The presence of feather grass Stipa sp., since the beginning of the settlement, has pointed toward the existence of patches of xerothermic steppe-like vegetation during the Holocene climatic optimum and in younger periods.
The site was subject to environmental shifts in younger periods, with a phase of arid conditions and erosion at least prior to the Bronze Age, succeeded by a phase of more humid conditions and rising lake levels mostly in the last two millennia, and finally a return to arid conditions and declining lake levels.
A subject was defined as postmenopausal, if she met any one of three criteria: (1) over age 55 and periods stopped; (2) 55 years or younger, periods stopped and no hysterectomy; (3) 55 years old or younger, periods stopped and bilateral oophorectomy.
The threshold value γ ¯ k decreases with the tax rate of the second period while it increases with the tax rate paid during the young period.
During the first period of life (young period) productivity in simple and complex jobs is determined exclusively by the worker's acquired ability.
We assume that each period lasts 30 years, so that the young period will go from the age of 25 to 54 years old and the second period from 55 to 84 years old.
During the second period of life, the individual consumes d t k, which depends on savings made during the young period, on the retirement pension and on the net wage earned if he keeps working during the old age.
Suppose an (i -th type i -thidual born atypeme (t) who lindividual periods and obornns utility from young atd old period consumptime ((c_{1,t}^i ) and (c_{2,t+1}^i ), respectively) and disutility from young period labor, (n_t^i in (0,1)), whore totalivese endowment per period is normalized to unity.
Expectations are rational, so that the worker chooses from the very beginning of life the optimal amount to save during the young period and the intended retirement date so as to maximize lifetime utility.
We consider an overlapping generations framework à la Michel and Pestieau (2000), where we focus on a single cohort of individuals living for two periods who perfectly anticipate a shift of the technological frontier between their young period and their old period.
