Two physicists claim that dark matter making up as much as 99 per cent of the universe, may have changed the course of life on earth. Samar Abbas and Asfar Abbas of the Institute of Physics at Utkal University in Bhubaneswar (Orissa), suggest that the earth might haw encountered dense clumps of dark matter in space and this may have produced lot of heat in the planet's interior. Scientists estimate, given a uniform distribution of dark matter through space, the earth could 'capture' as many as a million particles per second. This means that our planet would eventually gather so many dark matter particles in its dense core that they would begin to collide, annihilating themselves in the process. These annihilations could create about 10 billion watts of heat in the lower mantle (New Scientist, Vol 153, No 2064).