70,000 years ago Lake Toba erupted in Sumatra, Indonesia, leaving a detrimental effect as there were suggested to be 2,000 humans left after the eruption. Not only did it affect the population but the bottleneck effect as it has resulted in a low genetic diversity amongst the individuals and also evolution as a whole. As there was a loss of genetic variability, the risk of extinction increases with only a few who are left remaining in the population, restricting its gene flow. Therefore some alleles will be lost and others amplifies, leaving the small population left contributing to the different allele frequencies. As there were small populations the chances of mutations passing through to offspring increases. These mutations could be catastrophic and be one of the reasons for full extinction. There are advantages to mutations however such as the individuals culture having tribal arrangements where a vast number of men were in charge for the breeding going on in the community. This could have a leading effect in the future as a new species of hominids could be created. The bottlenecks in this species of time have been recognised to be the ones responsible for the quick functioning progress of hominids over time, adding to the population instead of leading to extinction. With bottlenecks facing evolution by such a catastrophe, they are facing pressures such as allopatric speciation which separates the species, having some chances of evolving to become a new species. The new species would grow as a group by their culture through the ability to craft tools, hunt and gather, control fire which allowed them to keep on growing after the eruption instead of dying out
Hominids have been able to find the link into avoiding human extinction through the use of gene flow. Gene flow is the movement of individuals between populations which may result in rapid changes in allele frequencies from the result of emigration and immigration of individuals. Emigration may decrease the variety of alleles present in the population of the emigrant group is not representative of the whole population. Whereas immigration may increase the variety of alleles for a particular trait
BREEDING
Human existence has been able to grow as we are capable of a sexual reproduction, adding to the population. With producing a child with the opposite sex new alleles and traits of the child have been passed on, eventually passing on to their children swell, adding to the genetic diversity of homo sapiens. With the ability of reproduction comes its negatives of interbreeding. Luckily from the technology and knowledge, we as a population are able to reduce the existence of interbred offspring. These offspring lead to affected alleles which lead to abnormalities as they grow up with diseases such as down syndrome. This leads to a lower genetic diversity if interbreeding continues throughout the generation. As more people interbreed the chances of having similar alleles becomes greater, limiting interbreeding for modern homo sapiens, resulting in the population being genetically varied
OUT OF AFRICA
IS OUT-OF-AFRICA GOING OUT THE DOOR ?
In-text: ("Is Out-Of-Africa Going Out The Door ?")
Your Bibliography: "Is Out-Of-Africa Going Out The Door ?". Ramsdale.org. N.p., 2016. Web. 26 Sep. 2016.
It has been hypothesised that the first group of homo sapiens left Africa 1.8 million years ago and diverged into various kinds of species. These new species were known by reproductive isolation so the evolution of these species was separate. There have been fossils found that belong to this diverged group of species, with only one branch of the family tree being linked to todays society, it was African. This explains why Africans today are more genetically variable than various other populations and shows how genetically similar they are to todays human population, meaning they had limited time to diverge to the fullest of their ability. This is a result of parallel evolution where the same environment effects the individuals of having distinctly same traits
MULTIREGIONAL
KATO, A.
Did we, modern humans, come from the same origin? - Human Origin - Beaverland Historica - Wonders and Mysteries of the ancient World History
In-text: (Kato)
Your Bibliography: Kato, Akira. "Did We, Modern Humans, Come From The Same Origin? - Human Origin - Beaverland Historica - Wonders And Mysteries Of The Ancient World History". Beaverland.web.fc2.com. N.p., 2002. Web. 26 sep. 2016.
Through the hypothesis of the first group of homo sapiens leaving 1.8 million years ago from Africa, they never diverged into other species. With gene flow, they shared genes with each other which has led to our existence being apart of this species, leading to a new and evolved behaviour from the first species of human. Through the development of gene flow from ancient populations, it has bought about a low level of genetic variation amongst the human population. The cause of natural selection has also altered our present population as our behaviour and morphology have developed since archaic aged humans. With Africa having a greater population size, there is the consequence of having larger variation within Africa, leading to higher amounts of ecological diversity and local selection, providing Africa the main role in the family tree of homo sapiens leading to todays human population