Human Evolution

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Human Evolution
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Could the Ape Family Be Mans Ancestor?
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There are two ways to approach this question.
One is to investigate the DNA. The other is
to investigate the fossil evidence.
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The textbook presents the fossil evidence so let
us investigate the DNA evidence. There is
general agreement that the human probably
descended from the chimpanzee. It is usually
maintained that the DNA order is only 1.4
different.
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The 1.4 number was obtained by comparing only
substitution type mutations in a fraction of the
total DNAs. If insertions, deletions and
substitutions are considered in only 1 of the
DNA the number rises to 5. In 2004, numbers
were reported to be 7.7 and 20 as more of the
DNA was compared.
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Think CriticallyWhen it is recognized that
chimps have 10 more DNA and two more chromosomes
than humans, is the 1.4 difference reasonable?
Of the numbers 5, 7.7 and 20, which is the
most reasonable?
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Assume that the chimp and human genomes have the
same number of base pairs. Using the 7.7 figure
and 3,200,000,000 as the total number of base
pairs there is a 246,000,000 base pair
difference.
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This difference is the same number of letters
contained in approximately 43 textbooks like
yours if there were nothing but letters on each
page no pictures, charts or tables.
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Think CriticallyHow could this have come about
when mutations are random chance happenings and
the following constraints are considered? 1.
Under the best of conditions, only one in one
thousand mutations is considered favorable. The
rest are unfavorable and possibly fatal or
neutral at best.
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2. Unless the mutation occurs in THE particular
egg or sperm that is to be used in reproduction
then the mutation has no effect on future
generations. In other words it has to occur in
one particular cell out of about 30 trillion
cells.
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3. Not only do the mutations have to occur in
that particular cell but the same mutations have
to occur in a member of the opposite sex at the
same time and place to make the change
dominant.4. These two chimps have to mate and
have a successful pregnancy.
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Think CriticallyExplain any conflicts that exist
between the fossil and DNA approaches.
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