Stress in the modern world is generally viewed as a hindrance to a healthy life.
Indeed, excess stress is associated with numerous problems, including cardiovascular disease, high blood pressure, insomnia, depression, obesity, and other conditions. While the physiological mechanisms associated with stress can be beneficial, as Kelly McGonigal points out in The Upside of Stress, the modern wellness industry is built on the foundation of stress relief.
The effects of stress on pregnant mothers is another longstanding area of research. For example, what potential negative effects do elevated levels of cortisol, epinephrine, and norepinephrine have on fetal development?
A new study, published in the Journal of Developmental Origins of Health and Disease, investigated a very specific aspect of stress on fetuses: does it affect sex? Their findings reveal that women with elevated stress are twice as likely to give birth to a girl.
For this research, the University of Granada scientists recorded the stress levels of 108 women before, during, and after conception. By testing cortisol concentration in their hair and subjecting the women to a variety of psychological tests, the researchers discovered that stress indeed influences sex. Specifically, stress made women twice as likely to deliver a baby girl.
The team points out that their research is consistent with other research that used saliva to show that stress resulted in a decreased likelihood of delivering a boy.
Lead author María Isabel Peralta Ramírez, a researcher at the UGR's Department of Personality, Evaluation and Psychological Treatment, says that prior research focused on stress levels leading up to and after birth. She was interested in stress's impact leading up to conception. She says:
"Specifically, our research group has shown in numerous publications how psychological stress in the mother generates a greater number of psychopathological symptoms during pregnancy: postpartum depression, a greater likelihood of assisted delivery, an increase in the time taken for lactation to commence (lactogenesis), or inferior neurodevelopment of the baby six months after birth."
While no conclusive evidence has been rendered, the research team believes that activation of the mother's endogenous stress system during conception sets the concentration of sex hormones that will be carried throughout development. As the team writes, "there is evidence that testosterone functions as a mechanism when determining the baby's sex, since the greater the prenatal stress levels, the higher the levels of female testosterone." Levels of paternal stress were not factored into this research.
Previous studies show that sperm carrying an X chromosome are better equipped to reach the egg under adverse conditions than sperm carrying the Y chromosome. Y fetuses also mature slowly and are more likely to produce complications than X fetuses. Peralta also noted that there might be more aborted male fetuses during times of early maternal stress, which would favor more girls being born under such circumstances.
In the future, Peralta and her team say an investigation into aborted fetuses should be undertaken. Right now, the research was limited to a small sample size that did not factor in a number of elements. Still, the team concludes, "the research presented here is pioneering to the extent that it links prenatal stress to the sex of newborns."
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Stay in touch with Derek on Twitter and Facebook. His most recent book is "Hero's Dose: The Case For Psychedelics in Ritual and Therapy."
What is the price of peace?
Or put another way, how much better off would we all be in a world where armed conflict was avoided?
Around $14.4 trillion in 2019, according to the Institute for Economics and Peace (IEP) which crunched the numbers. That's about $5 a day for every person on the planet.
To give some context, 689 million people - more than 9% of the world's population - live on less than $1.90 a day, according to World Bank figures, underscoring the potential impact peace-building activities could have.
Just over 10% of global GDP is being spent on containing, preventing and dealing with the consequences of violence. As well as the 1.4 million violent deaths each year, conflict holds back economic development, causes instability, widens inequality and erodes human capital.
Putting a price tag on peace and violence helps us see the disproportionately high amounts spent on creating and containing violent acts compared to what is spent on building resilient, productive, and peaceful societies.
—Steve Killelea, founder and executive chairman, Institute for Economics & Peace (IEP)
The cost of violence
In a report titled "The Economic Value of Peace 2021", the IEP says that for every death from violent conflict, 40 times as many people are injured. The world's 10 most affected countries are spending up to 59% of their GDP on the effects of violence.
Grounds for hope
But the picture is not all bleak. The economic impact of violence fell for the second year in a row in 2019, as parts of the world became more peaceful.
The global cost dropped by $64 billion between 2018 and 2019, even though it was still $1.2 trillion higher than in 2012.
In five regions of the world the costs increased in 2019. The biggest jump was in Central America and the Caribbean, where a rising homicide rate pushed the cost up 8.3%.
Syria, with its ongoing civil war, suffered the greatest economic impact with almost 60% of its GDP lost to conflict in 2019. That was followed by Afghanistan (50%) and South Sudan (46%).
The report makes a direct link between peace and prosperity. It says that, since 2000, countries that have become more peaceful have averaged higher GDP growth than those which have become more violent.
