Introducing Evolution Introducing Evolution E-Book

Dylan Evans

• Herausgeber: Icon Books
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 103

Veröffentlichungsjahr: 2015

Beschreibung

In 1859, Charles Darwin shocked the world with a radical theory - evolution by natural selection. One hundred and fifty years later, his theory still challenges some of our most precious beliefs. Introducing Evolution provides a step-by-step guide to 'Darwin's dangerous idea' and takes a fresh look at the often misunderstood concepts of natural selection and the selfish gene. Drawing on the latest findings from genetics, ecology and animal behaviour- as well as the work of best-selling science writers such as Richard Dawkins and Steven Pinker- this book reveals how the evidence in favour of evolutionary theory is stronger than ever.

Leseprobe

Published by Icon Books Ltd, Omnibus Business Centre, 39–41 North Road, London N7 9DPEmail: [email protected] 

ISBN: 978-184831-186-2

Text copyright © 2012 Icon Books Ltd

Illustrations copyright © 2012 Icon Books Ltd

The author and illustrator has asserted their moral rights

Originating editor: Richard Appignanesi

No part of this book may be reproduced in any form, or by any means, without prior permission in writing from the publisher.

Contents

Cover

Title Page

Copyright

The Central Idea in Biology

Fear and Loathing in Kansas

Old Questions

Universal Acid

An Idea in Two Parts

What is Evolution?

The Fixity of Species

Independent Creation

Enough Time

The Age of the Earth

Old Bones

Dragons’ Teeth

What the Fossils tell Us

The Evidence from Carbon Dating

The Tree of Life

The Conquest of the Land

Four Legs Good

A Very Recent Species

Living Fossils

“Scientific” Creationism

Missing Links

How does Evolution Happen?

Darwin’s Contribution

So Simple, yet so Powerful

Three Conditions

Animal and Plant Copies

A Tale of Butterflies

A Change in Environment

Multicoloured Butterflies

Evolution by Natural Selection

Darwin’s Dangerous idea

The Argument from Design

Animals and Artefacts

Adaptations

Another Explanation for Biological Design

A Single Step

Many Small Steps

Start the Story Again

Cumulative Selection

What Good is Half a Wing?

The Blind Watchmaker

Occam’s Razor

No Need for that Hypothesis

Natural Selection Observed

Looking in More Detail: Heredity

Genes

The Function of Proteins

Development

Growth and Specialized Cells

Genes and Development

Genes and Environment

Mutation or Incorrect Copying

No Mutation, No Evolution

Random Drift

Adapation and Natural Selection

Not Everything is an Adaptation

Adaptive Prediction

Beneficial Mutations are Rare

Mutations are Random

Accumulation of Design

The Gene’s-eye View

The Selfish Game

Altruism

Biological Altruism is Common in Nature

Parental Care

The Puzzle of Altruism is Solved

A Thought Experiment

Two Conditions for Selfish Genery

The Green Beard Effect

Do Genes Influence Behaviour?

Genetic Determinism

Can Organisms Tell When Others Have the Same Genes?

Kin Selection

Blood is Thicker Than Water

Another Theory of Altruism

Tit-for-Tat

Reciprocal Altruism is Rare

The Peacock’s Tail

Why do Peahens Prefer Big Tails?

Natural Selection and Sexual Selection

Female Choice and Male Competition

The Runaway Process

Arms Races

The Antibiotics Arms Race

Co-evolution

The Origin of the Eukaryotes

Other Differences

Let’s Talk About Sex

Virgin Births

Clones and Genetic Difference

Meiosis and Gametes

Male and Female

Isogamy and Anisogamy

The Cost of Sex

What’s the Advantage of Sex?

The Family Swap

Reproductive Isolation

Gene Pools

The Biological Species Concept

The Phenetic Species Concept

Speciation

Splitting

Allopatric Speciation

Higher Groups and Lower Groups

Varieties of Dogs

Empires and Domains

Which is the Highest Group?

