Transcript The Early Earth

UNIT 4
EVOLUTION
A. THE ORIGIN OF LIFE
1. The Early Earth
a. the earth was formed about 4.6 billion years ago
b. it was hot, volcanic and bombarded by particles
& cosmic rays from space
c. it took about 100 million years to settle down
2. Early Life
a. Factors needed for early life
FACTOR
What was available in the early Earth
CO2, NH4, SO2, CH4 were in the atmosphere;
Basic organic
molecules
in the lab, adding steam & a spark to these gases
in a Miller-Urey apparatus
will result in thermal protenoids
& other molecules of life
FACTOR
Organizing
basic organic
molecules
What was available in the early Earth
certain types of clay converts simple carbonbased molecules to complex ones at
hydrothermal vents
Feb.
2007
Most hydrothermal vents spew out water at 400oC, very acid and full of
sulphur
The Lost City vents water is 28oC  90oC and slightly alkaline with
many dissolved carbonates
The Lost City vent produces more organic molecules (eg. butane) that are
the basis for many molecules in cells
Energy
source
geothermal energy from deep sea vents;
or solar energy both provide lots of energy
FACTOR
Protective
capsule
Reproductive
molecule
What was available in the early Earth
phospholipids will spontaneously form
LIPOSOMES which are double layered
membranes
RNA can reproduce without any
enzymes because of an effect called
ribozymes
[DNA can only reproduce with enzymes]
ScienceDaily (Oct. 31, 2007) —
Remarkably, a solution of highly poisonous cyanide in
ammonia, frozen solid in a refrigerator for 25 years,
produced adenine, a necessary component of life.
What was the early Earth like?
THREAT
strong UV LIGHT –
no ozone
if they avoid UV
light – how do they
get solar energy?
How early life coped
by living in ocean
water stops UV light
use deep sea vents as
source of thermal energy
therefore early life has to be
CHEMOAUTOTROPHIC
THREAT
EXTREME
TEMPERATURES
– lots of volcanoes
DESSICATION –
low atmospheric
pressure so air very
dry
How early life coped
by living in ocean
water absorbs temperature
changes although it remains
at temperatures over 70oC
water is wet
3.0 by
4.0 by
prokaryote
with internal
membranes
the first
prokaryote life
forms
2.0 by
O2 abundant
in the
atmosphere
1.0 by
endosymbiotic
life with
mitochondria
multicellular
lifeforms
endosymbiotic
life with
chloroplasts
0.0
600 my
500 my
shelled
invertebrates
first vertebrates
jawless fishes
400 my
300 my
200 my
100 my
0.0
600 my
500 my
400 my
plants invade land
arthropods invade land
jawed fish in seas
300 my
200 my
100 my
0.0
600 my
500 my
400 my
300 my
amphibians on land
trees appear
insects appear
200 my
100 my
0.0
600 my
500 my
400 my
300 my
200 my
early
dinosaurs
reptiles
appear
100 my
0.0
600 my
500 my
400 my
300 my
200 my
100 my
first birds
early mammals
0.0
600 my
500 my
400 my
300 my
200 my
100 my
0.0
dinosaurs
disappear
first
primates
4. Mass extinctions
WHEN ?
530 million
years ago
WHAT ?
trilobites, brachiopods
mollusk, echinoderm
WHY ?
change in sea level
occurred at this time
WHEN ?
440 million
years ago
WHAT ?
trilobites,
echinoderms and
nautaloids
WHY ?
sea levels rose rapidly & the
beginning of the glaciation
WHEN ?
365 million
years ago
245 million
years ago
208 million
years ago
WHAT ?
70% of all species
vanished mostly
in the sea and
lakes
WHY ?
climate change, in this case
a global cooling, was an
important factor
96% of all
marine species
were lost
fluctuations in sea-level, a
change in ocean salinity
and volcanic activity plus
climate change
sponges,
cephalopod,
brachiopod,
insects and many
vertebrate groups
climate change, seems to
be important and, in
particular, an increase in
rainfall.
Showing the extent of ice in the most recent ice age
WHEN ?
65 million
years ago
WHAT ?
85% of all species
including all of the
dinosaurs, many fish,
plankton and many
plants either died out
completely or
suffered heavy
losses
WHY ?
a giant meteorite crashing into the
earth, severely disrupting the earth's
ecosystem
or volcanic activity, climate
change, environmental pollution
WHEN ?
Next?
WHAT ?
50% of species
including all plants
and animals
WHY ?
Human induced climate change