Temple University researchers have assembled the largest and most accurate tree of life calibrated to time, and surprisingly, it reveals that life has been expanding at a constant rate. "The constant rate of diversification that we have found indicates that the ecological niches of life are not being filled up and saturated," said Temple professor S. Blair Hedges, a member of the research team's study, published in the early online edition of the journal Molecular Biology and Evolution. "This is contrary to the popular alternative model which predicts a slowing down of diversification as niches fill up with species." The tree of life compiled by the Temple team is depicted in a new way — a cosmologically-inspired galaxy of life view — and contains more than 50,000 species in a tapestry spiraling out from the origin of life.