(ominous music)
On Mars you would have a feeling
like we're just not familiar with.
You feel lighter than you do on Earth.
Like that sort of strange sensation you have
when you're walking in an airplane and it starts to descend.
On Mars life will feel both strangely familiar
and unlike anything we've ever experienced before.
Extreme isolation, tens of millions of miles from home.
As we adjust to living on the Red Planet
and work to make it more like our Earth,
inside our bodies something extraordinary
will begin to take place.
If humans end up living on other planets, like Mars,
that could trigger evolutionary changes
that might lead us down a path
by which we eventually become new species of humans.
In the distant future, ready or not,
we will become Martian.
(ominous music)
(moves into contemplative music)
Humans are built for our planet.
Our bodies are really configured
to allow us to walk around on two legs
with exactly the amount of gravity
that we experience here on the surface of the Earth.
Our hearts are adapted to be able to provide blood
to all of the parts of our body
under earth gravity conditions.
Our eyes are really well adapted to see
in the light conditions here on Earth.
Our brains evolved to help us
to make sense of the environment
that our species evolved in.
These changes to our bodies
took place over grand scales of time.
So gradually that our ancestors never perceived
how they were adapting to their changing world.
(rocket thrusters roaring)
And now humans are approaching the moment
when they will leave Earth for Mars.
A planet with conditions that neither we,
nor our ancestors, ever faced before.
We're always under evolutionary pressure.
But nothing like what people living on Mars will experience.
The challenge is to adapt to conditions on Mars
will be more extreme than almost anything that's happened
in the history of evolution here on Earth.
Thanks to the International Space Station though,
we can start to get a glimpse
of the kinds of changes our bodies will go through
once we leave Earth.
The most significant hazard present
on the International Space Station is a lack of gravity.
Aboard the ISS in low Earth orbit
some of the effects of microgravity become apparent quickly.
When you go into microgravity,
a significant amount of your blood volume
shifts to your upper body.
And you see the crew members,
the pictures demonstrate it quite well,
their faces get very puffy.
The fluid inside your head shifts as well.
And you're disrupted by the idea of my ears are clogged,
my nose is stuffy, my eyes are watering.
It may not actually be a negative impact
on how your brain functions,
but part of your thought process
is distracted by the distress you feel.
You're just uncomfortable.
That persistent discomfort
might play a role in a phenomenon
astronauts often complain about, known as space fog.
The crew members feel fuzzy,
their functions start to slow down,
and it takes them longer and longer to do,
you know, pretty regular procedures
that we all take for granted.
Inside the astronauts bodies,
the lower gravity is driving more substantial changes
to the muscular and skeletal systems.
The body is trying to understand the lack of signal.
The body is stopping its investment
in things like bone and muscle.
Bones become more weak and brittle.
And one particular muscle
experiences and especially dramatic change.
In a lower gravity environment
we expect the heart to become weaker
because it won't have to pump quite as hard
to be able to move blood all around the body.
After a routine mission to space
lasting a few months to a year,
astronauts can typically rebuild their muscle and bone mass
after they return to Earth,
but we don't know how our bodies would react
if that mission to space ended instead
on the surface of Mars,
where the gravity is just 3/8ths as strong as the Earth's.
Would we ever regain the strength we had on our home planet?
If you've watched any of the rovers land,
it's a rough landing.
So we have to think about protecting the crew
because they're no longer as robust as they were
when they left Earth.
The potential danger of a broken bone
would threaten humans as long as they stayed on Mars.
Imagine breaking a bone on Mars
and losing the ability to manipulate objects with your hands
or to move your wrist.
If you have a broken bone on Mars,
it's gonna make it really hard
to do all of the intense physical labor
that's gonna be necessary to make a living
and to thrive in the Martian environment.
You know, the austerity of the environment
takes, you know, an issue that here on Earth we could fix
to something that is catastrophic and or fatal.
How our bodies respond to Mars' gravity
will not only affect those first settlers.
