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)