1. Human Biology, Science, and Society
Chapter 1
Human Biology, Science, and Society

2. The Characteristics of Life
Living things
Have a different molecular structure than nonliving things
Require energy and raw materials
Are composed of cells
Maintain homeostasis
Respond to their external environment
Grow and reproduce
Can have populations capable of evolving

3. Signs of Life

4. Living Things Are Grouped According to Characteristics
Five-kingdom classification system
Fundamental criteria
Presence or absence of a nucleus
Number of cells
Type of metabolism

5. Living Things Are Grouped According to Characteristics
Monera: unicellular, prokaryotic
Animalia: multicellular, eukaryotic, heterotrophic
Plantae: multicellular, eukaryotic, photosynthetic
Fungi: eukaryotic, decomposers (molds, yeasts, mushrooms)
Protista: unicellular and simple multicellular, eukaryotic (protozoa, algae, slime molds)

6. Living Things Are Grouped According to Characteristics
Three-domain classification
Addresses two fundamentally different types of prokaryotes
Encompasses kingdoms

7. Living Things Are Grouped According to Characteristics
Domain: Bacteria
Kingdom: Bacteria
Domain: Archaea
Kingdom: Archaea
Domain: Eukarya
Kingdom: Animalia Kingdom: Plantae Kingdom: Fungi Kingdom: Protista

8. Figure 1.4 Plants (photosynthesis) Fungi (decomposers) Animals
(ingestion)
EUKARYA
Animals
Plants
Protists
(eukaryotic,
mostly
unicellular)
Fungi
Protists
ARCHAEA
Archaebacteria
Monerans (prokaryotic, unicellular)
BACTERIA
Unknown ancestor
a) Five-kingdom system.
b) Three-domain system.
Figure 1.4

9. Figure 1.4a Plants (photosynthesis) Fungi Animals (decomposers)
(ingestion)
Protists
(eukaryotic,
mostly
unicellular)
Monerans
(prokaryotic,
unicellular)
a) Five-kingdom system.
Figure 1.4a

10. EUKARYA
Animals
Plants
Fungi
Protists
ARCHAEA
Archaebacteria
BACTERIA
Unknown ancestor
b) Three-domain system.
Figure 1.4b

11. Living Things Are Grouped According to Characteristics
Classification of humans:
Animalia
Vertebrates
Mammals
Primates
Homo sapiens

12. Living Things Are Grouped According to Characteristics
Smallest unit of classification system is species
One or more populations of organisms
Similar physical and functional characteristics
Can interbreed and produce fertile offspring
Second smallest unit is genus
All living human beings belong to the same genus and species
Homo sapiens

13. Defining Features of Humans
Bipedalism - able to stand upright and walk on two legs
Opposable thumbs - able to grasp objects between thumb and tips of fingers
Large brain - relative to body size
Capacity for language - both spoken and written

14. Human
Chimpanzee
Figure 1.5

15. Human Biology Can Be Studied On Any Level of Organization
Atom and molecule
Cell
Tissue
Organ
Organ system
Community
Ecosystem
Biosphere

16. Organism
Organ system
Population
Atom
Molecule
Organ
Tissue
Cell
Community
Ecosystem
Biosphere
Figure 1.7

17. Science Is Both a Body of Knowledge and a Process
Science is the study of the natural world
Science is two things
Knowledge about the natural world
The process used to acquire knowledge
Called the scientific method

18. The Scientific Method Is a Process for Testing Ideas
Steps in the scientific method
Observe and generalize
Formulate a hypothesis
Make a testable prediction
Experiment or observe
Modify the hypothesis as necessary and repeat

19. The Scientific Method Is a Process for Testing Ideas
Observe and generalize
Make generalizations based on observations about the world with inductive reasoning
Observation: “Every winter in the past was colder than the preceding summer.”
Generalization: “Winter will always be colder than summer.”

20. The Scientific Method Is a Process for Testing Ideas
Formulate a hypothesis
A hypothesis is a tentative statement about the natural world

21. The Scientific Method Is a Process for Testing Ideas
Make a testable prediction
Hypotheses should be tested under many different conditions
Testable predictions
Should be based on the hypothesis
Should employ deductive reasoning
Are often in the form of “if…then” statements
Should be specific in order to be testable

22. The Scientific Method Is a Process for Testing Ideas
Experiment and observe
Truth or falsehood of prediction is tested by observation and experimentation
Experiment: A carefully planned and executed manipulation of the natural world.
In controlled experiments, all but one variable are accounted for

23. The Scientific Method Is a Process for Testing Ideas
Modify the hypothesis as necessary and repeat Steps 3 and 4
If prediction is false, the hypothesis must be modified.
If the prediction is true, only one small part of the hypothesis has been tested. Further testing required.
Hypotheses cannot be proved true, only supported or disproved.

24. Inductive reasoning Inductive reasoning Inductive reasoning2 5 5 4 4 1
Formulate a
hypothesis
Modify
hypothesis as
necessary
and repeat
steps
3 and 4
Modify
hypothesis as
necessary
and repeat
steps
3 and 4
Direction of
Increasing
confidence in
hypothesis
Experiment or
observe
Experiment or
observe
Observe
and
generalize
Deductive 3
reasoning
Make a testable
prediction
reasoning 3
Deductive
reasoning
Make a testable
prediction
Deductive 3
Make a testable
prediction
Figure 1.8

25. The Scientific Method

26. Figure 1.9 Select a large number of appropriate subjects.
Randomly divide the subjects into two groups.
Group 1
Group 2
Treat the groups equally
in all ways but one.
Experimental group:
receives treatment
Control group:
receives placebo
Observe or make measurements.
Are blood pressures lower
in the experimental group?
Compare results.
Yes No
Hypothesis received support.
Modify hypothesis to fit the new findings.
Figure 1.9

27. Making Findings Known Findings can be disseminated in Popular press
Peer-reviewed journals
Experts must approve articles before publication
Results are assumed to be valid only for conditions under which experiment was done
Popular press
Electronic publications
Internet is less regulated than print and broadcast media

28. Hypothesis Becomes a Theory
For a hypothesis to become a theory it must
Be broad
Be extensively tested
Be supported over time
Explain a broad range of facts
Have a high degree of reliability
Theories may be refuted in the future

29. Learning to Be a Critical Thinker
Become a skeptic
Appreciate the value of statistics
Learn to read graphs
Distinguish anecdotes from scientific evidence
Separate facts from conclusions
Understand the differences between correlation and causation

30. The Role of Science in Society
Science improves technology and the human condition
Science has limits
Science helps us to make informed choices