now let's consider a very deep question in development economics mainly how persistent or the forces which a prosperity in other words if your country is prosperous today does the supplier country was probably prosperous also hundreds of years ago you can think of this investigation is looking more closely at the role of geography in economic development and also updating some of the results found in jared diamond's guns germs and steel of course look at alex is video on that book i'll be drawn a good deal on this excellent paper available online i recommend you go to the source and read the whole thing one thing those offers do is they take one measure of current prosperity namely the lobby of two thousand five per capita income and they're going to ask what predicts that measure of prosperity as explanatory variables they use some important geographic features mainly absolute latitude or distance from the equator percentage of the land area in the tropics other country whether that country is landlocked and also whether that country is an audit and if you take those together in a well specified model of economic growth the geographic factors what appeared to explain about forty four percent of the contemporary variation in the lobby of per-capita income another words geography really does matter and uh... both variables absolute latitude matters the most there's another interesting paper by all sending kids cited here they make some changes in the analysis they exclude countries settled by recent migrants for instance that would include say in new zealand and they find that geography then explains about fifty five percent of current prosperity even more if we look only at the old world geography then would appear to explain about sixty four percent of the variation in current prosperity direct these papers and general we're finding that geography explains more than biology so for instance if you consider jared diamond's argument that the importance of domestic ball animals for subsequent economic growth that seems to matter less than where our country or region is located econometrica success in earlier times is population density and we're going to