Page 95 - THE MELANESIA DIASPORA FILE CETAK ISI 10022017

fertilized, only mitochondria from the mother form part of newly-formed embryo cells.
As a result, mitochondrial DNA (mtDNA) is only inherited from the maternal line and not
from the DNA of both parents. In other words, a mother will pass on her mtDNA to all of
her descendants and the daughters will in turn pass it on, and so on across the generations
(Wallace, 1995). Therefore, the study of mitochondrial DNA provides us information about
female kinship and migration history, all the way back to the first woman.
It is also possible to trace the journey of male ancestry through the Y-chromosome. The
Y-chromosome is a long strand consisting of 60 million base pairs (bp) of one DNA copy from
sperm that is also inherited from one parent. Inside the Y-chromosome there are repetitive
short sequences of nucleotide bases called Short Tandem Repeats (STR) and other markers
in the form of single nucleotide bases named Single Nucleotide Polymorphisms (SNP). Both
of these can be used to reconstruct the history of male kinship and migration. These DNA
markers are much more informative compared with classical genetic markers, which in the
past used blood type. There are a number of reasons for this. First, there have been many
characters collected to enable better past kinship analysis. Further, both mitochondrial DNA
and Y-chromosomes are inherited from only one parent, female and male respectively, and
this could illustrate recent demographic processes and the latest evolution history. Another
supportive factor is that both are neutral markers because they do not affect phenotypes
and therefore are free from environmental influence.
Genetic information, the blueprint of life in the form of DNA strands, is passed down
to our children and subsequent generations. However, the multiplication or replication
of DNA molecules which occurs during this is not always accurate. Errors in copying
the genetic information can cause mutations or changes in the nucleotide bases of the
DNA. These mutations are accumulated from one generation to another. The larger the
number of mutations accumulated in the DNA of two individuals living at different times,
the greater the kinship distance between them. The variation in bases or polymorphism
resulting from this process is called SNPs. SNPs can be used to differentiate one individual
from another and is the most commonly found DNA variation. SNPs can also play a role
as a genetic background or as a predisposition factor which influences susceptibility or
sensitivity to certain diseases. Data from various research reports also indicate that SNP is
population specific.
The combination of bases in certain locations in mtDNA is used to determine the
maternal inheritance line. This combination is called the mtDNA haplotype and is
generated based on polymorphism variations found in various locations in D-loop

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