good morning Hank it's Tuesday I have a
cold and it's super unpleasant and my
younger and more vulnerable years having
a cold was like a slightly annoying
background hum and now it's a borderline
catastrophe I just feel horrible all of
which led me to wonder whether viruses
are strictly speaking necessary so there
are a lot of viruses in the world like
in a healthy River there are often over
400 million viruses in a single teaspoon
of water if you get the flu you might
have over a hundred trillion flu viruses
inside of your body there are more
viruses on earth than there are grains
of sand I don't know which particular
virus is causing my cold because over
200 viral strains can cause colds but
whatever it is there are more of them
inside of my body right now than there
are stars in the Milky Way that's a fun
thing to think about when you're a
germaphobe but it gets worse or possibly
better depending on your perspective
because like all mammals I don't just
contain viruses I am part virus a bunch
of human DNA something like five to
eight percent of our total genome comes
from viruses which bears a bit of deeper
explanation so viruses cannot replicate
on their own which is one of the reasons
they're often seen as not being alive
instead viruses rely upon the cells they
infect to make copies of themselves
viruses insert their genome into the
host cells DNA and then the host cells
start making the proteins that the virus
needs to make more of itself that's
what's happening right now a virus is
using a bunch of my host cells to make
more of itself and there's a battle
going on and eventually I will win that
battle hopefully but sometimes a virus
will infect a reproductive cell a sperm
or an egg and if that's firmer egg goes
on to you know help create an organism
the viral changed DNA will be in all of
that organism cells and the viral
proteins that are now being regularly
produced by this new organism will
sometimes be used by that organism for
new tasks because from an evolutionary
perspective it's a lot easier to use
proteins that your DNA is already making
than it is to like invent entire new
ones this process was for instance
critical to the development of placentas
like over a hundred million years ago
there was this small shrew like creature
that developed a placenta using proteins
from a virus without that virus
placentas would not have evolved as they
did humans would not exist as they do
and i would not be able to be miserably
SiC on account of hell I would not exist
so there are two takeaways for me here
one I cannot unambiguously hate viruses
because I am partly a product of them
and two life is weird
like really really weird Hank you've
helped me get my head around the
extraordinary diversity and ubiquity of
life on Earth with your new show journey
to the micro cosmos which is maybe my
favorite YouTube channel of all time
like not since I watched Carl Sagan host
cosmos as a kid have I felt such awe
toward the strange universe around us
zoom way out and we're just one solar
system among billions of solar systems
in a galaxy that is among billions of
galaxies but zoom way in and look at for
instance how microscopic organisms eat
and hunt and a teaspoon of water becomes
a universe of its own and whether it
comes to defining life or fathoming our
place in the world looking at the micro
cosmos can be especially interesting
because as you said in a recent video
when you look very very close every
sharp line turns out to be blurry now
there aren't viruses in Journey to the
micro cosmos because even by microscopic
standards viruses are very small also
based on the photographs I've seen of
viruses I'm not sure I need to see video
of them but Hank your show has helped me
to see the microscopic world as
something more than a mere threat and I
really appreciate that
all right go watch journey to the micro
cosmos it's so good I'm gonna go to bed
Hank I will see you on Friday