What are subtle fluids?

Jean Baptiste Lamarck believed that all bodies had ‘subtle fluids’. These were weightless fluids pervading all space and bodies. Two good examples of eighteenth – century subtle fluids were electricity and heat. Lamarck believed that subtle fluids were responsible for both movement and change. For example, Lamarck pointed out that snails have poor vision because the feelers on their heads acted as their eyes. According to him, the ancestors of snails did not have feelers. They groped about with their heads to find their way around. This groping sent subtle fluids to the front of the head, and the constant presences of moving subtle fluids eventually brought about the development of feelers, and these feelers were passed from generation to generatio 



Butterfly Evidence



         Lamarck supported his theory of evolution with the example of butterflies. According to him, you find different species of butterflies in different places because butterflies in one place acquire certain characteristics to survive in their environment, and pass on these characteristics to the next generation.



 



 



 



Lost Worlds



        The duck billed platypus of Australia is a strange looking bird that was discovered only in 1799. This made several people believe that there might be many other weird animals alive in some remote corner of our planet and that animals that were thought to be extinct might still exist in some unknown place.



.


Why Apollo 17 is considered the last moon mission?

 



The Apollo 11 was the first manned mission that successfully landed on the Moon. Manned by three American astronauts, Apollo’s lunar module, the Eagle, landed on the face of the Moon on July 20th, 1969. Neil Armstrong and Edwin Aldrin were the first men to walk on the Moon. Three years later, Apollo 17 was the last Apollo Mission to land men on the Moon. It carried the only trained geologist to walk on the lunar surface – Harrison Schmitt. The Apollo 17 astronauts traversed the greatest distance on the Moon, using the lunar roving vehicle. They also returned the greatest amount of samples of rock and soil. The last human being to walk on the Moon was the Commander of Apollo 17, Eugene Cernan. No humans have visited the Moon since December 14th 1972.


Why is Jean Baptiste de Lamarck a key figure in the history of evolution?

Jean Baptiste Lamarck was a French scientist who developed a theory of evolution at the beginning of the 19th century. His theory involved two ideas. The first was the law of use and disuse, which stated that a characteristic which is used more and more by an organism becomes bigger and stronger, and one that is not used, eventually disappears. The second law was the law of inheritance of acquired characteristics. It stated that any feature of an organism that is improved through use, is passed to its offspring. However, Lamarck’s theory cannot account for all the observations made about life on Earth. For instance, his theory would predict that all organisms gradually become complex and simple organisms disappear. But we know that this is not the case, and that simple organisms still exist. So today, Lamarck’s theory is largely ignored.


What are the evolutionary findings from the Cambrian Period?

The Cambrian explosion is a brief time when most major groups of animals that have bilateral symmetry first appear in the fossil record. Do you know what a bilateral animal is? It is one whose body has two mirror-image halves. Modern examples are lobsters, people, dogs, and butterflies. The event is referred to as an ‘explosion’, because a rich diversity of species appeared in a relatively short amount of time. There is growing evidence that these different groups had a common ancestor that lived during the Cambrian Period. Evidence is growing to support this theory, at least from the fossils that date back to this period. After the Cambrian Period, very few additional animal phyla, or large animal categories, arose.



 


Why was there an explosion of life during the Cambrian Period?

The Cambrian Period marks an important point in the history of life on Earth. It is the time when most of the major groups of animals first appear in the fossil record. This event is sometimes called the ‘Cambrian Explosion’, because of the relatively short time over which many life forms appeared. Many reasons have been suggested for this explosion. The first is that the increase in oxygen levels in the atmosphere led to the evolution of more complex body structures. Moreover, many species became extinct at the end of the Vendian Period, and this allowed new life forms to develop. It is also thought that a change in the ocean chemistry made possible the development of hard body parts such as teeth and skeletons. Animals could now swim, burrow, defend themselves, hide, and hunt. However, the sea was still the centre of activity.