This is the first episode in the BBC Natural History series Life on Earth. First broadcast on 16th January 1979 the episode focuses on the variety and evolution of life. The episode starts by explaining Charles Darwin’s theories on the origins of species and natural selection, using examples such as giant tortoises from the Galapagos Islands, explaining how one species has an arch in its shell from the way it gathers its food and how another species has a more rotund shell. An example is also shown with iguanas who have adapted to feed off not vegetation by seaweed, living on a barren rocky outcrop they swim out to sea and dive to the seabed in order to feast off the seaweed.
Next the focus is on fossils that provide evidence of early life forms and the action shifts to the Grand Canyon and the rocks found by the bed of the Colorado River which are 2,000 million years old but barren of fossils. That is because they are not the correct flint-type rocks which contain the fossils. These flint rocks were the sorts used in firearms centuries ago. They can be found in Canada on the shores of Lake Superior. Scientists cut wafer thin slices of the flint called chert and rub it down until it is translucent and study it under a microscope where they reveal filaments of algae.
The next segment focuses on micro-organisms and explains how they got their hydrogen from water and created a waste product of oxygen that kick started the development of life forms on Earth. The final part focused on the evolution of single celled forms to more complex structures and finally to multi-celled life forms such as sponges and jelly fish, with a particular focus on the Portuguese Man o’ War, although it isn’t really a jellyfish but a siphonophore. It is made up of many minute zooids each with a particular structure and focus such as protection, hunting, reproduction. All of them integrated together to create the colonial organism that is the Portuguese Man o’ War.
I really enjoyed this episode, it is the first time I am watching the series and although I didn’t expect it to be like this. It came as a complete surprise. I was expecting it to be a nature programme like recent ones have been. The focus on evolution and natural selection I found to be very interesting. It is really refreshing to watch an episode and learn something, not only that but to watch a segment and be interested enough that it encourages you to read up and research the subject matter more. I am looking forward to the rest of the series and learning more about the makeup and evolution of life of Earth.
