Have been thinking about writing some science for some time.
Here is a question that we in one of our class here at KSU (Kansas State University) discussed which is almost at the interface of science and philosophy, so picking that.
One of the most interesting debates we had in our evolution class was about the "two fold cost of males". According to the theory of evolution a species evolves and advances its genetic heritage to next generation. Every species including human beings undergo struggle for existence and the most fit forms which has adaptations to succeed in a particular environment survives and reproduces extending its genetic heritage to its progenies. Every time in nature they get better adapted to the existing environmental conditions. If any species fail in this battle, they are not fit and eventually that particular species go extinct since there are no individuals who can advance their genetic heritage. Any heritable variation (genetic changes or mutation) will be carried to the next generation and conserved there. So basically the "fitness" of a population is to have as many progenies as it can produce and advance it's genetic heritage to next generation. Then what's the need of two sex forms (male and female) in a population? Isn't it enough that one form can reproduce and advance their progeny to next generation and thus the population survive? Such questions tend to get philosophical and sometimes even spiritual.
Now take the greatest debate between atheist and believers in the West. In USA, the State of Kansas has become so (in)famous for instituting "theory of intelligent design" in their schools. The theory of evolution by Darwin was the single most jolt to the evangelist since that completely disowns the Genesis chapter of Old Testament and the way in which it has described how GOD created various life forms. As per Darwin's theory of evolution, simplest atoms and molecules came together to form the primordial cell (after the Earth became suitable for making those) and as time advanced, they got more and more complex, sophisticated, multicellular forms. Every time they evolved new adaptations which allowed it to tide over unfavorable conditions and almost a million year ago, from a neanderthal, one Homo sapien (human being) also came into being. Against this evolution theory, evangelists proposed "intelligent design" which says GOD did all this design of various species in the most intelligent manner as you can see now. In the State of Kansas, after a lot of opposition from scientists (especially Biologists who are 'real scientists') political parties and evangelists were able to institute intelligent design to schools so that kids learn that also.
Now coming back to the cost of males. Take the case of simple, single celled forms; they don't have two sex forms. Bacteria, viruses and many fungi are just only one kind and they advance their life like that reproducing by budding or fission and many other similar methods. The problem with a form which cannot give birth (males) is that it cannot reproduce by itself and it also tend to produce new unproductive forms of itself. So the resources had to be given for an unproductive member in a population and that also leads to the production of another unproductive member. This is the two fold cost of males in a population. As per theory of evolution, this is not economical. When there are limited resources, the species cannot succeed in fitness if there are members which cannot give rise to off-springs.
So scientifically speaking, why there are males in a population?
Ha ha it would be funny to imagine a population where there are only mothers, daughters and sisters in a population and there are no fathers, sons or brothers:-D.
One answer is to create variation. Suppose there are only females and they give rise to only females. Every time they give rise to new progeny which look alike. The presence of a complementary life forms creates more opportunity for variation in population. The importance of variation is that it will allow to succeed in a particular environment. For example, if there was an epidemic outbreak (like SARS), all identical forms will get susceptible and eventually wiped out due to the disease. If there is one member who is a variant which can resist the disease, he will survive and give rise to progenies that will also survive. So males are needed for diversity of a sexually dimorphic population.
PS: Have resorted little bit of dilution in some concepts to simplify the scientific theory.
