History of Life 1

Brian O’MearaEEB464 Fall 2015

Tucson Botanical Gardens

Learning outcomes:

• Get a deep perspective on time• Understand major events in earth history• Generate hypotheses regarding what

happens after mass extinctions

Big Bang 13.73 BYA

First stars produce more complex elements, then

(some) explode

Borb

Solar system (sun, planets) form 4.6 BYA

Moon broken off from Earth, 4.53 BYA

Ow!

Heavy bombardment, 4.1 - 3.8 BYA

Life evolves~3.8 BYA

Photosynthesis evolvessomewhere 3.5 - 2.8 BYA

OH H

OCO

+ = OOSugar+

Great oxidation event2.45 - 2.22 BYA

OH H

OCO

+ = OOSugar+

Huronian glaciation3.2 - 2.4 BYA

a long time passesArchaea+Eukaryotes and Eubacteria

divergeEukaryotes diverge from Archaea

Life is still single-celled

An

dre

e V

alle

y

Bacteria Archaea Eukarya

Circular chromosome Y Y N

Histones with DNA N Y Y

Flagella Spinning Spinning Waving

Unicellular Y Y Varies

Organelles ~N N Y

http://www.youtube.com/watch?v=9w421z4fsOU

a long time passesArchaea+Eukaryotes and Eubacteria

divergeEukaryotes diverge from Archaea

Life is still single-celled

An

dre

e V

alle

y

Ediacaran fauna0.63 BYA = 630 MYA

Wikimedia commons

Cambrian542 MYA

John Sibbick

Wikimedia commons

Permian-Triassic extinction251 MYA

Permian-Triassic extinction251 MYA

Permian-Triassic extinction251 MYA

KT (Cretaceous-Tertiary) extinction65.5 MYA

Brian Franczak

Sun eventually becomes red giant, expands

Franck et al. Causes and timing of future biosphere extinctions. Biogeosciences (2006) vol. 3 (1) pp. 85-92Schröder and Smith. Distant future of the Sun and Earth revisited. Monthly Notices of the Royal Astronomical Society (2008) vol. 386 (1) pp. 155-163

Life

evo

lves

Mul

ticellu

larit

y

NOW

Life

goe

s ex

tinct

Discussion: how might a major extinction like the one at the end of the Permian affect life?