1. Observation & Inference

2. Observation
An observation is gathering information about events or processes.
They can be quantative which are measurable or countable or they can be qualitative which are describable and not numerical.
Observation is the skill of describing events.

3. Inference
An inference is a conclusion or deduction based on observations.
Making an inference is the process of drawing a conclusion from given evidence.
Practice:
Observations:
A student is in a wheelchair
The student has a cast on their leg
The student is wearing a football shirt
Inference = ?
The student broke his leg while playing football.

4. Look at these two sets of animal tracks.
FRAME 1
Look at these two sets of animal tracks.
What are 3 OBSERVATIONS
Make an INFERENCE

5. Now what do you think?
FRAME 2
Make 3 OBSERVATIONS
Make an INFERENCE

6. Now what do you think?
FRAME 3
Make 3 OBSERVATIONS
Make an INFERENCE

7. Truth: Evolution is just a theory.
In everyday language, theory is often used to mean a hunch with little evidential support. Scientific theories, on the other hand, are broad explanations for a wide range of phenomena.
In order to be accepted by the scientific community, a theory must be strongly supported by many different lines of evidence.
Evolution is a well-supported and broadly accepted scientific theory; it is not ‘just' a hunch.

8. Misconception: Evolution is not science because it is not testable.

9. Truth: Science is not always testable.
Many scientific investigations do not involve experiments or direct observation.
Astronomers cannot hold stars in their hands and geologists cannot go back in time, but both scientists can learn a great deal about the universe through observation and comparison.
In the same way, evolutionary biologists can test their ideas about the history of life on Earth by making observations in the real world.
In organisms with short generation times like bacteria or fruit flies, scientists can actually observe evolution in action over the course of an experiment.

10. Remember: Hypothesis vs. Theory
Hypothesis: Possible explanation for a set of observations or possible answer to a scientific question.
Theory: well tested explanation that unifies a broad range of observations

11. How is Evolution Supported?
The Fossil Record
Geographic Distribution of Living Things (Biogeography)
Anatomical Evidence
Homologous Body Structures
Vestigial Limbs
Similarities in Early Development
Molecular DNA

12. Evidence for Evolution through studying fossils
BRAINPOP on Fossils:

13. The Fossil Record is Incomplete
Fossils = Traces of dead organisms such as footprints, insects, bones, leaf impressions, etc.
The fossil record shows a sequential appearance and disappearance of species
New species have generally appeared gradually, with species
becoming more complex over time
Fossils found in rock layers tells us two things:
What the creatures and plants looked like.
How long ago they existed. (Generally the deeper, the older.)
The fossil record is incomplete. This is because
very few species turn into fossils. Most decay away.

14. Forming Fossils Not all parts of an animal become fossilized.
It may not be possible to know some details of what an ancient animal or plant was like because many parts of the anatomy may not fossilize.
What color were the scales on this Allosaurus?
Why do scientists not know the answer to this question?

15. Dating Fossils Radioactive decay determines age.
Half-life = how long it takes for half of the radioactive atoms in a sample to decay.
Carbon 14 has a half life of 5730 years
It would take 5730 years for 12 grams of Carbon 14 to breakdown into 6 grams of Carbon 14.
The process of evolution is very slow, and takes thousands of years.

16. Relative vs. Absolute Dating
The absolute age of a fossil can be determined though radiometric dating and determining the age of the layer of rock in which the fossil was found.
The relative age of a fossil is determined by comparing it to other fossils.
Older layers are found deeper within the earth than newer layers.

17. Fossil Transitional forms – More evidence
Transitional fossils are bones that contain traits ancestral groups and descendent groups. These link new species to old species
These intermediate fossils give the history of a slow transformation
Example: Whales came from 4 legged animals
It took them 60 million years to evolve into
what they are today. There are a series of fossils found that show the tail and fins developing slowly and the legs disappearing.
Whale Video

