A long time ago Earth was a very different place.
Millions of years of constant change led to the world we know and live in
today. Trying to observe that past world, so different and yet so similar to
ours, seems attractive itself, however, it has an additional value. Learning
about the history of life.
Paleontology-
the Study of the Past Life
The term paleontology refers to the study of life that existed before
the current geological epoch- The Holocene. This discipline takes on topics
like the physiology, evolution and relations of past organisms. It also studies
the inorganic past of Earth. All of that makes it an interesting combination of
historical and experimental science. It also relates a lot to biology and
geology, often using tools from even more sciences. The most commonly known
method used by paleontologists is probably analyzing fossil record. Fossils are
all kinds of traces and remains of organisms from before our age. Body fossil
is usually the remains of hard tissues. They are quite rare because of all the
processes that can occur to them during such a long time (imagine lying in the
dirt for at least 11,700 years!) Trace fossils, on the other hand, are just a
sign of biological activity, like foot traces.
Geology
In Studying the History of Life
Geology, despite being the study of non-living forms, contributes
a lot to studying the history of life. Firstly, geology studies the structure
of Earth, and beneath, uncovering layers of very old material. Then, it also
provides information on age of said material, and determines its history.
Therefore it enables the organization of timelines and gives information about
the history of Earth. Methods used by geologist include work in the field,
collecting the material, and then analyzing it using tools from chemical
engineering, physical experiments and simulations. All that provides major
evidence for a history of life. Geologists also work on understanding past
climate changes and its causes, for example, a connection between plate
tectonics and the Cambrian explosion.
The Geological Time Scale
Other
Tools in Studying the History of Life
History of life is a complicated matter, so we can expect that
studying it will require many different methods. Despite discussed paleontology
and geology, there are a few more quite important fields. We can suspect that
there will be some biology involved, the same goes for evolution studies.
However, that is far from what we need. Paleoanthropology and archaeology
include the study of evolution, behavior of humans. Biogeography helps with
finding patterns in the adaptation of organisms. Ecology helps to describe the
relations between species in the environment. Taxonomy makes it possible to
place them in genetical relations with each other. Including all of the
important fields would take much more time and space, but that is not what we
are going for. Scientific disciplines are all connected. If we want to discuss
the history of life, we need to include various disciplines, and find the
connections between them.
The Geological Time Scale
Combining solutions from different fields helped with creating a
geological time scale (GTS). It shows the current view on development of life
on Earth. We will use it to navigate through the series. Before analyzing it,
let’s get familiar with basic time units. Eon is equal to a billion years. Eons
are divided to eras, which do not have a fixed number of years, but their
division focuses on similarities of life forms. Lastly, periods are
subdivisions of eras, their length depends on a system of dating analysis.
There are four eons. Hadean starts with the formation of Earth, and ends with the
beginning of life. Archaean involves the formation of continent and ends with
raising the amount of oxygen. In Proterozoic first eukaryotes and multicellular
forms appeared. Lastly, there is Paleozoic, started by the Cambrian explosion,
divided into 6 eras, and that is the eon we live in.
Author’s
Message
I hope you the first article from the History of Life series gave you the basic information you need for a good start. If you enjoyed it, please share with family and friends.
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