5 Signs Humans Are Still Evolving

Lealisa Westerhoff, AFP/Getty Images
Lealisa Westerhoff, AFP/Getty Images

When we think of human evolution, our minds wander back to the millions of years it took natural selection to produce modern-day man. Recent research suggests that, despite modern technology and industrialization, humans continue to evolve. "It is a common misunderstanding that evolution took place a long time ago, and that to understand ourselves we must look back to the hunter-gatherer days of humans," Dr. Virpi Lummaa, a professor at the University of Turku, told Gizmodo.

But not only are we still evolving, we're doing so even faster than before. In the last 10,000 years, the pace of our evolution has sped up, creating more mutations in our genes, and more natural selections from those mutations. Here are some clues that show humans are continuing to evolve.

1. Humans drink milk.

Historically, the gene that regulated humans' ability to digest lactose shut down as we were weaned off our mothers' breast milk. But when we began domesticating cows, sheep, and goats, being able to drink milk became a nutritionally advantageous quality, and people with the genetic mutation that allowed them to digest lactose were better able to propagate their genes.

The gene was first identified in 2002 in a population of northern Europeans that lived between 6000 and 5000 years ago. The genetic mutation for digesting milk is now carried by more than 95 percent of northern European descendants. In addition, a 2006 study suggests this tolerance for lactose developed again, independently of the European population, 3000 years ago in East Africa.

2. We're losing our wisdom teeth.

Our ancestors had much bigger jaws than we do, which helped them chew a tough diet of roots, nuts, and leaves. And what meat they ate they tore apart with their teeth, all of which led to worn-down chompers that needed replacing. Enter the wisdom teeth: A third set of molars is believed to be the evolutionary answer to accommodate our ancestors' eating habits.

Today, we have utensils to cut our food. Our meals are softer and easier to chew, and our jaws are much smaller, which is why wisdom teeth are often impacted when they come in — there just isn't room for them. Unlike the appendix, wisdom teeth have become vestigial organs. One estimate says 35 percent of the population is born without wisdom teeth, and some say they may disappear altogether.

3. We're resisting infectious diseases.

In 2007, a group of researchers looking for signs of recent evolution identified 1800 genes that have only become prevalent in humans in the last 40,000 years, many of which are devoted to fighting infectious diseases like malaria. More than a dozen new genetic variants for fighting malaria are spreading rapidly among Africans. Another study found that natural selection has favored city-dwellers. Living in cities has produced a genetic variant that allows us to be more resistant to diseases like tuberculosis and leprosy. "This seems to be an elegant example of evolution in action," says Dr. Ian Barnes, an evolutionary biologist at London's Natural History Museum, said in 2010 statement. "It flags up the importance of a very recent aspect of our evolution as a species, the development of cities as a selective force."

4. Our brains are shrinking.

While we may like to believe our big brains make us smarter than the rest of the animal world, our brains have actually been shrinking over the last 30,000 years. The average volume of the human brain has decreased from 1500 cubic centimeters to 1350 cubic centimeters, which is an amount equivalent to the size of a tennis ball.

There are several different conclusions as to why this is: One group of researchers suspects our shrinking brains mean we are in fact getting dumber. Historically, brain size decreased as societies became larger and more complex, suggesting that the safety net of modern society negated the correlation between intelligence and survival. But another, more encouraging theory says our brains are shrinking not because we're getting dumber, but because smaller brains are more efficient. This theory suggests that, as they shrink, our brains are being rewired to work faster but take up less room. There's also a theory that smaller brains are an evolutionary advantage because they make us less aggressive beings, allowing us to work together to solve problems, rather than tear each other to shreds.

5. Some of us have blue eyes.

Originally, we all had brown eyes. But about 10,000 years ago, someone who lived near the Black Sea developed a genetic mutation that turned brown eyes blue. While the reason blue eyes have persisted remains a bit of a mystery, one theory is that they act as a sort of paternity test. “There is strong evolutionary pressure for a man not to invest his paternal resources in another man’s child,” Bruno Laeng, lead author of a 2006 study on the development of blue eyes, told The New York Times. Because it is virtually impossible for two blue-eyed mates to create a brown-eyed baby, our blue-eyed male ancestors may have sought out blue-eyed mates as a way of ensuring fidelity. This would partially explain why, in a recent study, blue-eyed men rated blue-eyed women as more attractive compared to brown-eyed women, whereas females and brown-eyed men expressed no preference.

Mystery Solved: Scientists Have Figured Out Why Some Squirrels Are Black

Rena-Marie/iStock via Getty Images
Rena-Marie/iStock via Getty Images

It can be something of a surprise to see an animal sporting a fresh coat of paint. Blue lobsters occasionally surface after being caught in traps. A pink dolphin was spotted in Louisiana in 2007 (and several times since). In the Chinese province of Shaanxi, a cute brown and white panda greets zoo visitors.

Another anomalous animal has joined their ranks. Black squirrels have been spotted in both the United States and the UK, and now scientists believe they know why.

