the average person can hold their breath
underwater for like one or two minutes
but every day on an archipelago in
southeast asia the bajao people dive
down more than 60 meters deep to catch
fish and they can hold their breath for
more than 10 minutes
how
that's better
this ability it doesn't just come from
years of training it's thanks to a
genetic change in this population in
other words it's an example of very
recent human evolution that makes a
group of people better adapted to their
environment
but what about the rest of us
are we still evolving as humans live
longer die less and make more and more
tools to protect us from the dangerous
world that we live in does that mean
that we've bypassed that great filter of
natural selection
what is the future of human evolution
[Music]
hey smart people joe here the bajao
people sometimes spend five hours a day
holding their breath i mean that's more
time underwater than a sea otter what's
even cooler is how they do it so the
secret to their superhuman breath
holding is an actual physiological
change bajao spleens are up to 50
percent larger than yours or mine
you know the spleen is an
underappreciated organ it acts like an
oxygen reservoir by storing red blood
cells the ones that carry oxygen so a
super-sized spleen means more oxygen can
get into your bloodstream between
breaths
other highly adapted diving mammals like
whales and seals they have super spleens
too
now you and me we can't just beef up our
spleens by diving a lot that's not how
evolution works the jowl divers have
lived in a watery environment for
thousands of years somewhere along the
way a genetic change happened that gave
some people there bigger spleens those
people ate more they survived more and
over many many generations that
adaptation became more common
this is natural selection it's a gene
becoming more common in a population
over time because the individuals who
carry that gene are more likely to
survive the pressures of their
environment
since our species showed up we have
spread to every environment on earth our
ancestors faced countless environmental
pressures different foods different
climates
and once we settle down in large groups
domesticated plants and animals and
started building civilizations we've had
to face a lot of deadly germs because
civilization
is filthy y'all a lot of people died as
a result of those new pressures but our
ancestors survived often because of new
and improved versions of genes that they
carried
like himalayan populations whose lungs
can breathe air with 40 less oxygen than
what most of us breathe
or people in parts of africa who are
more resistant to the germ that causes
lassa fever or how populations who
migrated closer to the poles developed
lighter skin to make the most of less
intense sunlight at high latitudes you
know since our bodies need sunlight to
make vitamin d and speaking of vitamin d
let's talk dairy
love this stuff
calcium in milk also aids in vitamin d
production but most animals can't digest
milk very well after they grow up
losers
luckily for some of us a genetic change
allowed us to keep our milk drinking
abilities switched on throughout our
lives and because milk is a reliable
source of protein and calories milk
drinking evolved independently in lots
of different places
changes like these and countless others
that helped shape our species they
happened because of natural selection
genes becoming more common because they
make it easier to survive
but today
is different
i mean humans have invented so many
tools we've got medicines sanitation
environmentally controlled living pods
more food than we literally know what to
do with i mean name the last time you
thought you might be eaten by a tiger on
your way to get lunch right
people just don't die as much as they
used to human life expectancy has more
than doubled over the past 200 or so
years
and now that almost everyone is
surviving past the age where they can
make babies
does that mean natural selection doesn't
apply to us anymore is this the post
darwin age of humanity have we entered
the hyper technological transhuman
utopia
have we stopped evolving
no
because natural selection isn't the only
way evolution happens folks
some genetic changes just become common
by random chance let me show you what i
mean
this jar is full of m ms every bag of m
ms has this population makeup but this
population of m ms has a very different
makeup from the original population and
so will the future population and that
happened because of a chance event when
i grabbed a random handful
delicious now i could do that again and
again and i'd get different results each
time and this can happen to genes too
when random events decide what genes
survive and become more common
not the environment that's not natural
selection it's genetic drift well let's
say a bunch of highly advanced life
forms live here
until a meteor hits
thanks to random chance these ones
survive and over time the population
looks a lot different
or maybe through a series of unfortunate
events a few of them end up on this
island
what this new population looks like will
depend on the individuals that founded
it this kind of thing happens with
humans too if you're from european
ancestry there's a 90 chance or more you
got wet sticky earwax if you're native
american or from east asia you've got
about a 90 chance of having dry flaky
earwax this difference is caused by two
