The idea that life on Earth was seeded by ETIS accidentally or purposefully. However, there is a 1.5 billion year time lapse between the appearance of life and the appearance of eukaryotic organisms. SETI forces assign a value of 0.1-1.0. Some argue that intelligence is selectively advantageous. The concept of convergence support this idea.
Convergence occurs when unrelated taxa evolve similar morphologies or behaviors.
Convergence does not imply that the converging taxa are identical. It has been suggested that an average of 1000 descrete mutations separate neighboring species. Chimpanzees and dolphins possess the ability to respond accurately to complex four or five element sentences. There is no longer much doubt that the higher cetacea are as bright as apes. So the concept of convergence seems to imply larger values of .