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Genes: A Very Short Introduction 2nd Edition

Jonathan Slack

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Genes: A Very Short Introduction

VERY SHORT INTRODUCTIONS are for anyone wanting a stimulating and accessible way into a new subject. They are written by experts, and have been translated into more than 45 different languages. The series began in 1995, and now covers a wide variety of topics in every discipline. The VSI library currently contains over 700 volumes—a Very Short Introduction to everything from Psychology and Philosophy of Science to American History and Relativity—and continues to grow in every subject area.

Very Short Introductions available now:

ABOLITIONISM Richard S. Newman

THE ABRAHAMIC RELIGIONS

Charles L. Cohen

ACCOUNTING Christopher Nobes

ADDICTION Keith Humphreys

ADOLESCENCE Peter K. Smith

THEODOR W. ADORNO

Andrew Bowie

ADVERTISING Winston Fletcher

AERIAL WARFARE Frank Ledwidge

AESTHETICS Bence Nanay

AFRICAN AMERICAN HISTORY

Jonathan Scott Holloway

AFRICAN AMERICAN RELIGION

Eddie S. Glaude Jr

AFRICAN HISTORY John Parker and Richard Rathbone

AFRICAN POLITICS Ian Taylor

AFRICAN RELIGIONS

Jacob K. Olupona

AGEING Nancy A. Pachana

AGNOSTICISM Robin Le Poidevin

AGRICULTURE Paul Brassley and Richard Soffe

ALEXANDER THE GREAT

Hugh Bowden

ALGEBRA Peter M. Higgins

AMERICAN BUSINESS HISTORY

Walter A. Friedman

AMERICAN CULTURAL HISTORY

Eric Avila

AMERICAN FOREIGN RELATIONS

Andrew Preston

AMERICAN HISTORY Paul S. Boyer

AMERICAN IMMIGRATION

David A. Gerber

AMERICAN INTELLECTUAL HISTORY

Jennifer Ratner-Rosenhagen

THE AMERICAN JUDICIAL SYSTEM

Charles L. Zelden

AMERICAN LEGAL HISTORY

G. Edward White

AMERICAN MILITARY HISTORY

Joseph T. Glatthaar

AMERICAN NAVAL HISTORY

Craig L. Symonds

AMERICAN POETRY David Caplan

AMERICAN POLITICAL HISTORY

Donald Critchlow

AMERICAN POLITICAL PARTIES AND ELECTIONS L. Sandy Maisel

AMERICAN POLITICS

Richard M. Valelly

THE AMERICAN PRESIDENCY

Charles O. Jones

THE AMERICAN REVOLUTION

Robert J. Allison

AMERICAN SLAVERY

Heather Andrea Williams

THE AMERICAN SOUTH

Charles Reagan Wilson

THE AMERICAN WEST

Stephen Aron

AMERICAN WOMEN’S HISTORY

Susan Ware

AMPHIBIANS T. S. Kemp

ANAESTHESIA Aidan O’Donnell

ANALYTIC PHILOSOPHY

Michael Beaney

ANARCHISM Alex Prichard

ANCIENT ASSYRIA Karen Radner

ANCIENT EGYPT Ian Shaw

ANCIENT EGYPTIAN ART AND ARCHITECTURE Christina Riggs

ANCIENT GREECE Paul Cartledge

ANCIENT GREEK AND ROMAN

SCIENCE Liba Taub

THE ANCIENT NEAR EAST

Amanda H. Podany

ANCIENT PHILOSOPHY Julia Annas

ANCIENT WARFARE

Harry Sidebottom

ANGELS David Albert Jones

ANGLICANISM Mark Chapman

THE ANGLO-SAXON AGE John Blair

ANIMAL BEHAVIOUR

Tristram D. Wyatt

THE ANIMAL KINGDOM

Peter Holland

ANIMAL RIGHTS David DeGrazia

ANSELM Thomas Williams

THE ANTARCTIC Klaus Dodds

ANTHROPOCENE Erle C. Ellis

ANTISEMITISM Steven Beller

ANXIETY Daniel Freeman and Jason Freeman

THE APOCRYPHAL

GOSPELS Paul Foster

APPLIED MATHEMATICS

Alain Goriely

THOMAS AQUINAS Fergus Kerr

ARBITRATION Thomas Schultz and Thomas Grant

ARCHAEOLOGY Paul Bahn

ARCHITECTURE Andrew Ballantyne

THE ARCTIC Klaus Dodds and Jamie Woodward

HANNAH ARENDT Dana Villa

ARISTOCRACY William Doyle

ARISTOTLE Jonathan Barnes

ART HISTORY Dana Arnold

ART THEORY Cynthia Freeland

ARTIFICIAL INTELLIGENCE

Margaret A. Boden

ASIAN AMERICAN HISTORY

Madeline Y. Hsu

ASTROBIOLOGY David C. Catling

ASTROPHYSICS James Binney

ATHEISM Julian Baggini

THE ATMOSPHERE Paul I. Palmer

AUGUSTINE Henry Chadwick

JANE AUSTEN Tom Keymer

AUSTRALIA Kenneth Morgan

AUTISM Uta Frith

AUTOBIOGRAPHY Laura Marcus

THE AVANT GARDE

David Cottington

THE AZTECS Davíd Carrasco

BABYLONIA Trevor Bryce

BACTERIA Sebastian G. B. Amyes

BANKING John Goddard and John O. S. Wilson

BARTHES Jonathan Culler

THE BEATS David Sterritt

BEAUTY Roger Scruton

LUDWIG VAN BEETHOVEN

Mark Evan Bonds

BEHAVIOURAL ECONOMICS

Michelle Baddeley

BESTSELLERS John Sutherland

THE BIBLE John Riches

BIBLICAL ARCHAEOLOGY

Eric H. Cline

BIG DATA Dawn E. Holmes

BIOCHEMISTRY Mark Lorch

BIOGEOGRAPHY Mark V. Lomolino

BIOGRAPHY Hermione Lee

BIOMETRICS Michael Fairhurst

ELIZABETH BISHOP

Jonathan F. S. Post

BLACK HOLES Katherine Blundell

BLASPHEMY Yvonne Sherwood

BLOOD Chris Cooper

THE BLUES Elijah Wald

THE BODY Chris Shilling

THE BOHEMIANS David Weir

NIELS BOHR J. L. Heilbron

THE BOOK OF COMMON PRAYER

Brian Cummings

THE BOOK OF MORMON

Terryl Givens

