Translator: Rhonda JacobsReviewer: Ellen Maloney Imagine this.
You have just wonten million dollars in the lottery.
(Laughter) You have just eaten the most delicious, warm, chocolate brownie that has ever been baked.
have just had sex.
(Laughter) And you.
have just done all three at the same time.
Congratulations to you, too.
(Laughter) In these situations, our brainsproduce chemicals called neurotransmitters which give us these great feelingsof energy, excitement and happiness.
And without such chemicals inside of us, we wouldn't feel such emotionsduring such pleasant circumstances.
So instead, imagine this: You've just been fired.
You're about to sit an exam.
You have depression.
In these situations, our brains, instead, produce different chemicals, making us feel stressed and anxious.
The highs and lows of lifeare controlled by our emotions and these chemicals in our brains.
This vital organ inside all of us that controls everythingthat we feel, think and do.
However, as a biologist, I've alwaysfound it strange to comprehend that every feeling, thought, and action that we have is controlled by a three-pound, soggy lump of cells inside of our heads, until I discoveredthat this might not be the case.
The story I want to share with you todayunfolds a fascinating new revelation in our understanding of human physiology, that we each have a second brain, another organ in our body which controls as muchof our physical and mental functions as the brain in our heads, and which may be the key link betweenmodern disease epidemics, globally, from obesity to cardiovascular disease, maybe even to mental health.
But first, to give you a littleintroduction to this story, I want to tell you a little bitabout my background.
I was brought upin a family of psychologists.
My mom is a clinical psychologist; my dad a professorof psychology in a university; my sister even has a PhD in psychology.
So when it came to me going to university, I wanted to study something different.
I'd heard enough about the brainand how it worked at home so I wanted to study something new.
I considered what I was interested in, and I figured outthat from a very early age, I'd had a big interest in food.
I loved eating food.
So, I decided to study human nutrition.
And this was greatbecause I got to study food, how it affected our bodies, how it could contribute to disease, and more importantly, how we could use itto fight and prevent disease.
This story begins back in 1845 with the birth of a curiousyoung boy in Russia who became an incredible man, but who was forgottenby history and medicine.
Ilya Mechnikov was fascinatedby everything in nature, and by the age of eight, he was taking notes on all the living thingsin his vibrant back garden.
He became so good at sciencethat he discovered the role of phagocytes, some crucial cells in our immune systems, for which he won the Nobel Prize in 1908.
But it was his scienceafter winning the Nobel Prize that was even more crucialto our understanding of human health, through a tale of discovery, death, and self-experimentation.
See, everyone in this roomhas something in common.
We all spent the firstnine months of our existence inside our mothers' wombs.
And this was essentiallya sterile environment where no other living thingsexisted, just you.
But as you emerged into this world, you were smotheredin an invisible coating of microbes, friendly microbesfrom your mother's birth canal.
And these bacteria grewto form what is now a three-pound invisible organinside your large intestine, the same weight as your brain, and which has become knownas our microbiota, or microbiome.
And this invisible organhas grown so much, in fact, that right now, 90 per cent of the cellsin your body are bacterial cells; only ten per centare your own human cells.
So you are more bacteriathan you are human.
(Laughter) This ecosystem of microbes in your gutis as diverse as the Amazon rainforest.
Thousands of speciesall with different functions.
And your health is incredibly dependent upon the life and vibrancyof this rainforest.
Your gut bacteria digest certain foods, produce essential vitamins and hormones, respond to medicine and infections, control your blood sugarand blood cholesterol levels.
Meaning the typesof bacteria in your intestines can significantly controlyour risk of certain diseases from obesity to diabetes, maybe even osteoporosis.
They're involved in just aboutevery process in your body.
They function almost as a second brain.
Well, Ilya Mechnikov may havefigured this out himself in 1892.
He lived in France, in Paris at the time, where a deadly choleraepidemic had broken out with thousands of deaths.
Naturally, as a scientist, he decidedthe best way to study this was to drink a broth of cholera himself.
Remarkably, he didn't get sick.
So again, as a true scientist, he needed to increase his sample size, so he recruited a colleagueto do the same thing.
This guy didn't get sick either.
But when he recruitedanother colleague to do the same, this poor guy got critically illand very nearly died.
By studying cholera under the microscope, Metchnikov found that certain speciesof bacteria from the human intestines supported and stimulated cholera's growth, while other species prevented it.
He subsequently claimed that our gutmicrobiota, or our gut bacteria, were essential for human health, and that the right balanceof microbes inside of us could help stave off disease.
However, popularunderstanding at the time, was that the human gutwas a noxious reservoir of toxins.
Surgeons had even begun removingentire sections of human intestines in patients with gut discomfort.
Mechnikov's death in 1916 meant that his ideas that our gutbacteria were good for us were forgotten.
A decade later, antibiotics were discovered, and drastically became overused.
C-sections became common.
Diets became Westernized.
A war was waged on microbes and we spenta century trying to kill them, which turned our intestinal rainforestsinto barren wastelands.
This Nobel Prize winner's ideaswere lost in time.
Some of the implications of thiswere identified recently.
See, right now, one in three childrenin America are born by C-section, meaning they don't get this initialinnoculum or coating of bacteria that's been designed by evolutionto be in the mother's birth canal.
Instead, they're first coatedwith other bacteria on the skin or in the hospital environmentwhich has contributed to up to a 25 per centincreased risk of obesity, asthma, immune deficiencies and inflammatorybowel disease in later life.
Fortunately, in recent times, we've realized we mustrestore our relationship with gut microbesfor our own physical health.
