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Bigger balls are better when it comes to spreading DNA, according to a new study.

After analyzing a published sequence dataset from 55 species of primates, scientists found a link between molecular evolutionary rates across a genome and testes weights. The latest research used the weight of tests as a proxy for increased sperm production and competition.

It is believed that the production of more sperm results from more rounds of cell division, which lead to more mutations during sperm production.

"In general, the speed of genome evolution is higher for species in which males have large testes in comparison to species in which males have small testes," researcher Alex Wong said in a news release. "This finding helps us to understand why genomes evolve at different rates in different species, and has implications for our understanding of the relationship between female mate choice and the overall fitness of a population."

After analyzing correlations between testes size and substitution rate in primates, Wong and his team found a positive correlation when accounting for other confounding factors.

Researchers said the latest findings provides support for the theory that sperm competition should result higher substitution rates as a consequence of higher spermatogenic activity in species that mate with more than one male.

Researchers explain that females of many primate species mate with multiple partners. This often leads to an intense competition amongst males to pass along their DNA to be king of the genome.

"The current finding of covariance between sperm competition intensity and substitution rates adds to a growing body of knowledge concerning the sources of substitution rate variation," said Wong. "The extent to which this covariance is widespread is not yet clear; application of robust comparative methods to large phylogenetic datasets in other taxa, such as birds and insects, will help to establish its generality."

The findings are published in the journal Molecular Biology and Evolution.