BORDERS Alexander C. Diener and Joshua Hagen

THE BRAIN Michael O'Shea

BRANDING Robert Jones

THE BRICS Andrew F. Cooper

BRITISH CINEMA Charles Barr

THE BRITISH CONSTITUTION

Martin Loughlin

THE BRITISH EMPIRE Ashley Jackson

BRITISH POLITICS Tony Wright

BUDDHA Michael Carrithers

BUDDHISM Damien Keown

BUDDHIST ETHICS Damien Keown

BYZANTIUM Peter Sarris

CALVINISM Jon Balserak

ALBERT CAMUS Oliver Gloag

CANADA Donald Wright

CANCER Nicholas James

CAPITALISM James Fulcher

CATHOLICISM Gerald O’Collins

CAUSATION Stephen Mumford and Rani Lill Anjum

THE CELL Terence Allen and Graham Cowling

THE CELTS Barry Cunliffe

CHAOS Leonard Smith

GEOFFREY CHAUCER David Wallace

CHEMISTRY Peter Atkins

CHILD PSYCHOLOGY Usha Goswami

CHILDREN’S LITERATURE

Kimberley Reynolds

CHINESE LITERATURE Sabina Knight

CHOICE THEORY Michael Allingham

CHRISTIAN ART Beth Williamson

CHRISTIAN ETHICS D. Stephen Long

CHRISTIANITY Linda Woodhead

CIRCADIAN RHYTHMS

Russell Foster and Leon Kreitzman

CITIZENSHIP Richard Bellamy

CITY PLANNING Carl Abbott

CIVIL ENGINEERING

David Muir Wood

THE CIVIL RIGHTS MOVEMENT

Thomas C. Holt

CLASSICAL LITERATURE

William Allan

CLASSICAL MYTHOLOGY

Helen Morales

CLASSICS Mary Beard and John Henderson

CLAUSEWITZ Michael Howard

CLIMATE Mark Maslin

CLIMATE CHANGE Mark Maslin

CLINICAL PSYCHOLOGY

Susan Llewelyn and Katie

Aafjes-van Doorn

COGNITIVE BEHAVIOURAL

THERAPY Freda McManus

COGNITIVE NEUROSCIENCE

Richard Passingham

THE COLD WAR Robert J. McMahon

COLONIAL AMERICA Alan Taylor

COLONIAL LATIN AMERICAN LITERATURE Rolena Adorno

COMBINATORICS Robin Wilson

COMEDY Matthew Bevis

COMMUNISM Leslie Holmes

COMPARATIVE LITERATURE

Ben Hutchinson

COMPETITION AND ANTITRUST

LAW Ariel Ezrachi

COMPLEXITY John H. Holland

THE COMPUTER Darrel Ince

COMPUTER SCIENCE

Subrata Dasgupta

CONCENTRATION CAMPS

Dan Stone

CONDENSED MATTER PHYSICS

Ross H. McKenzie

CONFUCIANISM Daniel K. Gardner

THE CONQUISTADORS

Matthew Restall and Felipe Fernández-Armesto

CONSCIENCE Paul Strohm

CONSCIOUSNESS Susan Blackmore

CONTEMPORARY ART

Julian Stallabrass CONTEMPORARY FICTION

Robert Eaglestone

CONTINENTAL PHILOSOPHY

Simon Critchley

COPERNICUS Owen Gingerich

CORAL REEFS Charles Sheppard

CORPORATE SOCIAL

RESPONSIBILITY Jeremy Moon

CORRUPTION Leslie Holmes

COSMOLOGY Peter Coles

COUNTRY MUSIC Richard Carlin

CREATIVITY Vlad Glăveanu

CRIME FICTION Richard Bradford

CRIMINAL JUSTICE

Julian V. Roberts

CRIMINOLOGY Tim Newburn

CRITICAL THEORY

Stephen Eric Bronner

THE CRUSADES Christopher Tyerman

CRYPTOGRAPHY Fred Piper and Sean Murphy

CRYSTALLOGRAPHY A. M. Glazer

THE CULTURAL REVOLUTION

Richard Curt Kraus

DADA AND SURREALISM

David Hopkins

DANTE Peter Hainsworth and David Robey

DARWIN Jonathan Howard

THE DEAD SEA SCROLLS

Timothy H. Lim

DECADENCE David Weir

DECOLONIZATION Dane Kennedy

DEMENTIA Kathleen Taylor

DEMOCRACY Naomi Zack

DEMOGRAPHY Sarah Harper

DEPRESSION Jan Scott and Mary Jane Tacchi

DERRIDA Simon Glendinning

DESCARTES Tom Sorell

DESERTS Nick Middleton

DESIGN John Heskett

DEVELOPMENT Ian Goldin

DEVELOPMENTAL BIOLOGY

Lewis Wolpert

THE DEVIL Darren Oldridge

DIASPORA Kevin Kenny

CHARLES DICKENS Jenny Hartley

DICTIONARIES Lynda Mugglestone

DINOSAURS David Norman

DIPLOMATIC HISTORY

Joseph M. Siracusa

DOCUMENTARY FILM

Patricia Aufderheide

DREAMING J. Allan Hobson

DRUGS Les Iversen

DRUIDS Barry Cunliffe

DYNASTY Jeroen Duindam

DYSLEXIA Margaret J. Snowling

EARLY MUSIC Thomas Forrest Kelly

THE EARTH Martin Redfern

EARTH SYSTEM SCIENCE Tim Lenton

ECOLOGY Jaboury Ghazoul

ECONOMICS Partha Dasgupta

EDUCATION Gary Thomas

EGYPTIAN MYTH Geraldine Pinch

EIGHTEENTH-CENTURY BRITAIN

Paul Langford

THE ELEMENTS Philip Ball

EMOTION Dylan Evans

EMPIRE Stephen Howe

EMPLOYMENT LAW David Cabrelli

ENERGY SYSTEMS Nick Jenkins

ENGELS Terrell Carver

ENGINEERING David Blockley

THE ENGLISH LANGUAGE

Simon Horobin

ENGLISH LITERATURE Jonathan Bate

THE ENLIGHTENMENT

John Robertson

ENTREPRENEURSHIP Paul Westhead and Mike Wright

ENVIRONMENTAL ECONOMICS Stephen Smith

ENVIRONMENTAL ETHICS

Robin Attfield

ENVIRONMENTAL LAW

Elizabeth Fisher

ENVIRONMENTAL POLITICS

Andrew Dobson

ENZYMES Paul Engel

EPICUREANISM Catherine Wilson

EPIDEMIOLOGY Rodolfo Saracci

ETHICS Simon Blackburn

ETHNOMUSICOLOGY Timothy Rice

THE ETRUSCANS Christopher Smith

EUGENICS Philippa Levine

THE EUROPEAN UNION

Simon Usherwood and John Pinder

EUROPEAN UNION LAW

Anthony Arnull

EVANGELICALISM

John G. Stackhouse Jr.

