Culture as Biological Strategy
All living things die. Life inherently seeks to continue life, which means grappling with the fundamental problems of survival and reproduction. Survival means sustaining the individual life as long as possible. But creating permanent life (immortality) has proven impossible, so the key to long-term sustenance of life is reproduction. Natural selection has favored organisms that can survive and, even more important, can reproduce.
Human beings have adopted a rather unusual strategy for surviving and reproducing (see Baumeister, 2005). We create social systems established on shared information, exchange and trade, morality, and group effort based on interlocking roles. In a word, we rely on culture to produce survival and reproduction. It has worked quite well for our species. Human beings survive and reproduce much more effectively than any other mammals on the planet. It's why we put the other mammals in zoos rather than vice versa. No other creature has tripled its average life expectancy, because no other one has mastered the cultural practices of accumulating scientific knowledge and using it to inform medical treatments and public health practices. And while the populations of most other creatures on earth, and certainly all other mammals, has declined in recent centuries (with a few exceptions that are overseen by human intervention, such as breeding chickens and keeping dogs as pets), the human population has ballooned to an astonishing degree and continues to increase. Culture has greatly increased human life.
The future is culturally constructed. Time will proceed regardless of culture, and even if humankind commenced a nuclear war and wiped itself out of existence, there would be a physical future in the sense that the earth would continue to rotate and each place on earth would undergo an alternation of night and day. But without humankind, that alternation would lose most of its meaning. Human conventions construct the future, with national and religious holidays, weekends, and more. Individuals fill in their specific details, such as anniversaries, appointments, deadlines, and travel plans.
The individual human mind learns to operate within the socially created structure of past, present, and future. It is safe to predict that citizens in Western civilization will celebrate Christmas on a particular date in 5 years. That date is based on a presumptive but almost certainly erroneous calculation of the date of birth of a particular individual a couple thousand years ago. Even people who have no belief in Christian doctrine will celebrate the holiday: They will stay home from work, give gifts to their children and relatives, and eat a holiday feast of some sort. Thus their individual beliefs about the validity of religious doctrines are somewhat irrelevant to altering their actions on a particular, prearranged day.