Longing for a baby? Don't go by the looks while opting for your partner, for a study says that handsome hunks may not be the best bet for women hoping to get pregnant.

Instead, ugly men with fewer notches on their belts are likely to be more productive between the sheets – because in many species, the most desirable males restrict their sperm load with each mating to ensure enough to go around.

A smaller sperm load reduces the chances of any female getting pregnant. And the same could be true of humans as well as other primates, 'The Daily Telegraph' reported.

Researcher Sam Tazzyman of University College London said: "In some species females mate with many different males.

Each male's sperm competes with that of other males in process known as 'sperm competition'.

"Since males have finite resources to allocate to breeding, they allocate them carefully to each mating to maximise their number of offspring. If a male puts a lot of resources into each mating he will get more offspring per mating, but at the expense of fewer matings.

"If, on the other hand, a male puts few resources into each mating he will secure less paternity per mating, but will be able to carry out more matings overall. Thus, there is

a trade-off between number of matings and success per mating."

According to the researchers, the more attractive a male is, the more females will be willing to mate with him, reducing the value of each mating to him. This means it is optimal for him to contribute fewer sperm per mating.

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