mathematics i was interested in biology and i was trying to decide what species study is and when i graduated from college i got a fellowship from my university which gave me a year to travel around the world by myself the rules were i couldn't take courses i just had to keep moving and it was just enough money to go nd class so i found out what life is really like you know they have the five star who knows so i just stayed in the cheapest places i could find and i took nd class trains and and i saw that a very very large part of the world is poor very poor very poor very poor and there were  children who were not getting a fair shake in life and i remember and east africa i got out of the vehicle and little kids ran up to me and they were sort of staring up at me and i looked down into their faces and they had flies walking around in their eyes and they didn't even try to brush them away and that's because the flies were there all the time you know and i knew that those flies carried an infectious disease called for coma yes which can be treated if you have the medicine can be treated but these kids didn't have the medicine and i didn't have it and i knew that those kids in the matter somewhere between months and years would be blinded by that  it was it was a wrenching experience to see people who didn't get educated they didn't have enough food from the time they were born they didn't have opportunities and they weren't being i remember i came out of the train station it was a hot sunny day with dust all over the place and i came out of the train station and there were people lying on the ground covered by light gray cl and they were covered with dust and they weren't moving and i was met by my indian host and i asked him if those people were alive or dead and he said oh don't worry if they don't move for three days the station master has carted away you know well i just i didn't find that very reassuring and i saw poverty of a kind that i had just you know never seen before had never seen before and that had a stroke or it had a the world's poorest two billion the average annual income is four hundred dollars or a dollar a day yes and on that you know people can't eat people can't have much of what it really means to be a human being which is to participate in the past and to have a meaningful role and in a social life and and to to be intact as a human being and that had a personal affect and you were affected what you wanted to do academically with your life right and so when i came back to school after that year i had already decided to do a doctorate in mathematics and i did that and then i went down and i did another doctor and public health tropical public health coming up for the earth the season is over the very appropriate because you're looking at these questions which are fundamental to them standing on a logical inference for but i'm wondering maybe and also you take an historical frame of reference and you also take the future oriented for us to get to where at the time prize there were movie a quarter of a one billion but maybe you go through that share the pace at which the population increase on the planet earth and give us a historical perspective on that if you were well let me go back a little bit further to the last ice age ended about ten to twelve thousand years ago and people at that time numbered about five million so roughly five to six million we don't know with much precision that i'm going to ask you how how can we know of are we estimate between two million and twenty million but our estimates are based on population density today among people who live by hunting and gathering i see that we make an extrapolation from just a guess basically so it's a five or six million dollars worldwide total worldwide so that's less than the population of new york city in the population doubled every sixteen or seventeen centuries for several millennia until by the time of christ the population had risen to about two hundred and fifty million and again the real numbers are between one hundred million and three hundred and fifty million we don't know but let's say roughly the population of the united states today that's very interesting that and we do have an idea of the the spread of the population and i mean it would have been you know i mean we had the time of christ and six hundred and fifty the population doubled from a quarter of a one billion to half of the and then around that time the new world and the old world started to exchange food foods like corn came to the old world after all right and people and people started going from the old world to the new world and ideas and resources and as a result the population began to accelerate tremendously nutrition improved in the old world and the old world experienced the early riser population so that the next doubling instead of taking sixteen or seventeen centuries took and then the pace with improvements in sanitation and the industrial revolution the pace picked up even more another doubling to from one billion to two billion only took a century and so by  another doubling over the past four billion around one thousand nine hundred and seventy four if you look back from where we are now from the last most recent doubling has occurred in just forty years so anybody on the planet who is forty years old or older has lived through a doubling the population and that is what is unprecedented that because never before the nd half of the th century had any human being lived t of absolute increase it took from the beginning of time to eight hundred and thirty to put the st one billion people on the planet as i mentioned the most recent one billion people have taken only twelve years and to be this yes well the rate of increase has steadily increased with the exception of catastrophes like the plague that swept europe and the middle east in the th century so there was a little crash but