Doctor's complete solution

David Attenborough - Presenter: Three and a half million years separate the individual who left these footprints in the sands of Africa from the one who left them on the moon. A mere blink in the eye of evolution. Using his burgeoning intelligence, this most successful of mammals has exploited the environment to produce food for an ever-increasing population. In spite of disasters when civilisations have over-reached themselves, that process has continued, indeed accelerated, even today. Now mankind is looking for food, not just on this planet but on others. Perhaps the time has now come to put that process into reverse. Instead of controlling the environment for the benefit of the population, perhaps it's time we control the population to allow the survival of the environment.