Nearly all mammalian species demonstrate sexual promiscuity. Even mate-for-life prairie voles, the animal kingdom's poster child of monogamous relationships, produce pups from different fathers twenty percent of the time. Moreover, for humans, historians say, promiscuous behavior is not new at all.

Anthropologists have uncovered clues to how our Paleolithic ancestors lived. Before the advent of agriculture, humans faced a short, brutal lifespan. Some survived to age 50, but most died young or at birth with average life expectancy in the 30-to-40 range.

With such a short lifespan, ancestral children were likely to experiment with sex by age six. Most couples lived in temporary relationships, and being unfaithful was common for these cave dwellers.

When our forbears found themselves in an unhappy situation, they simply walked away and found another cave. Scientists believe that hunter-gatherers had sex mostly for fun, not just to reproduce.

Research professor at Rutgers University, Helen Fisher, who has written five books on the future of human sex, love, and relationships, says that marriage has changed more in the last 100 years than the previous 10,000, and it will change more in the next 20 years than the past 100!

We're shedding traditions that have survived since our culture began 10,000 years ago, Fisher says, and it appears we're returning to the ancient sex and romance practices of our hunter-gatherer days.

Concepts such as, 'till death do us part, a woman's place is in the home, and men as the primary wage earner, began disappearing in the last half of the 20th century. Relationships are now undergoing radical changes. Divorce is viewed more as a solution than shame; working-women are the norm; living together without marriage is gaining popularity; and some states have even legalized same-sex weddings.

In addition, our concept of infidelity is also changing. Some married couples agree that it's OK to have brief sexual encounters when they travel separately; others sustain long-term adulterous relationships with their spouse' approval. Moreover, recent studies have shown that relationships like these with less pressure on 'being faithful' are more stress-free for both participants, leading to happier lives.

Internet dating wields its impact on relationships too. Matching people with great partners is getting so efficient, and the process so enjoyable, that marriage itself may one day become obsolete.

As we wind through the 21st Century, new relationships will challenge many of our traditions and social policies. Houston futurist Sandy Burchsted, who recently spoke at a World Future Society conference, believes that in the future, most people will marry at least four times and experience extramarital affairs with little public censure. Marriage will be considered an evolutionary process, not a one-time-only event.

It may be time to rethink monogamy, especially given the way that the world has politicized the concept of marriage. As prairie voles aren't "pure as the driven snow," there is also no biological evidence to suggest that human beings are naturally monogamous. We may be culturally and socially encouraged to be faithful, but it is unclear how much that sway really has over our biology.

Some believe a monogamous relationship is the best way to achieve happiness; but a University of Michigan study says not so fast. Researchers found non-monogamous relationships reported higher levels of satisfaction and intimacy, and less jealousy than experienced by monogamous pairings.

Today, we live in a sea of technologies that reshape our lives. To bond is human and drives to fall in love are embedded in our nature. With new sex and romance aids, such as Viagra and estrogen replacement, and science providing us with longer healthier lifespans, we have the opportunity to create a more fulfilling partnership than at any other time in history. Welcome to the future! Comments welcome.