since that time and in the last six centuries the global population growth rate has steadily crept up words and the big change came at world war two before world war two the growth rate had never exceeded one percent a year even that on a worldwide worldwide basis we're not talking about individual countries because they've been a lot of fluctuation yet but on a worldwide scale one percent a year had never been attained globally before world war two after world war two the rich countries of the world learned how to export health with out exploiting wealth and as a exactly a high level of in from mortality had been matched by a high level fertility after world war two the mortality dropped and the difference between birth rates and death rates was the growth rate and the growth rate just shot way up to what kind of figures have we looked at right if it grew to about two point one percent a year at the all time peak which was around and at that time the human species turned a corner and we became the st species probably in all of evolution voluntarily to control our own dropped for about ten years and then for another fifteen years it was completely flat and then recently it's begun to come down again so it is starting to come down it is starting to come that it is weak or can't really predict very well you know because the world growth rate is determined by decisions made by millions of couples in the bedroom absolutely and this is a human issue it's not some abstract theoretical thing it's a decision made by all of us jointly but just to round out what would what w have constituted generations both that period of time what has happened to the lifespan of the population were the days of the world well those are those are two slightly different question yes generation length is sort of what's the average time from the birth of a child to the average birth and the next every birth by those by that person and that's more or less on the order of quarter of a century one of the twenty five years that hasn't varied a great deal there are trends toys for earlier marriage will put later marriage in different countries but that is more or less around twenty to twenty five years from the huge change that has happened is  increase in life expectancy life expectancy simply means the it's the average number of years that a newborn infant will live on that's what at the beginning of this century you look back the life expectancy in the united states and at the turn of the century is what it was lower than it is in the poorer parts of the world today now the global life expectancy is about sixty five if it has grown the life expectancy has grown by the length of a generation it is a remarkable achievement but that really conceals two different worlds and in fact all of economist took careful language the bow fired and the arrow landed five meters to the right of the deer and then the ecologist to careful aim and fired and the arrow landed five meters to the right so the statistician looked at both arrows and looked at the deer and said we got it we got it one of the little rough hunting deer with the average arrow is like hunting the truth about the world and with global statistics in fact there really are two worlds there's about one billion two hundred million dollars people living in the rich world and their average income is about seventy thousand dollars a year and then there are the other eighty percent that's four and a half one billion people and their income is about one thousand dollars a year and so to talk about a rising average overlooks the fact that the richer fraction of the world has been getting a steadily increasing here of the world's economic pie while the poor part has been getting a steadily  and so we have to be very careful of you know when we use global statistics they're convenient handles but they don't capture the fact that for example the population is growing by ninety million  ninety tonight yes roughly ninety thousand nine hundred and five percent of that population growth is in the countries that are poorest that have the least means to give every child good life and only a small fraction of that population shift yes the rich one billion two hundred million are increasing in numbers at about two tenths of one percent a year and a better way to think about that is the doubling time is about four hundred and thirty years very slow at the present rate for centuries ok and the poor old is growing about one point nine percent one almost ten times faster than with a doubling time and converted that way thirty six years so it's roughly ten times faster that's a huge difference or it means that the poor countries have to double their supply of schools if they're going to keep the same class sizes in the same technology for education in just thirty six dollars you have to double their supply of hospitals if they're going to have the same kind of restructure part of the exploration of how do we understand the the difference between the attitude of people that have very large one thousand and twelve dollars children perhaps in the less developed world but and in the tendency through time do they used to have larger families in the develop the scholars who have devoted their lives to a don't understand fully or so i'm giving you the best understanding that i have but i think we have a lot to learn and yes i understand people who are farmers can readily use the help of children from an early age to do fine chores and of people who grew up on farms in the united states had to do farm chores from the time they were kids and that's why our school system has summer vacations because the kids were needed to go work on the farms and that has been true throughout the ages before so children in a farming community children are an asset when you put when people move to cities there's no farm work to be done and the kids have to go to school and when