Download Chapter 1 - Cynthia Clarke

Chapter 1
Science & Evolution
Evolution
• Both cultural and biological evolution interest anthropologists.
• Evolution is change in living organisms over time.
• Evolution is essentially the idea that new species develop from earlier species by accumulated changes.
• This is sometimes referred to as "descent with modification".
• It is also sometimes called "microevolution".
• The idea of evolution was developed from many observations of life.
• It has been tested and challenged many times and in many ways, and has survived largely intact.
• There are also many independent lines of evidence which are consistent with evolution as a real process.
• There is NO observed evidence against evolution. Evolution therefore holds the high status of near certainty: it is a
scientific theory.
• This course is a science course and is a biological science.
• Therefore it presents scientific explanations from an evolutionary stance.
• I do not ask you to agree with the science of evolutionary theory but will ask you to be able to explain this set of
interpretations and to differentiate it from non-scientific statements. This is important in that a 1985 survey determined that:
Agree with evolution: 40%; Disagreed: 40%; and Not sure: 20%
Source: Flammer, L. (1999). “ENSI “ Retrieved from http://www.indiana.edu/~ensiweb/lessons/ev.not.html
Characteristics of Science 1
• Science is a process of understanding phenomena through observation, generalization, verification and refutation. Science is a
way of viewing the world.
• This requires an objective, empirical approach
• Interestingly, in cultural anthropology they have challenged (I think well) the concept that we are objective.
• Scientific method is a research method whereby a problem is identified, a hypothesis is stated and that hypothesis is tested
through the collection and analysis of data.
• Step 1: State the research problem.
• Gather information to resolve it (the observation component) in the form of data (facts from which conclusions can be drawn;
scientific information)
• Can be quantitative (numbers based) or can be qualitative (based on descriptions as is common in cultural anthropology).
• Step 2: Develop a hypothesis.
• Hypotheses as plural; hypothesis is a provisional explanation; explanations of things and events.
• Based on observations. A fact is another name for an observation
• Some call this an ‘educated guess” I call this a perspective (as compared to an opinion).
Characteristics of Science 2
• Step 3: Test the hypothesis through data collection and analysis.
• Scientists strive to improve understanding by testing hypotheses showing how and why the object of study is related to other
objects of study.
• Repeated testing is required.
• (Re)test the hypothesis/hypotheses
• Step 4: Propose a theory
• If the hypothesis is supported, it becomes a theory.
• A theory and a hypothesis are NOT the same thing. A theory is more general, suggesting and implying associations and
attempting to explain them.
• A theory is a set of hypotheses that supports a well-substantiated explanation of natural phenomena.
• Evolution is BOTH a theory and a fact.
• Please, do not say that evolutionary theory is ‘just a fact’. I am fine if you disagree with evolutionary views, but precision of
terms is key in science so please be aware of this
• Also do not mix up hypothesis and theory as in ‘I have a theory’. No! One has a hypothesis.
Development of Evolutionary Theory 1
• Pre-Darwinian thought
• Evolutionary principles were developed in western Europe, made possible by scientific thinking dating to the 16 th century.
• Western science, however, borrowed ideas from Arab, Indian, and Chinese cultures where notions of biological evolution had
already developed.
• During the Middle Ages, the western worldview was that the world is static (not changing).
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The meant that the idea of fixity of species dominated understanding. Fixity of species is the idea that all living species do
not change once they are created.
• Also, the Earth was ‘full’; there was no room for any new species to be created.
• Further, the Aristotle’s vision of the Great Chain of Being stated that all species are organized in a hierarchy, with
humans at the top and so on down the Chain.
• Overall, this all culminated into the idea of the Argument from Design (life engineered by a purposeful God). God had
created everything in perfect form and so to challenge this perfection was to be anti-Christian
John Ray (1627-1705)
• Introduced the concept of species as based on reproductive success. He realized that groups of organisms could be
differentiated based on the ability to reproduce with each other (or not).
• Today we call this idea the Biological Species Concept (BSC)
• The BSC can be defined in terms of reproductive capability.
• If organisms from two populations are capable of breeding naturally and can produce fertile offspring, they are
classified in the same species.