Monophyletic and Paraphyletic Groups

Cladism

The Tree of Life Again

The Trunk of the Tree

The Origin of Life

A Warm Little Pond

The Primordial Soup

Near the Sea-bed

Panspermia

Extinction

Mass Extinctions

The End of the Dinosaurs

Why Did the Dinosaurs Go Extinct?

A Hundred Million Megatons of TNT

The Lucky Ones

The Sixth Mass Extinction

Ecological Disaster

The End of the Human Race

Is the Earth One Giant Organism?

Organisms Are Designed By Natural Selection

Gaia

The Deadly Species

Killing Our Cousins

The Neanderthals

The Advantage of Language

Efficient Information-sharing

Extended Memory

The Speaking Animal

Human Universals

What is Human Nature?

Evolutionary Psychology

Massive Modularity

The Walls Came Tumbling Down

Science and Speculation

Survival Machine or Courtship Device?

Is Art a Sexual Display?

Humans and Culture

The Evolution of Culture

Memes or Mind-viruses?

Why Do Some Ideas Catch On More Than Others?

The Naturalness of Religious Ideas

Evolutionary Epistermology

Evolutionary Ethics

Moral Evolution

Moral Instincts

Moral Sentiments

Are Ideas Alive?

Artifical Life

Genetic Algorithms

Evolutionary Robotics

The Virtual World, Tierra

A Common Thread

The Controversy Continues

A Scientific Answer to the Deep Questions

The Wonder of Evolution

Science and Values

Further Reading

The Authors

Acknowledgements

Index

The Central Idea in Biology

“Nothing in biology makes sense except in the light of evolution”, said the great Russian geneticist, Theodosius Dobzhansky (1900–75). The theory of evolution is indeed the central idea in modern biology.

And yet, in August 1999, one hundred and forty years after Darwin published The Origin of Species, the Kansas State Education Board removed the topic of evolution from the official curriculum.

Biology students in Kansas would now be able to graduate without learning the most fundamental idea in their discipline! Why? What could motivate a State Education Board to deprive students of such an important piece of knowledge?

Fear and Loathing in Kansas

The members of Kansas State Education Board clearly disliked the theory of evolution. They are not alone. Ever since Charles Darwin (1809–1882) and Alfred Russel Wallace (1823–1913) proposed the theory at a meeting of the Linnaean Society in 1858, it has inspired much fear and loathing, and many attempts have been made to suppress it.

When the Bishop of Birmingham’s wife heard about Darwin’s theory in 1880, she said to her husband...

My dear, let us hope it is not true; but, if it is true, let us hope it will not become generally known.

So what is it about Darwin’s theory that upsets people so much?

Old Questions

Darwin’s theory of evolution upsets people because it threatens all the old ideas about who we are and why we are here.

For thousands of years, human beings have wondered about the meaning of life.

Where do we come from?

And what is our purpose?

The traditional answers, provided by many religions, have usually involved the idea of a God – or gods.

God made us, the story goes, and put us here for a special reason. All of these traditional answers see humans as exceptional creatures. Humans are not just animals. Unlike animals, humans have spirits or souls. Only humans have free will. Only humans can survive death.

Universal Acid

The theory of evolution threatens all these old ideas. It undermines the central claims of many religions. It seems to leave no room for God, or the soul, or life after death. Humans, it tells us, are just another kind of animal.

The American philosopher, Daniel Dennett (b. 1942), has described the theory of evolution as a kind of “universal acid”.

Did you ever hear of universal acid? This fantasy used to amuse me and some of my schoolboy friends... ...Universal acid is a liquid so corrosive that it will eat through anything!

Like universal acid, the theory of evolution eats through just about every traditional religious idea. This is why Dennett calls it “Darwin’s dangerous idea”.

An Idea in Two Parts

Darwin’s dangerous idea comes in two parts: the theory of evolution, and the theory of natural selection. We will look at each of these two theories in turn, and then put them together. It is only when the two theories are put together that they become really dangerous.

It is not the theory of evolution on its own, nor the theory of natural selection on its own... ...but the theory of evolution by natural selection that really undermines religious beliefs.

