It is a symbol of femininity. Women with long eyelashes that frame their eyes look more attractive. Big eyes with long eyelashes are related to youth and fertility. In addition, beauty lashes evolved to keep dirt out of our delicate eyes, and long eyelashes suggest femininity and youth.
For example, my brother has dense eyelashes and looks very masculine, while my wife has sparse eyelashes and looks very feminine. She also noted that, as predicted, one of her studies showed that eyelash augmentation benefited older women rather than younger women, who were perceived as more attractive and healthy. Adam also recognizes that eyelashes are just one feature that affects the perception of age and attractiveness. She notes that her research suggests that longer eyelashes “may serve as an external signal for health and femininity and can therefore be used as an indicator of fertility, rather than simply an “arbitrary cultural preference”, and are specifically preferred by women.
My brother now has two young children with ornate eyelashes and, for what it's worth, as of press time, at least their eyelashes haven't met the same grim fate as their father's. Aimee Adam, in “Beauty Is in the Eye of the Beautiful” (202), examined the impact of false eyelashes on perceived attractiveness. However, more recent research points to the idea that long eyelashes are valuable because of the illusion they create of wide eyes and gazing eyes. In other words, you may sometimes reach positive conclusions, simply based on the length of your eyelashes.
Some scientists believe that if eyelashes have any real function, it is to diffuse airflow that could threaten to dry out the eyeball, and that their length is generally determined in relation to the size of the eyeball itself and not to the gender of the mammal to which they belong. Speaking more about history, personality, charisma, kindness and compassion are traits that influence personal attraction, regardless of eyelash length. On the one hand, the presence of healthy eyelashes can be a sign of general health; several diseases, disorders and congenital conditions can cause eyelash loss (sometimes referred to as milfosis or madarosis). Specifically, just like head hair, eyelashes change over time and can serve as external mating signals.
The T and minoxidil in my eyebrows for a few months made my eyelashes extremely long and feminine, and they were already those things to begin with. Look at other people's eyes and you'll see that there's not much of a pattern as to who has dense eyelashes and who has sparse eyelashes.