Sex is expensive. At a minimum, it requires persons of opposite gender to come together. It may superficially seem to be a non-issue because for every female, there is a male around (well almost). But it does take quite a lot for a person from Venus and another from Mars to come to a meeting place on Earth. Yet getting together is just the beginning. They must then like each other to begin a meaningful conversation that could lead them further. Thereafter they need to love each other. It demands a lot of effort to impress one another. Too much energy goes in singing, dancing, feeding, eating, gift buying, villain-bashing, showing off beauty and strength, chatting (love letters in the past), and so on. All done. Then each of the lovers need to shun the competition. Because signalling does not discriminate between individuals of the opposite gender. Ask a plant which spends so much energy producing flowers with all their visual beauty and fragrance and then gets a bunch of freeloader insects who would not assist with pollination. Is it all worth it?
The above para was intended for fun. But there is a huge scientific cost too to this whole business of sex. Finding mates is a huge biological/ecological problem. Then there are costs associated with the fundamental sexual process of cell division – meiosis. Unlike mitosis (cloning) which finishes in under 2 hours usually, the sexual cell division of meiosis takes much longer to finish. If a female were to self-reproduce, she could pass all of her genetic material to the offspring and not just half. And then, ecologically speaking, half of the progeny in the form of males would not need to be produced at all. Why even bring these un(re)productive beings to life just to eat up resources?
What on Earth then are the benefits of sexual reproduction that the nature has preferred this mode over cloning? Well, that is one of the trickiest questions which the scientific world is yet to find a satisfactory answer to.
Cloning would produce the same individual every generation with the exception of cases affected by mutation. Does sexual reproduction enable life to stay ahead in the arms race with the villain who wants to disrupt life? By disturbing the pattern of life form just a little every generation? Making every eukaryotic individual unique? So that the villain cannot come up with a strategy based on its understanding of the earlier generation? And under this ever changing guise, life quietly goes a step further? But who is this ‘villain’? Even harder question is: who or what is this ‘life’?
With science, every answer leads to further questions, no?