Biology2

Every organism at one time or another has to learn to adapt to a new environment. This is why evolution of organism is needed in order to survive changes to its environment, such as the case of the flightless birds. For one reason or another over a period of 100,000 years the need for wings was unnecessary to their survival. There could be many reasons why the birds evolved to be more adaptable to their environment. …

…thing could have been that it was hard for predators to catch the birds if they stayed in think under brush or traveled along the ground. For whatever reason the birds didn't need their wings this trait was passed of from generation to generation. The reason this trait was passed on was because it helped the survival of these individual birds. They were able to reproduce and pass these traits through heredity. Bibliography lycos.com