EVIL Luke Russell

EVOLUTION Brian and Deborah Charlesworth

EXISTENTIALISM Thomas Flynn

EXPLORATION Stewart A. Weaver

EXTINCTION Paul B. Wignall

THE EYE Michael Land

FAIRY TALE Marina Warner

FAMILY LAW Jonathan Herring

MICHAEL FARADAY

Frank A. J. L. James

FASCISM Kevin Passmore

FASHION Rebecca Arnold

FEDERALISM Mark J. Rozell and Clyde Wilcox

FEMINISM Margaret Walters

FILM Michael Wood

FILM MUSIC Kathryn Kalinak

FILM NOIR James Naremore

FIRE Andrew C. Scott

THE FIRST WORLD WAR

Michael Howard

FLUID MECHANICS Eric Lauga

FOLK MUSIC Mark Slobin

FOOD John Krebs

FORENSIC PSYCHOLOGY

David Canter

FORENSIC SCIENCE Jim Fraser

FORESTS Jaboury Ghazoul

FOSSILS Keith Thomson

FOUCAULT Gary Gutting

THE FOUNDING FATHERS

R. B. Bernstein

FRACTALS Kenneth Falconer

FREE SPEECH Nigel Warburton

FREE WILL Thomas Pink

FREEMASONRY Andreas Önnerfors

FRENCH LITERATURE John D. Lyons

FRENCH PHILOSOPHY

Stephen Gaukroger and Knox Peden

THE FRENCH REVOLUTION

William Doyle

FREUD Anthony Storr

FUNDAMENTALISM Malise Ruthven

FUNGI Nicholas P. Money

THE FUTURE Jennifer M. Gidley

GALAXIES John Gribbin

GALILEO Stillman Drake

GAME THEORY Ken Binmore

GANDHI Bhikhu Parekh

GARDEN HISTORY Gordon Campbell

GENES Jonathan Slack

GENIUS Andrew Robinson

GENOMICS John Archibald

GEOGRAPHY John Matthews and David Herbert

GEOLOGY Jan Zalasiewicz

GEOMETRY Maciej Dunajski

GEOPHYSICS William Lowrie

GEOPOLITICS Klaus Dodds

GERMAN LITERATURE Nicholas Boyle

GERMAN PHILOSOPHY

Andrew Bowie

THE GHETTO Bryan Cheyette

GLACIATION David J. A. Evans

GLOBAL CATASTROPHES Bill McGuire

GLOBAL ECONOMIC HISTORY

Robert C. Allen

GLOBAL ISLAM Nile Green

GLOBALIZATION Manfred B. Steger

GOD John Bowker

GÖDEL’S THEOREM A. W. Moore

GOETHE Ritchie Robertson

THE GOTHIC Nick Groom

GOVERNANCE Mark Bevir

GRAVITY Timothy Clifton

THE GREAT DEPRESSION AND THE NEW DEAL Eric Rauchway

HABEAS CORPUS Amanda L. Tyler

HABERMAS James Gordon Finlayson

THE HABSBURG EMPIRE Martyn Rady

HAPPINESS Daniel M. Haybron

THE HARLEM RENAISSANCE

Cheryl A. Wall

THE HEBREW BIBLE AS LITERATURE Tod Linafelt

HEGEL Peter Singer

HEIDEGGER Michael Inwood

THE HELLENISTIC AGE

Peter Thonemann

HEREDITY John Waller

HERMENEUTICS Jens Zimmermann

HERODOTUS Jennifer T. Roberts

HIEROGLYPHS Penelope Wilson

HINDUISM Kim Knott

HISTORY John H. Arnold

THE HISTORY OF ASTRONOMY

Michael Hoskin

THE HISTORY OF CHEMISTRY

William H. Brock

THE HISTORY OF CHILDHOOD

James Marten

THE HISTORY OF CINEMA

Geoffrey Nowell-Smith

THE HISTORY OF COMPUTING

Doron Swade

THE HISTORY OF EMOTIONS

Thomas Dixon

THE HISTORY OF LIFE

Michael Benton

THE HISTORY OF MATHEMATICS

Jacqueline Stedall

THE HISTORY OF MEDICINE

William Bynum

THE HISTORY OF PHYSICS

J. L. Heilbron

THE HISTORY OF POLITICAL

THOUGHT Richard Whatmore

THE HISTORY OF TIME

Leofranc Holford-Strevens

HIV AND AIDS Alan Whiteside

HOBBES Richard Tuck

HOLLYWOOD Peter Decherney

THE HOLY ROMAN EMPIRE

Joachim Whaley

HOME Michael Allen Fox

HOMER Barbara Graziosi

HORMONES Martin Luck

HORROR Darryl Jones

HUMAN ANATOMY Leslie Klenerman

HUMAN EVOLUTION Bernard Wood

HUMAN PHYSIOLOGY

Jamie A. Davies

HUMAN RESOURCE

MANAGEMENT Adrian Wilkinson

HUMAN RIGHTS Andrew Clapham

HUMANISM Stephen Law

HUME James A. Harris

HUMOUR Noël Carroll

THE ICE AGE Jamie Woodward

IDENTITY Florian Coulmas