It may also affect the evolution of our species.
If we're able to reproduce on the planet.
Those who will pass their genes onto the next generation
will more likely be those who experience
less cognitive decline and who tend to grow denser bones,
even in low gravity, than their peers.
And while the ability to perform manual labor
on this hard scrabble landscape
is one area where having denser bones could be a benefit,
denser bones would be even more essential
to women during pregnancy.
During pregnancy a woman's bones already become brittle
because some of the calcium from her skeleton
is being transferred to the growing fetus's skeleton.
At the same time,
increasing amounts of pressure are placed on the pelvis,
One of our most remarkable adaptations.
The pelvis allowed us to walk upright as humans
and it's the bone which helps females
support their wombs during pregnancy
and later deliver their babies.
If women experience a fractured pelvis during childbirth,
that could threaten her life and the life of the baby.
And that means that women that have relatively denser bones
would be less likely to fracture a pelvis during childbirth,
and that would make them more likely to survive
and to be able to pass on their genes for stronger bones.
Another possibility is if childbirth is just too risky,
we might see a rise in ceasarean section births.
Interestingly, if we have a situation
where most births are through a C-section
that actually could free up the head
to become larger and larger
because the head would no longer be constrained
by having to fit through the birth canal.
The idea that when there's a lot of C-section births,
the head could become larger,
is supported by studies here on Earth that have found that
in places where C-sections are especially common,
like in the US and Brazil,
the heads of babies are already becoming noticeably larger.
Over time, humans on Mars
could develop thicker frames
or larger heads than their earthbound relatives.
But to succeed on Mars, our species will need to adapt
to more the just Mars' low gravity.
We'll need to develop some protections
against the persistent radiation that engulfs the planet.
Radiation, which has the power to mutate our genes
and perhaps accelerate our rate of evolutionary change.
So out in space, there are all these energized particles
moving very, very quickly through the solar system,
close to the speed of light.
Some of them come from our sun and some of them are coming
from far outside our solar system.
Mars lacks a magnetic field and without a magnetic field
particles can actually go down
and impact the surface of Mars.
Like UV radiation,
the kind of radiation that we're familiar with on Earth,
those can also cause damage to the molecules in your body.
For the first wave of settlers,
this could lead to increased rates of cancer.
Subsequent generations would be impacted further.
When you think about reproducing
on something like the Mars surface,
DNA damage can definitely be passed along.
The generational scale of the effects of radiation
are something we'd really want to understand better
before we decide we're going to start having families
on the surface of Mars.
And these just aren't experiments we can do on humans.
And on some level, the first people to go live on Mars
will be our experiments.
This is part of the uncertainty
inherent in our future evolution.
In all living organisms,
mutations ive species an opportunity to experiment
with different survival strategies.
Some of these mutations will lead to failure.
Some however could lead
to surprising successful adaptations.
We know that the pigments in our skin here on Earth
help protect us from the intense ultraviolet radiation
from the sun.
People that live in different parts of the Earth
have adapted to the different
ultraviolet radiation environments
by evolving different amounts of the skin pigment eumelanin.
Eumelanin is a natural sunscreen
that protects our skin from damaging ultraviolet light.
It's possible that people living on Mars
will adapt skin pigmentation that increases their ability
to tolerate the intense radiation
that we experienced on the surface of Mars.
[Narrator] And the skin pigmentation
that evolves out of life on Mars
could look like what we find here on earth,
or it could be an entirely new pigment for our species.
Here on Earth some organisms use carotinoids
to protect themselves from radiation.
Carotinoids are what give carrots their orange color
and beta carotene is an example of a carotinoid
that can be found in sunscreen
because it helps protect from ultraviolet light.
It's possible that mutations could arise
that lead to carotinoids like beta carotene
being produced in the skin of people on Mars.
That could make people on Mars develop orange skin.
Shrunken hearts, heavy skeletons,
large heads, and orange skin.