"This differential is significant and represents a GDP per capita that is 30% larger when compounded over a 20-year period," the report says adding that peaceful countries also have substantially lower inflation and unemployment.
"Small improvements in peace can have substantial economic benefits," it adds. "For example, a 2% reduction in the global impact of violence is roughly equivalent to all overseas development aid in 2019."
Equally, the total value of foreign direct investment globally only offsets 10% of the economic impact of violence. Authoritarian regimes lost on average 11% of GDP to the costs of violence while in democracies the cost was just 4% of GDP.
And the gap has widened over time, with democracies reducing the cost of violence by almost 16% since 2007 while in authoritarian countries it has risen by 27% over the same period.
The report uses 18 economic indicators to evaluate the cost of violence. The top three are military spending (which was $5.9 trillion globally in 2019), the cost of internal security which makes up over a third of the total at $4.9 trillion and homicide.
Peace brings prosperity
The formula also contains a multiplier effect because as peace increases, money spent containing violence can instead be used on more productive activities which drive growth and generate higher monetary and social returns.
"Substantial economic improvements are linked to improvements in peace," says the report. "Therefore, government policies should be directed to improving peacefulness, especially in a COVID-19 environment where economic activity has been subdued."
The IEP says what it terms "positive peace" is even more beneficial than "negative peace" which is simply the absence of violence or the fear of violence. Positive peace involves fostering the attitudes, institutions & structures that create and sustain peaceful societies.
The foundations of a positively peaceful society, it says, are: a well functioning government, sound business environment, acceptance of the rights of others, good relations with neighbours, free flow of information, high levels of human capital, low levels of corruption and equitable distribution of resources.
The World Economic Forum's report Mobilizing the Private Sector in Peace and Reconciliation urged companies large and small to recognise their potential to work for peace quoting the former Goldman Sachs chair, the late Peter Sutherland, who said: "Business thrives where society thrives."
Reprinted with permission of the World Economic Forum. Read the original article.
Natural selection, after all, has no reason to clear away unnecessary traits if they pose no evolutionary disadvantage. And when we say "started the whole thing," what we mean is that, this being Twitter, some arguing was inevitable. Some people took issue with Amir's use of the word "vestigial." One issue with the word is that early traits may still be beneficial in ways we don't yet know — the microbiome-managing appendix and the immune system's tonsils were both considered among these for some time. A trait's stated assumed value is also always just our best guess, so a certain amount of uncertainty is understood to be baked-in. It's important to remember, too, that if a mutation just happened to happen and persisted because it was useful, it's not the same thing as saying it has a reason to exist. The reason was randomness, unless one doesn't believe in evolution.
The plica semilunaris
The human eye in alarming detail. Image source: Henry Gray / Wikimedia commons
At the inner corner of our eyes, closest to the nasal ridge, is that little pink thing, which is probably what most of us call it, called the caruncula. Next to it is the plica semilunairs, and it's what's left of a third eyelid that used to — ready for this? — blink horizontally. It's supposed to have offered protection for our eyes, and some birds, reptiles, and fish have such a thing.
Palmaris longus
Palmaris longus muscle. Image source: Wikimedia commons
We don't have much need these days, at least most of us, to navigate from tree branch to tree branch. Still, about 86 percent of us still have the wrist muscle that used to help us do it. To see if you have it, place the back of you hand on a flat surface and touch your thumb to your pinkie. If you have a muscle that becomes visible in your wrist, that's the palmaris longus. If you don't, consider yourself more evolved (just joking).
Darwin's tubercle
Darwin's tubercle. Image source: Wikimedia commons
Yes, maybe the shell of you ear does feel like a dried apricot. Maybe not. But there's a ridge in that swirly structure that's a muscle which allowed us, at one point, to move our ears in the direction of interesting sounds. These days, we just turn our heads, but there it is.
Goosebumps
Goosebumps. Photo credit: Tyler Olson via Shutterstock
It's not entirely clear what purpose made goosebumps worth retaining evolutionarily, but there are two circumstances in which they appear: fear and cold. For fear, they may have been a way of making body hair stand up so we'd appear larger to predators, much the way a cat's tail puffs up — numerous creatures exaggerate their size when threatened. In the cold, they may have trapped additional heat for warmth.
Tailbone
Coccyx.
Image source: Decade3d-anatomy online via Shutterstock
Way back, we had tails that probably helped us balance upright, and was useful moving through trees. We still have the stump of one when we're embryos, from 4–6 weeks, and then the body mostly dissolves it during Weeks 6–8. What's left is the coccyx.
