Why elephant hunting has a 'drastic' impact on our global climate
The loss of elephants accelerates climate change.
- Elephants help keep the central African forests they live in healthy.
- Without elephants, the forests see a striking reduction in their carbon dioxide-storage capacity.
- Study calls elephants "natural forest managers."
As long as there's profit in it — and as long as there are those who simply enjoy killing animals — we're likely to continue losing elephants, and it's a disturbing loss.
To see these endearing, intelligent creatures taken down by people — humans — is nothing short of heartbreaking. Today, new research, published in the July installement of Nature Geoscience, reveals their decimation isn't just a moral issue — the loss of forest elephants damages the carbon-storage capacity of the central African forests in which they live.
The researchers write: "Large herbivores such as elephants, can have important effects on ecosystems and biogeochemical cycles."
Image source: Siegfried.modola/Shutterstock
Led by ecologist Fabio Berzaghi of Climate and Environmental Sciences in France, researchers collected field measurements of forests in the Congo basin, comparing the tree densities and composition of areas in which elephants are still present, and areas in which they no longer live. It's estimated that the animals' overall population has been reduced 10 percent from historical levels.
What the analysis reveals is that forests in central Africa no longer home to elephants are characterized by a reduction in larger trees, and critically, fewer hard-wood trees. These trees have a more robust CO2 storage capacity than soft-wood trees.
The trick to working out the impact of losing elephants is that their influence on forest ecosystems plays out over a longer term — think 100 years — than the period for which data is available. To address this, the researchers developed computer simulations that exposed changes in the way different types of trees compete for nutrient, water, and light with and without elephants.
The researchers concluded that without the creatures, some three billion tons of carbon would no longer be captured by the forests — that amount is roughly equal to France's total carbon emissions for 27 years. That's about a 7 percent reduction in the forests' ability to absorb the greenhouse gas.
Co-author Chris Doughty sums it up this way: "Our simulations suggest that if elephant loss continues unabated, central African forests may release the equivalent of multiple years of fossil fuel CO2 emissions from most countries, thus potentially accelerating climate change. Therefore, their loss could have a drastic impact both locally and on global climate."
How elephants change forests
Image source: David JC / Shutterstock
Experts already suspect this link, but the new study for the first time comprehensively quantifies it. Previous guesses about how elephants have such a striking effect on their habitats' biomass have focussed on seed dispersal via defecation, generally moving things around, and stepping on and crushing small trees. All of these things seem to be true. Berzaghi says, "Forest elephants are natural forest-managers that thin forests by 'pruning' or removing small trees which increases the growth of large trees and the production of wood."
A obvious solution
Image source: GUDKOV ANDREY / Shutterstock
Stop killing elephants.
"Our study shows that even at high population densities, forest elephants continue to improve the carbon storage potential of central African forests, so there is no ecological concern for their comeback," says Berzaghi. Increasing their population size in these forests carries with it no discernible risk.
Their resurgence would also confer benefits beyond better carbon storage. Study co-author Stephen Blake notes that "Forest elephants are the gardeners and guardians of biodiversity in the Congo Basin." Their seed dispersal alone, according to the study authors, contributes to the germination of over 100 tree species that provide habitats for birds, primates, and insects.
Young people could even end up less anxiety-ridden, thanks to newfound confidence
- The coronavirus pandemic may have a silver lining: It shows how insanely resourceful kids really are.
- Let Grow, a non-profit promoting independence as a critical part of childhood, ran an "Independence Challenge" essay contest for kids. Here are a few of the amazing essays that came in.
- Download Let Grow's free Independence Kit with ideas for kids.
Many Americans are being misled on serious scientific issues, and science journalists have to spend an inordinate amount of time debunking myths which seemingly never die.
Technique may enable speedy, on-demand design of softer, safer neural devices.
The brain is one of our most vulnerable organs, as soft as the softest tofu. Brain implants, on the other hand, are typically made from metal and other rigid materials that over time can cause inflammation and the buildup of scar tissue.
New research establishes an unexpected connection.
- A study provides further confirmation that a prolonged lack of sleep can result in early mortality.
- Surprisingly, the direct cause seems to be a buildup of Reactive Oxygen Species in the gut produced by sleeplessness.
- When the buildup is neutralized, a normal lifespan is restored.
We don't have to tell you what it feels like when you don't get enough sleep. A night or two of that can be miserable; long-term sleeplessness is out-and-out debilitating. Though we know from personal experience that we need sleep — our cognitive, metabolic, cardiovascular, and immune functioning depend on it — a lack of it does more than just make you feel like you want to die. It can actually kill you, according to study of rats published in 1989. But why?
