The head at the top, the tail is just for getting to the egg
It happens when the two groups become sufficiently different and the two can no longer interbreed. A known example of speciation is the London underground mosquito where it formed a new species within the existing genus. There are examples in micro-evolution but not in macro-evolution.
Genetic drift scientific explanarions are based on empirical data and evidence
War veterans returning from either Afghanistan or Iraq