Development of Evolutionary Theory 2
• Pre-Darwinian thought (continued)
• Carolus Linnaeus (1707-1778)
• A Swedish naturalist who developed a method of classifying plants and animals.
• In Systema naturae, first published in 1735, he standardized Ray’s use of genus and species terminology and established
the system of binomial nomenclature.
• He standardized the genus and species into this binomial nomenclature
• He added to more levels of classification: class and order
• He also included humans in the classification system
• Homo sapiens (note that the genus is capitalized, the species is not; also in italics).
• Including humans was controversial as most thought of humans as separate from other living organisms.
• He did create a set of racial groups within the listing wherein he put Europeans at the apex and Africans at the base.
• He grouped humans into his classification system
• Homo sapiens is the scientific name for humans
• This was a controversial position at the time; it countered the idea that humans were special, made in the image of
the Christian deity.
• Georges Cuvier (1769-1832)
• Studied fossils in quarries and discovered that many species no longer existed.
• Introduced the idea of catastrophism to explain this fossil record. Multiple disasters resulted in the repopulation of
regions by newly created organisms
Development of Evolutionary Theory 3
• Pre-Darwinian thought (continued)
• Jean-Baptiste Lamarck (1744-1829)
• First scientist who codified his beliefs into a system that attempted to explain evolution.
• Thought physical alteration occurred because of bodily needs (called besoin)
• Basic idea was the inheritance of acquired characteristics (use-disuse theory) where a trait acquired during lifetime is
based down to offspring. In the Lamarckian view:
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(1) changes in an individual's physical organs, due to the socalled Law of use or disuse (organs are strengthened by use or
weakened by misuse)
• (2) during the individual's lifetime, can somehow be transmitted
to the next generation due to inheritance of acquired
characteristics.
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An example is the giraffe: having stripped the leaves from the
lower branches of a tree, the animal tries to reach leaves on
upper branches.
• The neck becomes slightly longer.
• The longer neck is passed on to offspring.
Lamarck’s view of evolution: The
individual changes and then transmits
that change to offspring.
Development of Evolutionary Theory 4
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Uniformitarianism and geologic time
• James Ussher (1581-1656)
• Famous for his use of biblical text as basis to estimate age of earth.
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• He determined that the world began on October 23, 4004 B.C.E.
James Hutton (1726-1797)
• Proposed uniformitarianism which is the theory that the earth’s features are the result of long-term natural processes (i.e.
wind, water erosion, local flooding, frost, decomposition, volcanoes, earthquakes, and glacial movements) that continue
to operate in the present as they did in the past.
• Means we can use the study of these processes as one way to estimate age of earth.
• This theory opposed catastrophism and contributed strongly to the concept of immense geological time (Earth is old)
Charles Lyell (1797-1875)
• A lawyer, geologist, and, for Charles Darwin’s friend and mentor.
• Before meeting Darwin in 1836, Lyell had earned acceptance in Europe’s most prestigious scientific circles, thanks to
his praised Principles of geology, published during the years 1830–1833.
• His work suggested that small biological changes could add up over time. His work strongly influenced Charles Darwin.
We now know the age of the earth is 4.6 billion years.
Development of Evolutionary Theory 5
• Many of the early transmutationists were strongly anti-Christian; this set the tone of the discussion for many by the time that
natural selection was suggested
• The idea of transmutation is the shift of one type of species into another over time.
• Both Darwin and Wallace introduced transmutation; its time had come:
• Charles Darwin formulated theory of natural selection.
• Darwin talked to the idea of struggle for existence.
• The idea that in each generation more offspring are born than survive to adulthood, coupled with the notions of
competition for resources and biological diversity led to the theory of evolution.
• He wrote,“ It at once struck me that under these circumstances favourable variations would tend to be preserved,
and unfavourable ones to be destroyed.”
• FYI: Herbert Spencer (not a biologist) coined the phrase survival of the fittest.
• Alfred Russel Wallace uncovered the key to the evolutionary process.
• Charles Darwin (1809-1882) and natural selection
• Charles Darwin Ideas were formed while serving as a naturalist on the 5-year voyage of the HMS Beagle.
