9:59:59.000,9:59:59.000
So it all came to life

9:59:59.000,9:59:59.000
in a dark bar in Madrid.

9:59:59.000,9:59:59.000
I encountered my colleague[br]from McGill, Michael Meaney.

9:59:59.000,9:59:59.000
And we were drinking a few beers,

9:59:59.000,9:59:59.000
and like scientists do,

9:59:59.000,9:59:59.000
he told me about his work.

9:59:59.000,9:59:59.000
And he told me that he is interested

9:59:59.000,9:59:59.000
in how mother rats

9:59:59.000,9:59:59.000
lick their pups

9:59:59.000,9:59:59.000
after they were born.

9:59:59.000,9:59:59.000
And I was sitting there and saying,

9:59:59.000,9:59:59.000
this is where my tax dollars are wasted,

9:59:59.000,9:59:59.000
on this kind of soft science.

9:59:59.000,9:59:59.000
And started telling me

9:59:59.000,9:59:59.000
that when the rats, like humans,

9:59:59.000,9:59:59.000
lick their pups in very different ways.

9:59:59.000,9:59:59.000
Some mothers do a lot of that,

9:59:59.000,9:59:59.000
some mothers do very little,

9:59:59.000,9:59:59.000
and most are in between.

9:59:59.000,9:59:59.000
But what's interesting about it

9:59:59.000,9:59:59.000
is when he follows these pups[br]when they become adults,

9:59:59.000,9:59:59.000
like years in human life,

9:59:59.000,9:59:59.000
long after their mother died,

9:59:59.000,9:59:59.000
they are completely different animals.

9:59:59.000,9:59:59.000
The animals that were licked[br]and groomed heavily,

9:59:59.000,9:59:59.000
the high licking and grooming,

9:59:59.000,9:59:59.000
are not stressed.

9:59:59.000,9:59:59.000
They have different sexual behavior.

9:59:59.000,9:59:59.000
They have a different way of living

9:59:59.000,9:59:59.000
than those that were not treated

9:59:59.000,9:59:59.000
as intensively by their mothers.

9:59:59.000,9:59:59.000
So then I was thinking to myself,

9:59:59.000,9:59:59.000
is this magic?

9:59:59.000,9:59:59.000
How does this work?

9:59:59.000,9:59:59.000
Us geneticists would like you to think

9:59:59.000,9:59:59.000
perhaps the mother had[br]the bad mother gene

9:59:59.000,9:59:59.000
that caused her pups to be stressful,

9:59:59.000,9:59:59.000
and then it was passed[br]from generation to generation.

9:59:59.000,9:59:59.000
It's all determined by genetics.

9:59:59.000,9:59:59.000
Or is it possible that something else

9:59:59.000,9:59:59.000
is going on?

9:59:59.000,9:59:59.000
So in rats we can ask this question

9:59:59.000,9:59:59.000
and answer it.

9:59:59.000,9:59:59.000
So what we did is[br]a cross-fostering experiment.

9:59:59.000,9:59:59.000
You essentially separate the litter,

9:59:59.000,9:59:59.000
the babies of this rat, at birth,

9:59:59.000,9:59:59.000
to two kinds of fostering mothers,

9:59:59.000,9:59:59.000
not the real mothers,

9:59:59.000,9:59:59.000
but mothers that will take care of them,

9:59:59.000,9:59:59.000
high-licking mothers[br]and low-licking mothers.

9:59:59.000,9:59:59.000
And you can do the opposite[br]with the low-licking pups.

9:59:59.000,9:59:59.000
And the remarkable answer was,

9:59:59.000,9:59:59.000
it wasn't important

9:59:59.000,9:59:59.000
what the gene you got from your mother.

9:59:59.000,9:59:59.000
It was not the biological mother[br]that defined this property

9:59:59.000,9:59:59.000
of these rats.

9:59:59.000,9:59:59.000
It is the mother that[br]took care of the pups.

9:59:59.000,9:59:59.000
So how can this work?

9:59:59.000,9:59:59.000
I am an a epigeneticist.

9:59:59.000,9:59:59.000
I am interested

9:59:59.000,9:59:59.000
in how genes are marked by a chemical mark

9:59:59.000,9:59:59.000
during embryogenesis, during the time[br]we're in the womb of our mothers,

9:59:59.000,9:59:59.000
and decide which gene will be expressed

9:59:59.000,9:59:59.000
in what tissue.

9:59:59.000,9:59:59.000
Different genes are expressed in the brain[br]than in the liver and the eye.

9:59:59.000,9:59:59.000
And we thought, is it possible

9:59:59.000,9:59:59.000
that the mother is somehow

9:59:59.000,9:59:59.000
reprogramming the gene of her offspring

9:59:59.000,9:59:59.000
through her behavior?

9:59:59.000,9:59:59.000
And we spent 10 years,

9:59:59.000,9:59:59.000
and we found that there is[br]a cascade of biochemical events

9:59:59.000,9:59:59.000
by which the licking and grooming[br]of the mother, the care of the mother

9:59:59.000,9:59:59.000
is translated to biochemical signals

9:59:59.000,9:59:59.000
that go into the nucleus and into the DNA

9:59:59.000,9:59:59.000
and program it differently.

