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Category Archives: Human Reproduction

Public health needs evolutionary thinking – pnas.org

Breastfeeding is the best way to feed an infant. Not only does it supply the proper nutrition, but it also supports the development of the immune system, provides healthy microbiome, reduces risk of diseases, and brings down overall mortality (1). There are also benefits resulting from the ability of breastfeeding to suppress maternal ovarian function and to delay the next pregnancy. Birth spacing is an important predictor of infant mortality, maternal health, and, in an evolutionary perspective, maternal reproductive success.

Todd and Lerch (2) document a significant decline in the ability of breastfeeding to cause suppression of the ovarian function and thus to reduce the chance of the next pregnancy. In breastfeeding mothers from 84 low- and middle-income countries, the duration of lactational amenorrhea (i.e., the length of time without menstrual cycles after having given birth) strongly decreased between 1975 and 2009. For example, lactational amenorrhea in Bangladesh decreased from 15.2 to 7.7 mo during the span of about 40 y. In some countries, thanks to substantial public health efforts in recent years, women extended their breastfeeding, but despite this, the timing of cycle resumption did not change! Even though it sounds like a mystery, it is not, from an evolutionary vantage point.

In Ethiopian villages, womens daily walking routine, due to installation of water pumps, shrank from about 3 h to 15 min. However, in response to this innovation, the risk of conceiving in a given month rose more than threefold (3). In the rural Gambia, increases in energy intake by nutritional supplementation provided to women during pregnancy and lactation were related to changes in the levels of prolactin and sex hormones, and shortened the time until next pregnancy (4). In Guatemala, women who, prenatally and during first 3 y of life, received supplement with higher energy and protein,

1Email: jasienska{at}post.harvard.edu.

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Public health needs evolutionary thinking - pnas.org

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Nebraska eliminates the majority of sex education topics from proposed health standards – Norfolk Daily News

The Nebraska Department of Education released a second draft of the state health education standards on Thursday after months of public criticism regarding sex education topics in the original proposal.

The standards human growth and development section was heavily revised to eliminate many of the previous guidelines around sex education, gender identity, sexual orientation, stereotypes and more, but some still remain.

The first draft included several in-depth standards such as teaching students, starting in elementary school, about genitalia differences, human reproduction, sexual health and pregnancy.

The new proposed standards dont contain the majority of these topics, and if they do, they are more brief and generic, which is based on reading through both sets of standards. More complex standards, which some parents deemed inappropriate for younger students, are also introduced more at the high school level rather than in elementary school.

Students would still learn about consent and sexual harassment. When it comes to human reproduction, students would now only learn how puberty prepares human bodies for the potential to reproduce in fifth grade and other levels.

Fertilization, fetal development and the birth process are standards included at the high school level. High school students would briefly learn about sexual health when it relates to preventative exams, STDs and the different stages of pregnancy.

The first draft also proposed students would learn about gender expression; different kinds of family structures such as same-gender families; and sexual identities such as heterosexual, bisexual, lesbian, gay and more.

But the second draft is mostly devoid of these standards. The only standard that is similar is when students would recognize that biological sex and gender identity may or may not differ in seventh grade.

Gender identity is also listed as a term in the new drafts glossary, defining it as Internal deeply held thoughts and feelings about gender.

Gender roles are defined as attitudes and behaviors that a society considers appropriate for males and females.

The department of education faced heavy backlash from Nebraska communities since the first draft was released in March. Many families argued that sex education topics dont have a place in schools.

Groups of school officials, including the Norfolk Public Schools Board of Education, also objected to the standards, saying it should be the parents responsibility to bring up such topics with their children.

In the new draft, the Nebraska Department of Education asks school districts to consider sex education in their curriculum so students have the essential knowledge and critical skills needed to decrease sexual risk behaviors.

The department encourages districts to make decisions about these topics with the consultation of parents, school boards, teachers and community members.

The 53-page second draft still contains seven other sections besides human growth and development, including topics like nutrition, disease prevention, mental health and substance abuse prevention.

Matthew Blomstedt, the states education commissioner, was expected to announce more details about the new draft and next steps in the process during a press conference on Thursday at 11 a.m.

This second draft was also expected to be posted Thursday morning to the Nebraska Department of Educations website and is open to public comment.

The State Board of Education estimated it will vote on a final draft this fall, but the number of drafts before that decision is still unknown. If passed, the standards will be optional, and school districts could choose not to adopt them.

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Nebraska eliminates the majority of sex education topics from proposed health standards - Norfolk Daily News

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Male fertility is declining studies show that environmental toxins could be a reason – The Conversation US

In the U.S., nearly 1 in 8 couples struggles with infertility. Unfortunately, physicians like me who specialize in reproductive medicine are unable to determine the cause of male infertility around 30% to 50% of the time. There is almost nothing more disheartening than telling a couple I dont know or Theres nothing I can do to help.

