In a 2017 publication in the journal "Science", mathematical modeling of 50,000 bird eggs data showed that bird egg shape is a product of flight adaptations and not the outcome of nesting conditions or a bird's life history. A strong correlation was found between egg shape and flight ability on broad taxonomic scales, such that birds engaging in high powered flights usually maximize egg size by having elliptical shaped eggs while maintaining a streamlined body plan. Selection acting during incubation, such as breeding site and incubation posture, are also thought to influence egg-shape variation across birds.