ...
    (soc.culture.magyar)
  • Re: sea urchin genome
    ... for stereo vision etc. So there's a lot going on. ... massively parallel processor called the brain to try and fit all the ... certain kinds of self-organising cells to grow or not grow, or die, ... edge detectors and angle detectors and motion detectors and detectors ...
    (talk.origins)
  • Re: Evolutionary question concerning God.
    ... and that neurons that are involved in our conscious ... List of regions in the human brain - Wikipedia, ... The cells in the visual cortex do ... You could stop all the wars, and create equality and justice on Earth, ...
    (talk.origins)
  • Re: Evolutionary question concerning God.
    ... Matt Silberstein wrote: ... and that neurons that are involved in our conscious ... List of regions in the human brain - Wikipedia, ... The cells in the visual cortex do ...
    (talk.origins)