November 10, 2017 Friday
Bedtime Story
The Two MRCA : The Matrilinear MRCA (mt-MRCA) or Mitochondrial Eve and the Patrilineal MRCA (Y-MRCA) or the Y-Chromosome Adam
But it is not too difficult an exercise to
calculate or estimate the time at which the MRCA existed.
The time when MRCA of a certain group of
individuals existed is called time to MRCA or in short TMRCA.
We will not go into the details of how
TMRCA is calculated as that is a highly technical field and more importantly,
we will completely digress tangentially from our story line just as if earth
was been flung off its orbit tangentially in the absence of sun.
It has to be born in mind that when we
speak about MRCA in organisms that reproduce sexually like we do, there
obviously will not be one but two MRCAs, the male and the female.
These two MRCA who are the mother and
father of all their descendents are biologically termed matrilinear MRCA and
patrilineal MRCA respectively.
Since we humans always wish to keep
ourselves apart from the rest of living individuals (just like rich like to
keep themselves apart from the poor and educated from the illiterate), we have
given to our MRCA even more fancier name.
And not surprisingly, even here right in
the heart of evolutionary biology religion has managed to cast its ugly shadow
on it.
In humans, the matrilinear MRCA (mt-MRCA) has
been imaginatively named as the mitochondrial eve and the patrilineal MRCA
(Y-MRCA) as the Y-chromosome Adam.
Now let us go back to the topic of cousins
that I was initially interested in.
In English language and in English speaking
world, a system of “degrees” and “removals” are used to describe the different
kind of cousins.
For two individuals to fit in the criteria
of being cousins, they must be:
(a) They must share a common ancestor
(b) Their MRCA has to be at least two or
more generations away from each individual.
Moreover to be cousins, those two cannot
posses the following properties:
(a) These two individuals who are cousins
cannot be ancestor or descendent of each other.
(b) This also means that cousins cannot
share a parent.
(c) Lastly, they cannot be siblings of a
common ancestor.
Cousins are further specified by removal
and degree.
The removal of cousins specifies the number
of generations they are apart.
There is another way of putting it.
Cousins are removed if the cousins are
separated by a different number of generations from the MRCA.
This is better understood with an example.
Stay tuned to the voice of an average story storytelling
chimpanzee or login at http://panarrans.blogspot.com
Good night mon ami and my fellow cousin ape.
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Another great educator and a teacher that I am aware of is
Professor Subhashish Chattopadhyay in Bangalore, India.
While I narrate stories, Professor Subhashish an electronic
engineer and a former professor at BARC, does and teaches real mathematics and
physics.
He started the participation of Indian students at the
International Physics Olympiad.
Do visit him here:
All his books can be downloaded for free through this link:
For edutainment and English education of your children, I
recommend this large collection of Halloween Songs for Kids:
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