IDEOLOGY Michael Freeden

THE IMMUNE SYSTEM

Paul Klenerman

INDIAN CINEMA

Ashish Rajadhyaksha

INDIAN PHILOSOPHY Sue Hamilton

THE INDUSTRIAL REVOLUTION

Robert C. Allen

INFECTIOUS DISEASE Marta L. Wayne and Benjamin M. Bolker

INFINITY Ian Stewart

INFORMATION Luciano Floridi

INNOVATION Mark Dodgson and David Gann

INTELLECTUAL PROPERTY

Siva Vaidhyanathan

INTELLIGENCE Ian J. Deary

INTERNATIONAL LAW

Vaughan Lowe

INTERNATIONAL MIGRATION

Khalid Koser

INTERNATIONAL RELATIONS

Christian Reus-Smit

INTERNATIONAL SECURITY

Christopher S. Browning

INSECTS Simon Leather

IRAN Ali M. Ansari

ISLAM Malise Ruthven

ISLAMIC HISTORY Adam Silverstein

ISLAMIC LAW Mashood A. Baderin

ISOTOPES Rob Ellam

ITALIAN LITERATURE

Peter Hainsworth and David Robey

HENRY JAMES Susan L. Mizruchi

JAPANESE LITERATURE Alan Tansman

JESUS Richard Bauckham

JEWISH HISTORY David N. Myers

JEWISH LITERATURE Ilan Stavans

JOURNALISM Ian Hargreaves

JAMES JOYCE Colin MacCabe

JUDAISM Norman Solomon

JUNG Anthony Stevens

THE JURY Renée Lettow Lerner

KABBALAH Joseph Dan

KAFKA Ritchie Robertson

KANT Roger Scruton

KEYNES Robert Skidelsky

KIERKEGAARD Patrick Gardiner

KNOWLEDGE Jennifer Nagel

THE KORAN Michael Cook

KOREA Michael J. Seth

LAKES Warwick F. Vincent

LANDSCAPE ARCHITECTURE

Ian H. Thompson

LANDSCAPES AND GEOMORPHOLOGY

Andrew Goudie and Heather Viles

LANGUAGES Stephen R. Anderson

LATE ANTIQUITY Gillian Clark

LAW Raymond Wacks

THE LAWS OF THERMODYNAMICS

Peter Atkins

LEADERSHIP Keith Grint

LEARNING Mark Haselgrove

LEIBNIZ Maria Rosa Antognazza

C. S. LEWIS James Como

LIBERALISM Michael Freeden

LIGHT Ian Walmsley

LINCOLN Allen C. Guelzo

LINGUISTICS Peter Matthews

LITERARY THEORY Jonathan Culler

LOCKE John Dunn

LOGIC Graham Priest

LOVE Ronald de Sousa

MARTIN LUTHER Scott H. Hendrix

MACHIAVELLI Quentin Skinner

MADNESS Andrew Scull

MAGIC Owen Davies

MAGNA CARTA Nicholas Vincent

MAGNETISM Stephen Blundell

MALTHUS Donald Winch

MAMMALS T. S. Kemp

MANAGEMENT John Hendry

NELSON MANDELA Elleke Boehmer

MAO Delia Davin

MARINE BIOLOGY Philip V. Mladenov

MARKETING

Kenneth Le Meunier-FitzHugh

THE MARQUIS DE SADE John Phillips

MARTYRDOM Jolyon Mitchell

MARX Peter Singer

MATERIALS Christopher Hall

MATHEMATICAL ANALYSIS

Richard Earl

MATHEMATICAL FINANCE

Mark H. A. Davis

MATHEMATICS Timothy Gowers

MATTER Geoff Cottrell

THE MAYA Matthew Restall and Amara Solari

THE MEANING OF LIFE

Terry Eagleton

MEASUREMENT David Hand

MEDICAL ETHICS Michael Dunn and Tony Hope

MEDICAL LAW Charles Foster

MEDIEVAL BRITAIN John Gillingham and Ralph A. Griffiths

MEDIEVAL LITERATURE

Elaine Treharne

MEDIEVAL PHILOSOPHY

John Marenbon

MEMORY Jonathan K. Foster

METAPHYSICS Stephen Mumford

METHODISM William J. Abraham

THE MEXICAN REVOLUTION

Alan Knight

MICROBIOLOGY Nicholas P. Money

MICROBIOMES Angela E. Douglas

MICROECONOMICS Avinash Dixit

MICROSCOPY Terence Allen

THE MIDDLE AGES Miri Rubin

MILITARY JUSTICE Eugene R. Fidell

MILITARY STRATEGY

Antulio J. Echevarria II

JOHN STUART MILL Gregory Claeys

MINERALS David Vaughan

MIRACLES Yujin Nagasawa

MODERN ARCHITECTURE

Adam Sharr

MODERN ART David Cottington

MODERN BRAZIL Anthony W. Pereira

MODERN CHINA Rana Mitter

MODERN DRAMA

Kirsten E. Shepherd-Barr

MODERN FRANCE

Vanessa R. Schwartz

MODERN INDIA Craig Jeffrey

