Evolution, Genetics, and Man

By Theodosius Dobzhansky | Go to book overview

2
The Gene as the Basis of Evolution

Every species of organism reproduces itself. The process of heredity converts the food derived from the environment into more or less faithful copies of the assimilating organism and of its parents and more remote ancestors. The reproductive potentials of many organisms are immense. With abundant food and at favorable temperature, the colon bacteria, Escherichia coli, double in number about every twenty minutes.

Heredity is a conservative force. If children and parents were completely identical, evolution could not occur. Heredity, however, is opposed by a process of change, variability. Self-reproduction occasionally results in an imperfect copy of the parental living unit, and the altered copy, called a mutant, then reproduces the altered structure until new mutations intervene. One of the major achievements of biology during the current century has been the demonstration that the units both of heredity and of mutation are bodies of molecular dimensions, called genes.

In the last analysis evolution is a sequence of changes in the genes. Darwin and other pioneers of evolutionary biology realized very clearly the basic importance of heredity for understanding evolution. However, it is only during the current century, and particularly during the last twenty to thirty years, that a theory of evolution based on the findings of the study of heredity, genetics, has become possible. A brief outline of the fundamentals of genetics is, therefore, essential in a book dealing with evolution. Such an outline is given in Chapters 2, 3, 4, and also elsewhere in this book in connection with the various problems of general evolutionary biology discussed.

-23-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this book

This book has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this book

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited page

Bookmark this page
Evolution, Genetics, and Man
Table of contents

Table of contents

Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Help
Full screen
/ 406

matching results for page

    Questia reader help

    How to highlight and cite specific passages

    1. Click or tap the first word you want to select.
    2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
    3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

    OK, got it!

    Cited passage

    Style
    Citations are available only to our active members.
    Buy instant access to cite pages or passages in MLA, APA and Chicago citation styles.

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

    1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

    Cited passage

    Thanks for trying Questia!

    Please continue trying out our research tools, but please note, full functionality is available only to our active members.

    Your work will be lost once you leave this Web page.

    Buy instant access to save your work.

    Already a member? Log in now.

    Author Advanced search

    Oops!

    An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.