The Path We Followed.
Every single child on this planet earth asked their parent about their origin, means from where the first of us came. And if there is an answer, they don’t forget to ask- what is the origin of the thing or matter or whatever included in the answer. Many parents simply ignore it by saying it is out of their reach (which is actually it is out of their own reach) or answer it in term of god or the almighty. From now you will be able to answer that entire range of crazy seeming logical question, which hides deep mystery of our origin.
The question is about our origin. From where did we come. Here in this article, it will be our topic to track our ancestors.
Usually, the questions of children literally push you to the edge of the universe, in that case we use to track it from the very beginning of our universe but, that’s something pretty big type of story, so, keeping that as another factor for another day, we will prefer to start from the beginning of our very own planet.
Well, our own planet earth itself has grown very old by now if you consider it’s age, it is around 4.543 billion years old by now, whereas the age of the universe is considered to be about 13.7 billion years. It is a huge time hence earth also is pretty old, but on timescale of the universe it is quite a young planet, as it formed around 9.157 billion years after the formation of the universe, hence we can consider it as an young planet. There are a lot of theories about the origin of earth (better keep it as another factor for another story to be told another day.).
When you look back for the age of life on earth, you find it to be around 3.7 billion years old. From the previous data given it can be seen that it looks like earth and life was made for each other. It took around 9.2 billion years to form earth and just 0.843 billion (not even a full billion) years to put life on it.
Then after the advent of life, life modified itself a several time and that story is termed as organic evolution. And evolution is the advent with modification (Charles Darwin (Father of evolution) used the term “Descent with Modification” to describe evolution) and is the story of life on earth or the story of our ancestors.
To trace our ancestors, we have to go back 3.5 billion years when the first life appeared on this planet, the ancestor of all living things on earth. But, the Father of evolution, Charles Darwin hadn’t travelled that 3.5 billion years back instead he travelled only 4 yrs. 9 months and 5 days (from 27th December, 1831 to 2nd October, 1836) not across time but with time to various place (mainly Galapagos Island). During his journey, in Galapagos Island he observed some variety of finches, and also observed that all even those finches are distributed across islands and in a range of habits, they show a common characteristic by sharing common ancestry with the original seed eating variety. And that observation triggered the idea about common ancestry of human being. After all those observation he published his first major work on his findings, entitled “Zoology of the voyage of HMS Beagle.” and after that he published his famous theory of Natural selection in “On the origin of species.” And later after “The descent of man.” (This book wrote about connection of modern man to greater apes of Africa and caused him a great harassment, as people were not ready to accept their ancestor to be an ape.)
Although later it was proved that Darwin’s ‘Natural Selection’ and “The Descent of man” was right. But, his Natural Selection was based on naturally occurring small mutations coming as result of variation were too slow to conduct speciation, so Hugo De Vries came with his ‘Mutation Theory’, which says those variation which occur in large amount and single stage (he called these ‘Saltation’) are the key of speciation not those minor variations.
After establishment of those theories, we finally could trace our ancestors with the help of paleontology and dating system, and advent of advance technology made it truly possible.
The time after the formation of earth has been divided into various time periods to ease our study of our ancestors. There are a number of those periods between the advent of life on earth and advent of man or ancestor of man (man like species) on earth. On those numbers of periods other animals ruled the earth.
The table of periods (era) that our earth has passed and the animals that ruled there are given below.
Precambrian Time
The Precambrian's lower limit is not defined, but ended about 542 million
years ago. The Precambrian encompasses about 90% of Earth's history.
| Period | Duration(in million years) | Epochs | Events |
|---|---|---|---|
| Archaean (Greek archaios = ancient ) | 2,500? | Eoarchean (Greek eos = dawn + archaios = ancient) Paleoarchean (Greek palaios = old) Mesoarchean (Greek mesos = middle) Neoarchean (Greek neo = new) | Formation of oceans, atmosphere, and continents; bacteria |
| Proterozoic (Greek proteros = earlier + zoön = animal) | c. 2,000 | Paleoproterozoic (Greek palaios = old) Mesoproterozoic (Greek mesos = middle) Neoproterozoic (Greek neo = new) | Oxygen build-up; multicelled organisms |
Paleozoic Era
This era began 542 million years ago and lasted about 291 million years. The name was compounded from Greek palaios (old) and zoön (animal).
