Last summer I was hiking in the tundra near Gray’s and Torrey’s Peaks when I came upon a moss that looked strange. It had little flattened discs that looked something like this: What were these things? Then I happened to pick up a book called “Gathering Moss“, and suddenly I knew what it was I [...]

Looking around the ever-more-crowded globe, you might conclude that human sperm counts are just fine, thank you very much. Hitting the 7 billion mark as a species can lead to such conclusions. Yet that inference would counter what some involved in the field of endocrine-disruption research have long asserted: that sperm counts have, in fact, [...]

Stem cells have been coaxed into creating everything from liver cells to beating heart tissue. Recently, these versatile cells were even used to make fertile mouse sperm, suggesting that stem cell technology might eventually be able to play a role in the treatment of human infertility. Now two types of stem cells have been turned [...]

Two-part barbed penises, a physical struggle and 20 minutes of penetration. That’s how some sea slugs do it. But the real shocker is that, for one species at least, those in the female role seem to engage in these bizarre, violent sexual encounters more often than might be biologically necessary. Nothing about sea-slug sex sounds [...]

Moss, that cushy, moisture-loving ground cover, is more promiscuous than we thought. These plants might not have the sexy flowers of a peony, but according to new research, they do manage to attract small pollinators with a subtle sweet smell. Previously, scientists had presumed that these primitive plants needed a layer of water for their [...]

Fellas, want a better chance of passing along your genes? Try laying off the fried food. A more healthful diet will not only help you get fitter, but, new research indicates, it might also increase the odds that your sperm are in better shape, too. A whole host of factors might impair male fertility—including alcohol [...]

Sperm face steep odds when set free to fertilize an egg. A slightly faulty tail, a miscalibrated electrical charge on their cell membrane or some other subtle defect can keep these genetic couriers from becoming the lucky, lone swimmer that sires offspring. And now it seems that a surprisingly common genetic mutation might decrease a [...]

Once they’re inside the female reproductive organs, sperm pull out all the stops to outrace their rivals to the egg—especially if the opponent comes from another male. The process that determines which sperm wins, called "postcopulatory sexual selection," has been difficult to tease out, until now. By genetically engineering fruit flies that express green or [...]

The predictable swimming sperm featured in health class videos are rather uncharacteristic portraits of the life of these sex cells. Spermatozoa actually spend most of their time resting up in the male reproductive tract so they can make a dash to the egg once the opportunity arises. It has long been known that the little [...]