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Our Genetic Journey
Dr. Orville Boyd Jenkins
A review of the book by Spencer Wells
The Journey of Man:  A Genetic Odyssey (NY:  Random House, 2003.  211p.)

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I received this book as a Christmas present for Christmas 2004.  I started reading it immediately.  This is an excellent summary of genetic markers discovered in recent years, reconstructing the history of human migration, by analysis of frequency and correlation with location.

This was an engaging story.  Wells is concerned primarily to line out the historical conclusions from this comparative DNA study.  Though he references the formulas and gives a brief statement of the procedures used to compare and analyze the DNA for reconstructing a human history, Wells does not belabour the technical details.

A Human Saga
The book is written as a saga.  It moves along, and carries us along in the adventure of discovery.  It moves like a mystery story, as Wells points out clues along the way, gradually leading to the map he lays out to show a general sequence of migration.

It is now proven that new genes develop along the route of human history and migration.  In the passing of genes from one generation to the next, some minor changes occur, such as recombination (moving to a different place on the chromosome).  Sometime slight damage occurs to one or more genes.  These are usually benign and hidden due to the pairing of gene sets in the DNA ladder.

One source of differentiation in human populations seems to be due to the recombination process.  Other changes occur in some genes that related to the minor natural mutation of the tissue in reproduction and manipulation in reproduction.

Tracer Genes
Sometimes minor damage occurs that does not result in a noticeable mutation, but a mark is left point the Y chromosome that is carried on benignly by subsequent generations.  This becomes a "tracer" gene indicating descendant generations.  Comparing the genes on the Y chromosome gives an approximate historical depth of when a new gene appeared and how widely distributed various such "tracer" or marker genes were carried.

The sequential "tracer genes" in human male DNA thus give us a rough time frame and sequence of human migration, but don't tell us about the physical characteristics or types as such.  Correlating information can be found in mitochondrial DNA, which carries information about the female line.

Wells details the historical migrations of humanity, portraying the story that has now developed out of the comparative study of the DNA of human populations all over the world.

Language and Genes
He also includes a very good discussion of the relationship of language to genetic markers.  The author concludes with an analysis of cultural and ethnic attitudes and the social concept of race, in reference to language and genetics.

Mapping the Journey
Wells and the Waitt Family Foundation have launched the Genographic Project, in cooperation with National Geographic.  This Project attempts to visually map this chain of migration on the National Geographic website.

This DNA research and the Genographic Project have now definitively confirmed that the Neanderthal humans were a different species from Homo sapiens.  Archaeology and other historical disciplines had already determined that the Neanderthal hominids were intelligent, observed religious practices and left artifacts of art and culture, including burial customs.

From indications in early DNA comparison studies, scientists concluded that the Neanderthals were considerably different from Homo sapiens sapiens, and not the same species.  Recent thinking based on more extensive sampling and more detailed commparison led to a change of opinion on that, with some late discoveries leading to a shift in thought.  Indications now are that earlier human lineages interbred more comonly than thought, leading to a growing concensus that Homo groupings calle species should be considered sub- species.  In early 2022, new configurations are being considered based on new DNA findings.

You will enjoy the story, and might be intrigued by the science of genetics.  Note that all this is subject to a strong dose of interpretation, since the tracer genes do not give us social and cultural information.

There is some uncertainty as to the viability of correlating strict historical sequence to the populations who share these tracer genes.  The science will continue to develop and become more definitive as interpretive procedures become more firmly established and more corollary information is available for comparison.

See related reviews and articles on this site:
[TXT] Appreciating Differences
[TXT] Colour, Race and Genetics in the Horn of Africa
[TXT] Genetics Out of Africa
[TXT] Italians, Etruscans and Greeks:  Genetics and Ethnicity
[Review] Mapping Human Origins
[TXT] Race and Ethnicity in the Horn of Africa
[TXT] The Sabeans and Other Ancient Genetics and Tongues:  Distinguishing Fact from Legend and Modern from Ancient
Yemenis in Southern Africa: How Nguni South African and Yemeni Arab Genes Combined in Central Africa

Related on the Internet:
Genographic Project
National Geographic
Prehistoric humanoid DNA - raises more questions than it answers
Spencer Wells Page – Amazon
Tidy Neanderthals? - World Science
Crossbreeding of Prehistoric Human Lineages - Quartz Magazine

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Initial reading notes written December 2004.  Other notes added at various times.
Review written and posted on Thoughts and Resources 17 March 2008
Last edited 27 February 2022

Orville Boyd Jenkins, EdD, PhD
Copyright © 2008, 2022 Orville Boyd Jenkins
Permission granted for free download and transmission for personal or educational use.  Please give credit and link back.  Other rights reserved.

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