The political ideal is quite different from the political reality because reality proceeds by different logics. Ideally, we would pass bills and make laws through a process of first stating our values and goals (e.g. To reduce the cost of public transit in area A without negatively affecting quality of transit more than X amount), then we would bring in the science and data breaking down the problem, we would spend most of the time evaluating and comparing data and expert accounts of the problems, then once determining the most reliable data-set we would apply it to the problem given our values, and poof, a solution emerges mathematically.
This could realistically be the process for the majority of all legislation in politics. Health care, taxation, immigration, farming subsidies, war, infrastructure, education... a minimal quantification of values is all that is required, and the sufficient energy to carry out some scientific analysis. We waste more money than this would cost on pointless debates about ideologies and morals, about talking past each other, about not acknowledging our "opponents" by deliberately ignoring reality, on being egotistical and short-sighted rather than rational and far-sighted, goal-oriented.
Rational Politics is not impossible, I would say it is rather the Ideal, and structurally speaking, very possible indeed. But of course reality does not care for the Ideal, it cares for the Necessity, the shortest distance between two points given the implicit parameters of those involved. And since there has been no call for a rational approach to governance, such as I've outlined above, there is no reflection of its possibility in politics anywhere. We are still operating based on the old laws of the tribe, the jungle madness, the reptilian brain and all its arbitrariness.
Religion is only one manifestation, it is not a disease but rather a symptom.
It helps to realize that there is no solution, but only various degrees of problems. Humanity has no utopia waiting for it on the horizon, no glorious Communism, Socialism, Capitalism, Technologism, Anarchy, Revolution or New World Order. There is nothing but various exchanges of ranges of chaoses, that "evolution" which indeed proceeds as you say, like the shifting patterns of genes within influencing environments.
Humans are a short few steps away from the Ideal, from a more perfect and rational organization, life, psyche, possibility, power... just like they always have been, just like they always will be. Achieving the end is impossible because the end in this case is the culmination of various mens' ideals and values, which change with time, and although they eventually gather in the philosophical nature under similarly corresponding headings and vectors, philosophical minds do not write power into the world or exchange the powers of history, they do not shape things, they influence from the corners, write memos in the sidelines and contribute footnotes. No man has control over the whole picture, and so no mind, no vision regardless of how sane or rational, can ever prevail.
War might be the only expression that seems to "do" anything, in terms of elevate possibilities for reason and rational insight to take a primary seat at the table of history-making. Of course it is always the rationale of the victors, which means we are stuck in the same endless feedback loop rather in war or "peace" (covert war).