Insects are the most diverse group of organisms on Earth.
The true number of species is unknown, but some estimates
suggest that only a fraction have been identified.
They have successfully adapted to every ecosystem on our planet.
But insects still harbour many mysteries.
Where do they come from?
When did they first appear on Earth?
How and why have they diversified and multiplied so successfully?
At a time when certain insect species are in danger of extinction
and there is greater interest in their role within ecosystems,
this is the fascinating story of their origins.
This insect adventure begins in French Guiana
in the heart of the Amazonian rainforest.
It's a fabulous destination for scientists like Romain Garrouste,
a paleo-entomologist at France's National Museum of Natural History.
The climate in French Guiana provides ideal conditions
for the development of life.
Romain is measuring the abundance of life
in this entomologists' paradise.
TRANSLATION:
Scientists so far have identified over two million insect species
but believe that there are many, many more.
Some estimate that between 3 and 10 million species remain unknown.
HE COUGHS
The scientific community still has a long way to go
to fully understand all this biodiversity.
Accompanying Romain is a specialist in interactions between insects
and tropical ecosystems.
Philippe Grandcolas is an entomologist and research director
at France's CNRS.
The two scientists are heading to a site deep in the heart
of the rainforest to examine this extraordinary ecosystem.
To date, insect life has been relatively undisturbed
in French Guiana.
Insects are omnipresent in the forest.
Despite their tiny size, the biomass of insects
is greater than that of any other species on Earth.
To document certain species and even discover new ones,
Romain wants to explore one of the least studied areas
of this environment - the treetop canopy.
While numerous insect species are yet to be discovered,
the significant mystery for scientists is their origin.
How and when did they appear on our planet?
This is a crucial question when 40% of species
are in danger of extinction.
There are now indications that all insects
are descended from a single lineage,
but this hypothesis has yet to be fully proven.
To do this, scientists use the retro-evolution model,
tracing the insect evolutionary tree
back to the hypothetical first insect, which they've named LUCIA.
The acronym for Last Universal Common Insect Ancestor.
Information obtained from insect fossils found all over the world
provide essential evolutionary clues.
Some extraordinary specimens have been found at one site in Germany.
- We are actually here at the Messel pit.
It's an old volcanic crater that was filled up with water,
and so we had an ancient lake 50 million years ago.
- Torsten Wappler is the curator in charge of this former
oil shale mine.
- This lake was quite steep and at the bottom of the lake
we had anoxic conditions, so no oxygen,
so we have no organisms that destroy our fossils
at the bottom, like what happens normally.
This is the reason why we have this special kind of preservation.
So the information that you can get here from the fossil record
could be really quite detailed.
Now we can start to excavate here just smoothly,
then we can lift up these bigger plates
to see if we have some fossils on the surface.
You can estimate 0.1mm per year
how much time you have here in this piece.
You can read in this stone like a book.
So this is the first page, then the next chapter,
and then the next chapter, and then the next chapter,
so you can reconstruct Earth's history,
erm, for the last 50 million years.
Ah, OK, there's a light-brown structure...
..and close to this light-brown structure here,
there's a net-like structure. This is an insect remain.
It's not really easy to recognise.
And this is what the oil shale makes so fantastic and so interesting
for doing some research, because the preservation of all these materials,
particularly plants and insects, is so, so, erm, fine
and so precise that you have even colour preservation of insects.
When we found blue metallic, shining insects,
that is more or less the original colour of the insects
50 million years ago.
- Each fossil provides crucial information
for understanding certain chapters of insect evolution.
For example, these beetle fossils found in Messel.
Beetles are the insect family with the most species.
500,000, or one-quarter of all known insect species.
The morphological characteristics that define insects
are already present in these fossils.
A body divided into segments.
The head, the thorax, the abdomen,
as well as two pairs of wings and three pairs of legs.
Spiders, for example,
which have four pairs of legs,
aren't insects.
These characteristics haven't changed since the beginning of time.
This anatomical consistency
over tens of millions of years
is the first piece of evidence that allows researchers
to claim that insects,
despite their diverse and sometimes incredible forms,
could have the same common ancestor.
LUCIA.
Research in the field of phylogenetics -
the study of the genetic evolution of species -
is now making it possible to obtain new evidence
and even an idea of when LUCIA appeared.
This is what Bernhard Misof is working on in Bonn,
in his laboratory next to the Koenig Museum.
Thanks to DNA, Bernhard Misof is exploring
the hitherto hidden genealogy of living organisms,
particularly insects.
These species have been his lifelong passion.
