Winston Churchill

Vioxx

Conspiracy, and dirty little secrets

“Scientific facts” don’t always give us clear answers to important questions.

Who decides what to do with “scientific facts”?

What is “life” or “living”Something that has order ?

What is “life” or “living”Something that has order ?

What is “life” or “living”Something that reproduces ?

What is “life” or “living”Something that reproduces ?

What is “life” or “living”Something that grows and develops ?

What is “life” or “living”Something that utilizes energy ?

3Fe + 4H2O <-===-> Fe3O4 + 4H2Iron water iron (II,III) oxide hydrogen

What is “life” or “living”

Something that responds to the environment ?

What is “life” or “living”

Maintains status quo (homeostasis)?

Farmer fixing his fence (life)vs

Buffered lake (non-living)

Definition of life:

“I can not define it, but I’ll know it when I see it” -Supreme Court Justice Stewart

Life on Mars?

Life on Mars?

Martian romantics

Life on Mars? Happy face!

Life on Mars?Life in extreme Earth environments

Bacillus living at 55°C (131°F)

A novel thermophile isolated from

>300°C, 1500m deep, geothermal

water pool

Life on Mars - fossils ?

From Martian meteroite

Bacteria (on Earth)

Size: 1 µm vs 0.1 µm

Are Martian fossils biological ?Martian fossils:-Too small?-biological?

acid etches

Definition of life:

“I can not define it, but I’ll know it when I see it” -Supreme Court Justice Stewart

Maybe not so easy after all!

Symptoms of life:

Order, reproduction, growth, development, energy utilization, response to environment

But what distinguishes “life” from non-living chemical reactions?

The physical properties of living things can change, and these changes can be

inherited by offspring

The physical properties of living things can change, and these changes can be

inherited by offspring

This is possible because the physical properties of “life” are determined by a program.

This program can be copied, and when it is copied, it can be changed (mutated)

The physical properties of living things can change, and these changes can be

inherited by offspring

This is possible because the physical properties of “life” are determined by a program.

This program can be copied, and when it is copied, it can be changed (mutated)

Life is unique because it is a set of chemical reactions that can EVOLVE

So, we know what makes “life” unique

But there are still many questions about how all the diversity of life came to be…

Life is different from “non-living” things because life can Evolve

Evolution inevitably results in Natural Selection and Descent with Modification.

What’s that, and what’s the result?

Natural selection

1. The members of a population have heritable variations.

2. The population produces more offspring than the resources of an environment can support.

3. There is competition for resources; as a result, the better adapted individuals survive and reproduce more than the poorly adapted.

4. Across generations, a larger proportion of the population becomes adapted to the environment.

Natural Selection leads to Descent with Modification

Once you have life, and competition for resources, natural selection will lead a population to change over time.

Birds. Fig 1.11, page 9Dogs (artificial selection)

Descent with modification can lead to new species

How much of life’s diversity can be explained by

descent with modification?How many different times was life created from non-life in order to get all this diversity?

All modern life on Earth is related by descent from a common ancestor

(evolution). Why do we believe this?

Because all life is descendent from one original life-form through an evolutionary process, we can work backward through time to modern life’s earlier and more simple form.

Same 4 nucleotides in DNA

Same central dogma

Same 20 amino acids in protein

All life descended from one common ancestor

Figure 1.4, page 6.

Three main branches (Domains)

When did this occur? And how do they know that?

Stromatolites: like microfossils of early life

Modern stromatolites Ancient fossils (?)

How old is the oldest fossil?

Tape measure:

25 feet = 2.5 billion years

1 foot = 0.1 billion = 100 million years

1 inch ~ 10 million years

1/8 of inch ~ 1 million years

width of hair (~1/1000 inch) = 10,000 years

When did all this happen?

4 3 2 1 todayTime - billions of years ago

Earth forms

Period of heavy bombardment

Carbon isotope (first evidence of life)

First fossil microbes

Oldest eukaryotic fossil

dinosaurs

hominids

Animal diversity begins

Oxygen accumulates in atmosphere

And what does it mean?

When did all this happen? Geological timeline

Billion years ago What was happening 15 universe formed in Big Bang 4.5 Earth formed 4.0 Heavy bombardment stops 3.85 Fossils evidence of life (?) 2.0 Fossils of eukaryotes (?)

0.5 multi-cellular life becomes abundant 0.05 dinosaurs go extinct 0.005 chimp/human diverge 0.0001 firs modern humans 0.00001 humans colonize Americas (Indians) 0.000005 ancient Egypt, Greece, Rome, etc 0.0000005 dark ages of Europe 0.00000005 your parents were born

Life started quickly (~200 my), but intelligent life came so late it might have missed the party all-together (human intelligence arrived after 4 by of evolution, with only another 1 or 2 by left before all life on Earth ends)