the kids are in school they're not earning and not producing they're not helpful labor so the motion from a rural setting to an urban setting off from produces a change in the value of a child economically it becomes a child changes from being a productive a another complicating factor in france in the th century before the french revolution the peasants began to reduce their fertility because they didn't want to divide up their land holdings among many sons in those days it was the sons who inherited their problems wrecked they wanted to keep the land for well sometimes they would divide up sometimes or go to the eldest son but if if if the oats sons had to leave they would go to the cities and then they had reduced her to it but in a peasant system where people divide up the land that's also can be an incentive for lower fertility now the present state of the world is that seventy four percent of the rich world lives in cities almost three quarters but in the pool world only thirty five  historical generalization that's fine mist that's true because in europe and in the parts of the world that are now wealthy there was industrialisation as the same time that there was a gradual decline in fertility and that is not the whole story there are also circumstances where investments have been made in the education and health of women and where the economy is still very poor but fertility has fall so sometimes there are other factors in addition to industrialization that can lead people to lower fertility that's saying that industrialization seems to have made the difference for the wealthy countries for us but it's not clear that all countries have to follow the same path and attain a lower level of fertility again is interim because as we go through we d went through an add that it's clear that wealth alone is not sufficient to lower fertility there are oil producing countries where the average income is higher than in the united states and yet where the average family size that is the average number of children for a woman is sixty seven and eight and that reflects the cultural role that women have in those countries which is limited to childbearing and homemaking so that today it seems clear that if women have more options such as education employment  other activities outside of the home those other options compete with childbearing and may result in lower fertility but if those options are cut off even when there wealth if women are expected to be only bearers of children they may continue to have to and so the cultural role of women makes a tremendous difference and let me just support that with again some dollars for every one hundred dollars men who were either in jobs or looking for work there were about thirty seven dollars women who were in jobs or looking for paid work outside the home that's economically active in only twenty years the number of women economically active for one hundred economically active men rose from thirty seven to six to one almost double i don't think it's a coincidence that while fertility was going down economic activity of women was going up i think they are linked and as a matter of equity and self interest it's good for women to have more options it makes a huge difference to what they choose to do with their lives do you think it makes a difference that there are there we will know are forty it will be we have other kinds of ways so that know realize yes i think that modern contraceptive methods are an important fact and making them easily available to people is an aspect of individual liberty it gives people options and in that sense choices and i am in favor of people having these options and influence over the course of their own lives and  having the contraceptive services and information and health care available is a good thing in itself in my view but i don't think it's completely sufficient because people have to want to change their family sizes and the the again going back to the french presence in the th century they were able to do so with absolutely no technology whatsoever so when people choose to change their fertility if their motivation is strong enough they c the role that modern contraceptives way is to make it easier for people to jump that barrier and i have to say that there's room for great improvement our contraceptive methods  things some people see as the displacement of labor in the working out of the economic interests of the modern society that we have this tremendous tendency maybe it's just a passing phase or something so we would like to think but this ten classes the work of the developed world itself right at the same time the technological ability and knowledge base that we have abstractly to provide to the people of the world to fight drug coma and other things in the green revolution and other kinds of ability that we have this tremendous capability of providing life support for the population that there is the that that if they get to a point where they did that that there could be seen that we're we're we're we're we're gaining on our ability to provide two or bucky fuller forces used to talk about how we may actually be able to see that collectively in a system way that we have the ability to make what he called the earth work if we have the appropriate ability to to utilize with good design what our knowledge base tell those were capable of doing in a related stable way with the spaceship earth of ours to reach a point where we have that that capability and that that that people could be engaged in what might be a thought of over the long haul in what would have been like leisure activities the way that the status of the airplane grease the had the ability to do that and so that they could have real choice for lives as you put it in terms of a wide variety of abilities and they would not be under the iron gun of necessity of striving and so forth so that in a sense it would