The ancestors of modern humans


Evolution didn't happen in a day. Nor did it happen in a specific area to a specific species. Time after time environment has forced animals to evolve. Humans are no exception. Our story started four million years ago. Many different hominid species lived and died before us. Let us know our ancestors.

It is now understood that humans and apes shared a common ancestor. We diverged some four million years ago, by being full bipedal and developing pelvis required for walking upright. Bipedalism is the most distinct feature of hominids (human like species). But why did we become Bipedals? There are various theories but the most convincing one is: As the Eastern African forests got drier, they became grasslands.

The tall grass couldn't enable our ancestors to see very well. Since our ancestors were ape-like, their heaviness was a drawback. They couldn't climb trees swiftly and cling to branches like monkeys. With this disadvantage, hominids evolved Bipedalism. Even today's gorillas are seen walking upright few feets around tall grass. But evolution isn't a linear chain. It is a tree with many incomplete branches. There are gaps in evolution tree of humans because of the unavailability of fossils. Our ancestors were wide spread around the planet and fossils aren't very well preserved. Despite that anthropologists can tell multiple stuff by researching these fossil remains.

  1. Homo Heildelbergensis
    Homo Heidelbergensis
    (Image credits: humanorigins.si.edu).

    They lived in Asia and Europe 700,000 to 200,000 years ago. They had a a flat face and a bigger braincase. They were also the first to adapt to colder climates. They lived by building proper shelters and used fire, which was never seen in their previous predecessors. They could have coexisted with Neanderthals and Homosapien sapiens. Some scientists argue that they could have been a direct ancestor to modern humans. They could have been cannibalistic.


  2. Homo Rudolfensis
    Homo Rudolfensis
    (Image credits: humanorigins.si.edu).

    This ancestor of ours lived in Eastern Africa 1.7 million years ago. Their fossils are very rare compared to other hominid fossils. They had a huge body and a larger brain. They also had a long face with larger molars and premolars suggesting they mostly ate a vegetarian diet


  3. Homo Habilis
    Homo Habilis
    (Image credits: humanorigins.si.edu).

    They lived from 2.3 to 1.4 million years ago in Eastern and Southern Africa. This makes them one of the most successful species of our genus. They had longer arms and legs like apes but their face and teeth were small. They are the first "homo" genus bearers. They were the first among our ancestors who used stone tools.


  4. Homo Florensiensis
    Homo Florensiensis
    (Image credits: humanorigins.si.edu).

    They are popularly known as hobbits because they are the smallest species of our genus. Their fossils are found in Indonesian islands. They could have lived 100,000 to 50,000 years ago. Because of limited resources in islands, their adults only stood 3 feets tall. They had very small brains and no chin. They might have interacted with modern humans when they arrived at the islands. These hobbits lived in caves and jungles, making small stone tools.

  5. Homo Erectus
    Homo Erectus
    (Image credits: humanorigins.si.edu).

    They lived across Africa and Asia from 1.9 million years ago to 1,43,000 years ago. They are the most successful hominid species to have ever existed because they lived so long. They also spread across vast territories in their lifetime. They were the first to exhibit "homo" features having true bipedalism and showing sexual dimorphism (males and females are distinguishable). They used stone tools, took care of sick and elderly and had an early form of language.

  6. Neanderthals
    Neanderthals
    (Image credits: humanorigins.si.edu).

    Homo Neanderthalensis or Neanderthals are the best studied hominid species so far because we, modern humans have their DNA in us. We were 99.87% similar by DNA. Neanderthals lived in colder climates like Homo Heidelbergensis. They had a brain size almost similar to Homo sapiens. They were stoic and had big noses. They lived from 400,000 to 40,000 years ago in Northern Europe. They invented clothes for themselves to survive the cold climates. They used fire for variety of purposes and made many tools. They lived in a well knit society and buried their dead. They even painted on walls of caves and made few musical instruments for themselves. Some of these Neanderthals might have mated with Homo sapien females or the vice versa that we now share a 1-4% DNA with them. Neanderthals evolved separately in Europe. So this intermingling is only found in non African modern humans. These amazing primitive men died out probably because of competition with more advanced Homo Sapiens. Even in their peak stage, Neanderthal population could not cross 50,000 in numbers. So owing to their small numbers and habitat loss, Neanderthals died out, after contributing to our DNA a little bit.

  7. Homo Ergaster They were the first of the Homo group but they were not fully erect. They lived in Europe, Asia and Africa; 2 million to 1.4 million years ago. Some believe that these are the original fathers of: Homo Erectus and Homo Sapiens. But more research is needed to conclude that. Since they are so primitive we know very less about them. They could use stone tools and very wide spread. They too lived a very successful age.

  8. Ardipethicus Ramidus
    Ardipethicus Ramidus
    (Image credits: humanorigins.si.edu).

    They are the first of our ancestors to diverge from apes. They lived 4.4 million years ago in Africa. Their hips and feet helped them to walk upright. They could have the common ape-human ancestor from whom other hominid species descended.


These are just a few of our ancestors to discuss about. Our ancestry spans over four genus : Ardipithecus, Australopithecus, Paranthropus and Homo. The fact is that our ancestry spans over several generations of several species. Tons of fossils are being excavated every year and newer species are being added to our family. These fossils, dating far back into the future are what concretely supports the idea that humans are not much different from animals. We evolve and perish just like they do. Today only humans are left among the other hominid species. We survived because we were the best suited to the environment. But today we are changing our environment to our needs. This is actually accelerating our rate of evolution. Humans are still evolving. With time, useless traits are compromised and useful triats are accentuated.


Comments

Author: Reena Upadhya19 Sep 2018 Member Level: Diamond   Points : 8

Evolution of humans is and always will be a debated topic. Curiosity to know our origin led us to discover the facts regarding the process of evolution. Well, the complete history can be found out inside our genome. Our ancestors faced lots of genetic changes over a course of time. Our genome is the result of the genetic changes our ancestors experienced. Yes, as described by the author in this article, humans and apes did share a common ancestor. It is said that modern human beings did originate within 2,00,000 years from now in the African continent. Homo erectus was the common ancestor from whom evolution took place. We, modern humans, are Homo sapiens. In Latin, it means ‘wise man’. No species of Homo genus are surviving right now except modern humans. Homo erectus in Latin means ‘upright man’. They are extinct now.

To explain evolution, two models of Homo sapiens are popularly considered. One is a model that is named as ‘out of Africa’. Another one is a ‘multi-regional’ one. The previously mentioned model is the most accepted one. According to it, Homo sapiens did originate in Africa and then started migrating to different areas of the world. ‘Multi-regional’ one proposes that evolution did not take place in just a single place. Many places were involved and it took place over a longer duration. The blending of populations ultimately resulted in specie of Homo sapiens that we are witnessing today.

According to the genomic research, the evidence supports the theory of ‘out of Africa’ model. However, studies conducted on extinct species of Denisovans and Neanderthals say that around 1-3% of genome mixing is witnessed in Europeans and Asians. This kind of interbreeding that is seen in the populations of two different continents that were separated in previous times is known as an admixture.



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