Back to LearnView Iridium (abundant in meteorites) Learn more about element origins 
Where Did We Come From?
A Journey from Present to 13.8 Billion Years Ago
The elements that make up your body. When, where, and how were they created? Follow the grand story uncovered by science, with evidence at every step.
Present
We Are Here
Right now, you are reading these words. Your body is made of about 60 trillion cells. And those cells are made of atoms.
Elements in Your Body
O
Oxygen65%
C
Carbon18.5%
H
Hydrogen9.5%
N
Nitrogen3.2%
Ca
Calcium1.5%
P
Phosphorus1%
...
Others (K, S, Na, Cl, Mg...)1.3%
When and where were these elements created? Let's travel back in time to explore their origins.
~66 Million Years Ago
Act 1: Rise of Mammals
We humans are mammals. And mammals could flourish because of the mass extinction 66 million years ago. Dinosaurs went extinct, and the age of mammals began.
Scientific Evidence
- • Iridium layer at K-Pg boundary — Abnormally high iridium concentrations found in geological strata worldwide at this boundary
- • Chicxulub Crater — 180km diameter impact crater in the Gulf of Mexico
- • Disappearance of dinosaur fossils and increase in mammal fossils — Geological records show dramatic ecosystem change
250M - 440M Years Ago
Act 2: Big Five — History of Mass Extinctions
The history of life has experienced five mass extinctions. Life has continued to evolve, overcoming each crisis.
85%
End-Ordovician
440 million years ago
75%
Late Devonian
370 million years ago
96%
End-Permian
250 million years ago
80%
End-Triassic
200 million years ago
76%
End-Cretaceous
66 million years ago
Scientific Evidence
Fossil record discontinuities, chemical composition changes in strata, oxygen isotope ratio variations all support these extinction events.
~2.4 Billion Years Ago
Act 3: Oxygen Revolution — Gift of Cyanobacteria
The Great Oxidation Event (GOE). Photosynthesis by cyanobacteria caused a dramatic rise in atmospheric oxygen. It fundamentally changed Earth's environment.
Cause
Cyanobacteria released massive amounts of O₂ through photosynthesis. The previously reducing atmosphere became oxidizing.
Effect
Mass extinction of anaerobic organisms. However, this paved the way for complex life (eukaryotes) to evolve.
Scientific Evidence
- • Banded Iron Formations (BIF) — Layers where iron ions in the ocean reacted with oxygen and precipitated
- • Red sandstone — Evidence of atmospheric oxygen oxidizing iron on land
~3.8-4.0 Billion Years Ago
Act 4: Origin of Life
Where and how did the first life emerge? There are several compelling hypotheses.
Hydrothermal Vent Theory
Life emerged near deep-sea hydrothermal vents, utilizing chemical energy.
RNA World Hypothesis
RNA served as both catalyst and genetic information carrier, giving rise to the first self-replicating system.
Panspermia Theory
The seeds of life may have arrived from space on meteorites.
Scientific Evidence
- • Oldest microfossils in Greenland (3.8 billion years old)
- • Carbon isotope ratios — ¹²C/¹³C ratio characteristic of life activities
- • Stromatolites — Layered structures of cyanobacteria from 3.5 billion years ago
~4.6 Billion Years Ago
Act 5: Birth of Earth
About 50 million years after the solar system formed, Earth was born. Gas and dust from the protoplanetary disk gathered, and planetesimals repeatedly collided and merged to form Earth.
Planetary Accretion
Planetesimals from the protoplanetary disk repeatedly collided and merged, growing to Earth-sized over about 100 million years.
Moon Formation
Giant Impact hypothesis — A Mars-sized body collided with proto-Earth, and the Moon formed from the debris.
Scientific Evidence
- • Meteorite dating (4.567 billion years) — The oldest solid material in the solar system
- • Moon rocks (Apollo missions) — Isotope composition similar to Earth
- • Zircon crystals — Earth's oldest minerals (4.4 billion years old)
So where did the elements that make up Earth come from?
~Hundreds of Millions of Years to Present
Act 6: Element Factory — Stars, Supernovae & Kilonovae
Most elements that make up Earth were created inside stars or in explosive events. 'We are made of stardust' is scientific fact.
Stellar Nucleosynthesis
H→He→C→O→...→Fe. Elements are synthesized sequentially at high temperature and pressure inside stars. Elements up to iron can be made by fusion.
C, O, Ne, Mg, Si, S, Fe
Supernova Explosions
Some elements heavier than iron are created in supernova shockwaves. The s-process (slow neutron capture) also contributes.
Fe, Co, Ni, Zn, Sr
Kilonovae (Neutron Star Mergers)
The heaviest elements like gold, platinum, and uranium are generated by r-process (rapid neutron capture) during neutron star mergers.
Au, Pt, U, Th
Scientific Evidence
- • Stellar spectrum analysis — Identifies element composition in stellar atmospheres
- • GW170817 (2017 gravitational wave observation) — First observed neutron star merger, confirmed kilonova
- • Solar abundance ratios — Element abundances match nucleosynthesis theory
~13.8 Billion Years Ago
Act 7: Big Bang — The First Three Minutes
The beginning of the universe. In the first three minutes, hydrogen, helium, and lithium were created. No other elements existed yet.
75%
Hydrogen (H)
24%
Helium (He)
<1%
Lithium (Li)
Scientific Evidence
- • Cosmic Microwave Background (CMB) — The 'afterglow' of the Big Bang, discovered in 1965
- • Element abundances — The cosmic H/He ratio matches Big Bang nucleosynthesis theory
- • Hubble-Lemaître Law — Observational evidence of cosmic expansion
Just After Big Bang
Act 8: Symmetry Breaking — Why Matter Survived
Right after the Big Bang, matter and antimatter should have been created in equal amounts. Why is the universe filled with only matter? The answer lies in 'symmetry breaking.'
Symmetria (Goddess of Symmetry)
Once, all was symmetric. Matter and antimatter were indistinguishable.
Breakia (Goddess of Symmetry Breaking)
I broke the symmetry. That's why the universe exists. That's why you exist.
Why Matter > Antimatter?
CP symmetry breaking caused slight differences in how matter and antimatter behave. One part in a billion asymmetry. That's the origin of all matter in the universe.
Scientific Evidence
- • Wu Experiment (1957, Co-60) — First proved parity symmetry breaking
- • K meson CP violation (1964) — Discovered CP symmetry breaking
- • B meson CP violation (2001, Belle/BaBar) — Contributed to 2008 Nobel Prize
Epilogue: The Beginning of Beginnings
All was equal. Matter and antimatter, time and space. That was the beginning of beginnings.
The world of Symmetria. Perfect symmetry. Then Breakia appeared and broke the symmetry. And after 13.8 billion years, here we are.
'Why is there something rather than nothing?'
This question lies at the boundary of science and philosophy. Even current physics cannot fully answer it. New physics, unknown particles, yet-undiscovered symmetry breaking... The quest continues.
Which Element Are You?
Elements born through a 13.8 billion year journey. Which element is closest to your personality?