be a non alienated environment that is that they're secure in their own being and secure in the job that you know in the in their in the broader sense of their own being that is something that seems to be by these statistics of economic development desirable but is it perhaps that the to the st potential adverse side of that if people are truly secure and they're not alienated in a one million need positions that industrialization process work they they're out there doing those jobs because they have to they're being think what you rather a couple of things i'd like to comment on one is you mentioned the insecurity of workers in this country about their jobs and downside and there are competing theories about why that's happening one is that it's technological change as you mention another which is simply making it possible to produce the same goods with fewer people of work that's right another is that  the jobs are moving out of the country and i think people don't appreciate that low skilled jobs which used to provide an exit from poverty for people who lived in inner cities have left the country to them i q adorers of mexico and to the workers of china and to the workers of asia all over the place and outside the country they've left because the price of labor there is cheap and people will work for th of the salaries that they work for in the united states and the reason labor is cheap there is a population growth is rapid rise and so there's a connection between the exit of jobs from inner cities and rapid population growth in the develop unions should be on this they should be saying smaller families protect your job and they do smaller families worldwide which are protect but the only response any one response to  education worldwide to slow fertility and the nd is to upgrade the education of our own american workers so that they are technologically able to compete i was once on a plane going out to the west coast and seated to my right was mr route from india and i asked him what he would do mr route while he lives in bombay and he manages five hundred computer programmers who work for city than me and he was flying from bombay to portland oregon to install a new software system now the customers in portland have no clue that their software is written by highly intelligent highly skilled and poorly paid programmers in bombay and bangalore and bangalore and so it's not only the industrial jobs that are going out of the country those five hundred dollars programmers are not americans but india and so the intellectual middle class jobs are going out and when those jobs go the managers go to i mean mr rollo is from bombay so the middle of that downsizing is connected with the rapid growth of an states and people have them awakened to that problem there's another part of your question and that was suppose everybody becomes wealthy will they then choose to have children that would be that would be if we find my point of view that is essentially an unanswerable question of like what choices will be made i have two children i have a nineteen year old daughter and a sixteen year old son they won't tell me how many children they're going to have probably because they don't know and if you i've been talking about humans as if we lived on this planet by ourselves that is not the case and along with the five billion seven hundred million people that we have on the planet now we have four  hundred million large domestic animals sheep goats cattle zebras camel buffalo four billion three hundred million they outweigh the human population and in addition to that we have seventeen billion chickens about three chickens per person that number of chickens has more than doubled in the last ten years so if you look over the last twenty years average of grain that goes into a human now we feed another two pounds of it to our domestic animals it's as if our six billion people are being followed around by a shadow four billion people in when i think about the population problem i try not to think about it in isolation but i think about it in connection with three other things that you mentioned one is economics a  is culture and the rd is the environment and we simply cannot isolate any three to a one of those factors and they they go together  a lot of people talk about population and development but they leave out the fact that development depends on the quality of the environment and the soundness of the culture and institutions and legal set up and politics all of those things that go under the heading of culture some people talk about population and the environment but you again you can't talk about that without referring to the economic system which gives people incentives for behaving in certain ways so a few people talk about population economics and the environment but again culture is an absolutely central factor and let me give a concrete example  so the water demand of cotton is really immense from on the other hand round is made from cellulose which is normally extracted from old in something as simple as choice of fabric we place different demands on the environment and that runs through all of our choices whether people choose to have jaguars with a capital j or jaguars base we've just discovered that he lived through the you know we're just discovering almost exponentially new discoveries in the knowledge of what is is d there and also the what what might be called the ability of having with elegance of design being able to do more with less and exploited in a certain sense resources that we've not had available to us traditionally we don't depend on coal necessarily and that's right it had a single patterson engine where they might be able to get engine you know energy into that we might or the silicon chip itself or the look on some of these new materials and some of the possibilities of doing with the knowledge base being able to do more and more