An Insight into our existence-1

"Do you remember Darwin, Sis"?
"Who?"My half asleep sis growled.She oftens reacts like this whenever I come up with questions like this.
"Charles Darwin, you know,the guy of theory of evolution"I said.
"Hmmm... What about Him!!" she yawned.Deciding to take it as a"Great! tell me more"I continued.

"You see, today the idea of evolution is very obvious.In schools, students are taught about origin of species,genetics etc.But the time when it actually was discovered it was very difficult to accept.There was huge uproar among people against Darwin's theory of evolution."
"Hmm....."She nodded.
"Darwin's father was a successful medicine doctor so obviously he sent him for medical college. But anatomy digusted him,hospital case-work filled him with horror so basically he couldn't fit in it, though he possessed scientific interests and love for nature.Second option;clergyman--not bad!. But churchman had to have degrees. During his stay in Cambridge he came across couple of eminent botanists and naturalists who broadened his outlook enormously."
"And then he received an amazing invitation---an invitation that would steer his life and career toward adventure.He was invited to go on a voyage around the world. British govt was doing a survey of South American coast and Pacific islands and they needed a naturalist who would observe,record and collect anything of interest in these lands.This request was overwhelming.He was just a beginner and moreover what about his dad. He was definitely not going to approve it. And as expected he refused it.Darwin didn't have the courage to argue so The end......."

"Oh god! What a luck?"Curiously my sis blurted out with wide eyes.

"Yeah, I know!" I agreed. "But then he casually told his uncle about the offer and to his disbelief he promptly spoke to his father and convinced him.And within days he was at plymouth to see "Beagle"----the ship that would take him round the world."
"WOW"! "What a luck!"I heard.

"On Dec 27,1831 the Beagle set off for the voyage into atlantic ocean. It would be five years before he would see his home again. Life on ship was not easy.It was a small ship for over seventy people. Anyways after sixty-three  days  at sea they reached South America.To his amazement the place was lush tropical forest with birds,insects,plants and animals all around him.he could feel the the strange heavenly perfumes in air along with                        chirping,rustling,darting.It was an experience of life time."

"He would spend his days observing and collecting specimens-- mice,seeds,fish ,insects,beetles etc. He was also a great shooter. He also took part in crushing down a rebellion in Montevideo.
In the Galapagos islands he observed a striking fact that though the islands were similar and in sight of each other yet they possessed their own special populations.
 During his expedition once he stumbled on a graveyard of giant creatures which he later decribed as 'monsters of extinct races' in Argentina.This was some discovery!!Skeletons were huge.Few of them were big enough to sit on their hindquarters and reach up on a tree.They resemble the animals that are present today but the size were different.There was huge similarity with their modern equivalents.
"What was the link between them?" "He thought."Why had these huge creatures died out and how"?This question needed to be answered............