Whatever gives us an advantage
for surviving Mars' grueling surface conditions
will become more common in each new generation.
But evolution is often a grindingly slow process
and there is no guarantee that a Martian colony
would survive long enough
to see these beneficial adaptations
become common in future generations.
So what could we do now
to ensure the success of a permanent Martian settlement?
It might come down to whom we select
to be the first settlers.
I think the first people that will go to Mars
are gonna have to, first of all, be really hardy.
We'd want a diversity of skills, a diversity of outlooks,
a diversity of talents to make sure that
all of these components that make human culture
are being accommodated by that group.
For the Mars missions,
when you think about the diversity of skills,
it runs across many disciplines.
Geologists, agricultural specialist,
biologists, physicists, astronomers,
because all of those skills will be necessary
not only to do the science,
but to understand how to use and exist in the environment
that's present.
And even more important than skill diversity
will be genetic diversity.
The one thing that keeps on resonating
across all of biology is that the more diverse, the better.
Why, because it gives you a pool of opportunity
to be responsive and adaptive.
When you talk about the genetic basis for success,
you know, for any one gene that represents a vulnerability,
it also represents a resource.
The collection of genetic traits
that make it to Mars
will determine how future settlers will look, behave,
and adapt to the planet.
In the field of evolutionary biology,
this is known as the founder effect
and the more genetic breadth the founders carry with them,
the better chance we'll have of developing the right formula
for successful human life on Mars.
To illustrate how the founder effect works,
we can use colored gumballs
to reflect some of the genetic diversity
of the first Martians.
Each color representing a unique version of a specific gene,
known as an allele.
So if we take only a small number of individuals,
it's possible that we will leave out
some of the genetic diversity that's present here on Earth.
And that could be dangerous because some of those traits
in the genes present here on Earth
might be valuable in the Martian environment
in ways that are hard for us to anticipate.
What if the red gumball was an allele
that gave people the ability to fight cancer
caused by the high radiation environment on Mars.
We might not know that in advance,
but by leaving out some of the diversity present on Earth,
we lose the ability to benefit from those genes
when we get to Mars.
Humans hold some 20,000 genes.
And when you consider the number of variants,
or alleles those genes can exhibit,
it becomes clear just how much genetic diversity
our planet's population holds.
By sending the most diverse founding population possible
we better our chances of bringing with us
the advantageous cancer fighting allele,
represented by the red gumball.
So if this red trait ends up being really beneficial
in the Martian environment,
then in the next generation it might become more common.
Eventually over several generations
it might become very common.
And as generations pass,
it might eventually be present in all individuals.
This is the way that natural selection works.
It makes traits that are beneficial,
more common from one generation to the next.
If that cancer-fighting red trait
were present among the original founders,
humans could adapt more quickly and more effectively.
There could also be mutations that arise
that cause completely new versions of a trait
that aren't present at all on earth.
And maybe this now represents
an even more potent anti-cancer gene
that makes it even more likely that people can survive
in the intense radiation environment on Mars.
And so that trait was spread even quicker
and replace preexisting traits in the population
in just a few generations.
A Martian population,
all sharing this anticancer trait,
a trait unique to the planet Mars,
would be making a profound evolutionary leap.
The longer that people on Mars remain isolated
from people on the Earth,
the more new traits they'll acquire.
Eventually over time, people acquiring new traits on Mars
will look more and more different from people on Earth.
And eventually will give rise
to a new human species on Mars.
Eventually we will become Martian.
The challenges of settling on Mars are infinite.
But there will always be a degree of uncertainty present
that we probably will never eliminate
and that's what exploration is about.
I think that's what drives us to continue to move forward.
As a scientist, I'm hopeful that we can survive on Mars.
I think it's possible that we'll be able to get through
all of the challenges that Mars will give us
and be able to actually live and survive.
This will be one of the most incredible achievements,
not only in our history, but in the history of all life.
(tense music)