Life originated on earth around 3.5 million years ago. Earlier only cellular forms were seen but with time gradual evolution took place in the diversity of organisms that we see today. Human species is regarded as the most advanced species. Humans are said to be evolved from the chimpanzees as some similarity is found in the DNA tracing of these organisms. Various methods like fossil excavation and their study, radioactive dating, the study of DNA sequences have been used to find out the secret of human evolution. The classification of humans also gives a little idea of how humans are evolved.
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Kingdom - Animalia
Phylum - Chordata
Subphylum - Vertebrata
Class - Mammalia
Order - Primates
Family - Hominidae
Genus - Homo
Species - Sapiens
Humans belong to class Mammalia whose members are characterized by the presence of mammary glands to feed their young ones. In addition to this feature, all the other traits of Vertebrates and Chordates are also present in humans. Shrews were the first mammal-like creatures. Tree shrew is considered as the most primitive ancestor of primates. It used to have eyes with cones. Man, monkey, and apes belong to the order primates. It was also believed that humans came from apes but the reality is that the humans and apes had a common ancestor which had both the characters of humans and an ape. The name of the common ancestor was Dryopithecus which was more like an ape. This common ancestor led to the two branches of apes and humans which evolved in their own ways.
The role of fossils cannot be undermined in the tracing of human evolution. In fact, fossils are the strongest and the direct evidence of human evolution. Most of the fossils of the human ancestors have been found from Africa which shows that humans originated in Africa and then migrated from there to different parts of the world. Due to this reason Africa is known as the Cradle of mankind.
Some of the fossils that throw light on human evolution are mentioned below :
This is a fossil of the ape line. It was a primitive primate.
This was the first fossil of the hominid line. It was 15 million years old. He was more man-like rather than ape-like.
Both Dryopithecus and Ramapithecus were hairy.
It is found to be two million years old. It is believed to have a height of around 4 feet. It used to live in the East African grasslands. This fossil was excavated by Raymond Dart.
This was the first man which belongs to the genus Homo. A man from this genus was known as a toolmaker man as they made tools. It was believed that they were herbivorous.
Its biological name is Homo heidelbergensis and was excavated by Leaky.
In 1891 Eugene Dubois excavated its fossil from Java in Indonesia. It was named Homo erectus erectus by Mayer. He was the first man to use fire. He is believed to have observed cannibalism.
It was the first man with species as sapiens and genus as Homo. It was excavated in the Neanderthal valley of Germany. Its subspecies were neanderthalensis. He was present on the earth in between 100000-40000 years back. He was a caveman as it used to live in the caves. He was the first one to start a social life. He also observed ceremonial rituals on the death of a member of the population. He also started to use hides of animals as clothes.
1.Explain Why Evolution Should not be Equated with Progress?
Evolution refers to the creation of many branches from common descent or ancestry. Diversity of organisms is generated and the surviving species is the one which is naturally selected. The parent species from which the new species have come is not eliminated but still remains alive. The only difference is that they now become reproductively isolated. Apes still exist on earth but cannot reproduce with the man and it's a clear example.
Progress refers to a single person's development and comparison from the previous state. This definitely cannot be applied to evolution as less developed species are still present on earth with humans. Progress is like climbing a ladder but this can not be considered true for evolution.
2. What are the Different Types of Evolution?
There are three types of Evolution present.
In this type of Evolution, two different species evolve independently of each other. The species are unrelated to each other and it is not necessary that this evolution takes place in the same habitat or niche.
In this, two closely related species are evolved from a common ancestor or parent but become different from each other.
In this type of evolution, two unrelated species share common characters due to the same habitat. For example, whales and shark both live in water but their origin is different.