Category: MIL-OSI

Source: The Conversation – UK – By Michelle Spear, Professor of Anatomy, University of Bristol

In the animal kingdom, penises can be spiked, split, corkscrewed – even detachable. They’re one of the most diverse structures in biology. The human penis is so uniform, it’s an anatomical outlier. Understanding why penises evolved, and why they differ so widely, also helps explain why humans have one at all.

Penises first evolved as a solution to one simple problem: how to achieve internal fertilisation.

The first animals lived in the sea before our ancestors started living on land half a billion years ago. Today, many aquatic animals still simply release sperm and eggs into the water. However, as organisms moved to land, a new mechanism was needed to transfer sperm into the female body – enter the penis.

But here’s the twist: not all land animals use one. Around 97% of bird species have no penis at all. Instead, they reproduce with a “cloacal kiss”. This is a brief contact between a single opening that serves the digestive, urinary and reproductive systems and through which sperm is transferred.

The cloacal kiss demands choreography. For most birds, mating success hinges on split-second timing, elaborate courtship and perfect physical alignment. Animals with penises have an anatomical shortcut. They can deliver sperm straight to the target, even if the encounter is brief or a bit clumsy.

So penises are just one solution among many. But once evolution settles on a penis, the possibilities multiply. It is a prime example of convergent evolution, where different, unrelated, lineages develop similar traits in response to similar pressures.

In some species, penis size is driven by environmental constraints and access to mates. The barnacle, a crustacean glued to a rock for life, has the longest penis relative to body size of any known animal (up to eight times its own length). This allows it to “fish” for mates in the surrounding water. For those that may be wondering, the largest penis, at 2.5-3 metres, belongs to the blue whale.

The banana slug is a hermaphrodite with a thick penis as long as its body, evolved for deep sperm placement to boost fertilisation chances. Sometimes it gets stuck during withdrawal, and the partner bites it off. But the slug normally heals and survives.

Penile structures are often adapted for sperm competition, which is when multiple males mate with the same female, and their sperm compete internally for fertilisation. In these species, the penis becomes a competitive tool.

The domestic cat, for instance, has backward-facing spines on its penis. These stimulate ovulation in the female, ensuring sperm meets a ready egg, but also discourage mating with other males by making withdrawal painful.

In bedbugs, males take it further. They use a dagger-like penis to stab through the abdominal wall and deposit sperm directly into the body cavity. This “traumatic insemination” gives the male a bypass route – but at significant cost to the female. It’s not typically deadly, but the injuries take time and energy to heal.

Nowhere is this evolutionary struggle more vivid than in ducks. Some species of male ducks have corkscrew-shaped penises that can extend in under half a second. This is a response to female ducks evolving highly convoluted vaginas with dead-end pockets and spirals that twist in the opposite direction. This is a textbook example of sexual antagonistic co-evolution, where male traits that increase fertilisation rates are countered by female traits that limit male control.

In many reptiles, evolution has solved the problem of mating posture, the physical position and alignment of the bodies during copulation, with a pair of reproductive tracts. Snakes and lizards have hemipenes – two separate organs, only one of which is used per copulation. This redundancy probably evolved for flexibility, allowing mating from either side, and may be an adaptation to maximise success in brief mating windows.

In mammals, the penis can be reinforced by a bone: the baculum. Found in species such as dogs, chimpanzees and walruses, it allows penetration without relying on blood pressure. This structural support is useful in species where mating is prolonged or where mechanical stimulation during copulation is needed to trigger ovulation, in awkward or extended couplings like those of walruses, and when female anatomy or behaviour favours longer copulation.

What do these penises tell us about humans?

Compared to this dazzling variety, the human penis seems almost conservative. But this simplicity is deceptive.

Unlike many other mammals, humans lack a baculum. Instead, erection relies on blood flow. This mechanism may reflect a shift from brief, frequent copulations typical of high-sperm-competition species, to longer, emotionally bonded pairings. In this type of pairing, a visible, hydraulically produced erection serves not only a reproductive function, but also acts as a signal of arousal and health.

Human penile shape may still reflect adaptations to sperm competition. Scientists think the slight flaring of the glans at the corona, a prominent anatomical border between the glans and the shaft, may displace rival sperm during intercourse. This is not unusual among mammals, but in humans it may be especially important because intercourse and ovulation are often not perfectly timed, giving more scope for sperm competition. Human sperm can survive in the female reproductive tract for up to five days.

The glans and the sensitive underside frenulum contain a high concentration of sensory nerve endings that make them particularly sensitive to touch. This heightened sensitivity is thought to provide not only pleasure, but also real-time feedback. It allows the penis to respond to subtle variations in movement, pressure and partner interaction. Such feedback may have played a role in enhancing mutual sexual engagement.