- Here we are in the entomological collections of the Museum Koenig.
This is a quite extensive collection -
around 2 to 3 million specimens -
so it makes it a really, really precious thing,
because with these collections we can study
the evolution of diversity and we can also study
how diversity changed due to the impact of humans.
We've studied the morphology, the different shapes,
the different structures, in order to reconstruct
who is related to whom.
But this not an easy task because most likely
insects originated millions of years ago.
They also use these collections to extract molecular information,
for example, entire genomes, to reconstruct relationships
among different species based on the genomic information.
- In the past, visual analysis was the main method used
to establish relationships between different insect species.
Today, genome studies are revealing similarities
and genetic relationships that were once hidden to us.
A sample of the specimen is ground up
and then sequenced to chart each gene.
- If you really want to understand the evolution of insects,
we need to understand the relationship
between the evolution of the genomes and the phenotypes,
so this means which genes are responsible for which character,
and with the genome sequencing, we are starting to get
the necessary information to address these questions.
Now we have huge amounts of information available
from which we can extract information
on relationships of species.
The major challenge is really analysing the data.
- In his laboratory, Bernhard Misof has set up one of the largest
supercomputers in Europe, specifically dedicated to this task.
- You need a lot of computing power because...
..consider you want to reconstruct the phylogenetic relationships of,
let's say, 1,000 species.
The number of different trees you have to check is uncountable.
It's absolutely uncountable.
These machines have to check billions and billions of different
tree versions until they find a most likely, best solution.
The basic idea for biologists is, if we sequence the genome,
we might be able to say how that animal looks like.
We are not in that stage yet
and we don't know whether this will ever be feasible.
But, in theory, if we sequence insect genomes,
we should be able to trace the transition
and we should be able to say how the ancestral insects
might have looked like.
- So far, these new tools have confirmed
that there has been no break in the evolution of insects.
Unlike other living things such as flowers,
insects only appeared once on Earth.
It's the same original lineage that diverged over time
into numerous species.
Proof that LUCIA, the first universal common insect,
did indeed exist in a distant past.
To try to determine when LUCIA first appeared,
scientists have devised a predictive method - the molecular clock.
Using the available data, the clock estimates the time needed
for two species to diverge.
Then, by counting the number of branches
in the species' family tree,
it calculates how far back in time the tree can be traced.
- There's lots of uncertainty in these calculations.
Every single fossil helps.
As soon as we can place the fossil on the insect backbone tree,
it helps us to recalibrate all of our molecular calculations
of the origin of different groups.
The molecular analysis somehow suggests that the insects
appeared about between 470 and 500 million years ago, roughly.
- Even in the age of genetics and biocomputing,
fossils remain as important as ever, and the search for LUCIA
has opened up a new golden age for paleo-entomology.
Despite very few fossils bearing witness
to the early days of insects, the fossil record contains
vital clues for determining LUCIA's characteristics.
In the Cretaceous period, evolution accelerated rapidly,
with new species suddenly appearing in very large numbers.
This is what scientists call an evolutionary surge.
During this geological period,
which spans almost 100 million years
between 60 and 145 million years ago,
all the lineages of modern insects appeared,
including some totally unexpected ones,
such as this discovery made by Diying Huang,
professor at the Nanjing Institute of Geology and Palaeontology
in China.
TRANSLATION:
Not only are these fleas the earliest known,
they're also ten times the size of our modern flea,
with the females measuring over two centimetres.
They come from a site in Liaoning province
where, 145 million years ago,
a volcanic eruption preserved the landscape.
What still remains a mystery
is why fleas were here 145 million years ago.
What kind of environment and ecosystems supported them?
The flea fossil studied by Diying Huang
had already adapted to living in feathers.
We can distinguish the rostrum,
used to bite and suck the blood of their hosts,
and two mandibles with serrated edges to cling onto skin.
However, these ancient fleas hadn't fully evolved into modern fleas.
Their legs don't have the ability to jump.
This adaptation came later
to escape delousing and to colonise new hosts.
In the late Cretaceous, a major catastrophe caused the extinction
of almost 70% of life on Earth,
most notably the dinosaurs.
But fleas survived and continued to evolve.
Further proof of the incredible adaptive capacity
and resilience of insects.
Scientists are also examining another type of fossil -
amber.
Fossilised resin.
Some of these pieces are over 100 million years old
and contain insects that are particularly well preserved.
Grenoble in France is home to
one of Europe's most high-tech laboratories.
Using new imaging technologies, researchers can observe
the characteristics and properties of objects
right down to the atomic and molecular level.
