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Sunday, 04 December 2011 16:11

The Evolution of the Human Race

Written by  Marquez Comelab
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Religious dogmatism persist when people remain ignorant of their own history, of their own origins. Religionists, especially Young Earth Creationists, who believe that the Earth is less than 10,000 years old have their own versions of events. They tell us that we came from Adam and Eve and all the species today came from those that survived Noah's Great Flood. However, through the study of fossils, continental drift and our very own DNA, science tells us a different story: human evolution.

Find out how human beings evolved from earlier life forms on Earth for over 4.4 billion years, from single-celled organisms to the diverse multitude of species alive today. This article comes with a diagram of the evolutionary Tree of Life.

[Please give your browser a couple of seconds to load the larger image after which a zoom window should appear at the left of the image. Press "Ctrl and +" then "Ctrl + -" (or vice-versa) if needed to re-sync the zoom with your mouse movement]

In my book, The Tyranny of God, I went through how humans evolved from earlier species of life and how the evidence shows that all forms of life on Earth - living or extinct - came from the same source. This means that you and I, as well as all other human beings share a common ancestor with every animal and plant now living today. Isn't it remarkable to even consider that you once shared a common ancestor with your pet, if you have one, or with the plant that is outside your home?

To help us understand how this happened, I contacted Leonard Eisenberg, a science educator in the United States. He created a fantastic diagram depicting the evolutionary history of life as it happened here on Earth. I wanted to use it here to provide a graphical summary of our evolution.

The image shows how species of life evolved to other species over time. In using this image, remember that the x-axis, the horizontal line, is time. Unlike usual graphs where time 0 starts at the left and extends rightwards to the present, time on this chart, starts in the middle of the horizontal axis. Therefore, the events of approximately 4 billion years ago when Earth formed as a planet starts in the middle of the axis then as time goes by, it stretches out to both left and right.

I will go through the diagram with you. You can then zoom into the image to explore the details of our evolution. Please note that the diagram with its splitting 'branches of species' and the timescales given are not meant to be authoritative but rather just approximations of these major events in our evolutionary history.

4400 MYA (Million Years Ago): Earth is Formed

  • 4000 - 3000 MYA: Life in its early forms originates (bacteria).
  • 3000 - 2000 MYA: Oceans rust. Iron in the oceans at first floated around in the water. When the oxygen from photosynthesizing plants increased in the atmosphere, it combined with the iron to make rust.
  • 2000 - 1000 MYA: Multi-celled organisms (Eukaryotes) began to evolve, their descendants later become the plants, algae, fungi, sponges, corals and all other higher life forms. Eukaryotes are the kind of cell (it has a nucleus) that makes up all living things except for the most primitive stuff like Bacteria and Archaea.

700 MYA: Global Ice Ages

  • 700 - 542 MYA: The protostomes began to appear. Their descendants include the centipedes, crabs, spiders, dragonflies, grasshoppers, lice, flies, snails, ammonites, clams, octupus, sea urchins, starfish and sea squirts.

542 MYA: The Cambrian Explosion

  • 542 - 400 MYA: The earliest type of fish began to appear. Their descendants include sharks, cod, perch, salmon, herring, eels, gars, sturgeons and the lungfish.

440 MYA: 1st Known Mass Extinction

  • 440 - 370 MYA: The early tetrapod ancestors of amphibians and reptiles began to appear. Their descendants include salamanders, frogs, turtles, lizards snakes, crocodiles and the dinosaurs.

370 MYA: 2nd Known Mass Extinction

  • 370 - 250 MYA: The Earth's land surface was ruled by reptiles, mammal-like reptiles and giant amphibians.

250 MYA: 3rd Known Mass Extinction

  • 250 - 200 MYA: Early ancestors of dinosaurs and mammals began to appear.

200 MYA: 4th Known Mass Extinction

  • 200 - 65 MYA: Species of early mammals diversified. These mammals were the ancestors of present-day bats, shrews, horses, camels, dogs, cats, rodents and rabbits.

65 MYA: The 5th Known Mass Extinction occurred, killing off the dinosaurs

  • 65 MYA - Today: One variety of mammals diversified from tree shrews to lemurs, tarsiers, new world monkeys, old world monkeys, gibbons, orangutans, gorillas, chimpanzees and humans.

Today:

  • When dinosaur bones were first found, it was thought by human beings that they were placed under the rocks by God to test our faith in him. Many people still insist that the world is not older than 10,000 years. To them, humans do not share ancestors with earlier species and they are created by a god who created them in his/her own image. Further, the god in this belief system created the first woman, from the bone of the first man.

Okay, the last one was not on the diagram but just a poke at some people's insistence on their literal beliefs in ancient myths.

I was one of those people who did not know about this history. Despite having gone through primary school, high school and university, how can I not know when this knowledge had been accumulating for more than a hundred years? Sadly, I am not alone. There are plenty who still do not know or fully appreciate the gravity of this wonderful story. Having heard of evolution and accepting it as fact because scientists say it is true is one thing but to comprehend how it works to a point where it is hard to believe otherwise, is a different experience altogether.

In many schools around the world, parents and religions influence their children to rather believe in myths and deny the mounting evidence that we, human beings, evolved from earlier life forms. As a result, science teachers have to approach the subject tentatively and avoid having to say the truth to avoid confrontation. It is worse when they do not teach it at all. For me and many like me, we have been denied the right to know the truth.

This is why even if I am not a Science teacher, I am passionate about this stuff. Seriously, isn't it wonderful to know that indeed, we are all related, not just in some airy-fairy use of the word 'related', and not even as 'brothers and sisters' as poetically invoked by politicians and religious leaders in their speeches, but rather, we are literally cousins with every living thing on this planet. Yes genetic cousins! What is more, there is evidence for it! Apart from fossil evidence, the origins of the human race is spelt out in our DNA and in the DNA we share with every plant and animal alive today.

- Marquez Comelab

Special thanks to Leonard Eisenberg for the use of the poster and for casting a scientific eye on this article. Please visit his website at http://evogeneao.com/. There are interesting tid bits on his site. For example, the chimpanzee is our 240 thousandth cousin. The cat is our 27th million cousin. The octopus is our 300th million cousin. The large format copy of the poster featured above is also available on his site.

Last modified on Thursday, 19 January 2012 10:17

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