gas with less and less and provide a better living standard how polluting and degrading the environment in a way that traditionally has just not been available to us we didn't have the knowledge through these are hoping that i believe so i believe so strongly in the last twenty years the energy use per person in the united states has dropped by four percent and the energy use per dollar of g n p has dropped by twenty seven percent really so there are dramatic falls in the amount of energy that we have to consume to get a certain economic level of will be ok we have a drop in the energy or the the use of resources but we have a greater use fission c so that we in a certain sense may it is maybe something we may be able to have our cake and eat it too in a certain sense or if i have well i don't want to stray again no rational territory help what i think if we choose the right kind of cake yeah you can have quite a lot of them and enjoy it but that talking about what's happening in the united states doesn't tell you the larger picture the larger picture is that the energy use per person on a global scale has increased nineteen fo that we're using has increased about ninety five fold in about one hundred and thirty years and that is a staggering staggering change in the human ability to control mess up or beautified who way or the planet and the developing countries the poor countries in the phase now aggressively increasing the amount of energy to the person while some of the developed countries like the u western europe are gradually dropping i'm wondering whether some of the advantages of good design and understanding and using knowledge theories into work is perhaps more rapidly exportable to a whole world's world work off of there and as you say with the economic assumption that back again to your your very apt analogy of exporting health without exporting well and we live in this is a world where the injustice or unjust bangalore going to join the upper elite group and you're still going to have the mass of people in the same problem i think they have to be dealt with together and i think justice and giving people control over their own fertility go together and  you know when i cross th avenue at rush hour i'm neither optimistic or pessimistic i'm just plain careful and i know that if i step out without looking i want to get clobbered by a taxi  but if i wait for the light and i go and things are ok i can get across the street fine same thing about the future i am neither optimistic or i believe that if we devise just institutions and if people if the rich world recognizes that our well being depends on the well being of the poor world and it does because we share the same planet we share the same atmosphere they put carbon dioxide into it it's our carbon dioxide ecological world is there it's we it's one system a system that in interacts so if we if we take account of our stake in the well being of the developing countries and if we make energy efficient technologies available and help developing countries to educate their own people so that they develop their own energy efficient technologies i think we can make it for me that the key is to give the developing countries the ability to make their own way not for us to do it for me we can't they're just four times as many of the poor people are there are the rich people what we can do is educate everybody in the world and give people the power to direct their own life and also if i may is not only the not only the bridge between geographically but between the well to do and the those who are not a view if you're in t view view of the world with these understanding and so with that that we come up with some sort of a policy or some sort of a direction that is going to address that question of are we or are we not being fully able to utilize what it is we're technologically capable of doing so we allow capital formation shortfall to get in the way of what we're capable of doing to terms of infrastructure needs do we have a pattern that suits the future rather than being mired to the institutional with systems that we have from the past and this question is a broader question is it not intended of not only does tech technology that comes available through it with the knowledge grow but also that we have to have policy and political and economic leadership that can understand we're coming into some sort of a new condition right which i don't know it just doesn't seem like on a world scale that that yet has been grassed and the vision thing and people will talk about that there are people of vision who see some effect of an appropriate alternative the way we've done things is needed or not or can we muddle through at the birds they do you think in terms of the institutions that we have inherited or would you think that we need some sort of a vision that would bring some new way of operating the system in order for us to do border or bucky fuller would have  advantage of mughal india is there are lots of different competing ideas and if we do lots of local experiments some of them are going to work and some of them hide there are i believe real grounds for optimism the montral protocol to regulate chloral for carbon in the atmosphere showed that when country see a threat to their wellbeing they can come together and do things about i think we are developing trade regimes that are setting a new level of integration of the world economy it has become unfashionable to attack your neighbors and militarily and even though there are an increasing number of civil wars on a global scale the number of wars between countries has been dropping and so they make different assumptions about what people want from assume that people will be happy to be vegetarian and other people assume that everybody wants to live like an american twenty five percent of the calories for me some people assume that what we can grow is