Upon getting this news, couple after couple asks me questions that all follow a similar line of thinking. What about his work, his cellphone, our laptops, all these plastics? Do you think they could have contributed to this?

What my patients are really asking me is a big question in male reproductive health: Does environmental toxicity contribute to male infertility?

Infertility is defined as a couples inability to get pregnant for one year despite regular intercourse. When this is the case, doctors evaluate both partners to determine why.

For men, the cornerstone of the fertility evaluation is semen analysis, and there are a number of ways to assess sperm. Sperm count the total number of sperm a man produces and sperm concentration number of sperm per milliliter of semen are common measures, but they arent the best predictors of fertility. A more accurate measure looks at the total motile sperm count, which evaluates the fraction of sperm that are able to swim and move.

A wide range of factors from obesity to hormonal imbalances to genetic diseases can affect fertility. For many men, there are treatments that can help. But starting in the 1990s, researchers noticed a concerning trend. Even when controlling for many of the known risk factors, male fertility appeared to have been declining for decades.

In 1992, a study found a global 50% decline in sperm counts in men over the previous 60 years. Multiple studies over subsequent years confirmed that initial finding, including a 2017 paper showing a 50% to 60% decline in sperm concentration between 1973 and 2011 in men from around the world.

These studies, though important, focused on sperm concentration or total sperm count. So in 2019, a team of researchers decided to focus on the more powerful total motile sperm count. They found that the proportion of men with a normal total motile sperm count had declined by approximately 10% over the previous 16 years.

The science is consistent: Men today produce fewer sperm than in the past, and the sperm are less healthy. The question, then, is what could be causing this decline in fertility.

Scientists have known for years that, at least in animal models, environmental toxic exposure can alter hormonal balance and throw off reproduction. Researchers cant intentionally expose human patients to harmful compounds and measure outcomes, but we can try to assess associations.

As the downward trend in male fertility emerged, I and other researchers began looking more toward chemicals in the environment for answers. This approach doesnt allow us to definitively establish which chemicals are causing the male fertility decline, but the weight of the evidence is growing.

A lot of this research focuses on endocrine disrupters, molecules that mimic the bodys hormones and throw off the fragile hormonal balance of reproduction. These include substances like phthalates better known as plasticizers as well as pesticides, herbicides, heavy metals, toxic gases and other synthetic materials.

Plasticizers are found in most plastics like water bottles and food containers and exposure is associated with negative impacts on testosterone and semen health.Herbicides and pesticides abound in the food supply and some specifically those with synthetic organic compounds that include phosphorus are known to negatively affect fertility.

Air pollution surrounds cities, subjecting residents to particulate matter, sulfur dioxide, nitrogen oxide and other compounds that likely contribute to abnormal sperm quality. Radiation exposure from laptops, cellphones and modems has also been associated with declining sperm counts, impaired sperm motility and abnormal sperm shape. Heavy metals such as cadmium, lead and arsenic are also present in food, water and cosmetics and are also known to harm sperm health.

Endocrine-disrupting compounds and the infertility problems they cause are taking a significant toll on human physical and emotional health. And treating these harms is costly.

A lot of chemicals are in use today, and tracking them all is incredibly difficult. More than 80,000 chemicals are registered in the U.S. and nearly 2,000 new chemicals are introduced each year. Many scientists believe that the safety testing for health and environmental risks is not strong enough and that the rapid development and introduction of new chemicals challenges the ability of organizations to test long-term risks to human health.

Current U.S. regulations follow the principle of innocent until proved guilty and are less comprehensive and restrictive than similar regulations in Europe, for example. The World Health Organization recently identified 800 compounds capable of disrupting hormones, only a small fraction of which have been tested.

A trade group, the American Chemistry Council, says on its website that manufacturers have the regulatory certainty they need to innovate, grow, create jobs and win in the global marketplace at the same time that public health and the environment benefit from strong risk-based protections.

But the reality of the current regulatory system in the U.S. is that chemicals are introduced with minimal testing and taken off the market only when harm is proved. And that can take decades.

Dr. Niels Skakkebaek, the lead researcher on one of the first manuscripts on decreasing sperm counts, called the male fertility decline a wake-up call to all of us. My patients have provided a wakeup call for me that increased public awareness and advocacy are important to protect global reproductive health now and in the future. Im not a toxicologist and cant identify the cause of the infertility trends Im seeing, but as physician, I am concerned that too much of the burden of proof is falling on the human body and people who become my patients.

This article was updated to more accurately represent the chemical regulatory system in the U.S.

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The oldest tree in eastern US at risk after more than 2,600 years | TheHill – The Hill

It is the oldest known living tree on the East Coast, residing in North Carolinas wetlands, and it is endangered due to climate change.

The 2,624-year-old bald cypress is the fifth-oldest living non-clonal tree species in the world. But it is vulnerable to conditions such as drought, heat wave, storms, and flooding all while warming temperatures continue to create problems for plant growth, resilience and reproduction, The Guardian reports.

