Runways last winter were swarming with new trends: cutaway suits, bandage-inspired suits, and asymmetrical, single-shoulder suits. Many of these haven't been seen for years, or have never been seen at all. Indeed, the preoccupation in fashion with defining yearly trends, and the seasonal necessity of changing clothing types has bred an ecosystem of orphan species—strange, exuberant mutants who appear one season, full of promise, only to disappear without a trace. If nature is cruelly efficient in selecting among individuals in its ecosystems, then culture is doubly so when it comes to swimsuits.

The tankini was one of the most recent casualties in this yearly churn. Made popular in the early 2000s, this hybrid of a bikini and camisole top achieved explosive popularity in fashion houses from Gucci to Target. The suit was loved by an unusually wide range of body shapes because it balanced showing skin and smoothing it. Even more exciting, it came unexpectedly, after an almost uninterrupted decline in skin coverage since the 1960s. By some strange coincidence of designer choice, celebrity movie appearance, novel fabric technology, and inspiration from who knows where, the tankini was born. But despite the excitement from the market for this bravely demure new style, it was gone from shelves within a season or two.

The extinction of the tankini, like so many other promising innovations over the years, indicates a fundamental flaw in the most common model of technological development. We, as a culture, believe that technology “improves” over time. Light bulbs get brighter. Cars get faster. Computers get more powerful for the same price. This idea of constant, linear progress is deeply engrained in our cultural consciousness, and has colored theories from evolutionary biology to eugenics. And just as over time we have realized that there is no “master race” of humans, or “higher order” of animals, we ought to see that there is no globally optimal direction for technology.

In fact, looking back at swimsuits, we can see that revolutions in suit design were brought on, not by some overarching long-term goal, but by the instantaneous want of the designers, and the market. One year, it may be a competition to create the shiniest suit. Next year, the skimpiest. Every so often, one of these random directions catches firmly, and lives to spawn a new generation of derivatives next year, as the modern string bikini did in the 1960s (although the bikini suit was recorded in ancient Crete). More often, however, these yearly variations are overtaken by the next year of fresh attempts.

We should remember this as we plan trips to the coast, or Maui, or Ibiza: while we are making decisions that influence suit design in the near term, the long-term direction of this development is less controlled, and certainly not headed in a specific direction. And swimsuits are not unique. Technology certainly moves on a path as new innovations are adopted or abandoned, but our control of this path only really applies at any instant. Over a longer term, the real influences on technology are those out of our control: climate, disease, war and the whims of our collective cultural unconscious. There is no forward or backward to that movement, only intensity of change. The suit you wear this season, with its bandaged form, or slashed fabric inspiration, will echo in seasons to come, but how, and for how long, it is impossible to say.