MODERN IRELAND Senia Pašeta

MODERN ITALY Anna Cento Bull

MODERN JAPAN

Christopher Goto-Jones

MODERN LATIN AMERICAN LITERATURE

Roberto González Echevarría

MODERN WAR Richard English

MODERNISM Christopher Butler

MOLECULAR BIOLOGY Aysha Divan and Janice A. Royds

MOLECULES Philip Ball

MONASTICISM Stephen J. Davis

THE MONGOLS Morris Rossabi

MONTAIGNE William M. Hamlin

MOONS David A. Rothery

MORMONISM Richard Lyman Bushman

MOUNTAINS Martin F. Price

MUHAMMAD Jonathan A. C. Brown

MULTICULTURALISM Ali Rattansi

MULTILINGUALISM John C. Maher

MUSIC Nicholas Cook

MUSIC AND TECHNOLOGY

Mark Katz

MYTH Robert A. Segal

NANOTECHNOLOGY Philip Moriarty

NAPOLEON David A. Bell

THE NAPOLEONIC WARS

Mike Rapport

NATIONALISM Steven Grosby

NATIVE AMERICAN LITERATURE

Sean Teuton

NAVIGATION Jim Bennett

NAZI GERMANY Jane Caplan

NEGOTIATION Carrie Menkel-Meadow

NEOLIBERALISM Manfred B. Steger and Ravi K. Roy

NETWORKS Guido Caldarelli and Michele Catanzaro

THE NEW TESTAMENT

Luke Timothy Johnson

THE NEW TESTAMENT AS LITERATURE Kyle Keefer

NEWTON Robert Iliffe

NIETZSCHE Michael Tanner

NINETEENTH-CENTURY BRITAIN

Christopher Harvie and H. C. G. Matthew

THE NORMAN CONQUEST

George Garnett

NORTH AMERICAN INDIANS

Theda Perdue and Michael D. Green

NORTHERN IRELAND

Marc Mulholland

NOTHING Frank Close

NUCLEAR PHYSICS Frank Close

NUCLEAR POWER Maxwell Irvine

NUCLEAR WEAPONS

Joseph M. Siracusa

NUMBER THEORY Robin Wilson

NUMBERS Peter M. Higgins

NUTRITION David A. Bender

OBJECTIVITY Stephen Gaukroger

OBSERVATIONAL ASTRONOMY

Geoff Cottrell

OCEANS Dorrik Stow

THE OLD TESTAMENT

Michael D. Coogan

THE ORCHESTRA D. Kern Holoman

ORGANIC CHEMISTRY

Graham Patrick

ORGANIZATIONS Mary Jo Hatch

ORGANIZED CRIME

Georgios A. Antonopoulos and Georgios Papanicolaou

ORTHODOX CHRISTIANITY

A. Edward Siecienski

OVID Llewelyn Morgan

PAGANISM Owen Davies

PAKISTAN Pippa Virdee

THE PALESTINIAN-ISRAELI

CONFLICT Martin Bunton

PANDEMICS Christian W. McMillen

PARTICLE PHYSICS Frank Close

PAUL E. P. Sanders

IVAN PAVLOV Daniel P. Todes

PEACE Oliver P. Richmond

PENTECOSTALISM William K. Kay

PERCEPTION Brian Rogers

THE PERIODIC TABLE Eric R. Scerri

PHILOSOPHICAL METHOD

Timothy Williamson

PHILOSOPHY Edward Craig

PHILOSOPHY IN THE ISLAMIC

WORLD Peter Adamson

PHILOSOPHY OF BIOLOGY

Samir Okasha

PHILOSOPHY OF LAW

Raymond Wacks

PHILOSOPHY OF MIND

Barbara Gail Montero

PHILOSOPHY OF PHYSICS

David Wallace

PHILOSOPHY OF SCIENCE

Samir Okasha

PHILOSOPHY OF RELIGION

Tim Bayne

PHOTOGRAPHY Steve Edwards

PHYSICAL CHEMISTRY Peter Atkins

PHYSICS Sidney Perkowitz

PILGRIMAGE Ian Reader

PLAGUE Paul Slack

PLANETARY SYSTEMS

Raymond T. Pierrehumbert

PLANETS David A. Rothery

PLANTS Timothy Walker

PLATE TECTONICS Peter Molnar

PLATO Julia Annas

POETRY Bernard O’Donoghue

POLITICAL PHILOSOPHY David Miller

POLITICS Kenneth Minogue

POLYGAMY Sarah M. S. Pearsall

POPULISM Cas Mudde and Cristóbal Rovira Kaltwasser

POSTCOLONIALISM

Robert J. C. Young

POSTMODERNISM Christopher Butler

POSTSTRUCTURALISM

Catherine Belsey

POVERTY Philip N. Jefferson

PREHISTORY Chris Gosden

PRESOCRATIC PHILOSOPHY

Catherine Osborne

PRIVACY Raymond Wacks

PROBABILITY John Haigh

PROGRESSIVISM Walter Nugent

PROHIBITION W. J. Rorabaugh

PROJECTS Andrew Davies

PROTESTANTISM Mark A. Noll

PSEUDOSCIENCE Michael D. Gordin.

