The Human Odyssey: How we became human?

We all know that, extinction of the dinosaurs paved the path of evolution of humankind. But there were many other human like species who once roamed around this planet but became extinct over the course of time. Have you wondered why 'Homo Sapiens' were the only species of the order 'Primate' who thrived? How did they overcome the harsh environment of Africa? How did they conquer the lands and went cross the ocean? How did they become the humankind of today?

In order to understand these, at first we have to dive into the topic of 'Evolution'.

Evoluton and its significance:

Evolution is the process by which change occurs within the members of same or close species sharing the same habitat. It is the process by which changes occour in a genetic level by the heredity characteristics passed down by the ancestors to their offsprings from generation to generation . According to Charles Darwin's 'Theory of Natural Selection", the fittest of the organisms survive. So according to this theory, in order to survive or adapt to harsh environment, for the want of procreation and raising offsprings the species goes through mutations and changes through an extended course of time, which gradually leads to new species. One a question may arise, how is it connected to the rise of  Homo Sapiens?

According to the speculations of scientists, comparing the genes of humans and chimpanzees it is seen that about 96% of the genes were identical. So, it can be clearly assumed that humans and chimpanzees share some sort of genetical connection. But can we say that humans evolved from chimps?

Well, if you are agreeing than I would say thats not the case here. Actually, humans and chimpanzees both have a common ancestor. But if I said that common ancestor is a fish, would you believe that claim?

The fish that walked on land:

Researchers suggest that life on Earth began in the ocean. About 4.5 billion years ago, the hot chemicals that rose from the sea floor created the condition for elements like hydrogen and carbondioxide to react and form the organic compounds. These organic compounds again reacted to form complex organic compounds. These compounds combinedly formed the cell membranes which encapsulated molecules containing the heredity characteristics known as the DNA. Thus the first living cell known as Protocell was formed which could grow,reproduce, multiply & evolve on their own.

About 385 million years ago, due to the change in climate, water evaporated, in order to adapt to the changes some fishes crawled out of the ocean to the main land. In order to walk on land their fins converted into limbs, some even kept their fins and limbs intact. Later on, their gills transformed into lungs and scales began to form in their skins and the sea fishes turned to crocodile like creatures of today. Thus began the era of the reptiles.

A section of the reptiles diverged and evolved into mammals having mammary gland on their body and fingers in their hands. These mammals spread throughout the world and began to  live in different habitats. Over the course of time these mammals evolved into our ancestors known as the 'Primates'.

Notharctus tenebrosus:

About 54 million years ago, this primate first appeared on Earth. Its fossil was found in 1870, it was observed to have a lot of similarities with the lemurs of today. It was the first primate to adapt to live on trees as it was seen to possess hands with claws for grabbing, human-like toes with nails, flexible back for jumping and binocular vision. Moreover it had many similarites with human like it had opposable thumb to stretch fruits, hind limbs to balance on the tree branches and most importantly they had eyes with color vision.

These species of primates actually serves as the starting point of the primate evolution.

Ardipithecus Ramidus:

Estimated to have lived about 4.4 million years ago, they are the common ancestors of the human-African ape.These primates showed the first sign of upright walking. Though it showed adaptation like complex bone structure for tree climbing and bipedal activity, it had unique hip done structure which was very much similar to ours. These hip bone structure was the reason they could walk upright. Moreover it also possessed diamond shape canines similar to the humans which enabled them to consume both plant, meats and fruits.

It is assumed that Ardipithecus was the pivotal point of human evolution as the evolutionary line of Ardipithesus diverged into two ways. One lead to the evolutionary line of the modern chimpanzees and apes (the closest living relative to mankind) and the other diverged to form the evolutionary line of the humans of today.

Birth of the Homo lineage:

Around 2.4 million years ago, the evolutionary line of Ardipithecus  resulted in a chain of evolution forming the genus Homo. The genus Homo is composed of many species who are the direct predecessors of mankind.

At first Homo Habilis came into being. They are the most ancient representative of mankind. They are also the direct descendent of Ardipithecus. Their fossil was seen having cranium with several teeths in their lower jaw, hands with elongated bones. Moreover their cranial capacity was about 640 cm which is noticeably bigger than their predecessor. Researcher assumed them to be the first among the human evolutionary line to use tools made out of stones and formation of groups. They were also named as 'handy man' for their profiency in making stone weapons.

Homo Erectus was the decendent of H. Habilis found almost 1.5 million years ago. Their physical features were much more pronounced then that of their ancestors. They had large brains with cranial capacity of 900 cm similar to that of the modern day humans, they also possessed small jaws and teeths,

An interesting features about them was there were the first to use fire for cooking and hunting. Moreover they also showed the signs of cave painting and lived by forming colonies, took care of the injured.

Finally the last stage of human evolution was the Neanderthals. They came into being about 200000 years ago. They are very much similar to the modern humans. They possessed complex brain structure and had shorter limbs. Moreover they showed the signs of using cooking technique such as boiling, roasting etc, they were also the ancestors of agriculture. Furthermore scientists believe that they were the ones to create languages for communication and also made cloths like blankets in order to save them from the cold environment. From different engravings in the caves it was seen that they had the idea of counting and numbering, had the ability of singing using one type of flute, ability of planning and drawing. It is unclear why the Neanderthals went extinct but it is for sure that they extinction paved the path of the emergence of mankind.

Present & Future of Mankind:

Mankind has come a long way isn't it? Interesting fact is that the evolution hasn't stopped yet and it will continue till the end of time itself. But what does the future hold for us? Will we become robots with cybernatic hands? Well thats a topic for another day. For now, we should be proud for being born as this amazing race called "Humans".

References:

1.BiologyWise, Human Evolution: History, Timeline & Future predictions, https://biologywise.com/human-evolution-history-timeline-future-predictions

2. Barss.K(2022), Human Evolution, https://www.infoplease.com/math-science/biology/genetics-evolution/human-evolution