Tag: sex & reproduction

How Can a Baby Have 3 Parents?

By Jennifer Barfield, Colorado State University | June 15, 2018 11:21 am
baby-3-parents

(Credit: Shutterstock)

It seems impossible, right? We have been taught from the time we were young that babies are made when a sperm and an egg come together, and the DNA from these two cells combine to make a unique individual with half the DNA from the mother and half from the father. So how can there be a third person involved in this process? Read More

Astonishing Ways Animals Ensure Their Sperm Win

By Louise Gentle, Nottingham Trent University | February 14, 2018 9:43 am
Echidnas sport for penises (only two ejaculate). (Credit: Shutterstock)

Echidnas sport four penises (only two ejaculate). (Credit: Shutterstock)

We all know that individuals fight over potential love interests. Just think of Daniel Cleaver (Hugh Grant) and Mark Darcy (Colin Firth) scuffling, rather impotently, over Bridget Jones in a fountain. But you might be surprised to hear that the fierce rivalry continues behind the scenes — in the form of sperm competition. This is when the sperm of two or more males compete inside the reproductive tract of a female, to fertilize the eggs, something that is widespread in the animal kingdom.

It is generally assumed that the sperm in a female’s reproductive tract around the time of fertilization will belong to one male. But DNA fingerprinting has revealed that even “monogamous” bird species that form exclusive pair bonds are not as exclusive as was once thought. Read More

CATEGORIZED UNDER: Living World, Top Posts
MORE ABOUT: sex & reproduction

Chromosomes Aren’t the Only Determiners of a Baby’s Sex

By Kristien Boelaert, University of Birmingham | January 18, 2017 12:10 pm
shutterstock_100837744

(Credit: Shutterstock)

The concept of being able to predict the sex of a baby during early pregnancy or even influence it by eating or doing certain things when trying to conceive has been the subject of public fascination and debate for many centuries. But surely the sex of a fetus is exclusively determined by the father’s sperm, carrying an X chromosome for girls and a Y chromosome for boys?

It turns out this is not the full story. Since the 17th century, it has been recognized that slightly more boys are born than girls. This is strange – if the sex were determined solely by chromosomes, the probability of either should be 50 percent and not variable. This must mean that, although the same number of boys and girls are conceived initially, more female fetuses than male ones are lost during the pregnancy. Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts
MORE ABOUT: sex & reproduction

When Nausea During Pregnancy Is Life-Threatening

We need more – and better – research to treat HG. (Credit: Shutterstock)

Most women experience some type of morning sickness during pregnancy, but some women develop a far more serious condition.

Hyperemesis gravidarum (HG), which causes severe nausea and vomiting during pregnancy, affects as many as 3 percent of pregnancies, leading to over 167,000 emergency department visits each year in the U.S.

Until intravenous hydration was introduced in the 1950s, it was the leading cause of maternal death. Now, it is the second leading cause, after preterm labor, of hospitalization during pregnancy.

And yet, the disease is neither well-understood nor well-known, even with the flurry of headlines when it was announced that the Duchess of Cambridge during her pregnancies suffered from the condition. Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts

When Did Sex Become Fun?

By Holly Dunsworth | September 30, 2016 10:41 am
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The reproductive organs of a lily. (Bryan Neuswanger/Shutterstock)

(This post originally appeared in the online anthropology magazine SAPIENS. Follow @SAPIENS_org on Twitter to discover more of their work.) 

There are multiple answers to the question of where we come from: early hominins, monkeys, primordial goo, or the Big Bang, to name a few. Today’s answer, though, has probably, just a split second ago, popped into many readers’ minds. Today’s answer is sexual intercourse, a.k.a. “bleeping.” So let’s go back to the beginning, hundreds of millions of years before we invented euphemisms and censorship, and let’s ask: How in the evolutionary world did sex begin?