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The principal threat to our forests is people and human activity. One consequence of human activity is climate change, David Stahle, a dendrochronologist who was introduced to the Black Rivers bald cypress stand in 1985, said.

Rising sea levels are threatening the bald cypress, with little more than six feet of elevation standing between the tree and Atlantic Ocean. This means that rising sea levels could one day bury the tree underwater by around 2080 based on the estimates that at least 20 feet is possible in the between next 100 and 200 years or so.

With those bald cypress only two meters above sea level, thats a really serious threat, dendrochronologist and Harvard Forest senior ecologist Neil Pederson said. I see sea level rise as a train alarm, on a really long, overloaded train. And its going to take a long time to slow that train down.

In the case of the two millennium old tree that stations in a swamp, high tree mortality rates were predicted in a 2016 study, which found that drought conditions and extreme events were the cause behind the bald cypress dying.

Even though our forests seem to change slowly over time, every once in a while these things, like black swans, these unprecedented or unforeseen events, come and change an ecosystem, he said.

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Study: Neanderthals Sexed Themselves to Death With Humans – InsideHook

Mythology is filled with notoriously sexy, not-quite-human figures who lure their victims to a gruesome if erotic death by sex. Sirens that drove sailors to shipwreck and succubus poltergeists that destroyed their sex partners mentally and physically are among various other (usually female) demons and temptresses whose creation is probably a reflection of centuries of misogyny and hatred for female sexuality, but oh well. Anyway, it turns out getting sexed to death by a species-adjacent creature isnt just the stuff of folklore, but something that actually happened to the Neanderthals who walked the earth before humans lured them to their demise.

Per the Daily Mail, new research from Aix-Marseille University claims sex with humans may have played a key role in the extinction of Neanderthals. It wasnt exactly a Black Widow spider situation, however; the sex itself wasnt killing Neanderthals, nor were their human partners slaying unwitting sub-humanoids after sex. Rather, according to the study, sex with humans gradually decimated the Neanderthal species because relations between the two could lead to a rare and fatal blood disorder in their offspring.

The condition, called haemolytic disease of the foetus and newborn, causes a fatal kind of anemia and is relatively rare today, affecting only three in 100,000 pregnancies, according to the Daily Mail. The condition would have been quite common amongst Neanderthals, Stephane Mazieres, one of the authors of the paper, told the outlet. The presence and prevalence of the disease in Neanderthal-human newborns wouldve made reproduction difficult, taking a toll on Neanderthal offspring and gradually depleting the species.

These elements could have contributed to weakening the descendants to the point of leading to their demise, especially combined with the competition with Homo sapiens for the same ecological niche, according to the researchers.

So, long before humans invented sexist tales of shipwrecking mermaids and horny, man-eating demons, it turns out we were the original succubi, slowly fucking the life out of another species, and probably giving them herpes in the process.

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Cross-reactive antibodies against human coronaviruses and the animal coronavirome suggest diagnostics for future zoonotic spillovers – Science

The spillover of animal coronaviruses (aCoVs) to humans has caused SARS, MERS, and COVID-19. While antibody responses displaying cross-reactivity between SARS-CoV-2 and seasonal/common cold human coronaviruses (hCoVs) have been reported, potential cross-reactivity with aCoVs and the diagnostic implications are incompletely understood. Here, we probed for antibody binding against all seven hCoVs and 49 aCoVs represented as 12,924 peptides within a phage-displayed antigen library. Antibody repertoires of 269 recovered COVID-19 patients showed distinct changes compared to 260 unexposed pre-pandemic controls, not limited to binding of SARS-CoV-2 antigens but including binding to antigens from hCoVs and aCoVs with shared motifs to SARS-CoV-2. We isolated broadly reactive monoclonal antibodies from recovered COVID-19 patients that bind a shared motif of SARS-CoV-2, hCoV-OC43, hCoV-HKU1, and several aCoVs, demonstrating that interspecies cross-reactivity can be mediated by a single immunoglobulin. Employing antibody binding data against the entire CoV antigen library allowed accurate discrimination of recovered COVID-19 patients from unexposed individuals by machine learning. Leaving out SARS-CoV-2 antigens and relying solely on antibody binding to other hCoVs and aCoVs achieved equally accurate detection of SARS-CoV-2 infection. The ability to detect SARS-CoV-2 infection without knowledge of its unique antigens solely from cross-reactive antibody responses against other hCoVs and aCoVs suggests a potential diagnostic strategy for the early stage of future pandemics. Creating regularly updated antigen libraries representing the animal coronavirome can provide the basis for a serological assay already poised to identify infected individuals following a future zoonotic transmission event.

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Cross-reactive antibodies against human coronaviruses and the animal coronavirome suggest diagnostics for future zoonotic spillovers - Science

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