so what’s the science we use to study
the ancient migratory paths of your
ancestors it’s something called
population genetics and it helps us to
piece together how humans populated the
earth here’s how it works
historically people close to each other
tended to share more of those genetic
markers the little DNA typos passed on
from parents to their kids
than they did with people on the other
side of the world it makes sense after
all who are they more likely to meet
fall in love with and have babies with
the people living nearby over time this
created regional patterns of genetic
variation so the people living in say
northern Spain had more markers in
common with each other than they did
with people in Indonesia these regional
patterns of variation allow us to track
the migratory paths of your ancestors by
looking at where in the world your
markers are found we can figure out
where you came from and by looking at
the order in which these markers have
occurred over time and where in the
world they originated we can actually
track the journey your ancestors
followed from an African homeland to
where you came from more recently how do
we find these markers in the billions of
A’s C’s GS and T’s it’s not easy little
like finding needles in a haystack
that’s because when a mom and a dad have
a baby their chromosomes are copied and
passed on to their child but not in a
straightforward way instead mom and
dad’s chromosomes are shuffled when
they’re passed on to their kids
imagine a deck of cards containing only
hearts and another containing only
spades now shuffle em up and look at
your hand it’s going to be a mix of
hearts and spades the cards your parents
have that in a different combination
this makes tracking our markers really
hard for most of our chromosomes but we
found a shortcut there’s one of your 23
pairs of chromosomes that gets passed on
virtually unfelt it’s called the Y
chromosome if we look at your Y
chromosome the markers that your
ancestors left you from thousands of
years ago should still be in the same
order but there’s a catch to the Y
chromosome it exists only in males
passed on directly from five
– son in fact it’s the y-chromosome that
makes a male a male there’s another kind
of DNA though located in different part
of the cell it’s only passed on from
mothers to their children it’s called
mitochondrial DNA or mtDNA for short
it’s much smaller than the DNA that
makes up our 23 pairs of chromosomes but
it contains the same kind of markers the
little genetic typos that pass
untroubled from generation to generation
on the maternal line so by looking at
markers on the y chromosome and
mitochondrial DNA we can connect people
alive today to ancestors that live tens
of thousands of years ago over the last
several years the Genographic project
has studied the Y chromosomes in
mitochondrial DNA of more than half a
million people we now know that everyone
on earth belongs to one of hundreds of
distinct groups of related people based
on which markers they have on their Y
chromosome or mitochondrial DNA we call
these groups haplogroups each person in
these groups traces their descent from a
common ancestor haplogroups your branch
on the human family tree
the ancient migratory paths of your
ancestors it’s something called
population genetics and it helps us to
piece together how humans populated the
earth here’s how it works
historically people close to each other
tended to share more of those genetic
markers the little DNA typos passed on
from parents to their kids
than they did with people on the other
side of the world it makes sense after
all who are they more likely to meet
fall in love with and have babies with
the people living nearby over time this
created regional patterns of genetic
variation so the people living in say
northern Spain had more markers in
common with each other than they did
with people in Indonesia these regional
patterns of variation allow us to track
the migratory paths of your ancestors by
looking at where in the world your
markers are found we can figure out
where you came from and by looking at
the order in which these markers have
occurred over time and where in the
world they originated we can actually
track the journey your ancestors
followed from an African homeland to
where you came from more recently how do
we find these markers in the billions of
A’s C’s GS and T’s it’s not easy little
like finding needles in a haystack
that’s because when a mom and a dad have
a baby their chromosomes are copied and
passed on to their child but not in a
straightforward way instead mom and
dad’s chromosomes are shuffled when
they’re passed on to their kids
imagine a deck of cards containing only
hearts and another containing only
spades now shuffle em up and look at
your hand it’s going to be a mix of
hearts and spades the cards your parents
have that in a different combination
this makes tracking our markers really
hard for most of our chromosomes but we
found a shortcut there’s one of your 23
pairs of chromosomes that gets passed on
virtually unfelt it’s called the Y
chromosome if we look at your Y
chromosome the markers that your
ancestors left you from thousands of
years ago should still be in the same
order but there’s a catch to the Y
chromosome it exists only in males
passed on directly from five
– son in fact it’s the y-chromosome that
makes a male a male there’s another kind
of DNA though located in different part
of the cell it’s only passed on from
mothers to their children it’s called
mitochondrial DNA or mtDNA for short
it’s much smaller than the DNA that
makes up our 23 pairs of chromosomes but
it contains the same kind of markers the
little genetic typos that pass
untroubled from generation to generation
on the maternal line so by looking at
markers on the y chromosome and
mitochondrial DNA we can connect people
alive today to ancestors that live tens
of thousands of years ago over the last
several years the Genographic project
has studied the Y chromosomes in
mitochondrial DNA of more than half a
million people we now know that everyone
on earth belongs to one of hundreds of
distinct groups of related people based
on which markers they have on their Y
chromosome or mitochondrial DNA we call
these groups haplogroups each person in
these groups traces their descent from a
common ancestor haplogroups your branch
on the human family tree
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