Charlize Theron thinks women only ''come into their prime'' in their 40s.

The 39-year-old 'Prometheus' star, who is dating Sean Penn, 54, says 20-year-olds ''have no f**king concept'' about life and believes the beauty industry should focus on older women.

She told Women's Wear Daily (WWD) magazine: ''It's ironic that we've built the beauty world around 20-year-olds, when they have no f***ing concept about wisdom, what life is about, having a few relationships below [their] belt and feeling hardships, to grow into [their] skin and feel confident within [themselves] and to feel the value of who [they] are, not because of a man or because of something like that.

''And I think that's such a beautiful thing. And that's why I think people say women come into their prime in their forties.''

The South-African star, who has a two-year-old son, Jackson, also admits she feels a lot more sensual and secure about her looks as she gets older.

She said: ''It's like we wilt for some reason. And men are like fine wines - the older they get, the better they get. It's such a misconception, and it's such a lost opportunity because that's when I think women are really in the true moment of their sensuality.''

The Dior ambassador added: ''I think that women find their strength and power in their sexuality, in their sensuality within, [through] getting older and being secure within that.''