I like to start by saying that I do not want to be an alarmist today but we are in danger in fact we have always been in danger and we will always be in danger around us on us in us there are uncountable viruses bacteria protozoans fungi parasites looking for a minor breach in our defenses in order to invade us take over our bodies and benefit from us the whole history of humanity has been shaped by infectious diseases the Antonine plague took the life of 5 million individuals during the Roman Empire including one Emperor the
plague of Justinian named after the eastern Roman Emperor Justinian the first killed 40 million people in the 6th century the medieval Black Death cut short the life of a hundred million individuals in 14th century 100 years ago the Spanish flu outbreak killed 1 million people per week and more recently with outbreak of HIV 30 million people have died of AIDS and still today 35 million people are careers of infection all over the world many of them with an unfortunate prognosis with 750,000 deaths in the year 2018 other diseases such as tuberculosis malaria or fungal diseases
still kill millions of individuals around the world and every few years we also experience the outbreak of some new diseases such as we see now with the world famous and infamous coronavirus well this might sound scary right this says we are gonna die of so but this is not new this has happened throughout the whole history of humanity since they're very down of mankind there has been a constant interplay a constant interaction between humans and pathogens that is the engine of our evolution this orbits around a very simple principle if we acquire an infection before
we reach reproductive age and we die we don't pass on our genes to the future generations we were not resistant enough we were not adopted so our genes died with us however if we were resistant and we survived the infection we will have the opportunity to reproduce and to pass on their genes to future generations this is good for us this is good for our descendants and this is good for the overall survival of our species because the past influences the present and our ancestors form the heritage and the legacy of humanity of today in
many aspects including the response to diseases the majority of experts agree that Africa is the place where our species originated study suggests connections with ancestors who lived in this continent about 300,000 years ago and pathogens have played a central role in human evolution from those very early times probably the most well known example of a disease that has an impact on human evolution as that of malaria malaria has been present in African communities for hundreds of thousands of years and these communities the genome the physiology have been shaped by the severity of these infections malaria
is caused by a parasite a parasite that is transmitted to humans through the bite of infected mosquitoes once the parasites enter our body they enter the red blood cells are multiplied inside them however some people have a special type of red blood cells that makes them resistant to disease so we observe that in many African populations in places where malaria is endemic there are many people with this kind of special red blood cells that makes them resistant to the disease how does this happen well this is evolution this is a tale of natural selection let's
imagine we have an original population with five different characteristics with five different traits represented on the slide by five different colors at the beginning the original population has more or less the same amount of individuals with each of these different characteristics at a certain point a critical event such as a deadly disease appears causing a bottleneck in the population the survival of the fittest only those with good characteristics will survive while the others will perish the remaining population the survivors will have the opportunity to reproduce and to expand their advantageous traits and then give rise
to a new population to new generations adapted to the infection this is just one example of influence and in the case of malaria there are a handful of traits that confer an advantage to infection so people who have normal erythrocytes normal red blood cells are succeptible to have malaria but people who have sickle cells which are red blood cells with a specific shape and different properties are resistant to malaria because the parasite cannot enter these red blood cells so we observe that in places where malaria is endemic there are many people with sickle cells because
it is an advantage an evolutionary advantage to survive malaria and the grounds of this influence have the roots in processes that took place hundreds of thousands of years ago because the past influences the present however we don't live in the same way in which our ancestors lived they have nothing to do their way we live in which even the way our grandparents live and this also has consequences today in the last centuries and especially in the last decades improvements in the means of transport have a lot humans to travel faster and more distance than ever
before we have seen some incredible inventions in the last years we have now antibiotics we have electricity we have robots we have rockets we even have ice cream and I mean we have seen the birth and sometimes even contributed to the expansion of some incredible rests recent inventions such as the reggaeton and tinder that also help humans to pass on their genes to future generations and thanks to these and many other advances our lifespan the lifespan of many countries including the Netherlands has doubled in just one century our society is experiencing it global changes at
the speed never seen before in the whole history of humanity but evolution is slow process so all these sudden changes have consequences changes in hygiene patterns in the last decades half-brothers large improvements in sanitation drinking water garbage collection etc that have create Lee reduced our exposure to infectious diseases and the immune system of our ancestors is our immune system so it's my mean system your immune system your immune system the immune system of the person who is on the last row or under the influence of these processes and all our immune systems need a certain
degree of exposure to microbes underthe for the correct development of immunity the hygiene hypothesis proposes that the lack of exposure to germs and dirt is associated with a higher risk of developing asthma and allergies as we see nowadays what consequences does this have for example for our children so children who grow up farms who are much more exposed to microbes on dirt develop mass let's must less allergies and asthma so please to all those people who have gets here or thinking to have kids take them to the park let them play in farms let them
play with animals let them crawl on the floor because it's actually good for them for the future likewise the expression of genes related with inflammation is also related with increase we see nowadays in inflammatory diseases so we see nowadays that many diseases related with inflammation are spreading such as autoimmune or inflammatory diseases this also has to do with the functions or our of our immune system we see now as we are adapting to process food and stricter hygiene standards our bodies react by developing the so-called diseases of civilization these kind of diseases as I've just
mentioned before are related with this excessive inflammation we suffer under these conditions so for example we observe now in many countries high rates of diabetes celiac disease or inflammatory bowel disease and this is already a major health issue in Western countries but since we are also experiencing times of globalisation many other countries many other societies are embracing our lifestyles and this is causing big problems for example in Africa where people have been in contact with more powerful and terrible diseases for longer periods of time the inflammatory responses are higher so they have exacerbated responses in
their immune system this was useful for our ancestors to fight those powerful infections but today in our more sterile environment it causes inflammation and this is also related with higher rates of diseases such as lupus asthma heart diseases and some types of cancer in African populations so if the globalization of the sedentary Western lifestyles continues it will color with the inflammatory consequences of our past creating a major health issue worldwide so we bet stop it before it's too late because we what we do today has consequences for the next generations this not only concerns issues
like climate change but also involves how relief the diseases we get the vaccinations we get as well and that ceases we suffer how we treat our children and so on I like to give you one very particular example of this probably familiar to many of you the Dutch hunger winter in the autumn of 1944 during Second World War German troops blocked the western part of the country turning away all shipments of food the situation was followed by one of the hardest winters in decades with terrible cold and many people surviving on just 500 calories a
day the hunger winter as it is known killed 10,000 people and weekends many more but there was a specific population who was affected by this situation 40,000 women were pregnant during the Dutch hunger winter so the fetuses developed under very restrictive caloric conditions this had consequences that were obvious right after birth with low birth weights birth defects and high infant mortality but some other consequences were not visible and seen many years later so decades after the hunger winter researchers showed that individuals who had just stated under these conditions so individuals whose mothers were during the
Dutch hunger winter had higher rates of obesity diabetes and heart disease than individuals were gestated under normal conditions it seems that those fetuses adopted their metabolism and the physiological processes in anticipation of the harsh environment that was waiting for them outside well you might say this is logical the body adapts yes that is true but it doesn't stop here this goes once there beyond because also the grandchildren of those women who were pregnant present these characteristics so there is a dynamic adaptation to the environment that has consequences for the next generations all this examples show
that is a balance humans build offenses to fight diseases but we can't stop this is from happening so what makes us strong in one hand can also make us weaker on the other hand we can't forget that we the hairs of those people who wandered around the world looking for a better place to live we are the hairs for long tradition of survivors of terrible diseases that made our species stronger but also more vulnerable to the current changes of our lifestyle and knowing our past will prepare us for the future thank you very much you
