Steven Benner and Eric Gaucher at the Foundation for Applied Molecular Evolution, Frank and Rosalie Simmen at the University of Arkansas, and their colleagues from the United States and Norway carried out the study. They used a diverse array of disciplines to investigate why the pig, Sus scrofa, has three different genes that encode the enzyme aromatase an enzyme that catalyses the transformation of androgens, such as testosterone, into estrogens - whereas other hooved animals have only one.
The evidence that they collected suggests that the additional aromatase genes arose as a result of natural selection for pigs with larger litters than their ancestors. These larger litters may well have helped the animals to survive the dramatic cooling of the earth that started during the Oligocene period, around 35 million years ago.
Their investigations drew on the geological and palaeontological records, and used techniques from evolutionary biology, structural biology, chemistry and genetics. "As the geological, palaeontological and genomic records improve," write the authors, "our combined approach should become widely useful to make systems biology statements about high-level function for biomolecular systems.  Over the long term, we expect that the histories of the geosphere, the biosphere and the genosphere will converge to give a coherent picture showing the relationship between life and the planet that supports it."
The researchers used genetic information to estimate that the ancestral aromatase gene duplicated twice, to give three genes, between 27 and 38 mil
Contact: Gemma Bradley