The earliest life forms we know of were
microscopic organisms (microbes)
that left signals of their presence in rocks about 3.7 billion years old. The signals consisted of a type of carbon molecule that is produced by living things.
What animal was alive first?
A comb jelly
. The evolutionary history of the comb jelly has revealed surprising clues about Earth's first animal.
Which living things appeared first?
Prokaryotes
were the earliest life forms, simple creatures that fed on carbon compounds that were accumulating in Earth's early oceans. Slowly, other organisms evolved that used the Sun's energy, along with compounds such as sulfides, to generate their own energy.
How did the first living organism appear?
Bacteria
have been the very first organisms to live on Earth. They made their appearance 3 billion years ago in the waters of the first oceans. At first, there were only anaerobic heterotrophic bacteria (the primordial atmosphere was virtually oxygen-free).
When and where did life possibly start?
The earliest time that life forms first appeared on Earth is at least
3.77 billion years ago
, possibly as early as 4.28 billion years, or even 4.41 billion years—not long after the oceans formed 4.5 billion years ago, and after the formation of the Earth 4.54 billion years ago.
When and how did life begin?
We know that life began
at least 3.5 billion years ago
, because that is the age of the oldest rocks with fossil evidence of life on earth. These rocks are rare because subsequent geologic processes have reshaped the surface of our planet, often destroying older rocks while making new ones.
What was before dinosaurs?
The age immediately prior to the dinosaurs was called
the Permian
. Although there were amphibious reptiles, early versions of the dinosaurs, the dominant life form was the trilobite, visually somewhere between a wood louse and an armadillo. In their heyday there were 15,000 kinds of trilobite.
What was the first dinosaur?
For the past twenty years,
Eoraptor
has represented the beginning of the Age of Dinosaurs. This controversial little creature–found in the roughly 231-million-year-old rock of Argentina–has often been cited as the earliest known dinosaur.
Why was there no life on Earth?
All living things on
earth have adapted to our atmosphere
, which means all living things need our mix of atmospheric gases. Life elsewhere would be specifically adapted to their own conditions. Water is a really important ingredient to sustain the kind of life we know on Earth.
Who was first on Earth?
The First Humans
One of the earliest known humans is
Homo habilis
, or “handy man,” who lived about 2.4 million to 1.4 million years ago in Eastern and Southern Africa.
When did humans start on Earth?
The first human ancestors appeared
between five million and seven million years ago
, probably when some apelike creatures in Africa began to walk habitually on two legs. They were flaking crude stone tools by 2.5 million years ago. Then some of them spread from Africa into Asia and Europe after two million years ago.
When did the first cell appear on Earth?
Cells first emerged
at least 3.8 billion years ago
, approximately 750 million years after the earth was formed.
Where did all living things come from?
All life on Earth evolved from
a single-celled organism that lived roughly 3.5 billion years ago
, a new study seems to confirm. The study supports the widely held “universal common ancestor” theory first proposed by Charles Darwin more than 150 years ago.
Where did the first human come from?
Humans first evolved in
Africa
, and much of human evolution occurred on that continent. The fossils of early humans who lived between 6 and 2 million years ago come entirely from Africa. Most scientists currently recognize some 15 to 20 different species of early humans.
What is the origin of all life?
Life is coeternal with matter and
has no beginning
; life arrived on Earth at the time of Earth's origin or shortly thereafter. Life arose on the early Earth by a series of progressive chemical reactions. Such reactions may have been likely or may have required one or more highly improbable chemical events.
What did T Rex taste like?
rex tasted
more like poultry than
, say, beef or pork. Its flavor would likely have been closer to that of a carnivorous bird—perhaps a hawk—than a chicken. What does a hawk taste like? It's probably not far off from the dark meat of a turkey but would be more pungent because of its all-meat diet.
