Rebecca Martin of the University of Colorado at Boulder, and Mario Livio of the Space Telescope Science Institute in Baltimore, developed a rather wasteful theory suggests that, for the formation of life on Earth in the solar system should positively be an asteroid belt, and stringently, where it is now.
Observations exoplanetary systems show that the so-called warm dust, which, apparently, the result of asteroid is concentrated in areas close to the "snow line." This may be because it was her form giant planets; the light elements are not able to condense on the surface of a celestial body, whether it is closer to the Sun.
The tremendous gravity giants, according to scientists, prevent the formation of Earth-like planets in the asteroid belt: planetesimals in this case simply cannot be grouped, since the center of gravity of the asteroid belt pulls their gas giant (we - Jupiter). However, despite the universality of the scenario of the asteroid belt, its fate in more than 95% of the time does not coincide with the share of our zone. The facts that 96% of the planetary systems studied (501 of 520) are removed from the gas giants of his lights in the distance less than the distance to the "snow line." Formed her, due to the gravitational resonance they gradually migrated into it, scattering asteroids from the belt and dramatically reducing their concentration within the "snow line."
Americans believe that asteroids are not just needed for the formation of life on planets. Even if life is there without them, its development to complex forms is hardly possible. Why? First, the late heavy bombardment, apparently, brought to the surface of the earth much water from areas beyond the "snow line." And the appearance of life without water is difficult. Second, systematic fall of the belt asteroids have to "update frames", eliminating the dominant species that are on top of the food pyramid, and letting their younger brothers to try their luck in the new ecological niche vacated. In general, anything does not kill the biosphere completely, making it stronger, etc.
This hypothesis that a regular mini-Apocalypse necessary for the formation of complex forms of life, not fully proved in the proper biological environment and requires serious consideration. In some past era of the species appear to be no less than our own, in a reference to a good level of development of complex life without the intervention of an asteroid ... is not quite clear, however, that it should be kept in mind by the "snow line." According to the concept of a weak young sun, the asteroid belt at the dawn of the solar system, at least in part was within the "snow line", and now the situation has changed.