Title: Low fertility rate reversal: a feature of interactions between Biological and Economic systems,
Abstract: An empirical relation indicates that an increase of living standard decreases
the Total Fertility Rate (TFR), but this trend was broken in highly developed
countries in 2005. The reversal of the TFR was associated with the continuous
economic and social development expressed by the Human Development Index (HDI).
We have investigated how universal and persistent the TFR reversal is. The
results show that in highly developed countries, $ \mathrm{HDI}>0.85 $, the TFR
and the HDI are not correlated in 2010-2014. Detailed analyses of correlations
and differences of the TFR and the HDI indicate a decrease of the TFR if the
HDI increases in this period. However, we found that a reversal of the TFR as a
consequence of economic development started at medium levels of the HDI, i.e. $
0.575<\mathrm{HDI}<0.85 $, in many countries. Our results show a transient
nature of the TFR reversal in highly developed countries in 2010-2014 and a
relative stable trend of the TFR increase in medium developed countries in
longer time periods. We believe that knowledge of the fundamental nature of the
TFR is very important for the survival of medium and highly developed
societies.