Some people fear bats. After COVID19, this fear has increased several fold.  Some even suggested that we kill all the bats in the world! It took several days of explanations from us why bats are important to our ecosystems to subside that fear.

This was my explanation then:

No, you can't kill all bats - because they are very helpful to humans. 

70 percent of the bat species in the world feed off insects, many of which are harmful to agriculture and our health, like mosquitos that spread dengue and other diseases. With lots of bats eating lots of insects, there will be fewer insects to bug you. Farmers like bats because they can use fewer pesticides on their crops, which save the farmers lots of money.

In the tropics, fruit and nectar eating bats are important for dispersing seeds and pollinating flowers. In fact, more than 300 tropical plants depend on bats for seed dispersal and pollination. These plants include bananas, mangoes, avocados, date, and figs. By dispersing seeds, bats are helping rebuild rainforests that humans have cut down.

This might surprise you, but vampire bats are important to humans too. Vampire bats have a special chemical in their saliva that keeps blood from clotting. This allows them to easily drink blood from cows and pigs. Scientists studied this chemical and used it to develop medicine that helps humans that suffer from blood clots and strokes.

If you kill all the bats that would disturb ecological balance severely.

Now we have more reasons to save bats. 

 Like how fruit bats evolved to consume so much sugar may have implications for diabetes research.

Frugivory, the ability to thrive on a mostly fruit diet, has allowed mammals to expand their ecological niches. In bats, frugivory has evolved independently from the insectivorous ancestor.

 Fruit-eating bat - Image source: Google images

A high-sugar diet is bad news for humans, leading to diabetes, obesity and even cancer. Yet fruit bats survive and even thrive by eating up to twice their body weight in sugary fruit every day.

Now scientists have discovered how fruit bats may have evolved to consume so much sugar, with potential implications for the millions of people with diabetes. The findings, published in Nature Communications, point to adaptations in the fruit bat body that prevent their sugar-rich diet from becoming harmful.

 Fruit bats, which are frugivorous, have a genetic system that controls blood sugar without fail. Scientists are learning from that system to make better insulin- or sugar-sensing therapies for people.

They found that the fruit bat pancreas, compared to the pancreas of an insect-eating bat, had extra insulin-producing cells as well as genetic changes to help it process an immense amount of sugar. Additionally, fruit bat kidneys had adapted to ensure that vital electrolytes would be retained from their watery meals.

Even small changes, to single letters of DNA, make this diet viable for fruit bats. We need to understand high-sugar metabolism like this to make progress helping the people who are prediabetic.

In fruit bats, the compositions of the pancreas and kidneys evolved to accommodate their diet. The pancreas had more cells to produce insulin, which tells the body to lower blood sugar, as well as more cells to produce glucagon, the other major sugar-regulating hormone. The fruit bat kidneys, meanwhile, had more cells to trap scarce salts as they filtered blood.

Zooming in, the regulatory DNA in those cells had evolved to turn the appropriate genes for fruit metabolism on or off. The big brown bat, on the other hand, had more cells for breaking down protein and conserving water. The gene expression in those cells was tuned to handle a diet of bugs.

The organization of the DNA around the insulin and glucagon genes was very clearly different between the two bat species. The DNA around genes used to be considered 'junk,' but new data shows that this regulatory DNA likely helps fruit bats react to sudden increases or decreases in blood sugar.

While some of the biology of the fruit bat resembled what's found in humans with diabetes, the fruit bat appeared to evolve something that humans with a sweet tooth could only dream of: a sweet tooth without consequences. Bats biology has figured it out, and it's all in their DNA, the result of natural selection!

The study benefited from a recent ground swell of interest in studying bats to better human health.  One of the Jamaican fruit bats was used in the sugar metabolism study.

As one of the most diverse families of mammals, bats include many examples of evolutionary triumph, from their immune systems to their peculiar diets and beyond.

Bats are like superheroes, each one with an amazing super power, whether it is echolocation, flying, blood sucking without coagulation, or eating fruit and not getting diabetes.

Scientists are trying to learn all these tricks from bats. So, aren't bats very helpful? 

Wei Gordon et al, Nature Communications (2024). www.nature.com/articles/s41467-023-44186-y