9:59:59.000,9:59:59.000
So now the animal can[br]prepare itself for life.

9:59:59.000,9:59:59.000
Is life going to be harsh?

9:59:59.000,9:59:59.000
Is there going to be a lot of food?

9:59:59.000,9:59:59.000
Are there going to be a lot[br]of cats and snakes around,

9:59:59.000,9:59:59.000
or will I live in an upper[br]class neighborhood

9:59:59.000,9:59:59.000
where all I have to do[br]is behave well and proper

9:59:59.000,9:59:59.000
and that will gain me social acceptance?

9:59:59.000,9:59:59.000
And now one can think about[br]how important that process can be

9:59:59.000,9:59:59.000
for our lives.

9:59:59.000,9:59:59.000
We inherit our DNA from our ancestors.

9:59:59.000,9:59:59.000
The DNA is old.

9:59:59.000,9:59:59.000
It evolved during evolution.

9:59:59.000,9:59:59.000
But it doesn't tell us if you are going[br]to be born in Stockholm,

9:59:59.000,9:59:59.000
where the days are long in the summer[br]and short in the winter,

9:59:59.000,9:59:59.000
or in Ecuador, where equal number[br]of hours for day and night

9:59:59.000,9:59:59.000
all year round.

9:59:59.000,9:59:59.000
And that has such an enormous amount[br]on our physiology.

9:59:59.000,9:59:59.000
So what we suggest is perhaps[br]what happens early in life,

9:59:59.000,9:59:59.000
those signals that come through the mother

9:59:59.000,9:59:59.000
tell the child

9:59:59.000,9:59:59.000
what kind of social world[br]you're going to be living in.

9:59:59.000,9:59:59.000
It will be harsh, and you'd better[br]be anxious and be stressful,

9:59:59.000,9:59:59.000
or it's going to be an easy world,[br]and you have to be different.

9:59:59.000,9:59:59.000
Is it going to be a world[br]with a lot of light or little light?

9:59:59.000,9:59:59.000
Is it going to be a world[br]with a lot of food or little food?

9:59:59.000,9:59:59.000
If there's no food around,

9:59:59.000,9:59:59.000
you'd better develop your brain[br]to binge whenever you see a meal,

9:59:59.000,9:59:59.000
or store every piece of food[br]that you have as fat.

9:59:59.000,9:59:59.000
So this is good.

9:59:59.000,9:59:59.000
Evolution has selected this

9:59:59.000,9:59:59.000
to allow our fixed, old DNA

9:59:59.000,9:59:59.000
to function in a dynamic way

9:59:59.000,9:59:59.000
in new environments.

9:59:59.000,9:59:59.000
But sometimes things can go wrong.

9:59:59.000,9:59:59.000
For example, if you're born[br]to a poor family,

9:59:59.000,9:59:59.000
and the signals are, "You'd better binge.

9:59:59.000,9:59:59.000
You'd better eat every piece of food[br]you're going to encounter."

9:59:59.000,9:59:59.000
But now we humans[br]and our brain have evolved,

9:59:59.000,9:59:59.000
have changed evolution even faster.

9:59:59.000,9:59:59.000
Now you can buy a McDonald's

9:59:59.000,9:59:59.000
for one dollar.

9:59:59.000,9:59:59.000
And therefore, the preparation

9:59:59.000,9:59:59.000
that we had

9:59:59.000,9:59:59.000
by our mothers

9:59:59.000,9:59:59.000
is turning to be maladaptive.

9:59:59.000,9:59:59.000
The same preparation that was[br]supposed to protect us

9:59:59.000,9:59:59.000
from hunger and famine

9:59:59.000,9:59:59.000
is going to cause obesity,

9:59:59.000,9:59:59.000
cardiovascular problems,[br]and metabolic disease.

9:59:59.000,9:59:59.000
So this concept that genes[br]could be marked by our experience,

9:59:59.000,9:59:59.000
and especially the early life experience,

9:59:59.000,9:59:59.000
can provide us a unifying explanation

9:59:59.000,9:59:59.000
of both health and disease.

9:59:59.000,9:59:59.000
But is true only for rats?

9:59:59.000,9:59:59.000
The problem is, we cannot[br]test this in humans,

9:59:59.000,9:59:59.000
because ethically, we cannot[br]administer child adversity

9:59:59.000,9:59:59.000
in a random way.

9:59:59.000,9:59:59.000
So if a poor child develops[br]a certain property,

9:59:59.000,9:59:59.000
we don't know whether this is caused

9:59:59.000,9:59:59.000
by poverty

9:59:59.000,9:59:59.000
or whether poor people have bad genes.

9:59:59.000,9:59:59.000
So geneticists will try to tell you[br]that poor people are poor

9:59:59.000,9:59:59.000
because their genes make them poor.

9:59:59.000,9:59:59.000
Epigeneticists will tell you

9:59:59.000,9:59:59.000
poor people are in a bad environment[br]or an impoverished environment

9:59:59.000,9:59:59.000
that creates that phenotype,[br]that property.

9:59:59.000,9:59:59.000
So we moved to look

9:59:59.000,9:59:59.000
into our cousins, the monkeys.

9:59:59.000,9:59:59.000
My colleague Steven Soomey