An assay for determining presence of human DNA in a sample in which non-human DNA may also be present and for quantitating such human DNA. One embodiment uses intra-Alu based PCR and another uses inter-Alu based PCR. The assays are performed without unique, expensive equipment. The assays are based on detection of multiple-copy Alu elements recently integrated into the human genome that are largely absent from non-human primates and other mammals.