18. Evolution of birds Today’s organisms descended from ancestral species
Fossil of Archaeopteryx
lived about 150 mya
links reptiles & birds
The avian nature of the brain and inner ear of Archaeopteryx (Alonso et al. 2004) - Archaeopteryx, the earliest known flying bird from the Late Jurassic period, exhibits many shared primitive characters with more basal coelurosaurian dinosaurs (the clade including all theropods more bird-like than Allosaurus), such as teeth, a long bony tail and pinnate feathers. However, Archaeopteryx possessed asymmetrical flight feathers on its wings and tail, together with a wing feather arrangement shared with modern birds. This suggests some degree of powered flight capability but, until now, little was understood about the extent to which its brain and special senses were adapted for flight. Alonso et al. (2004) investigated this problem by computed tomography scanning and three-dimensional reconstruction of the braincase of the London specimen of Archaeopteryx. A reconstruction of the braincase and endocasts of the brain and inner ear suggest that Archaeopteryx closely resembled modern birds in the dominance of the sense of vision and in the possession of expanded auditory and spatial sensory perception in the ear. Alonso et al. (2004) concluded that Archaeopteryx had acquired the derived neurological and structural adaptations necessary for flight. An enlarged forebrain suggests that it had also developed enhanced somatosensory integration with these special senses demanded by a lifestyle involving flying ability.

19. Fossil Evidence of Evolution
Evolutionary change in body size and toe reduction of horses

20. Evidence that Supports Evolution: Biogeography
Biogeography: the study of the geographic distribution of species over time
Some plants and animals have similar appearance but are only distantly related
Convergent evolution: the independent development of similar structures in organisms that are not directly related
Convergent evolution is usually seen in animals and plants that live in similar environments but in different locations.
Green Tree Python from Australia
Emerald Tree Boa from South America

21. Evidence that Supports Evolution: Biogeography
Similar animals on each continent live in similar ecological conditions
They were exposed to similar pressures of natural selection.
Because of similar selection pressures, different animals ended up evolving similar characteristics
Beaver
NORTH AMERICA
Beaver
Muskrat
Beaver and Muskrat
Coypu
Capybara
Coypu and Capybara
Muskrat
SOUTH AMERICA
Capybara
Coypu

22. Evidence that Supports Evolution: Biogeography
Divergent Evolution: The process by which an ancestral species gives rise to a number of new species that are adapted to different environmental conditions and are less alike.
Often occurs when a species colonizes a new environment.
Also known as adaptive radiation.
Examples:
Darwin’s Finches.
Brown bears and polar bears

23. Evidence that Supports Evolution: Anatomical
Descent with Modification- Each living organism has descended, with changes from other species over time
Common Descent- all living things were derived (originated) from a common ancestor.

24. Evidence that Supports Evolution: Anatomical
Homologous Structures = Structures from different organisms that have different mature forms, but come from the same embryonic origin
homo- = same
-logous = information
same structure on the inside
same development in embryo
different functions on the outside
evidence of common ancestor
Ex) Forelimbs of human, cats, whales, & bats

25. Evidence that Supports Evolution: Anatomical
Ex) Wing of a bat and wing of a butterfly
Analogous Structures
Structures that look similar on the outside and have the same function but have different structure & development on the inside
different origin
no evolutionary relationship

26. Evidence that Supports Evolution: Anatomical
Vestigial Structures = structures that are present in an organism but do not serve any function
They are remnants of evolutionary past
Example:
Whales have a
pelvis and femur, but they
no longer walk
on land.

27. Evidence that Supports Evolution: Anatomical
Pythons have tiny femurs (leg bone) that are vestigial organs

28. Evidence that Supports Evolution: Embryology
Embryology – the study of developing embryos
The embryos of vertebrates are very similar during early development.
The same groups of embryonic cells develop in the same order and in similar patterns to produce tissues & organs.
Common cells & tissues growing in similar ways produce homologous structures.
Implies that common genes are involved.
Embryos of vertebrates develop gill slits and tails.

30. Chicken – 2 ½ days
Human – 31 days
Pig – 21 days
We grow into our “spine”. At first it appears to be tail-like.

31. Human – 9 weeks
Lemur – 3 ½ weeks
Pig – 30 days
The heart dominates the body cavity.

32. Limb Buds Pig foot – 30 days Human hand – 6 weeks
Chicken foot – 5 days

33. Human – 6 weeks
Pig – 30 days
Macaque – 4 weeks

34. Evidence that Supports Evolution: Molecular DNA
AKA Biochemical Evidence
Two closely-related organisms will have similar DNA, RNA, and protein (amino acid) sequences.
This also gives evidence of a common ancestor.

35. Evidence that Supports Evolution: Molecular DNA
Which primate is most related to Humans?