Kathleen Dollman is a specialist in 3D synchrotron tomography.
In fact, she's about to scan one of these pieces of amber
in an attempt to better understand how certain insect organs evolved
and help determine LUCIA's anatomy.
- This synchrotron is a 844-metre ring.
Basically, we accelerate electrons
and control their flow with magnets,
and by doing this, we produce very, very powerful X-rays
that we use for a number of experimental techniques.
- The insect trapped in the amber is often intact.
X-rays 100,000 times more powerful than a medical scanner
are able to reconstruct its volume by way of measurements
taken through the piece of amber.
- With something like amber insects, they're extremely small,
so when we mount them, we have to make sure that they're perfectly
aligned with where the beam, which is the X-ray energy
from the synchrotron, enters the experimental hatch,
which is the room that we're in.
We have a beam that is 2.5mm wide for something like this
and we have to align it perfectly down 220 metres of pipeline.
- BEEPING
BEEPING STOPS
ALARM BLARES
- I think you have 0.0001 seconds to survive
if you're in one of the hatches when the X-rays are on.
- Tomography is a revolutionary technology for paleo-entomology
as it enables a virtual dissection of fossilised insects.
LONG BEEP
- So, erm... So this, for example, that I'm showing you here,
is a beautiful slice through the amber specimen.
So this is, erm, the insect.
It's very beautiful.
So, to put it in perspective, the size of the specimen,
the specimen... One micron is equal to 1,000th of a millimetre,
so the specimen is extremely small but we can still see a lot
of details, like the individual ridges, these projections out.
- This specimen is particularly interesting as it represents
a lineage of primitive insects
that has mandibles starting to protrude from the head.
In some of their descendants, this will evolve to form the rostrum,
enabling them to bite plants and prey.
By tracing the evolution of an organ as complicated as this mandible,
scientists can deduce the evolutionary mechanisms
for the insect's entire anatomy,
enabling a first composite sketch of LUCIA...
..the original insect.
In his quest to find LUCIA, Romain has come across
traces of giant insects in the south of France.
Why were they so huge?
And what can they teach us about LUCIA?
These fossils date back to the Permian period -
about 260 million years ago.
They are much older and larger than the fleas found in China.
They are fossils of dragonflies of an unbelievable size...
..called Meganeura.
Aside from their exceptional size,
Meganeura looked quite similar to today's dragonflies.
A spherical head, large mandibles with teeth,
legs covered in hard hairs,
a large thorax
and a long, thin body.
They were, without question, formidable predators.
To explain why Meganeura was so big,
several theories have been developed,
but the most interesting one is linked to the levels of oxygen
in the atmosphere.
In this period, the air was made up of around 35% oxygen.
Today it's 21%.
This figure is key because insects have a very specific way
of breathing.
Running through insect bodies is a network of channels
whose branches bring air directly into the cells.
Each cell breathes on its own,
giving insects an evolutionary advantage.
Without a doubt, the LUCIA already had this system,
or at least a rudimentary version of it.
The combination of the composition of the atmosphere
and this unique breathing system
allowed large insects to fly.
The cells in the muscles needed for flying
benefited from the oxygen-rich air supply.
Then, 250 million years ago,
70% of vertebrates suddenly disappeared,
and we still don't know why.
This event marked the end of giant insects.
Today, the largest dragonflies have a wingspan of just 16cm.
The biggest known insects are the atlas moth
and the 30cm-long giant stick insect found in the Borneo forest.
After this extinction event, the insects that survived
employed a common strategy for escaping their predators.
INSECT BUZZES
Being small and using mimicry...
..this strategy allowing them to hide in their environment.
Throughout their history, insects have adapted
in many spectacular ways, with two particular evolutionary successes.
Flying...
..and metamorphosis.
But when did these changes appear?
And why?
To reach full maturity, many insects must go into chrysalises or cocoons,
or moult.
This spectacular process, which appeared in the Triassic period,
allows adults to take on very varied shapes and sizes
without the need for very complex larvae.
The larvae and the adults do not compete for food.
Insects can also speed up or slow down these metamorphoses
to wait for favourable conditions before becoming adults
and reproducing.
Thanks to this system, the variety of insects has increased.
But flying further boosted this family of species.
To explain the introduction of flight,
Romain is hoping to find clues in the middle of the Arctic Ocean.
These developments would have taken place 100 million years earlier,
between the Triassic and the Carboniferous periods.
Two crucial periods for the future of insects.
Jean Sebastien Steyer, a palaeontologist at France's CNRS,
is one of the specialists of this period.