A new study answers that question, and in an unexpected way. It appears that the sleeplessness/death connection has nothing to do with the brain or nervous system as many have assumed — it happens in your gut. Equally amazing, the study's authors were able to reverse the ill effects with antioxidants.
The study, from researchers at Harvard Medical School (HMS), is published in the journal Cell.
An unexpected culprit
The new research examines the mechanisms at play in sleep-deprived fruit flies and in mice — long-term sleep-deprivation experiments with humans are considered ethically iffy.
What the scientists found is that death from sleep deprivation is always preceded by a buildup of Reactive Oxygen Species (ROS) in the gut. These are not, as their name implies, living organisms. ROS are reactive molecules that are part of the immune system's response to invading microbes, and recent research suggests they're paradoxically key players in normal cell signal transduction and cell cycling as well. However, having an excess of ROS leads to oxidative stress, which is linked to "macromolecular damage and is implicated in various disease states such as atherosclerosis, diabetes, cancer, neurodegeneration, and aging." To prevent this, cellular defenses typically maintain a balance between ROS production and removal.
"We took an unbiased approach and searched throughout the body for indicators of damage from sleep deprivation," says senior study author Dragana Rogulja, admitting, "We were surprised to find it was the gut that plays a key role in causing death." The accumulation occurred in both sleep-deprived fruit flies and mice.
"Even more surprising," Rogulja recalls, "we found that premature death could be prevented. Each morning, we would all gather around to look at the flies, with disbelief to be honest. What we saw is that every time we could neutralize ROS in the gut, we could rescue the flies." Fruit flies given any of 11 antioxidant compounds — including melatonin, lipoic acid and NAD — that neutralize ROS buildups remained active and lived a normal length of time in spite of sleep deprivation. (The researchers note that these antioxidants did not extend the lifespans of non-sleep deprived control subjects.)
Image source: Tomasz Klejdysz/Shutterstock/Big Think
The study's tests were managed by co-first authors Alexandra Vaccaro and Yosef Kaplan Dor, both research fellows at HMS.
You may wonder how you compel a fruit fly to sleep, or for that matter, how you keep one awake. The researchers ascertained that fruit flies doze off in response to being shaken, and thus were the control subjects induced to snooze in their individual, warmed tubes. Each subject occupied its own 29 °C (84F) tube.
For their sleepless cohort, fruit flies were genetically manipulated to express a heat-sensitive protein in specific neurons. These neurons are known to suppress sleep, and did so — the fruit flies' activity levels, or lack thereof, were tracked using infrared beams.
Starting at Day 10 of sleep deprivation, fruit flies began dying, with all of them dead by Day 20. Control flies lived up to 40 days.
The scientists sought out markers that would indicate cell damage in their sleepless subjects. They saw no difference in brain tissue and elsewhere between the well-rested and sleep-deprived fruit flies, with the exception of one fruit fly.
However, in the guts of sleep-deprived fruit flies was a massive accumulation of ROS, which peaked around Day 10. Says Vaccaro, "We found that sleep-deprived flies were dying at the same pace, every time, and when we looked at markers of cell damage and death, the one tissue that really stood out was the gut." She adds, "I remember when we did the first experiment, you could immediately tell under the microscope that there was a striking difference. That almost never happens in lab research."
The experiments were repeated with mice who were gently kept awake for five days. Again, ROS built up over time in their small and large intestines but nowhere else.
As noted above, the administering of antioxidants alleviated the effect of the ROS buildup. In addition, flies that were modified to overproduce gut antioxidant enzymes were found to be immune to the damaging effects of sleep deprivation.
The research leaves some important questions unanswered. Says Kaplan Dor, "We still don't know why sleep loss causes ROS accumulation in the gut, and why this is lethal." He hypothesizes, "Sleep deprivation could directly affect the gut, but the trigger may also originate in the brain. Similarly, death could be due to damage in the gut or because high levels of ROS have systemic effects, or some combination of these."
The HMS researchers are now investigating the chemical pathways by which sleep-deprivation triggers the ROS buildup, and the means by which the ROS wreak cell havoc.
"We need to understand the biology of how sleep deprivation damages the body so that we can find ways to prevent this harm," says Rogulja.
Referring to the value of this study to humans, she notes,"So many of us are chronically sleep deprived. Even if we know staying up late every night is bad, we still do it. We believe we've identified a central issue that, when eliminated, allows for survival without sleep, at least in fruit flies."