Half-life of full-length LTR retrotransposons in Mt and rice. 526 Mt and 705 rice full-length elements are analyzed. Each bin represents 0.1 MY. Vertical bars under the histogram represent insertion events. a) The distribution of the insertion date of Mt elements. Fitting of this distribution to a exponential curve indicates that the insertions in the recent 0.1 MY have been significantly active. b) Fitting the dates to the exponential curve. The logarithm of the dates fits the straight line y = 0.52 - 2.71x well. Therefore the rate of the exponential curve is α = -2.71, which corresponds to a half-life of 0.26 MY. c) and d) display the fitting in rice, which gives a half-life of 0.4 MY.