The Demographic Transition: a model fit for the 21 century
A critical review of Chris, 2011, Understanding global demographic convergence since 1950, Population and Development Review, vol.37, no.2, pp375-388 and David S. Reher, 2004, The demographic transition revisited as a global process, Population, Space and Place, vol.10, pp19-41. 1.Introduction
The demographic transition model (MTD), proposed by American demographer Warren Thompson in 1929 has profoundly contributed to forecasting the future tendency of global population and potential demographic issues, such as aging population and the decreasing supply of workforce. However, it also created controversies among the demographers in almost a century. The main debate focused on a question: will the demographic transition is a global process in the future? These two articles discussed and analyzed this issue from different angles. The Wilson in his article understanding global demographic convergence since 1950 augured that there is a considerable demographic convergence around the world since the middle of twentieth century and this global convergence moved more rapidly and explicitly in fertility transition than that in mortality. Standing in sharp contrast to Wilson argument, Reher advocated that there are signs that the recent fertility transition did not follow the historical experience, especially in developing countries and recent transition participators will not take the advantages that the DT brought to the early transition countries. Consequently, this paper will provide detailed critical review these two articles, focusing on the fertility, mortality and demographical transition.

2.Summary
2.1 Understanding Global Demographic Convergence since 1950
This article justifies the demographic convergence will be the main tendency of development of the world’s population, by examining the global fertility and mortality transition from 1950 to 2010. Wilson did not classify the world as the same way as United Nation used to, instead he takes a new approach to divide the world into five groups in mortality transition and three in fertility. Firstly, the article compared the life expectancy for different ganders among five world regions, which respectively are other developed, USSR, other developing, Southern Africa and EMW Africa (East, Middle and West Africa) since 1950s in order to ague that the global demographic convergence is a general process, although some evidences show the sign of mortality divergence in specific regions, such as Southern Africa and USSR. The next paragraph provides a discussion of fertility transition in EMW Africa, other developing and other developed. The authors identified that although there are still a remarkable gap between fertility in Africa and other developing countries, the global fertility rate will converge in the nearly future. In conclusion, the Wilson combines both the trajectories of total fertility and life expectancy in the five regions. The data shows a remarkable similarity of the demographic trends around the world.

2.2 The Demographic Transition Revisited as a Global Process
This article aims to explain the history experience of demographic transition in Europa has little contribution to the recent transition in developing countries. Based on the different starting times of mortality decline, Reher divides the world into 4 categories: forerunners, followers, trailers and latecomers. Next, he provides a profound discussion and analysis on similarities and divergences of demographic transition between forerunners and recent transition counties. In the similarities sections, he maintains that the global demographical change follow the same trajectory that is mortality decline appears earlier than fertility decline, although other studies suggests that the cause of transition is considerable differences between Europe and developing counties. In addition, the other three differences also mentioned in the divergence