The aforesaid are the questions which have agitated the minds of biologists, anthropologists, and geneticists for years and years long. To understand this, one has to delve into the flow of events as they unfolded on the scientific screen of human evolution.
About 13.5 billion years ago, matter, energy, time and space came into being in what is known as the ‘Big Bang'. About 300,000 (3 lac) years after their appearance, matter and energy started to coalesce into complex structures, called atoms which then combined into molecules. About 3.8 billion years back, on a planet called Earth, certain molecules combined to form particularly large and intricate structures, called organisms. About 70,000 years ago, organisms belonging to the species Homo Sapiens started to form even more elaborate structures called cultures. These important revolutions shaped the course of history.
As the scientists say, we primarily belong to the animal world, which for countless generations, did not stand out from other organisms with which they shared their habitats on the planet Earth. As a matter of fact, there was nothing special about human beings when they, along with animals, first appeared about 2.5 million years ago. No body, least of all humans themselves, had any inkling that their descendants would one day walk on the moon, split the atom, fathom the genetic code, write books and scan the vastness of the cosmic world.
Biologists classify organisms into species. Animals are said to belong to the same species if they tend to mate with each other, giving birth to fertile off-spring. A bulldog and a spaniel may look very different, but they are members of the same species, sharing the same DNA pool. Species that evolved from a common ancestor are bundled together under the heading " genus " (plural genera). Lions, tigers, leopards and Jaguars are different species but have common ancestor. Genera (species having common ancestor ) are grouped into families, such as the cats (lions, cheetahs, house cats). All members of a family trace their lineage back to a founding matriarch or patriarch. All cats, for example, from the smallest house kitten to the most ferocious lion, share a common ancestor who lived about 2.5 million years ago.
The scientists say : "Like it or not, we are members of a large and particularly noisy family called the great apes. Our closest living relatives include chimpanzees, gorillas and orangutans. The chimpanzees are the closest. Just 6 million years ago, a single female ape had two daughters. One became the ancestor of chimpanzees, the other is our grandmother.
We are used to thinking about ourselves as the only humans, because for the last ten thousand years, our species has indeed been the only human species around. Yet, the real meaning of the word human is "an animal belonging to the genus Homo" and there used to be many other species of this genus besides Homo Sapiens.
Humans first evolved in East Africa about 2.5 million years ago from an earlier genus of apes called "Australopithecus" which means Southern Ape. About two million years ago, some of these men and women left their homeland to journey through and settle vast areas of North Africa, Asia and Europe. Since survival in the snowy mountains of Northern Europe required different traits than those needed to stay alive in the jungles of Indonesia, human population evolved in different directions.
Humans in Europe and Western Asia evolved into Neanderthals (Man from the Neander Valley) --bulkier and more muscular than the Homo Sapiens. The more eastern regions of Asia were populated by Homo erectus --Upright Man, who survived there close to two million years, making it the most durable human species ever. This record is unlikely to be broken by our own species--Homo Sapiens.
On the island of Java in Indonesia lived Homo soloensis ---Man from the Solo Valley who was suited to life in the tropics. On yet another island of Indonesia, Flores, humans underwent a process of dwarfing ---this unique species called by scientists Homo Floresiensis had maximum height of 3.5 feet and weighed no more than 55 pounds. The last dwarf like humans vanished from Flores about 12,000 years ago.
While humans were evolving in Europe and Asia, evolution in East Africa did not stop. The cradle of humanity continued to nurture numerous new species such as " Man from lake Rudolf ", “Working Man ", and eventually our own species---Homo Sapiens, The Wise Man. The scientific truth is that from about 2 million years ago until about 10, 000 years ago, the world was home, at one and the same time, to several human species like what we even today see in the case of foxes and bears etc. The earth of a hundred millennia ago was walked by at least six different species of man.
Two things put humans apart from other animals:
They have extraordinarily large brains---mammals weighing 130 pounds have an average brain size of 12 cubic inches. The earliest men and women 2.5 million years ago, had brains of about 36 cubic inches while the modern Sapiens (we) support a brain averaging 73-85 cubic inches. In Homo Sapiens, the brain accounts for about 2 or 3 percent of total body weight, but it consumes 25 percent of the body's energy when the body is at rest. By comparison, the brains of apes require just 8 percent of rest time energy.
We walk upright on two legs. Standing up, it is easier to scan savanna for game or enemies but the humankind has paid for this with backache and stiff necks. Women have paid extra. An upright gait required narrower hips, constricting the birth canal -- and this when babies’ heads were getting bigger and bigger.
The question arises as to what happened to other human species, such as Neanderthals, Homo erectus, Homo soloensis which were quite well entrenched in the continents of Europe and Asia before the Homo Sapiens arrived there from East Africa ? To this effect, two theories have been advanced by the scientists:
1---Interbreeding theory which says that when Homo Sapiens spread into Neanderthal lands, they bred with them until the two were merged. If this is the case, today's Eurasians are not pure. They are mixture of Homo Sapiens and Neanderthals. Similarly, when Homo Sapiens reached East Asia, they interbred with the local erectus , so the Chinese and Koreans are a mixture of Sapiens and Erectus.
2---Replacement theory ---According to this theory, Homo Sapiens replaced all the previous human populations without merging with them, may be through genocidal elimination.
If Replacement Theory is correct, all human beings presently inhabiting the planet earth have same genetic baggage, and racial distinctions among them are negligible. But if the Interbreeding theory is right, there might well be genetic differences between Africans, Asians and Europeans that go back hundreds of thousands of years.
However, the overwhelming scientific evidence collected so far is that, in terms of DNA, we all are, without a shadow of doubt, one species. The genetic variations that affect skin colour, hair type, and facial features involve an insignificant amount of the billions of nucleotides in an individual's DNA. Interesting to note that most of the Y chromosomes found in Jewish males are the same as those found among the Middle Eastern men. For all their bitter enmity, Palestinians and Israelites are genetically not so very different.
As beneath the skin we all are similar, there could hardly be any justification for institutionalized genocide of Jews, Roma and Sinti at the hands of Hitler during the Second World War (1939-1945 ) or for that purpose racial hatred exhibited against the blacks in USA or in South Africa during the apartheid, xenophobia, otherness, hierarchical ranking, supremacism etc. rampant in one form or the other in some parts of the world even today, now including India’s Hindutva led Hindu supremacy.
In a way, all such notions of superiority are based on false consciousness; as some truly say us becoming too much aware (conscious) was not short of a catastrophic development in human evolution.