• His notations on species variation over space and time, but did not interpret as a static world
• Darwin saw the importance of biological variation within a species.
• Most famous example is Darwin’s finches.
Development of Evolutionary Theory 6
• Charles Darwin (1809-1882) and natural selection (continued)
• His noted that species variation was also linked to environmental differences.
• In this context he went to Thomas Malthus who gave him insight into adaptation and evolution.
• Thomas Malthus (1766-1834)
• Author of an essay, An essay on the principle of population, that inspired both Charles Darwin
and Alfred Wallace in their separate discoveries of natural selection.
 Was arguing for limits of human population growth, not concerned with how species change.
• The limits for populations to increase is controlled by availability of resources. Concerned with
relationship of human population growth to food supplies.
• The idea of population-resources being linked was extended to all organisms by Darwin
and Wallace.
• Malthus is considered the father of demography.
• He influenced a group who came to be called social Darwinism
• Social Darwinists were concerned with the overpopulation of the lower classes
Malthusian curve
Development of Evolutionary Theory 7
• Charles Darwin (1809-1882) and natural selection (continued)
• Alfred Russell Wallace (1823-1913)
• Suggested species descended from other species (speciation) and new species were influenced by environmental factors.
• Wallace published a paper on speciation and soon sent another paper to Darwin in 1858.
• As a result, he presented joint paper, coauthored with Darwin, on evolution and natural selection to the Linnean
Society of London. Little notice was taken.
• Next, in 1859 Darwin published his On the origin of species, and an uproar began that continues today.
• The origin of species, according to Darwin and Wallace, is explained: Species are mutable (not fixed) and they evolve
from each other.
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Darwin and Wallace view of evolution: That environment acted to change populations of organisms over time through
natural selection: Differential reproduction PLUS differential survival
• Environment favors individuals with long necks
• Those individuals more likely than others to have offspring
Development of Evolutionary Theory 8
An example of natural selection
• Perhaps the most famous example of how natural selection works is that of the peppered moths in
England
• The variation in the species is found in their coloration: light and dark
• Prior to the Industrial Revolution, the majority were light-colored, allowing them to
camouflage themselves among the lichens.
• During the Industrial Revolution, the trunks of the trees became heavily sooted and the
Light and dark
dark-colored moths predominated.
moths
• Once the coal burning practices subsided, the light-colored moths increased in numbers.
• Several points can be drawn from this set of observations:
• There are not ‘good’ and ‘bad’ traits, it depends on the environment.
• Evolution is not unidirectional; it responses to changing conditions.
• Variation among a species is critical to survival as environments do change
• Another observation to keep in mind is that the peppered moths studies illustrate how the scientific method can be used to
explain observations
Development of Evolutionary Theory 9
• Modern evolutionary thought
• Darwin was able to explain natural selection acting on variation.
• His ideas about natural selection were tested and found to be supportable.
• But, the concept of natural selection is only one of the mechanisms of evolution (the others are mutation, gene flow, and
genetic drift which we discuss in Chapter 3).
• What Darwin never knew:
• He was NOT able to explain the origin of this variation
• He was also Not able to explain how inheritance works. He, at least for some part of his life, believed in blending
inheritance
• Evolution is now defined as changes in genetic composition of populations
• Evidence for evolution
• The fossil record has a plethora of data that shows evidence of evolution
• Another line of evidence is found in the shared genetic composition of all living organisms
• Yet another line of evidence is found in the anatomical similarities between species
• The distribution of species geographically also adds evidence.
• You might want to visit this link which is a 10-minute lecture on the evidence for evolution
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Science and Religion 1
• For some people, evolution represents an argument against their belief in the sudden creation of all life by a creator
• One response was to devise creation science to communicate their teachings in the context of scientific study.
• Not necessary, science and religion are two worldviews that are not in conflict, so no need to validate religion in the guise of
science.
• Both worldviews are valid.
• Where the difficulty arises in when supporters of faith-based worldviews insist that their explanations are scientific, but then do
not adhere to the processes. For instance, creationists argue their view is absolute and fallible, which is counter to science which
seeks testable hypotheses.
• Creation science: Devised by opponents of evolution to communicate their teachings in the guise of scientific study.