Algae, the green gunk that runs amok in our fish tanks, as well as the seaweed that stinks up our summer beaches, include some of the simplest sexually reproducing organisms on Earth. These lineages go back nearly 2 billion years. Algae do it. Plants do it. Insects do it. Even fungi do it. Much of this sex involves releasing sperm into the wind or the water so they can be carried to nearby eggs (as in mosses), relying on a different species to carry male gametes to female ones (many flowers), or maneuvering two bodies so that the openings to the internal reproductive organs are close enough together for fluid exchange (most insects and most birds). Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts

Yes, Other Animals Do Have Sex For Fun

By Jamie Lawson, Durham University | August 3, 2015 1:38 pm

dogs mating

There’s an idea circulating that humans are the only animal to experience sexual pleasure; that we approach sex in a way that is distinct from others. As with many questions about sex, this exposes some interesting facts about the way we discuss the subject.

On one level, the question of whether humans and nonhumans experience sex in the same way is fairly simply dismissed: how would we know? We cannot know how a nonhuman experiences anything – they can’t be asked. Sex as an experiential phenomenon for nonhumans is, quite simply, inaccessible. Science is obliged to propose questions that are answerable, and “how does a leopard slug experience sex?” is, at time of writing, about as unanswerable as they get.

Having said that, we can make educated guesses about whether sex is pleasurable for other species. Sex would be a very strange thing to seek if it didn’t bring some form of pleasure. It increases risk of disease, it wastes energy, it can seriously increase the likelihood of something bigger coming along and eating you (seriously, check out leopard-slug reproduction, below).

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CATEGORIZED UNDER: Living World, Top Posts
MORE ABOUT: sex & reproduction

Why Hospitals Aren’t Always the Best Place to Give Birth

By Neel Shah, Harvard Medical School | June 4, 2015 11:38 am

baby birth

There is a good chance that your grandparents were born at home. I am going to go ahead and assume they turned out fine, or at least fine enough, since you were eventually born too and are now reading this.

But since the late 1960s, very few babies in the United States or the UK have been born outside of hospitals. As a result, you may find the new guidelines from the UK’s National Institutes for Health and Care Excellence (NICE) just as surprising as I did. For many healthy women, the NICE guidelines authors believe, there may be significant benefits to going back to the way things were.

Shortly after the NICE guidelines were issued, the New England Journal of Medicine invited me to write a response. The idea that any pregnant patient might be safer giving birth outside the hospital seemed heretical, at least to an American obstetrician like me. Knowing that no study or guideline is foolproof, I began my task by looking for holes to form a rebuttal.

I soon realized that this rebuttal largely hinged on flaws in the American system, not the British one. While we take excellent care of sick patients, we do less well for healthy patients with routine pregnancies – largely in the form of turning to medical interventions more than strictly necessary.

As the guidelines suggest, some women in the UK with low-risk pregnancies may be better off staying out of the hospital. Why? Because the significant risks of over-intervention in hospitals, such as unnecessary C-sections, may be far more likely (and therefore more dangerous) for patients than the risks of under-intervention at home or in birth centers. But women in the UK have access to greater range of settings where they can give birth. For women in much of the US, the choice is often the hospital or nothing.

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MORE ABOUT: sex & reproduction

The Darker Side of the ‘Love Hormone’

By S Craig Roberts, University of Stirling | May 21, 2015 9:40 am

love hormone

A decade ago, a revolutionary paper showed that a hormone called oxytocin can actually make us trust other people. This spawned a flurry of research that revealed oxytocin’s potential to boost social interactions. Now a new study has shown that the hormone is actually very similar to alcohol, a well-known social lubricant. However, just like alcohol, it has a dark side.

In the first study, published in 2005, volunteers were asked to invest money in an anonymous trustee whose honesty could not be guaranteed. People who received a dose of oxytocin chose to invest more than those given a placebo – they were more trusting. Subsequent experiments have shown that oxytocin also leads people to become more empathetic, generous and cooperative. They become better at reading social nuances and facial expressions, believe others to be more approachable and become less fearful and anxious in social situations.

