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THE BEGINNING OF THE UNIVERSE
The Big Bang occurs and the universe is formed
The universe continually expands, as matter cools galaxies of stars and planets form
Thought to be about 13.7 billion years ago
THE MILKY WAY GALAXY FORMS
About 13.2 billion years go
Today consists of 200-400 million stars
Probably at least 10 billion planets considered a livable distance from a sun
THE SUN FORMS
About 4.57 billion years A supernova causes
shockwaves which forces clouds of gas together
It’s incredible mass and gravity cause fusion reactions to occur- releasing lots of light and heat
THE EARTH FORMS
About 4.54 billion years ago
Leftover gases and dusts come together forming planets
Only took 10-20 million years
Moon forms about 4.53 billion years ago
THE EARLY EARTH
Had no oxygen Was very hot and
molten, but slowly began to cool
Volcanoes spewed gases into the air, forming a primitive atmosphere
Meteor/asteroid strikes were common
THE OCEANS FORM
About 4.4 billion years ago
The earth had cooled enough for water to condense
Thought to be where life first began
COMPLEX MOLECULES FORM
UV radiation and lightening hitting simple gases was able to form complex molecules like: Nucleotides Proteins Carbohydrates
Proved to be possible – we can do this in a lab!
Some alien molecules landed with asteroids?????
AND LIFE BEGAN BY….
We really don’t know, but believe it was about 3.5-3.9 billion years ago
This is where things get very hypothetical, there are a few models, each which have some evidence supporting them and some flaws
This is NOT ADDRESSED by Darwin or Evolution
THE BASICS OF EXTREMELY COMPLICATED THEORIES
Self-replicating molecules must have formed Thought to possibly be RNA?
Metabolism must have evolved First life could manipulate its environment?
Membranes must have evolved Lipids were first form of life?
Some combination of above 3? Clay model?
THE UNIVERSAL COMMON ANCESTOR There is strong
evidence that all life shares a single common ancestor
Evidence also suggests that it was a heterotrophic prokaryote
No organelles, no photosynthesis
FEATURES OF THE LUCA FOUND IN EVERYTHING
Last Universal Common Ancestor
DNA as code RNA as code
carrier Ribosomes as
protein factories Amino
acids/proteins Cell membranes
PHOTOSYNTHESIS EVOLVED
In bacteria-like simple organisms about 3.3 billion years ago
Produced oxygen which led to the ozone layer
Also led to the evolution of aerobic cellular respiration
EUKARYOTES EVOLVED
About 1.5-2.1 billion years ago
At some point we think one cell engulfed a photosynthetic bacteria – forming a cell with a chloroplast
Same thing happened to create mitochondria
MULTI-CELLULAR ORGANISMS EVOLVE About 1 billion
years ago Probably has
happened several times
Colonies of single cells came together??
PLANTS COME TO LAND
About 475 million years ago
Provide food on land
Insects follow about 75 million years later
AMPHIBIANS COME TO LAND
About 350 million years ago
A population of fish was able to survive on land for longer and longer periods of time over many generations
THE FIRST MAMMALS EVOLVE
About 200 million years ago (about 100 million years after reptiles, 50 million years before birds, 70 million years before flowers)
Were around with the dinosaurs
HOMO GENUS EVOLVES
About 2.5 million years ago
Which exact species are the ancestor not well understood
HUMANS EVOLVE
About 200,000 years ago About 0.004% of Earth’s
existence, 0.005% of the time life has existed, and 0.03% of the time animals have existed
We have been around for a very short time (relatively)