[Music]
we all love cars for their beauty and
performance but except for guys like
these not everyone really understands
what's inside
[Music]
is this what you're looking for not even
close
you could stand over there oh okay I'll
just stand over here
[Music]
in a way cell biologists are like auto
mechanics each cell has an astonishing
number of intricate parts way more than
any car we studying what the parts are
how the parts work together and even
which parts of the cell can be left out
without causing too much harm if you
understand the inner workings of the
cell you can understand a lot about all
living things what makes them thrive
what makes them fail and what causes
them to evolve we'll cover more about
that later right now I want to look at
the topic of complexity you and I are
made of about 40 trillion cells they
comprise every part of our complex human
anatomy but the truth is that we can
reduce the number of parts and still
have function if we'd lost an eye and
ear or a hand and would be very
unfortunate but our lives could go on
the same applies to this rather complex
drill it has some cool add-ons but I
could take off this battery gauge during
this LED light for a few other gadgets
and I'd still have a working drill but
how far can I reduce its complexity and
not ruin it I don't want to take apart
my drill so let me move to another
example this mousetrap the complexity of
this machine entails five parts the
platform the spring the hammer the
holding bar and the catch now if I
reduce the number of parts from five to
four if I take away the holding bar or
the spring or any other part it wouldn't
work
every part is essential I call this
irreducible complexity
so does this apply to biology - do we
have examples of irreducible complexity
in life
try this one here's a bacterium a
single-cell microbe some bacteria have a
flagellum which is like an outboard
motor on a boat it rotates to propel
bacteria through liquid and it's
necessary for their survival in order to
swim to search for food a flagellum has
a number of parts a driveshaft a
universal joint a rotor bushings stator
even a clutch and braking system the
motor of the flagellum has been clocked
at a hundred thousand revolutions per
minute and as with the mousetrap
removing even one component of this
elegant machine destroys its function
and renders the bacterium shall we say
dead in the water
the flagellum is irreducibly complex now
we know that this was assembled in a
factory but how is the bacterial
flagellum developed in nature keep in
mind the flagellum is irreducibly
complex all the parts have to be in
place or it does not work
could it have been developed blindly in
stages let's say in the distant past the
bacteria first gained a driveshaft later
on a rotor not a stator and then the
rest then the parts got in sync as a
high-performance engine the theory of
evolution tells us that given enough
time any organic structure we see today
no matter how complex could have slowly
and fully developed by random unguided
forces will come back to the topic of
complexity in our next video which will
examine the power of evolution
[Music]
you
[Music]
you