20110207

Human Evolution, Briefly Explained

Human Evolution


Human evolution is the theory stating that humans (Homo sapiens) developed from apes or ape-like ancestors. This is a process that took about 5.8 million years. Modern humans first appear in the fossil record about 195 thousand years ago. Our species first displayed behavioral modernity 50,000 years ago; our ancestors first started doing things considered to be human, like performing ritualistic burials, making clothes, using complex hunting techniques, and painting on cave walls (the oldest known cave art dates back 35,000 years ago). Agriculture and village life began 10,000 years ago. Systems of writing date back as early as 5,000 years ago.

As far as the earth or the universe are concerned, humans have not been around very long; the planet is about 4.54 billion years old and the universe itself is estimated to be 13.75 billion years old. Life on this planet started about 3.5 billion years ago. Since then, many species have emerged and expired, including our ancestors.

I hope we use our time wisely.

Scientific Theory


Scientific theories are verifiable truths that have undergone scrutiny and have not been proven false. Saying that evolution, or more specifically human evolution is a scientific theory, is really saying that this is as close to factual as we can get.

From Wikipedia:
A scientific theory comprises a collection of concepts, including abstractions of observable phenomena expressed as quantifiable properties, together with rules (called scientific laws) that express relationships between observations of such concepts. A scientific theory is constructed to conform to available empirical data about such observations, and is put forth as a principle or body of principles for explaining a class of phenomena.

A scientific theory is a type of inductive theory, in that its content (i.e. empirical data) could be expressed within some formal system of logic whose elementary rules (i.e. scientific laws) are taken as axioms. In a deductive theory, any sentence which is a logical consequence of one or more of the axioms is also a sentence of that theory.

Stephen Hawking writes that:
A theory is a good theory if it satisfies two requirements: It must accurately describe a large class of observations on the basis of a model that contains only a few arbitrary elements, and it must make definite predictions about the results of future observations. [...]

Any physical theory is always provisional, in the sense that it is only a hypothesis; you can never prove it. No matter how many times the results of experiments agree with some theory, you can never be sure that the next time the result will not contradict the theory. On the other hand, you can disprove a theory by finding even a single observation that disagrees with the predictions of the theory.

References


New Scientist Human Evolution Time-line:
http://www.newscientist.com/movie/becoming-human

New Scientist Human Evolution:
http://www.newscientist.com/topic/human-evolution

Wikipedia, Human Evolution:
http://en.wikipedia.org/wiki/Human_evolution

Minnesota State University e-Museum, Human Evolution:
http://www.mnsu.edu/emuseum/biology/humanevolution/

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