The natural history broadcaster warned that the world is "heading for disaster" and without action the "natural world will do something", he told The Daily Telegraph.
He added that the natural world has been doing it "for a long time" and more discussion is needed.
"What are all these famines in Ethiopia, what are they about?" he said.
"They're about too many people for too little land. That's what it's about. And we are blinding ourselves.
"We say, get the United Nations to send them bags of flour. That's barmy."
He cited "huge sensitivities" like the right to have children and the Catholic Church's stance on contraception as barriers to talking about population control.
He added that the issue could also be misconstrued as an attack on poor people as the areas of concern are Africa and Asia.
His latest series David Attenborough's Rise Of Animals: Triumph Of The Vertebrates will begin at 9pm on Friday on BBC 2.