We will begin with the theory of evolution.

What is Evolution?

The theory of evolution states that species can change. One species can give rise to another.

According to the theory of evolution, humans are descended from non-human ancestors. Ultimately, every species on Earth is descended from a single common ancestor, just as the branches on a tree all spring from a single trunk.

This might not seem like a big idea, but for thousands of years people in the West believed that species were fixed, unchanging entities. So it was a great shock to learn that this was not true.

The Fixity of Species

The idea that species are fixed and unchanging dates back to Aristotle (384–322 BC), the great Greek philosopher and scientist. He based his belief on the evidence of his own eyes.

You never see a monkey give birth to a human, do you? Monkeys give birth to monkeys and humans give birth to humans.

So, not unreasonably, Aristotle concluded that one species could never give rise to another. Monkeys would always be monkeys. And humans must always have been human.

Independent Creation

For hundreds of years, Christian scholars accepted Aristotle’s theory of the fixity of species. They believed that God had created each species independently at the beginning of time, and that each species then remained exactly the same up to the present.

We believe that the story told in the Bible, in the Book of Genesis, is literally true ...

“And now, from the clay of the ground, all the beasts that roam the earth and all that flies through the air were ready fashioned, and the Lord God brought them to Adam, to see what he would name them; the name Adam gave to each living creature is its name still.” (Genesis 2:19).

Enough Time

Eventually, in the 18th century, some people began to suggest that species were not fixed. They realized that species might change gradually. A monkey could not have a human baby.

But it could have a baby that was ever so slightly more humanlike. And that offspring could have an even more humanlike baby, and so on. Given enough time, there could be a series of many small steps linking a monkey ancestor to a human descendant.

Given enough time. That was the crucial point. And that was what the Church disputed. Even if it were theoretically possible for one species to give rise to another by a series of many small steps, there simply had not been enough time for monkeys to evolve into humans, let alone for all life to be descended from a single ancestor. The world was simply not that old, according to the Church.

The Age of the Earth

When Bishop Ussher (1581–1656) added up all the figures in the Bible, he calculated that the world was created in 4004 BC. If the Bible was literally true, the earth could only be 6,000 years old. This was nowhere near enough time for evolution to take place.

But in the 19th century, geologists were already beginning to realize that the world was a lot older than this. There are clear patterns of erosions where rivers have cut into mountains – and yet it takes thousands of years for water to erode such rocks.

Today, a mass of other scientific evidence has confirmed what those early geologists suspected. The world is almost a million times older than Bishop Ussher thought. Current estimates put the age of the earth at around 4.5 billion years. That is easily long enough for evolution to have taken place.

Old Bones

So evolution could have taken place. There has been more than enough time for all the currently existing species to have descended from a single common ancestor in a series of many small steps.

However, it is not enough to know that evolution could have happened. We want to know whether or not evolution really did happen.

This is where fossils come in...

In 1811, Mary Anning found the skeleton of an Ichthyosaurus, a marine reptile that lived between 5 and 120 million years ago, in cliffs near Lyme Regis in Dorset.

The 21 foot long fossil found by Mary Anning.

For thousands of years, people have come across old bones in the rocks. Some of these bones resemble those from animals we see around us, but others clearly come from animals unlike anything alive today.

Dragons’ Teeth

Huge fossil teeth, for example, have been found that could not come from any currently existing species of animal. Where do they come from?

Legends and myths arose to explain these strange discoveries.

Perhaps the fossil teeth originally belonged to dragons? Perhaps the world was once full of strange creatures that no longer exist?

What the Fossils tell Us

The existence of strange fossils does not provide conclusive evidence against the fixity of species in itself. You can accept the idea that some species have become extinct without believing that one species can change into another. However, when you compare the various fossils that have been found, it is immediately obvious that they form patterns.

Many fossils can be arranged in sequences, in which there is a more or less continuous series connecting an earlier fossil with a later one.

When you compare the fossil at the beginning of the chain with the final one, they look very different. But between each of the intermediate fossils in the chain there is only a slight difference.