However yet, we've stillcompletely underestimated their role as our second brains.
And this is somethingthat I'm researching.
And I learned this firstthrough the intriguing story of a mouse.
If mice become colonizedby the microbe Toxoplasma gondii, an intriguing thing happens: they lose their fear of cats.
(Laughter) In fact, they become attracted to cats.
(Laughter) In essence, they go a bit mad, and unfortunately for them, usually end up as dinner for cats.
(Laughter) So, this microbe ingested by this animaltakes control of its brain, and changes the waythat it thinks and behaves.
So, by delving deep inside the intestinaljungle of bacteria in our intestines, we've begun to findsome incredible discoveries that are changing our appreciationfor bacteria forever.
See, our bellies and brains are physically and biochemicallyconnected in a number of ways.
First of all, our intestinesare physically linked to our brain through the vagus nerve which sends signals in both directions.
Interestingly, even thoughif this is severed, our intestines can stillcontinue to function fully without a connection to the brain, suggesting they have a mind of their own.
Secondly, our brains are made upof a hundred billion neurons which continuously send messagesto tell our bodies how to work and behave.
Well, interestingly, our gutshave a hundred million neurons.
Thirdly, our microbiomesare the centerpoint of our immune systems, meaning a disturbance down here can cause subtle immune reactionsall around the body, which if prolonged, can affect brain health.
And finally, do we remember our chocolate-eating, lottery-winningwomanizer here in the front row? He demonstrated for usthe neurotransmitters are these chemicals that can changethe way we think and behave, and how we feel.
As it turns out, most of these neurotransmitters are also produced in our gut, none more so than serotonin, nature's antidepressant, 90 per cent of whichis produced in our intestines, less than ten per centis produced in our brains.
Meaning the typesof bacteria inside of you may control the waythat you think and behave.
Has stress ever messed with your insides? Have you ever had a gut feeling? Or butterflies in your stomach? You may have to think twice about that.
So, you can see, despite my naivereluctance as a teenager, I've begun to study not onlyone brain, but two brains.
In the APC MicrobiomeInstitute in Ireland, we're fascinated in this linkbetween our belly and our brains, and we research howour modern diets and lifestyles are impacting this gut-brain relationship, and how we can design interventionsto target the microbiota in order to preventand treat chronic diseases.
For example, we've shown that the types of fatsthat you eat throughout life can drastically changethe types of bacteria that decide to reside in your intestines.
In addition, we've shown that by feedingspecific strains of bacteria, it can enhance memory, stress behavior, and stress hormone levels in animals.
And in addition to a numberof other researchers worldwide, we've identified lists of foodsthat can act as prebiotics, or foods that can stimulate the growthof healthy bacteria inside our intestines.
To me it's fascinating that our health is so dependentnot only upon nourishing ourselves, but upon feeding other livingmicroorganisms inside of us, meaning future strategiesto target and treat chronic diseases, including brain health, may dependon targeting or feeding our gut microbiomes.
As it turns out, Ilya Mechnikovmay have known this himself.
See, much earlier in his life he married, but his wife quickly became sickwith tuberculosis and died.
The stress and trauma of this led Metchnikov to takean overdoes of opium.
Thankfully, he survived.
He then re-married, and when his second wife got sickwith the deadly typhoid fever, this time he injected himselfwith a deadly tick-borne disease.
Thankfully, he survived again.
It was only after this, Metchnivok began studyingand appreciating the microbiota.
He moved to Paristo work in the Pasteur Institute where he began hypothesizingthe right balance of microbes in the gut could help stave off disease, and he published a seriesof books and lectures describing how to achieve thisand prolong life.
Despite the stress and mental turmoilthat he'd experienced in earlier life, he spent the rest of his life dedicated and obsessed withresearching how to prolong human life.
He began studying an interesting groupof people in Eastern Europe who were living exceptionally long lives, and he noted that they all drankbacterial-fermented milk every day and he suggested thatthis contributed to their longevity.
Interestingly, he began drinkingthis bacterial-fermented milk himself, and seemingly lived a healthy life rid of the stress and mental turmoilhe'd experienced in earlier life.
Maybe that was just coincidental.
He described the time in Parisas the happiest of his life.
But Metchnikov died in Francein 1916 at the age of 71.
The life expectancyin France at the time was 40.
As humans, we all needto adopt a greater appreciation for the microbes inside of us.
The incidental war we've wagedon bacteria over the last century has led to bacterial extinctionand sparked an epidemic of modern plagues.
I'm here on a Fulbright to research how we can restoreour relationship with microbes, and how this can be usedto prevent and treat chronic diseases.
But I feel that we all havethe responsibility and the potential to follow in Ilya Metchnikov's footsteps.
Not only to revive his scientific findingsthat were lost in time, but to adopt his desireto prolong healthy, human life.
Whether it's by educating ourselveson the risks and benefits of C-sections, restricting unnecessary antibiotic use, or by adopting a gut-friendlydiet and lifestyle, we can all support the life of microbesthat we've evolved to live alongside.
So imagine this: Imagine you've just eaten chocolate, or won the lottery, sat an exam or just been fired.
Imagine your thoughts, your emotions, your behavior, and your health could be controlled by a hidden organthat you knew little about.
Ilya Metchnikov fought to not onlyprolong healthy human life, but healthy microbial life.
I feel we can all contributeto this fight worth fighting for our own health, but more importantly, for future generations' health by restoring the relationshipbetween microbe and man.
There is some food for thought.
Thank you very much.