| Period | Duration(in million years) | Epochs | Events |
|---|---|---|---|
| Cambrian (Cambria, Latin name for Wales) | 54 | Lower Cambrian Middle Cambrian Upper Cambrian | Invertebrate sea life proliferating during this and the following period |
| Ordovician (Latin Ordovices, people of early Britain) | 45 | Lower Cambrian Middle Cambrian Upper Cambrian | Invertebrate sea life proliferating during this and the following period |
| Silurian (Latin Silures, people of early Wales | 28 | Lower Silurian Upper Silurian | Coral reefs; giant scorpions; first jawed fish |
| Devonian (Devonshire in England) | 57 | Lower Devonian Upper Devonian | Numerous fishes, other sea life; many plants, first trees; wingless insects |
| Carboniferous (Latin carbo = coal + fero = to bear) | 60 | Upper, Middle, and Lower Mississippian Upper, Middle, and Lower Pennsylvanian | Maximum coal formation in swampy forests; insects, amphibians, reptiles; fishes, clams, crustaceans |
| Permian (district of Perm in Russia) | 48 | Lower Permian Upper Permian | Large reptiles, amphibians; most species become extinct |
Mesozoic Era
This era began 251 million years ago and lasted about 186 million years.
The name was compounded from Greek mesos (middle)
and zoön (animal). Popular name: Age of Reptiles.
| Period | Duration(in million years) | Epochs | Events |
|---|---|---|---|
| Triassic (trias = triad) | 51 | LLower Triassic Middle Triassic Upper Triassic | Early dinosaurs, crocodiles, turtles; first mammals |
| Jurassic (Jura Mountains) | 54 | Lower Jurassic Middle Jurassic Upper Jurassic | Many seagoing reptiles; early large dinosaurs; later, flying reptiles (pterosaurs), earliest known birds |
| Cretaceous (Latin creta = chalk | 80 | Lower Cretaceous Upper Cretaceous | Dinosaurs and other reptiles dominate; seed-bearing plants appear |
Cenozoic Era
This era began 66 million years ago and includes the geological present.
The name was compounded from Greek kainos (new) and zoön (animal). Popular name: Age of Mammals.
| Period | Duration(in million years) | Epochs | Events |
|---|---|---|---|
| Paleogene (Greek palaios = old + genes = born) | 42 | Paleocene (Greek palaios = old + kainos = new). Eocene (Greek eos = dawn). Oligocene (Greek oligos = few). |
Rich insect fauna, early bats, increasingly diverse varieties of mammals and birds |
| Neogene (Greek neo = new + genes = born) | 23 | Miocene (Greek meios = less + kainos = new). Pliocene (Greek pleios = more). Pleistocene (Greek pleistos = most) (popular name: Ice Age). Holocene (Greek holos = entire), the last 10,000 years to the present. |
Further development of mammals and birds. Various forms of humans, including Homo sapiens |
Of those huge periods human are on the scene for just around 7 million
years only. In that brief time they achieved something other species will
call miracle. Human itself has its own history of evolution. Which is quite
interesting in itself and is an active field of research. Researchers are
continuously trying to find our ancestors hidden in deep dark of history
(another factor for another article). It is interesting to note that the
most significant trend in the evolutionary trend of human is it’s brain
capacity, which has shown a continuous increase from our very first ancestor
to ourselves. It indicates the extensive use of brain, which put man at the
top.
“Thus, from the war of nature, from famine and death, the most exalted
object which we are capable of conceiving, namely, the production of the
higher animals, directly follows. There is grandeur in this view of
life, with its several powers, having been originally breathed into a
few forms or into one; and that, whilst this planet has gone cycling on
according to the fixed law of gravity, from so simple a beginning
endless forms most beautiful and most wonderful have been, and are
being, evolved.”
― The Origin of Species
