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Copyright © 1997, Jay Ligda.  All rights reserved.  Published by Humans in the Universe and Jay Ligda.

The Evolution of Intelligence

      I define intelligence here as the ability to learn.  While it could be argued that the evolutionary process itself is a type of learning, I want to limit this discussion of intelligence to the subjective experience of the individual of the species.  Prior to this intelligence, behavior was either random (as in the random mutations that drive evolution) or instinctual (based on unalterable chemical reaction).

      Five elements, hydrogen, nitrogen, oxygen, phosphorus, and sulphur, reacting with a sixth element, carbon, make up 99% of the dry weight in all life (Margulis and Sagan, 1986).  Amino acids and nucleotides that make up the proteins and DNA structures are made of these six elements.  Proteins form to create cells and tissue based on the genetic coding in the DNA of the species.  The genetic code is made up of only four different molecules that can be arranged in infinite variations and create the multitude of life that we witness on the planet.  Margulis and Sagan (1986) compare the genetic code to the common universal language of builders of the Tower of Babel.

      The first life form known to exist on earth is bacteria, dating back as far as four billion years (Margulis and Sagan, 1986).  Early bacteria received energy through photosynthesis of the sun's energy.  Bacteria can divide at a rate of once every twenty minutes.  At this rate, in four days, a single bacteria can produce more individual bacteria than the number of protons physicists estimate to exist in the known universe (Margulis and Sagan, 1986).  At such a rapid rate of division, bacteria can mutate and produce new species very rapidly.  Each new variation of bacteria could improve the suvivability of the previous variation.  Soon the bacteria would be able to survive off of more than just the sun's energy such as raw minerals of the earth.  The bacteria were then able to inhabit more of the planet (Margulis and Sagan, 1986). 

      As cells mutated they were able to grow more complex, nuclei formed, more complex metabolic pathways were produced, and characteristics like the flagellum evolved, which allowed for mobility.  The first sex occurred in a primitive fashion, according to Margulis and Sagan (1986), when there was a "recombination of genes from more than one source" (p. 85).  In this case, two cells merged into one (quite the opposite of cellular division).  One reason this happens is a lack of food in the environment.  To survive, cellular organisms would ingest each other and become one organism (Margulis and Sagan, 1991).  Sex allows a greater variety of characteristics to be shared and increases the rate of evolution and the chance of survival.  The rate of change in characteristics is superior through recombination compared to that of random mutation alone (Margulis and Sagan, 1986).

      About 1,400 million years ago, cells began to live within communities (Margulis and Sagan, 1986).  This symbiosis increased the possibility of survival.  Cells could perform specialized tasks that would increase mobility and the capturing of food.  In order for this colony of cells to become a single organism the separate DNA of the various cells would have to evolve into one genetic code that creates the whole organism.  My research did not turn up an answer as to how this happens.  It probably has something to do with the recombination of genes within the colony.  This single organism would also need a way to reproduce, since simple cell division would not work for the reproduction of a multicellular organism.  Sex would have had to evolve to what we know it to be today.

      A multicellular organism would need to maintain a balance within the system.  A network of communication would be necessary.  In the human soma, a cancerous cell divides out of control when it ceases to maintain communication with the rest of the organism. 

      The nerve cell is a specialized cell that can transmit information to other nerve cells very rapidly (Edelman, 1991). Neurons connect to muscle tissue.  An impulse through the nervous system would trigger movement (behavior) of the muscle tissue.  The nervous system is an information network.  Instinctual behavior is a set path for impulses along the nervous systemlearned behavior occurs when the path for impulses varies according to the individual's needs.  It is this learned behavior that I refer to as intelligence.

      Pert (1990), describes neuropeptides and their receptors, which are found on cells all over the body, as another such information network.  Pert (1990) explains, "the identical molecular components for information flow are conserved throughout evolution" (p. 156). 

by Jay Ligda

(This work is a all or part of an original work first published/written for John. F. Kennedy University:  Final Integrative Project., Mar1996.)

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  • Margulis, L. & Sagan, D. (1986).  Microcosmos:  Four Billion Years of Microbial Evolution.  New York, NY:  Summit.
  • Margulis, L. & Sagan, D. (1991).  Mystery Dance  On the Evolution of Human Sexuality.  New York, NY:  Summit.
  • Edelman, G. M. (1991).  Bright Air, Brilliant Fire:  On the Matter of the Mind.  New York, NY:  Harper Collins.
  • Pearson, D. & Shaw, S. (1982).  Life Extension:  A Practical Scientific Approach.  New York, NY:  Warner.


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