The Received View of Evolution

Sex and Death: An Introduction to Philosophy of Biology

20.04.2005

Contents

2.1 The Diversity of Life

2.2 Evolution and Natural Selection

2.3 The Received View and its Challenges

2.1 The Diversity of Life

“design space” (Dennett, 1995) – All possible and actual “designs”

Regarding these we are highly atypical – Eukaryotic + simply life cycle + huge

Diversity and Disparity (Gould)– Diversity: number of species in existence – Disparity: amount of organisms that have

fundamentally different designs

2.1 The Diversity of Life

Why are some areas in design space occupied and some not?

Process Structuralists– Design space is highly constrained

Historical relativity – There are so many designs, that there was no

time to realize them all.

? ?

2.1 The Diversity of Life

Why do organisms come packed into species?

Life without species is possible No sharp distinction between spiecies and

varieties

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2.2 Evolution and Natural Selection

Basic elements of evolutionary theory (Mayr)

1. The living world is not constant

2. Evolution. change has a branching pattern

3. New species form when a population splits

4. Evolution. change is gradual

5. Adaptive change through natural selection

2.2 Evolution and Natural Selection

Natural selection is the inevitable result of – Phenotypical variation– Differential fitness– Heritability

Are the forces that induce genetic variation deterministic? ? ?

2.2 Evolution and Natural Selection

Cumulative selection – Innovation is the result of a sequence of selective

episodes

Conditions:– Direction of selection is constant – Low mutation rate – Each intermediate stage must be fitter than its

predecessor (adaptive landscapes)

2.2 Evolution and Natural Selection

Speciation – Cumulative selection in different environments

results in reproductive isolation – Hybrid matings will be penalized

2.3 The Received View and its Challenges

3 important debates – Units of selection – Selection and evolution – Evolution within Biology

2.3 The Received View and its Challenges

What is being selected

“gene’s eye” concept (Williams, Dawkins) Hierarchical view

??

2.3 The Received View and its Challenges

The “gene’s eye” Only genes are passed on directly from one

generation to the next Genes are replicators and use organisms as

“vehicles” Natural selection acts through vehicles and

targets the replicators Problem: gene – trait relationship

2.3 The Received View and its Challenges

Hierarchical view organisms are not the only entities that form

populations (hives, colonies, species) Selection can operate simultaneously at

different levels

2.3 The Received View and its Challenges

Selection and Evolution

Four major issues – Does the received view overstate the importance

of adaptation? – Relationship of selection and other factors – Methodological issues – The proper scope of evolutionary explanations

2.3 The Received View and its Challenges

The Importance of Adaptation

Fitness advantages only make survival more likely !

2.3 The Received View and its Challenges

Relationship between selection and other factors

Selection is historical, it is constrained by inheritances of the population

Some patterns seem to be independent of selection:

Evolution after the Cambrian explosion

2.3 The Received View and its Challenges

Methodological issues – How can we test our ideas?– How much evidence is needed to support a

hypothesis?

2.3 The Received View and its Challenges

Scope of evolutionary explanations Sociobiology (Wilson)

Explaining social / psychological processes with evolutionary mechanisms is possible vs.

This attempt is mistaken in principle. Since there is culture these rule do not apply to us anymore

2.3 The Received View and its Challenges

Evolution within Biology Evolution and Ecology

– Ecology describes the environment which generates selective pressure

Evolution and molecular Biology – Genetics did not make Evolutionary Theory futile– Different levels of explanation