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SAI International School
Subject- Biology
Chapter- Heredity And Evolution

Subtopic- Molecular Phylogeny, Evolution should not be equated with
progress, Human Evolution
Module-29
Lesson Notes

MOLECULAR PHYLOGENY

 The branch of biology that uses hereditary molecular differences in DNA
sequences and genetics to determine the evolutionary relationship of an
organism is known as Molecular phylogeny.
 It helps in determining the processes due to which a species achieves diversity.
→ It is based on the idea that changes in DNA during reproduction are the basic events
in evolution.
→ Organisms which are most distantly related will accumulate greater differences in
their DNA.

EVOLUTION SHOULD NOT BE EQUATED WITH PROGRESS

 Evolution is defined as a process of gradual changes which takes in primary
organisms over millions of years in which new species are produced.
 Evolution cannot be equated with progress. This statement is not justified
because it can't be said that the older designs before the evolution were not
efficient.
 There is no real ‘progress’ in the idea of evolution.
 Evolution is simply the generation of diversity and the shaping of the diversity by
environmental selection.
 The only progressive trend in evolution seems to be that more and more complex
body designs have emerged over time.

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