Where did sex come from? | Vivien Cumming | TEDxUniversityofMacedonia

As a scientist, photographer and writer (BBC), Dr Vivien Cumming spent the majority of her life exploring both remote and familiar corners of the planet. She has an extensive knowledge of the delicate intricacies of the natural world, and how they are intertwined with human lives. “Why humans are here and why they do the things they do”. Viv is foremost an earth scientist. Her postdoctoral research at Harvard and McGill Universities delved into questions deep in Earth’s history when climates were extreme and life was taking hold. In this talk Viv explores the origin of sexual reproduction and the evolutionary steps that led to sex as we know it. She takes us back to nature and the strange organisms where everything started, reminding us how our environment supports and nurtures evolution and ultimately us.

Vivien is foremost an Earth scientist. Her postdoctoral research at Harvard and McGill Universities delved into questions deep in Earth’s history when climates were extreme and life was taking hold. Having spent the majority of her life exploring both remote and familiar corners of the planet, she has an extensive knowledge of the delicate intricacies of the natural world, and how they are intertwined with human lives. Viv now combines science, photography and writing to tell exciting stories about the planet; inspiring sustainability, conservation and an understanding of Earth processes.

This talk was given at a TEDx event using the TED conference format but independently organized by a local community. Learn more at http://ted.com/tedx

Have you ever thought
about the origins

of sleeping, eating, or even sex?

Maybe you're thinking,
'Yeah, that's obvious!'

But actually, is it obvious?

Where do these actions
originally come from?

So let's see.

How many of you have thought
about sex today?

(Laughter)

I can see a few hands.

Don't be shy,

I'm the one standing up
here called Vivian Cumming

talking about where sex came from.

(Laughter)

Seriously, though, sex is everywhere.

You only have to look at
the animal kingdom.

For us, just like animals,

the initial desire usually isn't
even a conscious thought;

It's an instinct coded into our DNA,

just like the instinct to sleep
when we get tired

or to eat when we get hungry.

These are instinctive behaviours
that humans are programmed to do.

Our conscious thoughts - what we think -

only take up a small part
of what goes on in our brain.

The instincts that drive what we do

take up far more of
our brain's processing power.

Where did the program
to have sex come from?

Well, we all know
the real reason for sex

is to produce offspring that will
allow the survival of our species.

But humans weren't the first to have sex,

it actually showed up
on the planet a very long time ago.

Sometimes we have to go back to nature
and delve deep into Earth's history

to understand some of the actions
that make us who we are.

As an Earth scientist,
photographer, and writer,

I tend to go far back in time

looking for the juiciest stories
that nature has to offer.

My curious mind has taken me
on many adventures,

but it's outside in nature
where I find gravity in my thoughts.

For me, the natural world
is a source of great interest

but also of great fulfillment.

My curiosity about the story of sex

goes back to when
I was studying the rocks

on Baffin Island in Arctic Canada.

For me, rocks are absolutely fascinating.

They hold the story
of Earth's 4.6-billion-year history.

If you look at
a mountain range or a cliff face,

each layer of rock
holds a piece of time,

like the chapters in
a book waiting to be read.

Being a geologist exploring the world

is like walking into a library
of Earth's history.

Studying a mountain range
is like taking a book off the shelf;

you read each word and investigate
how that mountain was formed

to understand the story of the Earth.

So I'm sure you're all thinking,

'What on Earth can rocks
tell us about sex?'

Let's get some perspective here first.

If we look at the entire 4.6-billion-year
history of the Earth in a 12-hour day,

we'll call it our Earth Clock,

it's really difficult to understand
geological time in this way.

But if we look at it this way,

starting at midnight,
when the Earth was formed,

and going around the clock
to today, at midday,

then it's a little bit
easier to understand.

At midnight the Earth was formed,

and then at two in the morning
life first evolved,

3.7 billion years ago.

Life started as tiny,
tiny forms of bacteria,

and then as oxygen rose in
the atmosphere at around six o'clock,

things started to look good for life.

So at about nine o'clock,
life decided to have sex.

This was 1.2 billion years ago.

And to get even more perspective,

dinosaurs didn't show up until 11:45;

and us, homo sapiens, our species,

we've only been here for two seconds.

That's only two seconds
on our Earth clock.

I find it humbling to look
at Earth's history this way.

How do we know that sex
evolved 1.2 billion years ago?

Well, we need to look at the fossil record

held within rocks
to find out what did it first.

And it's rocks in Arctic Canada

that hold the clues
scientists are looking for.

A fossil held within these rocks

holds the first evidence
for sexual reproduction.

And it was a creature
vastly different to ourselves.

But before I tell you
what that creature was,

let me tell you a little bit more

about the real story of
the birds and the bees.

The dawn of sexual reproduction
has always been a puzzle for scientists.

Today on Earth,
99% of multi-cellular creatures,

the big organisms that we can see,
reproduce sexually.

