It's possible to save, go on to the Civilization stage, exit without saving, and do that ten times to get the achievement. (Doesn't work every time.)
If you start out as an omnivore tribe, you can both hunt and gather, making worrying about food a lot less important. Don't be ignorant and take it easy, time flies. However, being a herbivore is also easy even though you can't collect everyday meat, because fishing hot spots also are rich with edible seaweed.
Play the stage with Easy difficulty - the other tribes will not attack as much, speeding up the game.