Poets have pondered over this query for centuries, but the sonnets may all just go waste since scientists believe that the mystery can be unlocked only by - geneticists! The query - is 'love at first sight' a fanciful notion or is it, a reality?
In a study on fruit flies, American and Australian researchers have discovered that some males and females are more compatible than others at the genetic level.
In their opinion, this compatibility plays an important role in mate selection, mating outcomes, and future reproductive behaviours.
The researchers say that the experiments conducted by them have shown that before mating, females experience something called "genetic priming", which makes them more likely to mate with certain males over others.
"Our research helps to shed light on the complex biochemistry involved in mate selection and reproduction," said Mariana Wolfner, Professor of Developmental Biology at Cornell University and the senior scientist involved in the study.
She added: "These findings may lead to ways to curb unwanted insect populations by activating or deactivating genes that play a role in female mating decisions."
For the study, scientists mated two different strains of fruit fly females to males either from their own strain or to males from the other strain.
They noted the males with which females of each strain tended to mate, and then examined whether the females showed differences in behaviour soon after mating and in reproduction-related activities, such as how many offspring were produced and how many sperm were stored.
They also analysed females' RNA to compare the genes expressed in females mated to males of different strains.
It was found that despite observed differences in mating behaviours and reproduction activities in females mated to different strains of males, there were only negligible mating-dependent differences in gene expression between the groups.
Based on their observations, the researchers came to the conclusion that genetic changes involved in mate choice and reproduction existed before mating began.
The study has been published in the latest issue of the journal Genetics.