http

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Looking for LifeLecture Supplement

2

Our Capacity for Self-Awareness

We are probably the only species that can think about why and how we think, how life originated, and if life exists elsewhere in

the universe.

Camille Flammarion,”Flat Earth” woodcut (1888)http:/antwrtp.gsfc.nasa.gov

3

What is Life?

1. Able to regenerate or form offspring (asexually or sexually)2. Self-sustainable (has a metabolism)3. DNA contains genetic instructions4. Has a carbon-based ‘backbone’

4

The Diversity of Life

http://www.johnharveyphoto.com

http

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About 1.7 million species have been identified and named.

Over 280,000 plantsAlmost 50,000 vertebratesMore than 750,000 insects

5

Amazon Rainforest

http://library.thinkquest.org

Tropical and temperate rainforests are vast sources of biological diversity important to our entire planet.

6

Questions

• Does all life need to be carbon based?• Although a biological virus consists of DNA fragments surrounded by a

protein shell, it lacks a metabolism and relies on host cells for reproduc-tion.

• Some software can reproduce and may be self-sustainable (by some definitions), but have no DNA equivalent and are not carbon-based.

• A recent report suggests artificially-created life may be possible in the next ten years.

• Is life unique to our planet in a vast universe of maybe ten billion galaxies?

7

Life Resides Here

http://www.calpoly.edu

The only place we currently know that life exists.

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Does Life Exist Elsewhere?

Will humans ever travel to and inhabit Mars? If so, the biological sciences will be a big part of the quest.

http

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.org

Several robotic missions have been sent to Mars, including the Viking landers, to detect evidence of present or past life.

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Plurality of Worlds

http://home.europa.com

Other worlds teeming with life and inhabited with intelligent beings was a commonly-held belief in the late

Medieval and Renaissance periods.

10

Lowell Observatory, Flagstaff, Arizona

http

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http

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In the early-1900s, Percival Lowell thought he discovered signs of

intelligent life on Mars.

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Canals on Mars?

http

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.net

Lowell though he saw canals on Mars constructed by a dying civilization to channel water from the polar ice caps.

12

Random Pattern

http

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form

.org

Our brains try to make sense of the visual world and will connect the dots even when no pattern exists.

13

Before Mars Attacks!

http

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The possibility of intelligent and even hostile life on Mars remained in the public’s imagination for many years.

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We Explore

http://dayton.hq.nasa.gov

A technician examines the scoop and arm assembly on the Viking

spacecraft for collecting soil samples on Mars. �

Soil samples were deposited into a small laboratory to test for signs of

life during the Viking 1 and 2 missions in 1976.

The results were inconclusive.

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Phoenix Lander

http://nssdc.nasa.gov

NASA continues its search for chemical signs of past life on Mars.

16

We Listen

Hat Creek, Californiahttp://radio.seti.org

Radio telescopes are used to search for signals of life from elsewhere in our Milky Way galaxy—it’s a big search with at least ten billion stars,

many similar to our Sun.

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Our Galaxy

The Milky Way

(Montage of time exposures through a wide-field optical telescope)

http://eric.stubbs.ws

18

The Drake Equation

Average yearly rate of star formation in our galaxy (R*)

Fraction of these stars that have planets (Fp)

Average number of planets around these stars that can support life (Ne)

Fraction of the above planets that develop some form of life (Fl)

Fraction of the above planets that develop intelligent of life (Fi)

Fraction of planets that develop technology to release signals into space (Fc)

Length of time that a civilization releases detectable signals (Lt)

Nc = R* x Fp x Ne x Fl x Fi x Fc x Lt

Number of civilizations in our galaxy with which we might be able to communicate (Nc)

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We Announce Ourselves

http

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ages

.art

.com

Evidence of intelligent life on Earth is transmitted in non-intentional ways.

http

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Wider Viewing Audience?

Speed of light (and radio waves) = 186,000 miles per second60 seconds per minute60 minutes per hour24 hours per day365.25 days per yearAbout 50 years since the ‘I Love Lucy’ television episode= radius of 293,485,680,000,000 miles from Earth in 2009

21

We Explore

http://www.daviddarling.info

http

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http://upload.wikimedia.org

Pioneer 10, launched in 1972, was the first human-made object to leave

our solar system.

22

Gold Record, A-Side

http://upload.wikimedia.org

http://voyager.jpl.nasa.gov

Voyagers 1 and 2, launched in 1977—each contains a phonograph record with the sounds and songs of life.

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Gold Record, B-Side

http://voyager.jpl.nasa.gov

User instructions

http://upload.wikimedia.org

Instructions decoded

24

We Observe

http://bbsnews.net

The Hubble Space TelescopeWell above the ocean of air and its turbulence, enabling new

views of our universe.

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Richness and Vastness

http

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Hubble Ultra Deep Field digital image of a very small part of the sky.

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Back to Earth

Ecosystem African Savanna L.A. County Arboretum

Community All organisms All organismsPopulation Zebra herd Peafowl flockOrganism Zebra Peacock or peahenOrgan system Circulatory system Central nervous

systemOrgan Heart BrainTissue Heart muscle HypothalamusCell Heart muscle cell NeuronMolecule DNA DNAAtom Oxygen Carbon

We are focusing on the two ends of the spectrum on the organization of life in this course.

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Organ Systems

We won’t spend much time covering individual organ systems. If you take a course in physiology, you will study these systems

in some depth.

• Nervous • Musculoskeletal• Endocrine • Circulatory• Lymphatic• Pulmonary• Gastrointestinal• Renal

http://www.compassionatedragon.com

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Organ Systems

http://hrsbstaff.ednet.ns.ca

Try to name the organ systems.

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A Few Animal Cell Types

1. Blood

2. Purkinje (cerebellum)

Images 1 and 2, http://upload.wikimedia.orgImage 3, http://www.proteinpower.comImage 4, http://focus.harvard.edu

3. Adipose

4. Intestinal