Even with all this mesmeric
diversity of sexual methods

that we see in the animal kingdom,

sexual organisms follow the same
basic route to produce new offspring:

two members of the same species
combine their DNA to form a new genome.

But before sex evolved,

all reproduction was done
asexually by cell division,

an organism literally splits
in half to form two.

And it still happens today.

All bacteria, most plants,
and even some animals

reproduce asexually
at least some of the time.

The mechanism of asexual
reproduction is much more efficient

and less messy than sexual reproduction.

You don't have to waste time or energy

searching for and impressing a partner,

you just grow and divide in two.

The organisms produced
are clones of each other.

Would you really want
everyone to look like you?

I certainly wouldn't want
the world to look like this.

(Laughter)

It's the variation in nature
that produces the beauty in the world,

and it's sex that helps
to maintain that variation.

But asexual reproduction is
a much better evolutionary strategy.

Because it only requires one parent,

and all of that parent's genes
are passed onto its children.

So why did sex need to evolve?

Well, decades of work

by legions of scientists
have looked at this question,

and there are a number of theories
for the exact reason,

from protection from disease,

to removal of harmful traits
that aren't of benefit to the species,

but ultimate proof comes
from looking at organisms

that can sexually reproduce
and asexually reproduce.

Primitive single-cell organisms

like the ones that were found
on the early Earth

do just fine with asexual reproduction,

but if environmental
conditions become harsh,

they can turn into sexual species.

An example of one
of these organisms is hydra.

Not the snake-headed
monster of Greek mythology,

Hydra is actually a small animal
that lives in fresh water

though you can see
where it got its name from.

When food is plentiful,
hydra will reproduce asexually.

But if conditions change
and become unfavorable,

hydra will actually
turn to sexual reproduction

by actually growing
sexual organs in its body wall.

The early world was a much more
inhospitable place than today,

and in this harsh environment,

an asexual species may have been forced
to become sexual for the first time.

So sex is a widespread evolutionary force,

but what were the creatures
to first start doing it?

Well, humans evolved
from a common ancestor

that we share with apes,

which in turn evolved from
more primitive mammals,

and they all had sex the way we do.

The evolution of sex as we know it

can actually be traced back
to a 385-million-year-old fish fossil

called Microbrachius Dicki,

and it was actually found
in my home country of Scotland.

'Microbrachius' means little arms.

But it was only recently
that the scientists realised

what those little arms were for.

Careful analysis of the fossils showed

that the arms were involved
in sexual reproduction.

And it wasn't just any kind
of sexual reproduction;

these were the first vertebrates
to reproduce using internal fertilisation,

using an appendage like humans do,

paving the way for sexual reproduction
in its most familiar form.

So these fish may have been
the first vertebrates to have sex,

but they certainly weren't
the first organisms on Earth to have sex,

and to find this out we have to go
to the rocks in Arctic Canada.

They were deposited 1.2 billion years ago
on a marine tidal beach,

and they hold fossils

that show the first evidence
for sexual reproduction.

A fossil called
Bangiomorpha Pubescens

is a multicellular organism
that sexually reproduced;

the oldest reported occurrence
in the fossil record.

It wasn't a mammal or a fish,

it was actually red algae,
better known to us today as seaweed.

So yeah, it was seaweed
that first had sex.

The fossils show male
and female reproductive cells.

Today we know that seaweed
lacks sperm that actively swim;

they rely on water currents
to transport their reproductive cells,

and that's likely
how they've been doing it

for the last 1.2 billion years.

Seaweeds are a very diverse group,

and some of them have remained
very similar over Earth's history.

They're a remnant of the past
to remind us of where we come from.

Going back to the Earth clock.

We've only been here for two seconds,

sex has been here for about three hours,

the planet has been for 12 hours.

This may sound like a lot
to get your head around.

It's hard to imagine seaweed being
the instigator of the sexual revolution,

but it's these significant evolutionary
developments 1.2 bilion years ago

that paved the way
for life on Earth as we know it.

The important thing to remember here

is that it's the variations and changes
in nature that allowed sex to evolve,

and subsequently allowed us
and our intelligence to evolve.

Nature is of huge significance
to our existence.

I've been lucky to travel the world
and see some incredible things,

but sometimes, to put a piece
of the puzzle in place,

it doesn't take amazing mountain ranges
or vibrant coral reefs,

it just takes a piece of seaweed
on the beach at home.

Looking to Nature
and our planet's history

can help us to understand not only
ourselves and where we come from,

but also the potential existence
of life on others planets.

Here on Earth, sex came from seaweed,

and you'd be surprised
at the other stories

Earth's history has to tell us.

Really, we can't look at nature without,
at the same time, looking at ourselves.

Our fates are intertwined.

So let me just leave you
with the profound words

of the poet William Wordsworth:

'Nature never did betray
the heart that loved her.

Come forth into the light of things,
let Nature be your teacher.'

Thank you.

(Applause)