Evolution was an idea which had been around long before Darwin. Jean-Baptiste Lamarck (1744-1829), for example, had suggested that giraffes got their long necks by stretching and could somehow pass this 'slightly more stretched' character on to their offspring. But Darwin realised that true evolution occurred by natural selection of species. The fittest and best-adapted flourished and produced lots more of themselves. The rest died out. If most of the world was like the Antarctic, penguins would be the commonest creatures (I wish!) and people, who don't like the cold, would not exist at all. We penguins are supremely adapted to live successfully in bitterly cold oceans and on ice. If the world suddenly got hot (as is happening as humans cause climate change), penguins would be in serious trouble. Species evolve by random changes whose cause Darwin didn't know (see genes - mutations). Perhaps in a hot world, some penguins would change sufficiently to find warm water agreeable. But most of us would die.