Page 19 - The Dinosaur Book and Other Wonders of the Prehistoric World (DK-Smithsonian)

First life
The first living organisms must have
formed in water containing simple
chemicals dissolved from rocks. Today, this
type of chemical-rich water erupts from hot
springs on the ocean floor and in places like
Yellowstone National Park. The water
contains microscopic organisms that
resemble some of the earliest living things, so
it is likely that life began in such places. It is
this microbial life that gives Grand Prismatic Origin of life
Spring its vibrant colors.

Grand Prismatic Spring, Yellowstone National Park
The hot spring is
fringed with
microbial life.

Tiny, tough-walled
bubbles were the
first living cells.

First cells

Living cells
Life involves chemical reactions that occur in microscopic,
tough-walled containers called cells. The earliest living
cells were simple bags of fluid, like modern bacteria. They
soaked up energy and used it to turn simple chemicals into
complex substances vital to life, such as proteins. This
helped them grow, multiply, and form large colonies
like the ones that live around hot springs today.

Evidence of early life
The oldest-known rocks on Earth
contain microscopic structures that
have been identified as fossil Archaea—
organisms similar to bacteria. The rocks,
which formed on the ocean floor, are at
least 3.8 billion years old. But much
clearer evidence of early life exists in
the form of fossil stromatolites. Dating
from about 3.4 billion years ago, these
were once colonies of microbes called
cyanobacteria that built up in
dome-shaped layers. These layers
are clearly visible in the fossils.
Stromatolite fossil 17

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