While the Neanderthals of southern Iberia sustained to make typical Middle Palaeolithic artefacts, other Neanderthal groups did start producing more advanced stone tolls, bone tools, and apparently even necklaces and pendants during their period of coexistence with the Cro-Magnons for example, the makers of the Chatelperronian in France and northern Spain, and of the Uluzzian in Italy. Some experts believe that this is a sign of contact or trading between the two populations, while others believe it indicates technological competition between them for the available resources, competition which drove the Neanderthals to modernization and social change. Yet others argue that the Neanderthals were developing these advances independently, even before the Cro-Magnons arrived.
It is possible that many different kinds of interactions would have been possible, ranging from warfare, through avoidance, to peaceful coexistence, trade and even interbreeding. Given what we know of human behaviour today, any of these could have occurred, and indeed perhaps they all did at certain times and in certain places. Whether the two populations could have interbred successfully cannot be said.
Even if they were separate species, their genetic differences would not have been large, and they were probably as closely related as different mammal species today which can interbreed. So the main factors domineering possible hybridization were probably behavioural, cultural and social. Perhaps offspring had reduced fertility, or were ignored as potential mates by members of their parent populations. The evidence of DNA studies, both on recent Europeans and on a Neanderthal fossil, speak against Neanderthal genes surviving in Europe today, but whether their replacement was absolute remains to be seen.
The disappearance of the Neanderthals may in the end have been the result of a mixture of factors: the speed of climatic variations at this time and the resulting continually random environments, joined with the existence of newcomers who were maybe more flexible and original in adapting to these rapid changes. While the Neanderthals had survived such environmental stresses many times before by moving back to more sheltered refuges and then recovering when things improved, this time there may not have been enough space for both them and the Cro-Magnons to survive in the long term. By 25,000 years ago, this well recognized and successful human heredity had gone forever, leaving Homo sapiens as the only surviving human species on earth.
By looking at DNA a great deal of inferential in sequence about human evolution can be reconstructed. Genetic inheritance from Neanderthals can be gathered through time which can allow us to follow particular lines of genetic evolution, to estimate the time involved in their growth. Mitochondrial (and nuclear) DNA study present important tools for understanding the past, but the interpretations vary depending on the units of analysis.
Comparative analysis of DNA from different species allows us to make conclusions regarding the timing of speciation. Analysis of DNA sequences from individuals within a single species (e.g., living humans) can allow us insight into ancient population dynamics, such as population expansions or migrations. When analyzing mtDNA sequences from ancient fossils of Neanderthals, it is not clear which interpretive model should be used-separate species or variation within an evolving lineage?
The choice of model influences the interpretive meaning. If Neanderthals were a separate species, then the mtDNA evidence can inform us about when this line split off from the ancestors of modern humans. If Neanderthals are not a separate species, then these divergence dates mean little, and provide instead information on ancient patterns of population size and gene flow. Adcock et al.’s study, with its clear demonstration of lineage extinction in modern humans, suggests that the conclusion of separate species status for Neanderthals, while possible, is not conclusive.
Further Studies conducted have found that the Neanderthal DNA set closer to the human sequences, but still clearly distinct from them. The Neanderthal pattern was equally distinct from those of each modern population, from whichever continent. So the Neanderthal was no closer to a living European than to an African, Asian or Australian. However this did not support the idea that Neanderthals were specially linked with Europeans, as partial or complete ancestors. But researchers were able to use the differences between the living human, Neanderthal and chimpanzee DNA sequences to estimate the likely time depth of the Neanderthal line of evolution.
For Neanderthals its separation time from the modern human line is estimated at about 500,000 years. genes begin to differ before populations and species do, but this date is long before the estimated start of the difference of modern human mtDNA types, and indicates that this Neanderthal could not have been one of our ancestors, given its late date and its genetic and physical distinctiveness.
This was the only one progression from one Neanderthal fossil. Studies also point that the Neanderthal mtDNA sequence supported the fact that modern humans arose recently in Africa as distinct species and replaced Neanderthals with little or no interbreeding. But they pointed out that other genes might tell somewhat different stories. This is surely likely because mtDNA is only inherited through females. So any genetic heritage passed on from Neanderthal males to present-day populations, for example, would not be recorded in that particular DNA. However when put together with an increasing body of fossil research showing the distinctiveness of the Neanderthals, it appears that they could have had only a minimum genetic contribution, at best, on the modern populations that succeeded them.
In relevance to the question it is reasonably clear that the importance of genetic evidence for understanding Neanderthal extinction is essential. It not only allows an understanding to the possibilities of what led to their extinction, but it also supports the information on how these genetic traits may have been passed down and as a result became extinct through modern humans. On the contrary view however, competition for resources as survival of the fittest were also found as important evidence that may suggest their disappearance where other homo sapiens began occupying areas and it became difficult for both species to compete for the same resources. Both views are taken acutely, which suggest that both genetic and fossil evidence have equal importance in helping us to understand Neanderthal extinction; through their genetic make-up, physical attributes, environmental roles and psychological differences.
Stringer, Chris, Peter, Andrews (2005) The Complete World of Human Evolution.
Richard G. Klein (1989) The Human Career Human Biological and Cultural Origin. Chicago and London
Stringer, Chris (1998) “Chronological and biogeographic perspectives on later human evolution.” In T. Akazawa, K. Aoki, and O. Bar-Yosef, eds. Neandertals and modern humans in Western Asia. New York: Plenum Press. pp. 29-37.