Animal DNA in PCR reagents plagues ancient DNA research

Molecular archaeology brings the tools of molecular biology to bear on fundamental questions in archaeology, anthropology, evolution, and ecology. Ancient DNA research is becoming widespread as evolutionary biologists and archaeologists discover the power of the polymerase chain reaction (PCR) to amplify DNA from ancient plant and animal remains. However, the extraordinary susceptibility of PCR to contamination by extraneous DNA is not widely appreciated. We report the independent observation of DNA from domestic animals in PCR reagents and ancient samples in four separate laboratories. Since PCR conditions used in ancient DNA analyses are extremely sensitive, very low concentrations of contaminating DNA can cause false positives. Previously unidentified animal DNA in reagents can confound ancient DNA research on certain domestic animals, especially cows, pigs, and chickens.     

Capital Assistance for Small Firms: Some Implications for Regional Economic Welfare

This paper analyzes the role of finance capital in regional economic development. A cost‐benefit approach is invoked in order to estimate the welfare impacts of a regional loan and guarantee program for small firms in Israel. Program‐created employment is treated as a benefit and an employment account that separates net from gross employment, is presented. An estimate of net wage benefits is then derived. This involves adjusting wages across different earnings classes in order to account for the variation in opportunity costs of labor at different levels. The estimation of costs includes the opportunity costs of capital, administration, default, and tax‐raising costs. Results point to substantial regional welfare effects. We stress the need to account for changing regional economic structure in this kind of evaluation framework.