Evolutionary Theory, according to Darwin

Definitions and Components of Darwin’s Evolution

• Definition of Biological Change: Differential Persistence of Variation… Now, what does that mean? ( AND THIS IS WHAT DARWIN WANTED TO

EXPLAIN)• Definition of Evolution: Descent with Modification.

– And what does that mean?– Individuals Vary--- (materialism). Only variation is real!– Some variation is inheritable, meaning that some observable

variation is inherited from our parents, and some variation is unique to us.

– Individuals vary in their reproductive success. Some individuals leave 10 progeny; some individuals leave no offspring.

• Differences in reproductive success is known as FITNESS. The Individual who leaves 10 offspring is, in Darwinian

terms “more fit” than individuals who leave only 2 offspring

So what about Adaptation? What is Adaptation?

Adaptation is the consequence (or outcome) of reproductive success.

If individuals reproduce and their offspring live to reproduce, the parents are by definition adapted. Adaptation is a consequence of reproducing. And adaptation is closely related to fitness.

Fitness and adaptation are closely related:

If I have 2 children, and you have 10 children and all of our children live to reproduce, you are by definition more fit and better adapted than I am.

What are the causes (mechanisms) in variation

in reproductive success?

• Natural Selection: a concept to Darwin all the factors in any setting that resulted in differences in reproduction. There are no universal selective agents. There are only agents that affect reproduction in particular historical settings.

• (after Genetics was discovered, genetic drift was added as a mechanism of reproductive success)

SUMMARY

In contemporary evolutionary science, there are two parts to the differential persistence of variation:

1) variation at the scale of individuals.

2) Mechanisms of evolution, natural selection and drift, operate on that variation so that over time, there is differential persistence of variation.

Books:

Principles of Ethics

Principles of Biology

Principles of Psychology

Principles of Sociology

First Principles of the System of Philosophy

Herbert Spencer: Socal Darwinism

Components of Social Darwinism

• Definition of Change: “Transformation” from relatively incoherent to relative coherent. [analogy with organic life; higher life forms are more complex

and more coherent than lower life forms]

• With transformation, there is an increase in coherence and an increase in functional specialization.

Spencer’s Assumptions

1. All life was a single unbroken chain… all life connected and transformed [unlinear …one line]

2.Causes of transformation were inherent to life itself.

(Unlike Darwinism, there were no mechanisms that winnowed variation)

in the 19th Century, this was the “doctrine of progress”

Inherent directionality to all life that transformed from simple to complex.

3. The inherent direction was “hard”wired into organisms. Some organisms could progress further than other organisms.

Marriage of biology and culture is the third assumption

SPENCER’S CULTURAL EVOLUTION

• Inherent transformation toward greater complexity charactized humans

• The phrase for that transformation was ”survival of the fittest” . What he meant by that phrase was a kind of natural transformation driven by the inherent nature of humans. – The phrase was misinterpreted with natural transformation

equated with “good”. Those most capable of transformation survive.

• Became a justification for the scaling of societies from simple to complex in the 19th C.

• Darwin liked the phrase and said that in the context of natural selected it explained adaptation. Survival of the fittest explains differential persistence of variation

Contrast between Darwin and Spencer

Darwin Spencer

Evolution Descent with

Modification

Transformation

Components Variation

And selection

Cause Mechanism

“natural

Selection”

Internal; hard-wired

Description

of evolution

change

Bush Single line

20th Century Anthropological Evolution:Neo Evolution

Leslie WhiteJulian Steward

Leslie White

• Major assumption: human cultural development is unique. We need unique laws to explain it.– Evidence of uniqueness: language, symbolism– Cultural laws must explain cultural evolution

• Influences on his Intellectual framework: Spencer and Marx

• From Spencer: – cultural development really is progressive. Human cultures

develops from simple to complex. Progess is a fact!– The development of culture is unilinear [one large trunk]

• From Marx:– Fundamental to understanding cultural change is

economics or the modes of production. Modes of production underlie all other changes.

