Human brains got so big through natural selection favoring which increased the humans cognitive abilities that were and are advantageous for reproduction and survival.
Several different factors contributed to the increase in brain size, which includes social complexity, cultural development and environmental challenges, which all drove the evolution of larger and more complex human brains which are capable of processing of information and solving of problems much more effectively.
A human brain is significantly larger than the brains of chimpanzees and are roughly 3 times the size of chimpanzee brains.
The average human brain is around 1330 cc cubic centimeters in size and the average chimpanzee brain size is around 405 cc.
Humans and chimpanzees also share a similar basic brain structure, but humans have a much larger cerebral cortex, most particularly the association cortex, which is what plays a key role in higher level cognitive functions like awareness, attention and memory.
This dramatic increase in brain size in the human lineage is also a major factor in the evolution of human cognitive abilities and human intelligence.
Human brains also have a greater number of neurons, especially in the brains prefrontal cortex, which is also associated with planning, social behavior and complex thinking.
The closest relative to humans are bonobos and chimpanzees which share roughly 99 percent of human DNA.
Chimpanzees and bonobos are considered to be the closest relative to humans due to their shared ancestry with us humans, which also branched off from a common ancestor roughly 6 million to 8 million years ago.
Humans evolved and came into existence by evolving from apelike ancestors and most specifically, the lineage that lead to modern humans called Homo Sapiens which is what we modern humans are.
Homo Sapiens which is what us modern humans are diverged from the line which led to chimpanzees and bonobos about 6 million to 7 million years ago.
The divergence of humans marked the beginning of the hominin evolution, with early members of the hominin line exhibiting traits such as bipedalism, which is walking upright as well as smaller canine teeth.
And over millions of years, the early hominins evolved into various species, including different types of australopithecines and eventually the genus Homo, which also includes the species such as Homo neanderthalensis and Homo erectus and ultimately modern humans which is what we are Homo sapiens.
Us humans are also mammals with canine teeth, opposable thumbs and no tail and we basically evolved from earlier apes, which far enough back also shared a common ancestor.
Humans came into existence through a process of evolving from other species over time and then as a result the first modern human would've been born the same way as us modern humans are also born through being born from intercourse and growing in a woman's womb.
There was actually no first person on earth born from a scientific perspective as humans actually instead evolved gradually over millions of years from earlier hominin ancestors.
The process of humans evolving also involved a series of small changes in populations over time, which lead to the emergence of us modern humans, called Homo Sapiens.
So there is no actual specific birth date or person that can be identified as the first person or human born on earth.
Although according to Judeo Christian and Islamic traditions the first person or human on earth that was said to be born was Adam.
In the creation stories, Adam is created by God and is also the ancestor of all humankind.
Although from an evolutionary perspective, the concept of a single, "first human", is not accurate, as humans have evolved gradually over millions of years.
And various species of early humans, such as Homo habilis and Homo erectus are identified as ancestors of modern humans, although there is not a single person identified as the first human on earth and our species also known as Homo Sapiens.
The oldest known human remains are Jebel Irhoud, Morocco and are remains of Homo sapiens which is our own species and are dated to be around 315,000 years old.
The fossils push back the origins of our species by 100,000 years early than was previously thought.
Also among the oldest known human remains of Homo sapiens are also those found at the Omo-Kibish I archaeological site in south-western Ethiopia, dating to about 233,000 to 196,000 years ago, the Florisbad Skull founded at the Florisbad archaeological and paleontological site in South Africa, dating to about 259,000 years ago.
The oldest known hominin species is Sahelanthropus tchadensis who lived around 7 million to 6 million years ago in West Central Africa "Chad".
Sahelanthropus tchadensis exhibits a mix of ape like and human like features, which suggest that Sahelanthropus tchadensis may have been an early bipedal ancestor.
Fossil evidence places Sahelanthropus tchadensis between 7 and 6 million years ago, making it the earliest known hominin species.
The location of the foramen magnum (the opening where the spinal cord connects to the skull) suggests that Sahelanthropus tchadensis walked upright, a key characteristic of hominins.
Sahelanthropus tchadensis, had a smaller brain size than modern humans, and it is also possessed features such as small canine teeth and a short middle face, which are also more human like.
Another hominin species that was found is Lucy the first human and early human ancestor is an extinct hominin species which lived between 3.8 million to 2.9 million years ago and is classified as Australopithecus afarensis.
Lucy who was a famous early human ancestor was around 3.5 feet tall and was a member of the species of Australopithecus afarensis.
Lucy the famous early human ancestors remains were discovered in Ethiopia in 1974.
Lucy the first human and early human ancestor is an extinct hominin species which lived between 3.8 million to 2.9 million years ago and is classified as Australopithecus afarensis.
The fossils of Lucy were found in Hadar, Ethiopia, by paleoanthropologist Donald Johanson and his team and she weighed around 60 lbs.
The skeletal structure of Lucy, most particularly her femurs and hips, indicates that Lucy walked upright on 2 legs like us modern humans do.
And although Lucy, the first human was bipedal, Lucy also possessed features which suggest that she was also able to climb up trees.
Australopithecus afarensis is an extinct species of australopithecine which lived from about 3.9–2.9 million years ago in the Pliocene of East Africa.
The first fossils of Australopithecus afarensis were discovered in the 1930s, but major fossil finds would not take place until the 1970s.