Not only this, it seems that oxytocin may help to promote fidelity. Evidence for this comes most clearly in two intensively studied and closely related rodent species. One, the prairie vole, is monogamous; mated couples form close pair bonds and share nest-building and parental duties. In the other, the meadow vole, males leave the female with the babies and will try to mate again.

The two species vary in their sensitivity to oxytocin. However, experiments that increase the effective sensitivity to oxytocin by increasing hormone dosage or blocking receptors in the brain can actually change pair-bonding behavior, making it easier for female prairie voles to choose a partner and turning previously promiscuous meadow vole males into monogamous, caring dads.

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CATEGORIZED UNDER: Mind & Brain, Top Posts
MORE ABOUT: sex & reproduction

When Women Are Rare, Men Are Less Promiscuous

By Ryan Schacht and Monique Borgerhoff Mulder | January 14, 2015 12:21 pm

bar talkingThe Conversation

This article was originally published on The Conversation.

Popular wisdom and established evolutionary science hold that the sexes seek fundamentally different relationships: men want short-term, no-strings-attached relationships whereas women value longer-term, loyal partnerships.

The explanation generally comes down to biological differences between men and women. Because women invest more in reproduction than men do – think pregnancy, morning sickness and stretchmarks – being picky becomes important because choosing poorly can be costly, even devastating. However, for men, reproduction may only entail a brief sexual liaison and a bit of sperm – there are potentially no long-term costs. This calculus has been built into our psychology, many argue.

Think about it more carefully, though. Where do all the women sleeping with these guys come from? Shouldn’t it be difficult for men to find so many willing partners? As theorist Hanna Kokko noted, it takes two to tango.

If we go by the numbers, in a group with an equal number of both sexes, it is impossible, on average, for men to have more partners than women. So why do we expect male psychology to be so hellbent on one-night stands? And why, clearly in opposition to this notion, are many men often so devotedly paternal?

Here’s where an established body of literature in sociology and demography – called mating market theory (MMT) – can help out. According to MMT, relationship preferences are expected to follow not simply from these fixed biological propensities, but also to be heavily influenced by partner availability.

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CATEGORIZED UNDER: Mind & Brain, Top Posts
MORE ABOUT: sex & reproduction

Exercise During Pregnancy Benefits Mom—And Baby, Too

By Cameron Walker | May 8, 2014 2:25 pm

pregnancy exercise

When Linda May went in to see her obstetrician during her first pregnancy, he told her she probably shouldn’t jump, run, or even walk. But May, an exercise physiologist who studies pregnant women and their babies, knew a thing or two about the positive ways that being active can help a mom-to-be’s health. Women who exercise with baby on board have been known to have, among other things, lower risks of gestational diabetes and pregnancy-induced high blood pressure than those who don’t.

Since then, May and other researchers have discovered even more ways that prenatal exercise benefits not only an expectant mother, but her growing baby, too—sometimes for years into the future—as attendees learned at last week’s Experimental Biology 2014 meeting in San Diego.

Past Thinking

Decades ago, many more doctors gave similar advice to May’s obstetrician. Pregnancy was thought to be almost like an illness, a time when women needed to rest to protect themselves and their babies. In 1985, the American Congress of Obstetricians and Gynecologists came out with their first set of guidelines for exercise during pregnancy—guidelines, now considered conservative, that included suggestions like keeping strenuous activities to 15 minutes or less.

Since then, research has turned that idea on its head. Exercise is now thought to be—for most women with healthy pregnancies—a boon for the mother’s health, and for the baby she carries as well.  Researchers are now starting to look even more closely at how exercise can influence a baby’s health in the womb and how these effects might translate into protection from future health problems.

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CATEGORIZED UNDER: Health & Medicine, Top Posts
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