– Science was the was of understanding and explaining those changes.

Leslie White (con’t)

• How he modified and used his intellectual guides:

1. Progress was inevitable but no hard wired into the species. No inherent principle to humans that resulted in greater complexity. AND no value placed on greater

complexity. It simply is.

2. Causes of development are material. They are to be found in the material conditions of life, economics, technology, etc.

White’s Cultural Laws

• Law of Evolutionary Development: [C = E x T]– C = culture; E= energy capture or efficiency (technology);

T= time. (this is technology)– Examples: unilineal transformation from Bands to Tribes to

chiefdoms to state

• Law of Cultural Dominance: cultures that exploit energy more efficiently in one environment will spread at the expense of the less efficient.

Julian Steward: Multilinear Evolution

• Major premise: Culture change occurs because of the interaction between environmental setting and people in that setting. Steward is the beginning of cultural ecology in Anthroplogy. – Setting places constraints on the choices that individuals make.– Environment: a broad definition, including terrain, soils,

resources, and other social groups

AND The same cultural expression can occur in vastly different settings if the constraints are the same:

development of Bands in the Arctic and in the Great Basin

Steward (con’t)

• Culture Core: that part of a culture that relates people to their setting… So, to Steward it was the culture core that linked people to their setting and was the basis of the cultural expression.– "the constellation of features which are most closely related

to subsistence activities and economic arrangements"

(Steward 1955:37).  • Differences from White:• Culture change is not linear or progressive. Change is

locally determined by the setting and the essential features that relate folks to that setting.

• Technology does not drive culture change… interaction between organisms and their setting drive change.

Critique of Neo Evolution from both scienitsts and post-processualists

• culture evolution is not unique

• lineal sequence does not address the range of variation in societies

• post processualists argue that NE ignores people and fails to consider the variation within societies.

• Neo evolution does not allow for contingency

Contemporary Archaeological Evolutionary Ideas

Virginia ButlerLaura Betzig

Selectionism and Evolutionary Ecology

• Commonalities– Both proceed from a platform of science. Building

knowledge is the goal; answering WHY questions– Actively building theory. In fact, both have

theory, and that theory is Darwinian Evolution• Consequently Darwinian principles and

mechanisms apply: individuals vary, heritable variation, reproduction matters, mechanisms operate on and winnow variation resulting in differential persistence

Selection operates on the PhenotypeWhat is the phenotype?

Menstral Hut

Male Peacock

Bower Bird

DIFFERENCES

• Selectionism: Goal is to explain the archaeological record… ARTIFACTS in evolutionary terms

• Human Evolutionary Ecology: explain human behavior in evolutionary terms. Use evolutionary principles to account for human behavior… foraging strategies, mating systems, birth spacing

Selectionism ( Robert Dunnell)

• Key Components of his Ideas: materialism, archaeology as an historical science and explanation

• Artifacts are the focus of explanation: Why new forms, technologies evolve?

• Artifacts are part of the human phenotype. Therefore selection operates on artifacts

• Connect artifacts to two step evolutionary process– Produce variation; winnow

variation

Methodology of Selectionism

• Style: those artifact traits that do not contribute to reproductive success

• Function: artifact traits that contribute to affect reproductive success

• Mechanisms: • Selection operates on functional traits, and those

traits show directional changes in frequencies over time (selection operates on functional traits)

• Drift: random changes in gene frequencies

(drift operates on stylistic traits)

Function

Style

Shape of Stylistic versus Functional

Trait through time

Time

Frequency

Frequency

Time

Shape of selection curves operating on two alternative functional traits over time

How Operationalize?

• Select artifact traits to measure… forms, technology, attributes--- like corner and side notching

• Must be able to measure artifact traits over time… have to have the temporal dimension

• Count frequencies over time and construct curves

• Curve shapes tell you whether• Selection or drift is occurring

– This is an evolutionary description

• The WHY in evolutionary terms

Critique of Selectionism

We’ll do this together…