Uploaded by cembugrakaboglu

The Origins of Modern Humans in Africa

The Origins of Modern Humans in Africa
1. What is meant by population structure? Why is this significant?
It is the patterns in the population allele frequencies which can vary in terms of single
nucleotide polymorphisms (SNPs). It can be changed due to gene flow resulting from a
migration. Also loss of panmaxia (random mating) due to any other environmental effect can
lead to change in the allelic frequencies. It is an important indicator to understand any
migration event or the separation of the populations. Population structure allows a population
to diversify. It is an important tool for evolutionary genetics and human genetic research in
Africa where there is the highest allelic frequency differences in the world. It can point out the
past migration events and gave clues about effects that lead to those migrations, like past
climate changes which act as a drive for evolutionary change.
2. What is the founder effect, where at and what date are founder effects documented? Why is
this significant?
It is the loss of genetic variation when a small sub-population from a greater population
migrate and establish a new population. Due to loss of genetic variation it can cause
difference between parent and new sub-populations (can lead to speciation in extreme cases).
In human lineage one founder effect seen from South Africa to Middle and Northern Africa
by the 50-60 Kya according to Henn (2016). This is followed or co-occurred with another
founder effect at 50-60 Kya, from Africa to Near East. At 45 Kya one effect can be seen from
Southeast-Asia to Oceania. Another late founder effect seen at later date of 15 Kya, occurred
from North Asia to Americas. It is an important effect as it lead to phenotypic and genotypic
differences among human populations and can lead to changes in allelic frequencies and
speciation. It is an important aspect to consider for understanding human expansion over the
3. What sort of evidence (genetic and archaeological) is presented that shows where modern
humans originated in Africa?
There genetic and non-genetic evidences. Non-genetic evidences consists of archaeological
founds. They show regionally differences between human populations in the Africa during
Middle Stone Age. Rock art and skeletons and shell beads found all over the Africa validate
such claims of differences. Also linguistics is another important non-genetic area to show
human origins in Africa. Single language origin from some parts of the Africa is an important
phenomenon that can shed light to human origins in the continent.
There are also very important genetic evidences form genetics field. The fact that the most
genetic diversity is found in Africa, compared to the all other places in the world is an
important indicator of Homo sapiens radiation out of Africa initially. Y-chromosome studies
validates this higher genetic diversity in Africa. Also mitochondrial DNA studies gave out
similar results. They are important genetic areas to study as they gave out maternal and
paternal origins in human genome. Along with mtDNA and Y-chromosome studies,
autosomal chromosome studies yields important results. SNPs and microsatellites (short
sequences of nucleotides that repeats in unique patterns in the genome). All this genetics
indicators along with the phenomenon of population structure, allelic frequencies and gene
flow, shows a great deal of evidence to say that modern humans originated from the African
continent. Henn suggest that a simple single origin model is plausible and says South Africa
as the origin point for human lineage.