Human Evolution And The Fossil Record
Scientists continue to debate the history of man. It is generally
agreed upon by the scientific community, however, that humans evolved from
lesser beings, and this essay will function to provide evidence to support this
claim. Several points will be outlined, including the general physical changes
that occurred between several key species on the phylogeny of man, and a
discussion of dating methods used to pinpoint the age of the fossils.
This essay will begin with a brief discussion of dating techniques. In
the study of hominid evolution, two main methods of dating are used: carbon-14
and potassium-argon dating. Carbon-14 dating involves the decay of radioactive
C-14, which has a ...
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is died that allows a date for it
to be established. Potassium-argon dating, another dating method, is possible
due to volcanic ash and rocks found near many fossil sites. Rocks and ash
created in this manner contain potassium-40, but no argon. As time passes, the
potassium-40 decays into argon-40. In the laboratory, the sample is reheated,
and since argon-40 is a gas, it is released. The ratio of argon-40 released to
potassium-40 still present allows for a date to be assigned to objects near the
sample. However, due to potassium's high half-life (1.3 billion years), it is
only useful as a dating technique for finds older than 500,000 years old. Also,
it is only useful where volcanic activity existed. Both these methods have
error margins, ranging from a few thousand years in carbon-14 dating to tens of
thousands of years, or more, for potassium-argon dating. However, thanks to
scientific breakthroughs, these two processes can be used with reasonable
security in ...
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the 3 ½ to 5 feet believed for A. afarensis. Its jaws also portruded out.
The "keel" effect is very distinguishable on this species, as it is with many of
the older hominid species - a slight peak on the top of the cranium. Ridges
over the eyes were also prominent on this hominid.
The next species believed to be in our line of descent is Homo habilis.
This is the first being with the distinction of having Homo as its genus. This
species, which is dated back to between 1.5 and 2.4 million years ago, had a
face which portruded less than A. africanus and A. afarensis. Its teeth, though
still larger than modern humans, were smaller than those of its ancestors.
Finally, its ...
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"Human Evolution And The Fossil Record." Essayworld.com. Essayworld.com, 3 Jul. 2005. Web. 23 Apr. 2024. <http://www.essayworld.com/essays/Human-Evolution-And-The-Fossil-Record/29463>
"Human Evolution And The Fossil Record." Essayworld.com. July 3, 2005. Accessed April 23, 2024. http://www.essayworld.com/essays/Human-Evolution-And-The-Fossil-Record/29463.
"Human Evolution And The Fossil Record." Essayworld.com. July 3, 2005. Accessed April 23, 2024. http://www.essayworld.com/essays/Human-Evolution-And-The-Fossil-Record/29463.
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