PSYCHIATRY Tom Burns

PSYCHOANALYSIS Daniel Pick

PSYCHOLOGY Gillian Butler and Freda McManus

PSYCHOLOGY OF MUSIC

Elizabeth Hellmuth Margulis

PSYCHOPATHY Essi Viding

PSYCHOTHERAPY Tom Burns and Eva Burns-Lundgren

PUBLIC ADMINISTRATION

Stella Z. Theodoulou and Ravi K. Roy

PUBLIC HEALTH Virginia Berridge

PURITANISM Francis J. Bremer

THE QUAKERS Pink Dandelion

QUANTUM THEORY

John Polkinghorne

RACISM Ali Rattansi

RADIOACTIVITY Claudio Tuniz

RASTAFARI Ennis B. Edmonds

READING Belinda Jack

THE REAGAN REVOLUTION Gil Troy

REALITY Jan Westerhoff

RECONSTRUCTION Allen C. Guelzo

THE REFORMATION Peter Marshall

REFUGEES Gil Loescher

RELATIVITY Russell Stannard

RELIGION Thomas A. Tweed

RELIGION IN AMERICA Timothy Beal

THE RENAISSANCE Jerry Brotton

RENAISSANCE ART

Geraldine A. Johnson

RENEWABLE ENERGY Nick Jelley

REPTILES T. S. Kemp

REVOLUTIONS Jack A. Goldstone

RHETORIC Richard Toye

RISK Baruch Fischhoff and John Kadvany

RITUAL Barry Stephenson

RIVERS Nick Middleton

ROBOTICS Alan Winfield

ROCKS Jan Zalasiewicz

ROMAN BRITAIN Peter Salway

THE ROMAN EMPIRE

Christopher Kelly

THE ROMAN REPUBLIC

David M. Gwynn

ROMANTICISM Michael Ferber

ROUSSEAU Robert Wokler

RUSSELL A. C. Grayling

THE RUSSIAN ECONOMY

Richard Connolly

RUSSIAN HISTORY Geoffrey Hosking

RUSSIAN LITERATURE Catriona Kelly

THE RUSSIAN REVOLUTION

S. A. Smith

SAINTS Simon Yarrow

SAMURAI Michael Wert

SAVANNAS Peter A. Furley

SCEPTICISM Duncan Pritchard

SCHIZOPHRENIA Chris Frith and Eve Johnstone

SCHOPENHAUER

Christopher Janaway

SCIENCE AND RELIGION

Thomas Dixon and Adam R. Shapiro

SCIENCE FICTION David Seed

THE SCIENTIFIC REVOLUTION

Lawrence M. Principe

SCOTLAND Rab Houston

SECULARISM Andrew Copson

SEXUAL SELECTION Marlene Zuk and Leigh W. Simmons

SEXUALITY Véronique Mottier

WILLIAM SHAKESPEARE

Stanley Wells

SHAKESPEARE’S COMEDIES

Bart van Es

SHAKESPEARE’S SONNETS AND POEMS Jonathan F. S. Post

SHAKESPEARE’S TRAGEDIES

Stanley Wells

GEORGE BERNARD SHAW

Christopher Wixson

MARY SHELLEY Charlotte Gordon

THE SHORT STORY Andrew Kahn

SIKHISM Eleanor Nesbitt

SILENT FILM Donna Kornhaber

THE SILK ROAD James A. Millward

SLANG Jonathon Green

SLEEP Steven W. Lockley and Russell G. Foster

SMELL Matthew Cobb

ADAM SMITH Christopher J. Berry

SOCIAL AND CULTURAL

ANTHROPOLOGY

John Monaghan and Peter Just

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Richard J. Crisp

SOCIAL WORK

Sally Holland and Jonathan Scourfield

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SOCRATES C. C. W. Taylor

SOFT MATTER Tom McLeish

SOUND Mike Goldsmith

SOUTHEAST ASIA James R. Rush

THE SOVIET UNION Stephen Lovell

THE SPANISH CIVIL WAR

Helen Graham

SPANISH LITERATURE Jo Labanyi

THE SPARTANS Andrew J. Bayliss

SPINOZA Roger Scruton

SPIRITUALITY Philip Sheldrake

SPORT Mike Cronin

STARS Andrew King

STATISTICS David J. Hand

STEM CELLS Jonathan Slack

STOICISM Brad Inwood

STRUCTURAL ENGINEERING

David Blockley

STUART BRITAIN John Morrill

SUBURBS Carl Abbott

THE SUN Philip Judge

SUPERCONDUCTIVITY

Stephen Blundell

SUPERSTITION Stuart Vyse

SYMMETRY Ian Stewart

SYNAESTHESIA Julia Simner

SYNTHETIC BIOLOGY Jamie A. Davies

SYSTEMS BIOLOGY Eberhard O. Voit

TAXATION Stephen Smith

TEETH Peter S. Ungar

TERRORISM Charles Townshend

THEATRE Marvin Carlson

THEOLOGY David F. Ford

THINKING AND REASONING

Jonathan St B. T. Evans

THOUGHT Tim Bayne

TIBETAN BUDDHISM

Matthew T. Kapstein

TIDES David George Bowers and Emyr Martyn Roberts

TIME Jenann Ismael

TOCQUEVILLE Harvey C. Mansfield

LEO TOLSTOY Liza Knapp

TOPOLOGY Richard Earl

TRAGEDY Adrian Poole

TRANSLATION Matthew Reynolds

THE TREATY OF VERSAILLES

Michael S. Neiberg

TRIGONOMETRY

Glen Van Brummelen

THE TROJAN WAR Eric H. Cline

TRUST Katherine Hawley

THE TUDORS John Guy

TWENTIETH-CENTURY BRITAIN

Kenneth O. Morgan

TYPOGRAPHY Paul Luna

THE UNITED NATIONS

Jussi M. Hanhimäki

UNIVERSITIES AND COLLEGES

David Palfreyman and Paul Temple

THE U.S. CIVIL WAR Louis P. Masur

THE U.S. CONGRESS Donald A. Ritchie

THE U.S. CONSTITUTION

David J. Bodenhamer

THE U.S. SUPREME COURT

Linda Greenhouse

UTILITARIANISM

Katarzyna de Lazari-Radek and Peter Singer

UTOPIANISM Lyman Tower Sargent

VATICAN II Shaun Blanchard and Stephen Bullivant

VETERINARY SCIENCE James Yeates

THE VIKINGS Julian D. Richards

VIOLENCE Philip Dwyer

THE VIRGIN MARY

Mary Joan Winn Leith

THE VIRTUES Craig A. Boyd and Kevin Timpe

VIRUSES Dorothy H. Crawford

VOLCANOES Michael J. Branney and Jan Zalasiewicz

VOLTAIRE Nicholas Cronk

WAR AND RELIGION Jolyon Mitchell and Joshua Rey

WAR AND TECHNOLOGY

Alex Roland

WATER John Finney

WAVES Mike Goldsmith

WEATHER Storm Dunlop

THE WELFARE STATE David Garland

WITCHCRAFT Malcolm Gaskill

WITTGENSTEIN A. C. Grayling

WORK Stephen Fineman

WORLD MUSIC Philip Bohlman

WORLD MYTHOLOGY David Leeming

THE WORLD TRADE

ORGANIZATION Amrita Narlikar

WORLD WAR II Gerhard L. Weinberg

Available soon: IMAGINATION

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BIODIVERSITY CONSERVATION

David Macdonald

WRITING AND SCRIPT

Andrew Robinson

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ÉMILE ZOLA Brian Nelson

THE VICTORIANS Martin Hewitt

IBN SĪNĀ Peter Adamson

MINING Karen Hudson-Edwards and Hannah Hughes

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A Very Short Introduction second edition

Great Clarendon Street, Oxford, OX2 6DP, United Kingdom

Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries

© Jonathan Slack 2023

The moral rights of the author have been asserted

First edition published 2014 This edition published 2023

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Comments on the first edition

‘This is a concise and accurate account of genes, and what they are, in a readable and convenient format.’

Sir Paul Nurse, Director, Francis Crick Institute

‘Unlike the genetic material itself, this book is short, sharp, and to the point.’

Steve Jones, University College London

‘We all need to know what genes are. Slack tells us with authority, clarity and grace.’