Read more:
Scientists ignored animal clitorises for centuries – now we’re discovering just how varied they are

A 2011 genetic study published in Nature found that humans lost specific DNA sequences that control the development of penile spines – small, keratinised projections on the penis that in chimpanzees and macaques help increase friction and stimulate the female during mating. These spines probably increased stimulation and shortened copulatory duration. Their loss in humans may reflect a shift from competition to cooperation.

This ties into another crucial aspect of human reproductive evolution: concealed ovulation. Unlike many mammals, human females do not advertise their fertility. In response, males evolved a strategy based on sustained sexual access, emotional connection and mate guarding.

The human penis is not just a reproductive organ, but part of a broader behavioural system tied to trust, intimacy and long-term partnership.

Michelle Spear does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. The surprising world of animal penises and what they reveal about humans – https://theconversation.com/the-surprising-world-of-animal-penises-and-what-they-reveal-about-humans-261690

Source: The Conversation – UK – By Punita Chowbey, Senior research fellow, Sheffield Hallam University

Economic abuse may not be as obvious as physical abuse, but for the millions of people it affects in the UK, economic abuse can be totally devastating.

Economic abuse, which is recognised as a form of domestic abuse in law, involves controlling a person’s (often a woman’s) ability to acquire, use and maintain economic resources.

Separating or divorcing does not mean the end of economic abuse in a marriage, particularly when children are involved. Post-separation economic abuse is often related to child maintenance or spousal support payments, which may be manipulated or withheld by abusers.

This harms mothers’ financial independence, mental health and parenting, and has consequences for children’s wellbeing.

A recent national survey found that minority ethnic women face economic abuse at twice the rate of white women (29% vs 13%). Our recently-published research explores why, through the experiences of 28 separated or divorced British south Asian Muslim women. This research is part of our continuing research on divorce and economic abuse.

Two-thirds of our participants had been financially dependent upon their husbands during their marriages, in keeping with broader statistics on the low employment rates of British Pakistani and Bangladeshi women. Further, several participants described their husbands preventing them from working.

UK-born Afsana had to work secretly as a tutor for meagre pay: “This tutoring was undercover with my dad. My working would have looked bad on [my husband].”

After separation or divorce, women were left economically vulnerable. Some struggled to find work, due to lack of recent employment experience as well as labour market discrimination.

“I worked in one school as a volunteer, but the Jobcentre said ‘that’s not enough, we need more evidence of work,’” said one woman. “I said, ‘everywhere you apply, they ask for a qualification, and experience is the main thing.’ I was not going out … how could I have undertaken any work?”

A major theme in our research was how abusers used child maintenance as a means to control women economically. In 18 cases, the father was not paying any child maintenance. Of the rest, only two mothers felt that the amount paid was fair.

Many women described child maintenance mirroring earlier patterns of economic abuse during their marriages. As UK-born Afsana put it: “He didn’t provide when he was with me, so I didn’t expect him to provide when he was not with me.”

Where women had involved the Child Maintenance Service (CMS), they felt it was unresponsive, especially those in transnational marriages involving economic assets overseas.

UK-born Kiran described her experience with CMS after her ex-husband hid assets in Pakistan: “I’ve even given the telephone numbers and addresses in the properties which are in Pakistan. [But] ‘Excuse me. We know that you’re upset. It just takes a bit of time.’ I go, ‘How long does it need?’”

Women felt disbelieved, which undermined their confidence in the system. Although the CMS may face limits in investigating finances held overseas, women felt the evidence they provided was often ignored. Many of the men were in self-employment, which may have made it difficult for the CMS to investigate.

Legal blind spots and immigration abuse

Post-separation economic abuse can also occur through institutions like courts and banks. UK-born Hora described how her husband remarried via an unregistered Islamic marriage, which allowed him to transfer money and assets to his new wife.

She told us: “My barrister said, ‘You’re not divorced from this lady yet, but you’ve remarried.’ He said, ‘Yes judge, in my religion I can have four wives.’ And this is a High Court judge, and he said, ‘Yes, quite!’”

Hora felt that this comment suggested the judge supported her husband’s use of religious justification for re-marrying before divorce, rather than recognising it as part of financial abuse.

Women with an insecure immigration status might also experience “immigration abuse”. This too can be a form of economic abuse, where, for example, an abuser uses the threat of deportation or immigration enforcement to trap women in financially dependent relationships.

Several women described struggling to open a bank account or obtain credit due to their migration status being exploited by their abusers. Pakistan-born divorcee Fauzia had never had a national insurance number, child benefit or bank account until these were arranged for her by a social worker at the women’s refuge she turned to with her children.

