JOIN USAccurate, astounding astronomical knowledge accumulated over the past few decades has enabled cosmologists to form a precise picture of how our universe originated almost 14 billion years ago. The discovery of the cosmic microwave background and its minute variations across the sky enabled us to describe the very early history of the universe going back to yoctoseconds (10-24s) and extending up to the present. We are sure that much of the helium, heavy hydrogen and lithium must have been synthesised in the first few minutes and the Large Hadron Collider (LHC) is expected to mimic the conditions one picosecond after the big bang when exotic dark matter particles were created.
However, while cosmologists are so certain by and large about the origin of universe, cosmogenists cannot agree on the precise origin of Earth’s nearest celestial neighbour, the moon. Even the Big Splash theory (wherein a primordial planet Theia collided with Earth spewing out the debris which formed the moon) has been recently questioned. It seems the far side of the moon (not visible from Earth) is more mountainous and uneven than the near side, implying that there could have been more moonlets, which later crashed on to the far side, throwing up mountains.
Even stranger, palaeontologists are far from certain when exactly humans (the modern Homo sapiens) originated on Earth. Of all the millions of species on Earth, including about 200-odd primate species, humans are the only creatures curious about the universe and actively investigating the natural phenomena all around, making their discoveries by the day and even utilising them in technological innovations.
Earliest hominids
There was some sort of consensus that the modern human species originated in Africa, significantly the southern parts of the continent (where present-day countries like Tanzania, Ethiopia and Zambia are located). The oldest Homo sapiens fossils known so far are from an Ethiopian site called Omo Kibish, dated to 2,00,000 years ago. However as reported earlier this month, the announcement of discoveries of fossils unearthed on a Moroccan hillside at the site called Jebel Irhoud are about 1,00,000 years older.
The skulls, limb bones and teeth of at least five individuals were 3,00,000 years old. This blockbuster anthropological discovery was recently published in the journal Nature in two separate studies. This conveys the message that human species is much older than thought and did not emerge in an Adamic way, but from an Eden in East Africa. Another group of researchers also hope to find proof of human origins in Bulgaria as they recover fossils from a bay of a dried up river bed, near Rupkite. So where and when exactly did the human species originate and how? It seems that it is more difficult to answer than origin of whole universe and knowing all its workings!
Again, the anthropological status of Neanderthals, Cro-Magnons, Denisovan or the Homo floresiensis are not fully certain as their coexistence with ‘modern’ humans, even as recently as less than 1,00,000 years. There also have been hoaxes like that of the well-known Piltdown Man case, in which bone fragments were presented as the fossilised remains of a previously unknown early human.
Apart from Africa, which is the favoured continent for hosting the earliest hominids, other regions over the decades have had their candidates, including our own Ramapithecus punjabicus and China’s Sinopithecus. While there is a general consensus among cosmologists on the origin and evolution of the universe over billions of years, considerable confusion exists about the origin of humans on Earth (and no consensus on the so called ‘missing link’) although time periods are under thousand times shorter.
Important findings
The two Nature studies have extended the recorded existence of Homo sapiens by at least 1,00,000 years. This has nailed the long-held viewpoint that modern human emerged from an East African country.
The evolution of our species is not from a specific region but seems to have involved numerous populations spread across Africa along with episodic genetic mingling between them. The earlier date of the Moroccan site is also important for human evolution in Africa where at least two other species, Homo naledi and Homo heidelbergensis, may have coexisted with humans.
To add to the confusion, a new study published in the journal Proceedings of National Academy of Sciences recently (which involved clues of Neanderthal DNA), suggests that our close cousins were far more numerous than thought earlier. There is apparently a rich Neanderthal fossil record spread over several sites. Again using a new technique of sequencing DNA, it was found that Neanderthals split from the Denisovans much earlier than thought. Hardly anything is known about these so-called eastern cousins of the Neanderthals.
(The author is with the Indian Institute of Astrophysics, Bengaluru)