Armand Leroi, Imperial College, London

‘The essential guide for getting up to speed with the ever- changing and crazily complex science of genetics.’

Adam Rutherford, University College London

‘With more heat than light in many areas surrounding genetics, it is refreshing to have such a concise, precise and matter- of- fact introduction to the field. This is strongly recommended to anyone with even a passing interest in a field set to dominate our lives.’

Laurence Hurst, Director of The Milner Centre for Evolution, University of Bath

Preface xix

List of illustrations xxi

1 Genes before 1944 1

2 Genes as DNA 17

3 Mutations and gene variants 40

4 Genes as markers 60

5 Genes of small effect 87

6 Genes in evolution 109

Conclusion: the varied concepts of the gene 129

Glossary 133

Further reading 139

Index 143

Preface

What is a gene? In essence it is a molecule of DNA, present in every one of our cells, that controls the synthesis of one particular protein in our bodies. But this simple definition does not do justice to the richness of the gene concept and its many ramifications throughout the life sciences. For example, some genes do not code for proteins, some appear to have no function at all, others are presumed to exist but have not been identified in terms of DNA.

Everyone has heard of genes and we have come to feel that they are fundamental to who we are. But there is also a lot of uncertainty and confusion about what we are really referring to and what it means in a particular context. For example, does having cancer in a first degree relative mean I have ‘cancer genes’? If I have genes also found in Stone Age fossils, does this mean I am very primitive? Does the existence of ‘selfish genes’ mean that human nature is inherently selfish?

We also know that genes have become the basis of a huge technology which generates pharmaceuticals, diagnostic tests, forensic identification, paternity tests, and GM crops, which are welcomed by some people and feared by others. Many are suspicious of the gene concept as applied to ethnicity, intelligence, criminality, or other human attributes, while others presume that

most variation of these things is due to genetic differences between people. Despite their preconceptions, many have a desire to understand this entity which penetrates so deeply into their lives but still seems rather mysterious and confusing.

This book is not a textbook of genetics, but it is a brief introduction to the various conceptions of the gene currently used in the life sciences. These conceptions are quite distinct from each other. The ‘gene’ of molecular biology is, indeed, a piece of DNA that encodes a protein, or sometimes a functional RNA (ribonucleic acid). The ‘genes’ responsible for attributes such as human height or the incidence of many diseases are differences between DNA sequences that make up the same coding sequence in different individuals. The ‘genes’ in studies of ancestry are other differences in DNA sequence that are mostly not in coding genes at all. The ‘genes’ of evolutionary biology or sociobiology are hypothetical entities imagined to provide the basis for theories of how certain traits can arise in evolution. Most of these have not been identified in terms of DNA.

In what follows, some flesh will be put on each of these different concepts of the gene. The aim is to enable readers to appreciate the main ideas about genes, to evaluate contentious issues, and to navigate to more advanced texts if they wish. Terms introduced in italics are explained in the Glossary at the end.

I am indebted to the following for reading drafts and commenting on the manuscript: Helen Brittain, Jill Maidment, Janet Slack, and Zoe Yeomans.

Altruistic behaviour by the female nighthawk

19 Hypothetical genetics of altruism in social insects 123

Chapter 1 Genes before 1944

In 1938 a remarkable pair of articles was published in the Quarterly Review of Biology. They were by a little-known American biology professor from the University of Missouri, Addison Gulick, and they were about the nature of the gene. These articles are rarely consulted today since they were written shortly before it was discovered that genes consisted of deoxyribonucleic acid (DNA). However, they are remarkable in showing how much was known about genes even before their chemical nature was established. Gulick knew that genes were located in the chromosomes of the cell nucleus, and were complex structures that somehow directed the synthesis of enzymes and the development of the organism. He knew that they normally remained stable from one generation to the next, and that occasional changes, called mutations, could spread through the population and be the basis of evolution by natural selection. He also made surprisingly accurate estimates of the sizes and numbers of genes in various types of organism. These articles illustrate that to appreciate how our current understanding of the gene came about we need to go back much further than the famous ‘double helix’ structure of DNA, discovered in 1953.

Two completely separate lines of work led to our modern view, and they came together shortly after the appearance of Addison Gulick’s articles to create the new science of molecular biology.

One was the study of heredity by biological experimentation and the other was the study of the chemistry of DNA.

Biology of heredity

Before the 18th century there was little informed speculation about heredity. Even the word did not exist (‘heredité’ first appeared in France, ‘genetic’ in England, both about 1830). Historically there had been plenty of animal breeding and vague ideas of ‘blood lines’, but this was uninformed by much understanding of reproduction. Although selective breeding in agriculture had been happening for thousands of years, the first systematic applications took place in the 18th century. Robert Bakewell, a sheep breeder from Dishley, near Loughborough, England, bred a line of New Leicester sheep that grew faster and produced more meat than before (Figure 1). This was done by mating the best yielding males and females to create a self-reproducing population (breed) that maintained the new characteristics in a stable way. The experience of animal breeding conveyed the idea that heredity involved the blending, or averaging, of the distinct characteristics, also known as traits, of the parents. It was quite understandable that animal breeders should have believed in the blending of traits since this is what you see when animals are mated and characters such as height or weight or growth rate are measured. But the blending theory of inheritance was to become a serious problem for Darwin’s theory of natural selection.

By the time of Darwin’s work in the mid-19th century, the fact that biological evolution had occurred was already accepted by some scientists, mostly on the basis of the changes of the types of animal or plant remains seen at different levels of the fossil record. The real impact of Darwin’s work, and that of his contemporary Alfred Wallace, was to provide an actual and credible mechanism for the changes seen in living organisms over evolutionary time. This mechanism was natural selection, and the case for it is simply

1. New Leicester sheep. From David Low’s The Breeds of Domestic Animals of the British Islands, London, 1842.

stated. If a population of animals or plants varies with regard to some traits, if those traits are heritable, and if they affect the likelihood of reproduction, then the composition of the population will inevitably shift between each generation.

