How’s the sex? It depends a lot on your age and life stage.

Sexuality is nature’s gift to us at birth, developing as we age and peaking sometime between high-school graduation and our 20-year class reunion, when we likely get to come face-to-face with he or she who was our first sexual encounter. Thereafter, many of us invest more than a little effort trying to restore our sexual selves to their former glory, be it with breast implants or erectile-dysfunction helpers.

Nature and society conspire to make it increasingly clear that we’re not who we used to be in the bedroom (or backseat). Here’s the lowdown on male and female sexuality through life’s stages.

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• Female Teens to 30-Somethings: The Young and the Vigorous

  While women’s fertility is at its highest in their early- to mid-20s, their libidos don’t necessarily peak at the same time. The female sex drive is a mercurial force, affected by hormones, life circumstances, relationship status and self-image. Add technology to the list, too — as in the ready and not always responsible use of camera phones and the flirty thrills of sexting.

• Male Teens to 30-Somethings: The Young and the Vigorous

  Testosterone, the primary male sex hormone, peaks in males around the late teens and remains in abundant supply through the 20s and 30s. This is the stuff that gives the fellas their mojo and helps the, er, rocket achieve lift off. Men in their teens to late 30s generally have enough of this love potion coursing through their veins to ensure a robust libido.

• Female 40 to 50-Somethings: Ripe and Ready

  Conflicting forces have at the female libido in the midlife. Balancing motherhood and a career can have a dampening (or shall we say non-dampening?) effect on the sex drive. On the other hand, a study by University of Texas psychologist David Buss found that women in their 30s and 40s have both more sexual fantasies and actual sex than their younger counterparts, perhaps because of a subconscious evolutionary drive to conceive as many children as possible before the onset of menopause.

• Male 40 to 50-Somethings: Ripe and Ready

  Though testosterone levels begin to wane in the 40s and 50s, most middle-aged men still regularly desire sex. The main difference, according to Saul H. Rosenthal, M.D., author of the book Sex Over 40, is that erections are less spontaneous and require more physical stimulation. Men in their middle years may also find it more difficult to “get it up” again within 24 hours of orgasm, making it all the more important to observe the chivalrous rule of “ladies first.”

• Female 60-Somethings and Beyond: Seasoned and Sensual

  As women approach and pass through menopause, estrogen levels decrease significantly, sometimes resulting in vaginal dryness or thinning of the vaginal walls, making intercourse uncomfortable. On the bright side, the clitoris is located outside the vagina (let’s hope we’ve figured that much out over the years!) and is the main player in female orgasm. With corresponding changes in their mates’ sexual response, mature women can find themselves enjoying some of the most communicative, intimate and imaginative encounters of their lives. And aren’t those things the key to better sex at any age?

• Male 60-Somethings and Beyond: Seasoned and Sensual

  For a man, trying to have sex at 75 can be like trying to hit a dartboard with a noodle. The Mayo Clinic puts it more directly: “The penis may take longer to become erect, and erections may not be as firm.” Tomato, tomahto. The fact is that, while a man’s sexual desire often remains ardent, his body’s interest in cooperating may change once he’s past his 60s. The good news? As the tried-and-true methods decrease in effectiveness, couples have all the more reason to communication and creatively experiment. (There’s more than one way to pop a champagne cork, after all.) The pharmaceutically inclined also have a small arsenal of tools at their disposal.