different versions of a single gene but
the type of earwax you have doesn't
exactly give you a survival advantage so
which version became more common where
it's probably just the result of which
gene version was carried by the first
humans to migrate to those regions
catch my drift
genetic drift but these chance effects
of genetic drift are more likely to be
significant in small isolated
populations and humans are not that i
mean we move around we share culture and
as we move around and mix more than ever
genes are mixing too
so that's decreased the genetic
differences between human populations
overall
and when rare versions of genes do arise
it's more likely that they'll get
diluted out by the mixing
humans living longer or dying less
thanks to our awesome inventions may
reduce the effect of natural selection
humans moving around multiplying and
mixing a lot may reduce the effect of
genetic drift that means really wild new
adaptations like the bajau's super
spleens are probably going to be less
common in the future
when you put all this together well a
lot of people have claimed that as
darwin's ideas lose their grip on us and
as humans move around and mix ourselves
up we're going to start looking more and
more alike
but that's not how this stuff works
and even things like skin color or eye
color they involve a symphony of dozens
of genes all interacting in a ton of
combinations
i mean just consider the variation in
physical appearance we already see today
in people with mixed ancestry
people will always be plenty different
there is one more process though that
can influence our evolution apart from
natural selection
and it has to do
with how babies happen
ask your parents
jeans don't just randomly find each
other individuals have a choice in who
they mate with if you're attracted to
the largest fanciest antlers in a herd
well that will lead to fancier antlered
babies even if fancy antler jeans don't
necessarily make you better suited to
your environment
this is an example of sexual selection
where the genes that survive are tied to
who picks who to do the mating thing now
how sexual selection will impact the
future of human evolution that's up for
debate
but let's say the things that we're
attracted to today are tied to
intelligence and many scientists think
at least some are
that might mean more future humans that
have traits tied to intelligence like
bigger brains or a genetic
predisposition to watch this youtube
channel
again this isn't genes that help us
survive a germ or our environment it's
genes that may just make us more sexy
now this last part may feel a little bit
icky depending on how exactly you feel
about things but thanks to our tools the
future of human evolution may be in part
something that we can control
or at least try to
our species already relies on machines
to survive and thrive and we're only
going to continue to rely more on those
machines in the future
while taking more and more power out of
the hands of natural selection along the
way
and we will increasingly not just depend
on machines for help but one day we're
going to be physically or norally
integrated with them and frankly
no one knows what that will do to our
genes or which ones become more or less
common
with genetic engineering we now have the
ability to insert custom genetic
sequences into living things even
ourselves
perhaps even pick and choose the genes
that we want our offspring to have
this is a form of evolution that really
no other species can do
how big of an influence these future
forces have on our species is also up to
us but it will almost certainly have
some effect
evolution is just change
and that's a process that never stops
for our species or any other
natural selection happens to be just one
way that evolution happens but there are
many others so even if our big brains
have made it so natural selection
doesn't determine our future as much as
it used to
change is a constant you know it's
pretty interesting to think that we may
be the only species on earth with the
power to determine at least a little bit
of what our future change looks like and
that is a power that comes with great
responsibility
and also hopefully comes with a cold
glass of milk
and an oreo
stay curious
[Music]
hey what's up guys i'm down here in
florida making our next episode but
before you go i want to tell you
something that's going to make the
history buffs out there pretty excited
pbs has just launched a brand new
history focused youtube channel it's
called pbs origins it's going to be home
to a bunch of great new shows but right
now you can go check out historians take
which is a look at history through the
lens of pop culture what old cultures
can teach us about our own and our
future you're gonna love it there's a
link down in the description where you
can go check them out and make sure and
tell them that i sent you all right
we'll see in the next video and as
always a huge thank you to everyone who
supports the show on patreon we could
not do this without your support if you
would like to find out how you can
support the show and the videos we make
find out what we're doing behind the
scenes things like that and find out
about new videos before anyone else
click the link down in description i'll
see you in the next video
nice
bring your
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who's talking to you that's true
you got one shot at that