The Paleodemography of Central Portugal and the Mesolithic-Neolithic transition

Newly available information on the excavation of the Portuguese Mesolithic shell middens, Cabeço da Arruda and Moita do Sebastião, has allowed reassessment of the paleodemography of the sites. Following the restudy of Arruda and an examination of Moita site structure, we now discuss the problem of arriving at a minimum number of individuals (MNI) for Moita and use the age distribution of the dead to estimate the total fertility rate (TFR). We confirm the difference between Moita and Arruda and note their divergence from the Neolithic site of Casa da Moura. Our method of estimating TFR, deriving from the use of West model tables, is explained and is tested by reference to historical data sets and by calculation of equivalent demographic values using the Brass relational table approach. Our focus is the Mesolithic-Neolithic transition and we establish the context of demographic change in the late Mesolithic and early Neolithic of central Portugal by reference to changing environmental, nutritional and disease conditions. The low level of population growth at Moita would have increased during the occupation of Arruda. However, subsequent changes in climate and sea levels led to unfavorable conditions and we hypothesize that the Tagus lowlands were abandoned in favor of healthier uplands where there was a rebound and an increase in population growth in response to changed lifeways.