Like many animals with unusual color schemes, black squirrels are the result of a genetic detour. Researchers at Anglia Ruskin University, Cambridge University, and the Virginia Museum of Natural History collaborated on a project that tested squirrel DNA. Their findings, which were published in BMC Evolutionary Biology, demonstrated that the black squirrel is the product of interspecies breeding between the common gray squirrel and the fox squirrel. The black squirrel is actually a gray squirrel with a faulty pigment gene carried over from the fox squirrel that turns their fur a darker shade. (Some fox squirrels, which are usually reddish-brown, are also black.)

A black squirrel is pictured
sanches12/iStock via Getty Images

Scientists theorize a black fox squirrel may have joined in on a mating chase involving gray squirrels and got busy with a female. The black fur may offer benefits in colder regions, with squirrels able to absorb and retain more heat, giving them a slight evolutionary edge.

In North America, black squirrels are uncommon, with one estimate putting them at a rate of one in every 10,000 squirrels. In 1961, students at Kent State University in Ohio released 10 black squirrels that had been captured by Canadian wildlife authorities. The squirrels now populate the campus and have become the school’s unofficial mascot. Their coloring might help them hide from predators, which might come in handy at Kent State: The campus is also home to hawks.

[h/t The Guardian]

15 Scientific Ways to Relax for National Relaxation Day

iStock/anyaberkut via Getty Images
iStock/anyaberkut via Getty Images

Today is National Relaxation Day, so you have a great excuse to take it easy. Here’s how science can help you have the most laid-back day of the year.

1. Get a house or office plant.

Spending time in nature improves your overall wellbeing, but it turns out even just a little greenery is great for your health. Studies have shown patients in hospital rooms with plants report lower stress. Even just stepping into a lush space can reduce your heart rate. Plus, plants are effective at increasing oxygen and clearing out toxins, which should help you breathe easier—literally.

2. Avoid screens before bedtime.

Artificial light from TV and computer screens affects melatonin production and throws off circadian rhythms, which messes with your sleep. Studies have found that young adults were more likely to suffer from sleep disorders, high stress and even depression if they reported intensive use of cell phones and computers at night.

3. Eat a banana.

Potassium helps your body regulate blood pressure. Keeping that under control should help you bounce back more quickly from what’s got you stressed.

4. Indulge in some citrus.

Still hungry after that chocolate and banana? Try citrus. Recent studies show that vitamin C helps to alleviate the physical and psychological effects of stress.

5. Listen to classical music.

Portrait of a beautiful young woman lying on sofa with headphones on and closed eyes, relaxing
BartekSzewczyk/iStock via Getty Images

Any music you enjoy is bound to make you feel better, but classical music, in particular, has been shown to slow heart rate, lower blood pressure and even decrease levels of stress hormones.

6. Drink green tea sweetened with honey.

Green tea contains L-theanine, which reduces stress, and honey—unlike cane sugar—has been shown to counteract free radicals and reduce inflammation, which is sometimes linked to depression.

7. Give yourself a hand massage.

Especially if you spend all day typing, hands can get really tense. A quick massage should be doable at your desk and if you incorporate some lavender-scented lotion, you’ll get extra relaxation benefits.

8. Lock lips with someone.

Romance is relaxing! Kissing releases oxytocin, a chemical that is shown to reduce levels of the stress hormone cortisol.

9. Chew some gum.

No matter what flavor it is, the act of chewing gum has been proven to lower cortisol and improve reported mood.

10. Blow up a balloon.

Young woman blowing up a blue balloon against a yellow background
Deagreez/iStock via Getty Images

Reacting to stress with short, shallow breaths will only exacerbate the problem—your body needs more oxygen, not less, to relax. Blowing up a balloon will help you refocus on your breathing. No balloons around? Just concentrate on taking a few deep breaths.

11. Mow the lawn.

Research shows that a chemical released by a mowed lawn—that fresh-cut grass smell—makes people feel happy and relaxed. Plus, knocking it off your to-do list will give you one less thing to stress about.

12. Find something to make you laugh.

Watching a funny video online does more than just brighten your afternoon, it physically helps to relax you by increasing the endorphins released by your brain.

13. Grab some chocolate.

What’s also good at releasing endorphins? Chocolate. Studies show that even just 40 grams of dark chocolate a day can help you de-stress.

14. Focus on relaxing all of your muscles.

Take a break from whatever you’re doing and, starting at your toes and working upwards, spend a few moments slowly tensing, and then releasing, the muscles of each part of your body.

15. Take a mental vacation.

Man takes a break from work to meditate at his laptop
AaronAmat/iStock via Getty Images

If you’re feeling overwhelmed at work, take a moment to close your eyes and picture a particularly relaxing scene. It may sound cheesy, but numerous studies show that just a few minutes of disengaging from your stressors rejuvenates your ability to tackle the work.

SECTIONS

arrow
LIVE SMARTER