Our research suggests that south Asian women can face severe post-separation economic abuse due to multiple, intersecting disadvantages across the home, labour market and state institutions. Addressing these inequalities requires policies that take women seriously, while also being culturally sensitive and aware of the multiple challenges these women face.

Punita Chowbey receives funding from the NIHR, UKRI and Joseph Rowntree Foundation. Punita works closely with charities working on gender based violence.

Kaveri Qureshi receives funding from the NIHR and the ESRC. Kaveri Qureshi works closely with charities working on gender violence.

– ref. Minority ethnic women in the UK face economic abuse at twice the rate of white women. These are their experiences – https://theconversation.com/minority-ethnic-women-in-the-uk-face-economic-abuse-at-twice-the-rate-of-white-women-these-are-their-experiences-267263

Source: The Conversation – UK – By David C. Gaze, Senior Lecturer in Chemical Pathology, University of Westminster

Most of us think of orange juice as a simple breakfast habit, something you pour without much thought. Yet scientists are discovering that this everyday drink may be doing far more in the body than quenching thirst.

A recent study has shown that regular orange juice consumption can influence the activity of thousands of genes inside our immune cells. Many of these genes help control blood pressure, calm inflammation and manage the way the body processes sugar, all of which play an important role in long-term heart health.

The study followed adults who drank 500ml of pure pasteurised orange juice every day for two months. After 60 days, many genes associated with inflammation and higher blood pressure had become less active.

These included NAMPT, IL6, IL1B and NLRP3, which usually switch on when the body is under stress. Another gene known as SGK1, which affects the kidneys’ ability to hold onto sodium (salt), also became less active.

Such changes match previous findings that daily orange juice drinking can reduce blood pressure in young adults.

This is noteworthy because it offers a possible explanation for why orange juice has been linked to better heart health in several trials. The new work shows that the drink does not simply raise blood sugar. Instead, it appears to trigger small shifts in the body’s regulatory systems that reduce inflammation and help blood vessels relax.

Natural compounds in oranges, particularly hesperidin, a citrus flavonoid known for its antioxidant and anti-inflammatory effects, seem to influence processes related to high blood pressure, cholesterol balance and the way the body handles sugar.

The response also varies by body size. People carrying more weight tended to show greater changes in genes involved in fat metabolism, while leaner volunteers showed stronger effects on inflammation.

A systematic review of controlled trials involving 639 participants from 15 studies found that regular orange juice consumption lowered insulin resistance and blood cholesterol levels. Insulin resistance is a key feature of pre-diabetes, and high cholesterol is an established risk factor for heart disease.

Another analysis focusing on overweight and obese adults found small reductions in systolic blood pressure and increases in high density lipoprotein (HDL), often called the good cholesterol, after several weeks of daily orange juice consumption. Although these changes are modest, even slight improvements in blood pressure and cholesterol can make a meaningful difference when maintained over many years.

More clues come from studies that examine metabolites, the tiny molecules produced as the body processes food. A recent review found that orange juice influences pathways related to energy use, communication between cells and inflammation. It may also affect the gut microbiome, which is increasingly understood to play a role in heart health.

One study showed that drinking blood orange juice for a month increased the number of gut bacteria that produce short-chain fatty acids. These compounds help maintain healthy blood pressure and reduce inflammation. Volunteers also showed improved blood sugar control and lower levels of inflammatory markers.

People with metabolic syndrome, a cluster of risk factors that includes high blood pressure, raised blood sugar and excess body fat, may see particular benefits.

In one study, daily orange juice consumption improved the function of the lining of blood vessels, known as endothelial function, in 68 obese participants. Endothelial function describes how well blood vessels relax and widen, and better function is associated with a lower risk of heart attacks.

Not all studies report the same outcomes. A broader analysis of blood fat concentrations found that although levels of low density lipoprotein (LDL), often called the bad cholesterol, often fall, other lipid measurements such as triglycerides and HDL may not change much. Even so, people who regularly drink orange juice may still benefit.

A study of 129 workers in an orange juice factory in Brazil reported lower blood concentrations of apolipoprotein B, or apo-B, a marker that reflects the number of cholesterol-carrying particles linked to heart attack risk.

Altogether, the evidence challenges the idea that drinking citrus fruit juice is simply consuming sugar in a glass. Whole fruit remains the better choice because of its fibre, but a modest daily glass of pure orange juice appears to have effects that build up over time.

These include easing inflammation, supporting healthier blood flow and improving several blood markers linked to long-term heart health. It is a reminder that everyday foods can have more influence on the body than we might expect.

David C. Gaze does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. Your daily orange juice could be helping your heart – https://theconversation.com/your-daily-orange-juice-could-be-helping-your-heart-270492