“All meditative traditions, whatever the differences in underlying belief
systems and in specific techniques, agree in one essential respect: the cause of the dissatisfaction, anxiety and suffering which seem to be inseparable from our lives lies in a basic misinterpretation of the true nature of existence, a misinterpretation which clouds our perception of the actual facts, in consequence of which we persist in futile attempts to pursue and secure things (such as health, riches, happiness and so on) which are, by there very nature, ephemeral or unattainable.”
--- Amadeo Solé-Leris, “Tranquillity & Insight,” Buddhist Publication Society 1992, p. 9
The Buddha, like many other spiritual guides, contends that unhappiness is rooted in endless unsatisfiable craving: for things we want but cannot have, and for things we do not want but cannot avoid. This craving is shared by all beings, and happiness can only be found by casting off this desire.
Doing so is, at best, very very hard. At worst, it’s a losing battle. After all, if all creatures are driven by craving, it must be a very adaptive behavior in evolutionary terms. It’s a good default for any creature to strive for more than it has, and to avoid what is unpleasant with all its might. If you do this you won’t be happy, but your genes will prosper. If craving and aversion is built in by evolution, then trying to switch it off seems maladaptive (not to mention futile).
Still, meditation traditions have themselves survived cultural evolution; there must be some benefit to their practices. Perhaps society has progressed to the point where it is safe enough – that is, humans are powerful and wealthy enough – to benefit from reducing craving and aversion. The swelling of a twisted ankle must be evolutionarily adaptive; and yet, athletes are advised to ice their injuries in order to accelerate recovery. The over-reaction of the immune system in allergies makes sense as a general purpose response, but it is not adaptive in Spring-time, and we use drugs to mitigate it. Likewise, meditation looks like another technology that humans developed to improve their lot as culture has lessened the threats held by nature.