The palmar grasp reflex
Palmar reflex activated! Photo credit: Raul Luna on Flickr
You've probably seen how non-human primate babies grab onto their parents' hands to be carried around. We used to do this, too. So still, if you touch your finger to a baby's palm, or if you touch the sole of their foot, the palmar grasp reflex will cause the hand or foot to try and close around your finger.
Other people's suggestions
Amir's followers dove right in, offering both cool and questionable additions to her list.
Fangs?
Lower mouth plate behind your teeth. Some have protruding bone under the skin which is a throw back to large fangs. Almost like an upsidedown Sabre Tooth.
— neil crud (@neilcrud66) January 16, 2019
Hiccups
Sure: https://t.co/DjMZB1XidG
— Stephen Roughley (@SteBobRoughley) January 16, 2019
Hypnic jerk as you fall asleep
What about when you “jump” just as you’re drifting off to sleep, I heard that was a reflex to prevent falling from heights.
— Bann face (@thebanns) January 16, 2019
This thing, often called the "alpha jerk" as you drop into alpha sleep, is properly called the hypnic jerk,. It may actually be a carryover from our arboreal days. The hypothesis is that you suddenly jerk awake to avoid falling out of your tree.
Nails screeching on a blackboard response?
Everyone hate the sound of fingernails on a blackboard. It's _speculated_ that this is a vestigial wiring in our head, because the sound is similar to the shrill warning call of a chimp. https://t.co/ReyZBy6XNN
— Pet Rock (@eclogiter) January 16, 2019
Ear hair
Ok what is Hair in the ears for? I think cuz as we get older it filters out the BS.
— Sarah21 (@mimix3) January 16, 2019
Nervous laughter
You may be onto something. Tooth-bearing with the jaw clenched is generally recognized as a signal of submission or non-threatening in primates. Involuntary smiling or laughing in tense situations might have signaled that you weren’t a threat.
— Jager Tusk (@JagerTusk) January 15, 2019
Um, yipes.
Sometimes it feels like my big toe should be on the side of my foot, was that ever a thing?
— B033? K@($ (@whimbrel17) January 16, 2019
Twitter should always be so much fun.
About 66 million years ago, a massive asteroid slammed into present-day Chicxulub, Mexico, triggering the extinction of dinosaurs. Scientists estimate the impact killed 75 percent of life on Earth. But what's remained more mysterious is how the event shaped the future of plant life, specifically tropical rainforests.
A new study published in Science explores how the so-called bolide impact at the end of the Cretaceous period paved the way for the evolution of our modern rainforests, the most diverse terrestrial ecosystems on Earth.
For the study, researchers analyzed thousands of samples of fossil pollen, leaves, and spores collected from various sites across Colombia. The researchers analyzed the samples to determine which types of plants were dominant, the diversity of plant life, and how insects interacted with plants.
All samples dated back to the Cretaceous-Paleogene boundary, some 70 million to 56 million years ago. Back then, the region's climate was mostly humid and hot, as it is today. However, the composition and structure of forests were quite different before the impact, according to the study results.
For one, the region's rainforests used to have a roughly equal mix of angiosperms (shrubs and flowering trees) and plants like conifers and ferns. The rainforests also had a more open canopy structure, which allowed more light to reach the forest floor and meant that plants faced less competition for light.
What changed after the asteroid hit? The results suggest the impact and its aftermath led to a 45 percent decrease in plant diversity, a loss from which the region took about 6 million years to recover. But different plants came to replace the old ones, with an increasing proportion of flowering plants sprouting up over the millennia.
"A single historical accident changed the ecological and evolutionary trajectory of tropical rainforests," Carlos Jaramillo, study author and paleopalynologist at the Smithsonian Tropical Research Institute in Panama City, told Science News. "The forests that we have today are really the by-product of what happened 66 million years ago."
Today's rainforests are significantly more biodiverse than they were 66 million years ago. One potential reason is that the more densely packed canopy structure of the post-impact era increased competition among plants, "leading to the vertical complexity seen in modern rainforests," the researchers wrote.
The extinction of long-necked, leaf-eating dinosaurs probably helped maintain this closed-canopy structure. Also boosting biodiversity was ash from the impact, which effectively fertilized the soil by adding more phosphorus. This likely benefited flowering plants over the conifers and ferns of the pre-impact era.
In addition to unraveling some of the mysteries about the origins of South America's lush biodiversity, the findings highlight how, even though life finds a way to recover from catastrophe, it can take a long time.