TRANSLATION:
BIRDS SQUAWK
Until now, scientists have been faced with a significant problem.
Insect fossils have never been found in geological layers
dating back 325 to 385 million years.
The Devonian period is characterised by the appearance
of the first large trees,
and in particular trees with bark and tree ferns.
Low sea levels gave rise to vast marshes and forests.
It's in this environment that one of the most significant developments
in insect evolution took place.
Romain and Jean Sebastien hope to find a fossil
of one of the first flying insects
in the oldest rock layers on Svalbard.
But they will only be able to confirm the fossil's origin
and contents once they are back in the laboratory.
Even without fossils from the Devonian period,
which would help explain how insects came to fly,
scientists have been able to hypothesise where wings came from.
The commonly held theory is that the insect's abdomen segments evolved.
Paddle-shaped protrusions are thought to have helped
the first six-legged specimens to move through the trees.
These paddles then developed into wings.
Rigid at first for gliding,
the theory maintains that the developing wings
became articulated to enable flapping during flight.
For 150 million years,
insects were the only living beings capable of flight.
A major evolutionary advantage that still persists today.
INSECT BUZZES
The anatomy of some species was further simplified
by reducing the number of wings to a single pair.
INSECT BUZZES
Making insects swift and manoeuvrable
with fine and powerful control of their wing movements
allows the angle of attack,
rigidity and flapping frequency to be adjusted.
These flight capacities are so amazing
that they're now the subject of extensive scientific study.
In France, Camille Arachelof, a researcher
at the Physics and Mechanics Laboratory of Sorbonne University,
is studying the flight of dragonflies -
one of the most complex and fascinating species.
TRANSLATION:
After identifying each species,
Camille observes dragonfly flight in slow motion.
In flying insects, the muscles are either attached directly
to the wings or the whole thorax contorts, causing the wings to move.
These systems enable precise control of flapping and angle of movement.
Some dragonflies lie in wait for prey,
others swoop like hawks...
..reaching speeds of 22mph
and ascending at up to 3mph.
Camille is trying to understand how some insects, like dragonflies,
can generate lifting forces three times their weight.
Camille's first observations led her to think that the wing contortions
contribute greatly to the force being generated.
An energy-saving solution that could also be applied to industry.
Scientists are now attempting to reproduce and analyse
these exceptional evolutionary developments in the laboratory.
Engineers everywhere are looking to these biological models
for solutions to modern technological challenges.
This is called bioinspiration or biomimetics.
But while solutions can be found by studying modern insects,
even more can be obtained by studying ancient ones.
This concept is called paleo-inspiration,
giving the search for LUCIA, the foundation stone of this edifice,
even greater significance.
But one essential question still needs to be answered -
how did insects appear on Earth?
The answer is no doubt hidden somewhere in Miguasha,
a National Park in north-eastern Canada.
Olivier Matton is a palaeontologist and head of conservation
at this site.
He's been excavating here for the past 15 years.
Miguasha is a treasure trove for palaeontologists.
The fossils found here over the last 100 years
tell an extraordinary story.
It's about the origins of the first land animals,
when strange species began
their transition from water to land
in the Devonian period, 380 million years ago.
Bernhard Misof's molecular clock has made it possible to estimate
that insects appeared about 470 million years ago
in the early Devonian or late Silurian period.
Paleo-entomologists believe that the appearance of insects
is thus undoubtedly linked to when life became terrestrial.
In environments like Miguasha, rich in super predators
like the first fish with legs,
it's believed that certain crustaceans came out of the water
and gradually adapted to terrestrial environments.
So crustaceans may have been the ancestors of insects.
In fact, morphological similarities between the two species
validate this theory.
Some insect fossils show traces of organs resembling gills
on their legs.
The development of the nervous system in insects and crustaceans
is strikingly similar.
Even today, some crustaceans and insects
still live between terrestrial and marine environments.
It's thought that to adapt to a terrestrial environment,
insects differentiated themselves from crustaceans.
Their head became separate from their thorax,
the number of their body segments and legs decreased.
But no fossil has been found that confirms this theory.
Maybe one day Olivier will find one that finally proves
the origin of insects and reveals more of LUCIA's secrets.
Insects are indispensable to our world.
They play a vital role in it,
which is why it is so important to protect them.
But just as LUCIA and its descendants have withstood
cataclysms for hundreds of millions of years,
insects will continue their journey
with or without us.
Evolution hasn't ended...
..and who can predict what insects will look like
in 10, 50, 100 million years?