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Politics : Evolution -- Ignore unavailable to you. Want to Upgrade?

To: longnshort who wrote (48361)3/7/2014 6:36:02 AM
From: Solon  Read Replies (1) | Respond to of 69300
 
"when did the process of evolution start , before or after the big bang ?"

Your curiosity is laudable, Grasshopper. But I regret to inform you that the Big Bang (as we currently hypothesize the beginnings of this universe) happened something like 15 BILLION years ago. The Big Bang is a good guess with some evidentiary basis. But we have nothing to tell us what happened before the Big Bang. Biological Evolution deals only with how life has developed since our first inklings of it about 3.6 BILLION years ago. For philosophical or cosmological questions you would need to ask at your local university. Evolutionary scientists do not know how or where life began in the universe. Most of the universe is unknown and invisible to us. Evolutionary scientists do know, however, how life has grown over 3.6 Billion years to where it is today. Evolution is concerned with the last 3.6 billion years of life.

for the last 3.6 billion years, simple cells (prokaryotes);

for the last 3.4 billion years, cyanobacteria performing photosynthesis;

for the last 2 billion years, complex cells (eukaryotes);

for the last 1 billion years, multicellular life;

for the last 600 million years, simple animals;

for the last 550 million years, bilaterians, animals with a front and a back;

for the last 500 million years, fish and proto- amphibians;

for the last 475 million years, land plants;

for the last 400 million years, insects and seeds;

for the last 360 million years, amphibians;

for the last 300 million years, reptiles;

for the last 200 million years, mammals;

for the last 150 million years, birds;

for the last 130 million years, flowers;

for the last 60 million years, the primates,

for the last 20 million years, the family Hominidae (great apes);

for the last 2.5 million years, the genus Homo (human predecessors);

for the last 200,000 years, anatomically modern humans.

Periodic extinctions have temporarily reduced diversity, eliminating:

2.4 billion years ago, many obligate anaerobes, in the oxygen catastrophe;

252 million years ago, the trilobites, in the Permian–Triassic extinction event;

66 million years ago, the pterosaurs and nonavian dinosaurs, in the Cretaceous–Paleogene extinction event.


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