For a long time, biologists have been confused at the continued existence of males. Given that males do not themselves reproduce it is a wasteful drain on the species to produce them in 50% of the population. It would be much more sensible "in evolutionary terms to have an all-female asexual population which creates daughters who can reproduce rather than sons who cannot, such as the Mexican Whiptail Lizard."
So in as much as males do exist and evolution has not selected us out the assumption is that there must be a good reason for it. Why this same reasoning doesn't apply to that Mexican Lizard is not mentioned. The entire edifice of Darwinian theory rests on the assumption that there are limited resources that all species are in a perpetual death struggle to procure. The ones with the benefit of a useful, random mutation (though mutations are almost always non-beneficial) will be incrementally better at accessing those resources - thus thriving and passing on that beneficial trait to their progeny.
There are questions to be asked regarding these assumptions:
- Why do species "care" about survival in the first place? Why couldn't "nature" have randomly started with a death wish or with no motivation of any sort?
- Why has evolution selected celibacy, voluntary army service, abortion and other practices that limit the population (the supposed motivating drive of all species)?
- Where did the information come from for the radically different designs of males and females - can the steps be explained?
- What process generated the information that allows males and females to "work" together to reproduce?
- Is it presumable that the reproductive system would have to work perfectly from the beginning? What accounts for this perfection? If it developed over time, how did reproduction occur at earlier stages?
There is another way of looking at all of this - that males and females were created by a conscious designer - one who was aware of all of the benefits (including biological, sociological, spiritual) of having more than one gender. This conscious agent would also be capable of executing on the design from the get go so that no risky "random" mutating would be responsible for generating the staggering amount of specified functional information that is required for even the simplest organism to live and reproduce.
"What is man that you should remember him and the son of mortal man that you should be mindful of him? Yet you have made him but slightly less than the angels and crowned him with soul and splendor."
Tehillim (Psalm) 8:5-6