Whilst Homo sapiens also known as, well… humans, now rule supreme, we once had competition in the form of other human-like hominids that walked on two legs and used stone tools. Whilst it may be crazy to think that different species of human (genus: homo) once existed, it is in fact true!
These other species of homo that are all closely related to modern humans actually included a whole range of species, with some scientists proclaiming that there are in fact up to eighteen species of Homo. Only six of these however are considered to have interbred and contributed directly to the gene pool of modern homo-sapiens. These direct ancestor species included Australopithecus garhi, Australopithecus sediba, Australopithecus africanus and Australopithecus afarensis. However, the two most closely related and most well-known of these species are the Neanderthals and the Denisovans.
The Neanderthal (Homo neanderthalensis) are our closest extinct human relatives that lived across the European, South Western and Central Asian continent approximately 300,000 to 28,000 years ago, at the same time when early humans are believed to have lived in Africa.
The first discovery of Neanderthal remains was found in 1829 in what is now present day Belgium; however it wasn’t until further discovering in 1856 in Germany and again in 1864 that these remains were properly studied and identified as belonging to a species different to that of prehistoric humans. The name Neanderthal was given to the species after the Neander Valley in Germany where many fossils were found in a cave.
Neanderthals were usually a bit shorter and stockier in appearance compared to prehistoric humans (who were long and lean), and they were much stronger. Based on the study of known remains, it is estimated that male Neanderthals were usually 164-168cms and females averaged 152-156cms in height.
Their defining facial features which distinguish their remains from those of pre-historic humans include a low, flat, elongated skull, a large nose and a prominent brow ridge. It is now believed that most Neanderthals were fair skinned with red hair. Their brains were just as large if not larger than those of prehistoric and modern humans, however they were shaped differently.
Various remains of Neanderthals with degenerative diseases or injuries show that these individuals must have been cared for with their illnesses and thus lived in some sort of family unit or complex social group, probably ranging from 5-10 people. There is also evidence that Neanderthals had burial practises as many graves have been discovered with ‘grave goods’ and offerings.
Just like early humans, Neanderthals also mastered toolmaking and tools such as large wooden spears were used to kill large game of which their diet consisted mainly of (due to the climate conditions that they lived in meant that little edible vegetation existed). Many skeletons contain fractures similar to those of modern rodeo riders, possibly indicating that they were often injured when hunting large game. Tools were also used to make clothing, making Neanderthals the first early humans to wear clothing.
The Neanderthal is also believed to have had some type of language as they contained all the same physical contributes that would have allowed them to speak, and did have the same gene that humans have which is associated with language production. They were probably able to differentiate between many different sounds and may have had a ‘musical’ language, however the Neanderthal language debate is still ranging.
However unlike our prehistoric homo sapien ancestors Neanderthal society does not seemed to have evolved much and this lack of innovation may suggest a reduced thinking capacity, possibly hinting at one of the reasons why they became extinct.
There are three different hypotheses for Neanderthal extinction:
1) The movement of pre-historic humans from Africa and into Neanderthal territory created competition between the two species for resources. As early humans were just that little bit more advanced, they displaced the Neanderthals who then slowly died out.
2) It is believed that Europeans and some Asian peoples derive up to 4% of their DNA uniquely from Neanderthals indicating that the species may simply have interbred with humans and disappeared through absorption. Certainly modern findings would support this idea, as the remains of an individual dating from 40-30,000 years ago in Italy is a Human/Neanderthal hybrid.
3) Climate change may also have played a part with humans being simply more suited to changing climate conditions, leaving the Neanderthal to slowly die out in the new environment.
Or many simply suggest that it could have been a mix of all the above.
Whilst it is believed that Neanderthals contributed to the DNA of all modern humans except indigenous Africans, other populations such as those of Melanesia and Australian Aborigines also derive up to 6% of their DNA from another prehistoric human species called the Denisovans (Denisova hominins).
Denisovan remains were first discovered in the form of a juvenile female’s finger 2008 in the Altai Mountains of Siberia. It is believed that this individual lived approximately 80-70,000 years ago – at the same time as Neanderthals and Humans.
Unfortunately we do not have a skull fragment of any Denisovan however from studying the DNA found in finger and teeth fragments, scientists have claimed that they most likely had dark skin, with brown hair and brown eyes. Although some Pacific populations contain Denisovan DNA, no European or Asian population do (even though remains have been found in these areas), leading to interesting theories regarding population and migrations scenarios. One hypothesis is that perhaps an early wave of humans migrating out of Africa moved through Asia where they interbred with Denisovans before relocation to the Pacific region. Remaining Denisovans may then have been wiped out by later waves of human migrants.
Whilst much research is still being undertaken on the Denisovans, as they are a relatively new addition to the Homo family and there are few surviving fragments of remains, it is believed that like the Neanderthal, the rise of the Homo Sapiens led to a decline in the Denisovan population. However due to the mix of DNA found in modern populations, there must have been some sort of interbreeding as well.
Whilst these two populations became extinct many of thousands of years ago, it is interesting to know that some remnants of them still live on in modern populations of humans, shedding light on the interesting story of our own specie’s history.