There is not a definite standard of beauty, but most men do have a type and on average, there is a tendency where men generally prefer a certain type and don't like certain type.
The type of women, men are more likely to be sexually attracted to, is the product of evolution. This apply to both men and women and apply to all mammal. For example, why are girls more likely to attracted to masculine men at first meeting, because, in the tribal era, society require men to serve as warrior, to defend them, we cannot tell who have a better fighting skill, until they actually fight, but we know more masculine male have a better physical advantage, as a result evolution led women to be more attracted to tough guys, thus as a result, more attracted to masculine male and after seen they fight, they will be attracted those with better fighting skills.
Certain species are attracted to fat female, this is also a product of evolution, they live in cold climate and the fat of the female help keep the cub warm, as a result, male that are more likely to be attracted to fat female in that species are more likely to have decendent that grew up and pass on their gene.
Human male, are more attracted to women, who are fit, nice, logical, independent, intelligent (but due to male ego, not so much they felt intimidated), large breast and hip. Girls who are fit have more energy and are less likely to suffer health problem, which is an advantage of been a mother. Nice girls are more responsible, help make them better mothers. Logical and intelligent girls make better decision, making them better mother, independent girls are stronger, that make them better mother, especially if you passed away. Natalie Portman is very hot, but there are many other attractive Hollywood female celebrities, some are even hotter then her, but, Natalie Portman is the most desirable, because she got a PhD. Girls with wide hip are less likely to have complication in child birth and big breast girl, give more milk,
As a result, evolution led to men are more likely to be attracted to girls with big breast, wide hip, fit, logical, smart, nice (even better if she is a nerd) because these charactristic help to make a woman a better mother.