Creation science is not supported by factual evidence.
• Intelligent design (or intelligent design creationism): An approach stressing the idea that the biological world was created by
an intelligent entity, although “God” is not generally specified directly as the creator.
• Tries to divorce intelligent design for objections regarding the establishment of religion under the First Amendment.
• Basic concept is that there are certain characteristics of biological organisms that are too complex to explain through
natural selection (irreducible complexity)
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Science and Religion 2
• Stance of most scientists:
• Religion and science concern different aspects of the human experience, and they are not inherently mutually exclusive
categories.
• Belief in God does not exclude the possibility of biological evolution; acknowledgement of evolutionary processes doesn’t
preclude the existence of God.
• Stance of religious groups:
• Evolutionary theories are not rejected by all religions or by most forms of Christianity.
• Some groups do struggle with evolutionary ideas and include Christian fundamentalists and those who support scientific
creationism or intelligent design.
• Those in this later group argue that creation science and intelligent design (ID) is as much a scientific endeavor as is
evolution, and suggest scientific evidence to support creationist views.
• ID is not science, however
• Creationists argue their view is absolute and fallible, which is counter to science which seeks testable hypotheses.
Science and Religion 3
• One of the greatest controversies regarding education in the United States and other parts of the world is the teaching of
evolution.
• One noticeable casualty of the debate over teaching evolution has been the erosion in science education.
• Creationism has not gone away despite legal and theological objections. Many favor teaching of intelligent design as an
alternative to evolutionary theory.
• Famous trials over teaching evolution:
• The most famous example of a court case linked with evolution was the Scopes Monkey Trial (1925, Tennessee)
• Despite a recent Dover school board resolution favoring intelligent design, a subsequent court challenge reversed the ruling.
The presiding judge stated intelligent design was not a science.
• Kansas State Department of Education (2005) determined that teaching evolution and intelligent design must be given equal
time in their instruction.
• One response was by an Oregon State University student, who wrote a letter to this school board. This sparked the Flying
Spaghetti monster movement.
• In 2007, the Board rejected this policy (unrelated to the letter)
Science and Religion 4
• Five (5) myths about evolution
• Myth 1: Evolutionary theory denies the existence of God.
• Response 1: In fact, science does not ask these questions, so the debate does not really center here.
• Myth 2: Evolutionary theory claims life is one huge, incredible accident.
• Response 2: Just the opposite. There are very specific mechanisms of evolution that we will discuss in later chapters.
• Myth 3: A scientific debate exists concerning the existence of evolution
• Response 3: According to Newsweek (1987) “"By one count there are some 700 scientists with respectable academic
credentials (out of a total of 480,000 U.S. earth and life scientists) who give credence to creation-science...“ (Source:
http://www.religioustolerance.org/ev_publi.htm#earth )
• Evolutionary theory preaches progress.
• Response 4: “Evolution is not progress. Populations simply adapt to their current surroundings” (Colby, 1996)
• Evolutionary theory says humans are ‘just animals’.
• Response 5: Of course humans are animals; it is the just part that is in error. All animals have unique evolutionary histories,
and among those for humans is the use of culture to adapt. No other species is as good at it as we are. But, all species are
unique and this is important to note.
• Great website to read more: www.bio.ilstu.edu/armstrong/misconceptions.doc
Science and Religion 5
• So what is NOT evolution?
• It was NOT discovered or first explained by Charles Darwin.
• It is NOT an accidental or random process as there are built-in limits, constraints and selective elements.
• It is NOT the same thing as natural selection...(this deals with how evolution takes place).
• It is NOT something which happened ONLY in the past.
• It is NOT concerned with the origin of life (it deals only with the origin of species).
• It is NOT just concerned with the origin of humans.
• It is NOT something which happens to individuals, but to populations.
• It does NOT conflict with any religion.
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It does NOT deny the existence of God. (It is neutral; God is neither required nor eliminated).
It was NOT developed to undermine religion, but to explain many observations of life in a testable way.
Source: Flammer, L. (1999) ENSI. Retrieved from http://www.indiana.edu/~ensiweb/lessons/ev.not.html
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