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EARTH'S ORIGIN NOTES
LEARNING INTENTIONS
Discuss possible causes behind the anatomy of the first creatures that lived on
Earth and relate such causes to the Earth’s environment at the time.
Recognize that the diversity within living things today developed from changes
in past creatures, and that all such changes likely occurred due to environmental
changes.
NOTES
 The remains of the organisms that lived in the past were trapped in the soil
layers.
 The imprints left by organisms that lived thousands or millions of years
ago are called fossils.
 The imprint quality depends on two factors:
1. The kind of organism.
2. The material on which the imprint is made.
 The thin sediment found at the edges of a lake allows a better imprint,
more than in a solid place.
 Stratum is one of the horizontal layers of rock of the same kind.
 Stratification is the process in which different layers of soil are formed.
 We can calculate the fossil's age depending on the layers found above or
below it.
 Studying fossils, Scientists find a lot of information not only for what they
represent, but about the organisms' habits and the surroundings where
they are found.
 For many years, people thought that only the hard parts of the organisms
were the ones that could form a fossil, however, now it was discovered
that other parts can become a fossil, like the excrement. Fossilized
excrement is called: coprolite, and thanks to this, scientists can tell other
things about organisms, like their diet.
 There is one accurate method to determine the fossils' age. Fossils
contain materials that give off a kind of energy: radiation. The amount of
radiation given off by fossils lets scientists calculate their age, through a
method known as Carbon 14, that lets them determine dates up to 60
thousand years.
 The information collected from the fossil records, together with the
transformation of the Earth crust evidence, and the observations of the
plants and animals, helped Charles Darwin to reach to some conclusions
that he wrote about in his book “The Origin of the Species”.
 Darwin said that living organisms change in a very slow way but constant;
these changes are inherited from generation to generation. If the
surrounding conditions are favorable, the organisms survive.
 Darwin stated that individuals from the same species are born with
different characteristics not only physical but also functional and
behavioral. These different characteristics are sometimes beneficial and
other times a disadvantage.
 The benefited organisms can reproduce better and leave more
descendants than organisms with different characteristics in the same
conditions. Darwin called this “natural selection” and this is the base of
the evolution of life.
 When a group of individuals has accumulated many changes throughout
the time, it is possible that it can become a new species with
characteristics different than those of the original species.
 The organism’s extinction is a natural process that is due to environmental
changes. Some species can not adapt to the new conditions or do not
have time enough to accomplish it and that is why they become extinct.
 Human beings have the capability of changing the environmental
conditions constantly and in a very fast way, and some species can not
adapt to those changes, becoming extinct.
 All organisms need certain resources to survive like water, light, soil, or air.
If one of these resources is missing, the survival possibility decreases
considerably.
 The lack of resources can stop the communities development because
they are needed for the people’s survival. The excessive use of resources
generates many wastes that pollute the land, the water, and the air,
producing changes in nature.
 We all need the resources for our development, however we should think
that these are limited and that we should use them carefully. These
resources are not only food, but also water, oil, and energy of all kinds:
solar, eolian (wind) , and geothermic.
LEARNING INTENTION
Name the possible causes of the extinctions of some species.
NOTES
1. Climate: Heating and Cooling
 The species are not used to severe weather conditions and long
seasons.
 As more species die, it is more difficult for the survivors to find food.
 Diseases and epidemics increase with heat.
2. Changes in the sea levels and currents
 These changes are a result of the melting of fresh water.
 Denser salt water sinks and forms currents on which marine life
depends on.
 The rise of water occupies land that is already used.
3. Asteroid and cosmic radiation
 Asteroids hit the earth with extreme force.
 The “echo” could be felt around the world but the place where the
impact took place was completely destroyed.
 Cosmic radiations emitted or given off by the sun, when it is extreme,
can weaken species.
4. Acid rain
 When water vapor in the air mixes with pollution (sulfur dioxide
or/and nitrogen oxide) they form acid rain.
 When acid rain falls to the ground it increases the acidity of the
soil and affects plants.
 Acid rain that falls in rivers and lakes kills the plants and animals
that live there.
5. Disease/Epidemic
 Each species has defense mechanisms and the ability to fight
disease.
 Because of the changing climate, certain species are losing this
ability to fight diseases.
 As species become more susceptible to diseases and epidemics,
they can die and become extinct.
HUMAN CAUSES OF EXTINCTION
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Increased human population.
Destruction of habitats or habitat degradation.
Pollution
Climate changes/Global Warming.