The traits associated with more reproduction will become more common, and will eventually displace the alternatives. The direction and speed of the shift will be determined by the selective conditions that cause the differential reproduction of the individuals with the different traits. The theory of natural selection seems very compelling, and it is especially compelling as presented by Darwin in The Origin of Species (1859), which contains a huge array of examples drawn from natural history to support the case. At the time, the main opposition to the theory was from religious groups who realized that the principle of

natural selection undermined the ‘argument from design’, an important argument for the existence of God, and also from those offended by the idea of a biological kinship between humans and animals. However, there was also some scientific opposition; the most serious was that which focused on the difficulty of reconciling natural selection with blending inheritance.

Supposing that one individual is slightly better suited to reproduction than others due to the possession of a particular trait (e.g. they might be able to digest some additional component in their food), he or she will most likely mate with an individual lacking it and their offspring will then have it in a diluted form, as the favourable trait is rare. After three or four generations the hereditary factors responsible for the trait will be diluted out almost completely. Therefore selection has only a few generations to operate and this will not be enough to change the whole breeding population unless the reproductive advantage conferred by the new trait is very large indeed. Darwin himself was well aware of the problem but he was also opposed to the idea of large jumps in evolution and favoured the idea that evolution progressed in a smooth and imperceptible manner via many small changes.

Some thinkers followed this argument to its logical conclusion and concluded that the hereditary factors responsible for evolution must have large effects, such that substantial selection could occur before they became diluted out. In this way the trait might become common enough for some matings to occur between parents who both possessed it and it would no longer be diluted in their offspring. Among these thinkers was William Bateson, who collected in his book Materials for the Study of Variation (1894) a remarkable set of examples of discontinuous and qualitative variation within animal and plant populations. More direct evidence for the existence of large heritable changes came from observation of spontaneously occurring ‘mutations’. In particular the Dutch botanist Hugo de Vries in 1886 observed the

de novo appearance of dramatically new forms of the Evening Primrose, which bred true in subsequent generations. Despite these findings, blending inheritance remained a serious problem for the theory of natural selection.

In fact the solution to the problem had been provided as early as 1866 by Gregor Mendel, a monk at the Abbey of St Thomas in Brno, now in the Czech Republic. In the early 19th century Brno was a centre of textile manufacture and of sheep breeding, and the Abbey already had a two-hectare experimental garden. Mendel had received education about animal and plant breeding in the course of his studies of philosophy at the University of Olomouc, and he was encouraged to continue his work at Brno by the Abbot. Between 1856 and 1863, Mendel conducted a number of experiments with peas. He was fortunate enough to choose simple traits, which we would now call traits determined by single genes, rather than complex traits determined by many genes. Among these traits were a round or wrinkled appearance, and a green or yellow colour. Mendel postulated that there were invisible hereditary ‘factors’ causing each visible trait, and showed that there were predictable rules for their inheritance. His breeding experiments indicated that each individual plant contained two factors for each trait, one derived from each parent. When reproductive cells (pollen or eggs) are formed, each contains just one factor, randomly selected from the two possibilities available in that plant. In some cases one factor would suppress the other: we should now call this a dominant gene. For example, a cross between yellow and green peas gives only yellow offspring. However, if these offspring are crossed to each other, then 25 per cent of the next generation are green, indicating that the green factors are still there, but cannot be expressed in the presence of the yellow factors (Figure 2). The green factor would now be called a recessive gene. So, Mendel showed that the hereditary factors behaved as discrete units, such that each parent provided one to each offspring and the appearance of the offspring depended on the specific combination of factors inherited and the

(gg) (Yg) (Yg) (Yg) (Yg)

First generation

Second generation

2. Mendel’s peas. When yellow peas are crossed to green peas, the first generation seeds are all yellow. But when members of the first generation are crossed to each other, 25 per cent of the second generation seeds are green. Mendel explained this by postulating hereditary factors, here called Y for yellow and g for green, such that the yellow factor is dominant over the green where they occur together.

dominance rules between them. Mendel published his work in the Verhandlungen des Naturforschenden Vereines in Brünn in 1866. But this was what we should now call a ‘low-impact journal’, and nobody noticed. After he became Abbot in 1868 he was mostly occupied with administrative duties, and he died in 1884 with the wider world still ignorant of the founding principles of genetics that he had discovered.

The 20th century

In Western Europe and America, arguments continued over whether natural selection could work through blending inheritance, and whether mutations of large effect were a credible source of variation. Not until 1900 was Mendel’s work rediscovered and further developed. Several people were responsible for this including Hugo de Vries of mutation fame and the German botanist Carl Correns. It was rapidly realized that the major contradiction of blending inheritance had now been removed. Instead of being diluted out in each generation, Mendel’s factors were stable and persisted from generation to

Yellow (YY)
Green
Yellow (Yg)
Yellow (Yg) (YY) (Yg) (Yg) (gg)

generation. The variation in a population existed because of the differences between the hereditary factors that were present in each individual. Recessive traits could appear in offspring due to the random assortment of factors at reproduction, so it was not necessary to postulate new mutations to explain every newly appearing variation. Moreover the more complex characteristics, whose inheritance did appear to be of a blending nature, could be explained as resulting from the action of several different Mendelian hereditary factors.

In the late 19th century improved microscopes and new stains from the chemical industry had improved visualization of cells and their nuclei. The German anatomist Walther Flemming, working at Kiel, first identified chromosomes, and described the process of cell division, now called mitosis, in which the chromosomes enter the nuclei of both daughter cells. The Belgian cytologist Edouard van Beneden showed that there was a characteristic chromosome number for each species and that this number was found in the various different cell types of an organism. He followed chromosomes of the nematode worm Ascaris through cell division and showed that the number was conserved, but that it halved during the formation of the reproductive cells (divisions forming reproductive cells are now called ‘meioses’; singular, ‘meiosis’).

B the beginning of the 20th century, after Mendel’s work had been resurrected, Theodor Boveri in Germany and Walter Sutton in the USA independently showed that chromosomes behaved just like Mendel’s hereditary factors. From then on most scientists believed that the chromosomes were the hereditary factors or at least contained them. The hereditary factors themselves were named ‘Gene’ (in German this is plural, equivalent to ‘genes’ in English) in 1909 by Wilhelm Johannsen, Professor of Plant Physiology at the University of Copenhagen. The term was derived from the Greek γεѵεα (= generation or race). This is an interesting linguistic example of the entity being named after the process, as ‘genetic’

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