Six Criteria of Science

Consistency : The results of observations and/or experiments are reasonably the same when repeated. 1. Green plants will grow towards a light source. 2. Walking under a ladder will cause bad luck.

Observability : The event or evidence of the event, can be observed and explained. The observations are limited to the basic human senses or to extensions of the senses. 1. Some plants eat meat. 2. Extraterrestrial beings have visited Earth.

Natural : A natural cause (mechanism) must be used to explain why or how the event happens. 1. Green plants convert sunlight into energy. 2. With a rod, Moses parted the sea so his people could cross to the other side..

Predictability : Specific predictions can be used to foretell an event. Each prediction can be tested to determine if the prediction is true or false. 1. Without sunlight (or artificial light), green plants will die. 2. If you are a "Scorpio", your horoscope for today is “Lunar position highlights back pay, refunds and money!!!!!"

Testability : the event must be testable through the processes of science, and controlled experimentation. 1. The Bermuda Triangle causes ships and planes to sink and disappear. 2. Life comes from life and cannot come from non-life.

Tentativeness : Scientific theories are changeable and correctable, even to the point of the theory being proven wrong. Scientific theories have been modified and will continue to be modified 1. The number of human chromosomes was once "known" to be 48, but is now considered to be We know that the world began about 6000 years ago, and nothing will change that.

Scientific Method 1. Observation 2. Gather Information 3. Hypothesis 4. Experiment 5. Conclusion

Observation Using senses to gather information Using senses to gather information Observations lead to questions Observations lead to questions “what is the effect of …on …?”

Two types of Observations Qualitative: Uses senses to describe Uses senses to describe Ex: Mrs. Forsythe has RedHair Ex: Mrs. Forsythe has RedHair Quantitative: Uses tools to take a numerical measurement Uses tools to take a numerical measurement Ex: Mrs. Forsythe is 5 ft 8 in. Ex: Mrs. Forsythe is 5 ft 8 in.

Hypothesis Predicts the answer to a question Predicts the answer to a question BASED ON: Past experience Observations Research

The format for writing a hypothesis “IF... THEN...because….” Example : If we increase the temperature of the fish’s water, then the breathing rate will increase because breathing rate is dependent upon temperature.

Experiment A Test of your hypothesis Experiments tests a VARIABLE (factor that changes) Experiments tests a VARIABLE (factor that changes) Example: Variable = change in breathing rate Experiments need a CONTROL GROUP (to compare) Experiments need a CONTROL GROUP (to compare) Control Group =breathing rate at room temp

Types of Variables Dependent Variable: Dependent Variable: Is the data collected through observation and measurement Is the data collected through observation and measurement Ex: Breathing Rate Independent Variable: Independent Variable: Variable that is manipulated (changed) during the experiment. Variable that is manipulated (changed) during the experiment. Ex: Water Temp

Conclusion 4 parts: 1. Did the experiment support the hypothesis? 2. If you did the experiment again, what would you do differently? 3. What did you learn? 4. Possible Errors

Experimental Design Activity

Theory theory = hypothesis supported by many experiments over time theory = hypothesis supported by many experiments over time Examples of theories: Big Bang Theory Theory of Plate Tectonics

Jean Baptiste Lamarck Evolution occurs as structures develop through use, or disappear because of disuse, and these “acquired characteristics” are passed to offspring EXAMPLE: Over a Giraffes Lifetime it can stretch it’s neck and it’s offspring will be born with long necks…. Valid?

Darwin and The Monkey! THIS IS NOT WHAT HIS THEORY SAYS

Who was Charles Darwin Studied Medicine Studied Medicine Hated the sight of blood Hated the sight of blood Received a BA in Theology Received a BA in Theology Had 10 children Had 10 children

Theory of Evolution Darwin was an Naturalist on the HMS Beagle Darwin was an Naturalist on the HMS Beagle In The Galapagos Islands, Darwin collected species of finches (13) In The Galapagos Islands, Darwin collected species of finches (13) Each had a specialized diet and way of obtaining food. Each had a specialized diet and way of obtaining food. These finches all closely resembled a South American finch species These finches all closely resembled a South American finch species Hypothesized that the differences were do to gradual change Hypothesized that the differences were do to gradual change

Darwin’s Finches

Theory of Evolution Darwin referred to such change as “descent with modification” – evolution; Darwin referred to such change as “descent with modification” – evolution; Wrote Origin of Species He still wondered He still wondered “How does evolution occur?”

After his voyage, Darwin made following inferences: 1. There is variation within populations 2. Some variations are favorable (better) 3. Not all young each generation can survive 4. Individuals that survive and reproduce are those with favorable variations 5. And then those traits will increase in a population and population will slowly change

Darwin called this process by which populations change in response to their environment Natural Selection

Evolution happens because of natural selection Selection acts on individuals, populations evolve

Change creates advantages for some species & disadvantages for others Fossils reveal changes in species over millions of years

Adaptation Adaptations are inherited traits that increase a group’s chance of survival & reproduction This type of finch has a thick beak  adaptation for cracking open seeds

Variation Within a species, there is variation 1. Variation = differences between members of a population 2. Species = group that can breed & produce healthy offspring

Evidence for Evolution 1. Fossils show change over time scientists can date fossils & use them to support the theory of evolution scientists can date fossils & use them to support the theory of evolution common ancestors reveal whether species are related common ancestors reveal whether species are related – Anatomy of living species also shows relatedness shows relatedness

How Anatomy supports Evolution 2. Homologous Structures Traits similar in different species because they share a common ancestor Traits similar in different species because they share a common ancestor Ex: human arm, dog front limb, horse leg, whale fin Ex: human arm, dog front limb, horse leg, whale fin “ Look the Same”

3. Analogous structures Distantly related species have structures that have the same function but are different in structure Distantly related species have structures that have the same function but are different in structure Ex: wing of butterfly & bird Ex: wing of butterfly & bird “ Work the Same”

4. Vestigial structures Structures reduced in size & often unused Structures reduced in size & often unused Remains of functional structures inherited from an ancestor Remains of functional structures inherited from an ancestor Ex: leg & hip bones in pythons & whales Ex: leg & hip bones in pythons & whales

5. Molecular Evidence Also called biochemical evidence Also called biochemical evidence Compares biomolecules such as DNA or amino acid sequences between organisms Compares biomolecules such as DNA or amino acid sequences between organisms Related organisms have more of the same molecules in common Related organisms have more of the same molecules in common

How Do New Species Form?

How do new species form? 1. Geographic Isolation When members of a population are separated When members of a population are separated Ex: polar, grizzly, & black bears Ex: polar, grizzly, & black bears

2. Reproductive Isolation When members of a population can’t breed even though they live nearby When members of a population can’t breed even though they live nearby Ex: different mating seasons or different mating calls Ex: different mating seasons or different mating calls

Different Types of Evolution 1. Divergent evolution 2. Convergent evolution 3. Coevolution 4. Adaptive radiation

Divergent Evolution Isolated populations evolve independently Ex: polar & grizzly bears changed independently due to different habitats

Convergent Evolution Unrelated species become more alike because they live in similar environments Ex: shark & dolphin

Coevolution Species that interact closely adapt to one another Ex: flowers & hummingbirds

Adaptive Radiation Evolution of many diverse species from one common ancestor Ex: famous Galapagos finches discovered by Darwin

How fast does evolution occur? Gradualism One species changes slowly & eventually becomes two species This idea is supported by fossil evidence Punctuated Equilibrium Stable with short periods of change during which a new species forms