Human Activity Has Permanently Altered Earth, for Better or Worse (Mostly Worse)

iStock
iStock

Modern humans have roamed Earth for just a few hundred thousand years. In the grand scheme of things, that's a very short period. But in that time, we’ve triggered mass extinctions of plants and animals, polluted the planet, and developed nuclear weapons—and our legacy will linger in both nature and the geologic record long after historical records have been lost, according to Ted-ED’s video below.

Modern humans have altered the Earth’s landscape and atmosphere so profoundly that some scientists say we’ve ushered in a new epoch called the Anthropocene, or "new age of humankind," from anthropo (human) and cene (new). Before this, we were living in the Holocene (meaning “entirely recent”), which began around 11,700 years ago and faded sometime around 1950.

The 1950s ushered in both the plastics revolution and the atomic age, both of which permanently introduced chemicals into Earth’s fossil record. Meanwhile, humans have also shaped long-term plant and animal evolution with agriculture, fishing, and hunting. In short, our actions have long-term consequences, even if the human species ends up being a blip on the geologic time scale. Remember that the next time you drink from a plastic bottle, or see a cloud of smoke billowing through the sky.

Pandemic vs. Epidemic: What’s the Difference?

If scientists can't develop a vaccine for a new virus quickly enough, an epidemic can turn into a pandemic.
If scientists can't develop a vaccine for a new virus quickly enough, an epidemic can turn into a pandemic.
doble-d/iStock via Getty Images

As the new coronavirus continues to spread around the world, the words epidemic and pandemic are showing up in news reports more often than they usually do. While the terms are closely related, they don’t refer to the same thing.

As the Association for Professionals in Infection Control and Epidemiology (APIC) explains on its website, “an epidemic occurs when an infectious disease spreads rapidly to many people.” Usually, what precedes an epidemic is an outbreak, or “a sudden rise in the number of cases of a disease.” An outbreak can affect a single community or several countries, but it’s on a much smaller scale than an epidemic.

If an epidemic can’t be contained and keeps expanding its reach, public health officials might start calling it a pandemic, which means it’s affected enough people in different areas of the world to be considered a global outbreak. In short, a pandemic is a worldwide epidemic. It infects more people, causes more deaths, and can also have widespread social and economic repercussions. The spread of the Spanish influenza from 1918 to 1919, which killed between 20 and 40 million people around the world, was a pandemic; more recently, the H1N1 influenza created a pandemic in 2009.

Here’s where it gets a little tricky: There’s no cut-and-dried classification system for outbreaks, epidemics, and pandemics. Based on the definitions above, it might seem like the current coronavirus disease, now called COVID-19, falls into the pandemic category already—according to a map from the World Health Organization (WHO), there are more than 80,000 confirmed cases in 34 countries, and nearly 2700 people have died from the disease. It’s also beginning to impact travel, stock markets, and the global economy as a whole. But WHO maintains that although the situation has the potential to become a pandemic, it’s still an epidemic for now.

“It really is borderline semantics, to be honest with you,” Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told CNN earlier this month. “I think you could have people arguing each end of it. Pandemics mean different things to different people.”

[h/t APIC.org]

Fat Bats Might Be Resistant to Deadly White-Nose Syndrome

Penn State, Flickr // CC BY-NC-ND 2.0
Penn State, Flickr // CC BY-NC-ND 2.0

Good news for flying mammals: chubby little brown bats might be genetically resistant to white-nose syndrome, a fungal disease that’s killed more than 5.5 million bats since it was first documented in 2006 [PDF]. A new study in the journal Scientific Reports describes three genetic adaptations in the bats that could protect them from the pathogen.

Little brown bats (Myotis lucifugus), common in Canada and the eastern United States, are especially susceptible to white-nose syndrome. According to lead author Giorgia G. Auteri, a doctoral candidate at the University of Michigan, white-nose syndrome kills bats by disrupting their hibernation cycles.

“When they’re in hibernation in the winter, they’re not meant to be waking up. They’re supposed to be asleep,” Auteri tells Mental Floss. “But this fungus grows on them, and it causes the bats to keep waking up during hibernation. And because they’re waking up when they shouldn’t be, they’re running out of fat reserves too early.”

But while white-nose syndrome has devastated bat populations in North America, not all infected bats die from the disease—some recover. Auteri wanted to find out what made the survivors so special.

Auteri and her team compared the genetic makeup of nine surviving and 29 non-surviving little brown bats from northern Michigan. They discovered that survivors share three important genetic distinctions. “One is involved with fat metabolism,” she says. “And another is involved with regulating when the bats wake up from hibernation. And the third gene is involved in their echolocation ability, in their sonar for hunting insects.”

The results make sense, Auteri says. Because white-nose syndrome interrupts bats’ hibernation schedules, bats with genes that relate to more optimal fat storage (i.e., they’re fatter) and better hibernation regulation (i.e., they sleep longer) are more likely to survive the disease.

Auteri’s research could help scientists and conservationists find ways to preserve little brown bat populations. Besides being adorable, little brown bats also play an important ecological role as predators of insects like mosquitoes, moths, and other pests that are destructive to crops and forests.

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