Immunoglobulin G in 1·6 Million-year-old Fossil Bones from Venta Micena (Granada, Spain)

We studied the presence of immunoglobulin G (IgG) in equid fossil bones from Venta Micena (Granada, Spain), dated at 1·6 Myr old, and from Atapuerca (Burgos, Spain) (0·12 Myr), and in ostensibly hominid fossils VM1960 and VM3691 (1·6 Myr) from Venta Micena and CV1 and CV2 (1·4 Myr) from Cueva Victoria (Murcia, Spain). Samples taken from the specimens were crushed to a fine powder and their mineral structure was dissolved in an ethylenediaminetetracetic acid (EDTA) solution. Fossil extracts were tested with antibodies against human IgG and against horse IgG with two independent immunological methods: dot-blotting (DB) and a modification of this latter method: quantitative dot-blotting (QDB). IgG was detected by DB and was quantifiable by QDB in some of the fossils tested. Equid fossils from Atapuerca and Venta Micena gave stronger reactions with the antibodies against horse IgG than with the antibodies against human IgG. Fossils VM3691 and VM1960 reacted more strongly with the antibodies against human IgG than with antibodies against horse IgG, whereas no IgG was detected in fossils CV1 and CV2. These findings show that species-specific IgG can be detected in fossils as old as 1·6 Myr. The immunological analysis of fossil proteins may help to solve palaeontological controversies. 2002 Elsevier Science Ltd.