A man in India earned a Guinness World Record this week for doing, well, nothing at all. He didn't eat a bunch of hot dogs or jump off a building. All he did was forgo basic hygiene, by growing out his fingernails for an astonishingly long time.

Shridar Chillal hasn't trimmed his claws in 62 years. The last time he put scissor to nail was 1952 (to place that in perspective, Harry Truman was president of the United States at the time, and gas cost 20 cents a gallon). As a result of Chillal's refusal to trim, each of the fingers on his left hand ends in a swirling mass of keratin that cumulatively measures about 30 feet (9 meters) long.

Chillal's extreme fingernails raise questions — lots of questions. How does he cut his food or answer his iPhone, for example? Furthermore, how is this even possible? Here are answers to three of the most pressing fingernail-related queries.

1. Why do people have them?

Sure, nails look pretty all trimmed and polished, and they make opening a can of soda a lot easier, but these are not the reasons that humans have fingernails. So what is the reason?

It's because humans are primates, said John Hawks, a biological anthropologist at the University of Wisconsin-Madison. Unlike most mammals, which have claws for digging and climbing, humans and other primates have fingertips that are perfect for grasping tools and other objects, Hawks told Live Science in 2013.

But the fingernail is still something of a mystery, said Hawks, adding that scientists aren't sure if these features are just an evolutionary remnant of primates' lost claws or a useful adaptation that somehow helped early primates use their fingers more effectively.

A study by researchers at the University of Florida suggests that the latter explanation makes the most sense. Primates have had fingernails for at least 55.8 millions years, according to the study, which described the world's oldest known fingernail, found on the tiny, lemurlike primate Teilhardina brandti, The animal likely used its long nails to grasp small branches while moving around in its forest habitat, the study researchers told Live Science in 2011.

2. How do they grow?

Like squirting out of a tube — that's how fingernails grow.

Newly toothpaste formed cells at the base of the nail push older cells out toward the tip of the finger, according to a Medscape report. As these new cells meet up with the existing nail plate, or the part of the nail that you can see, they flatten and stretch out.

The base of the fingernail is located under the skin just above the first joint of the finger. Technically, this part of the finger is called a "proximal nail fold." Most growth (about 90 percent) takes place under this section of the finger, so you can't see it happening.

Specifically, the growth of the nail begins at the ventral floor, which is the part of the nail that connects the germinal matrix (that's where all the new cells are made) to the ligaments in your fingers. New living cells push forward along this germinal matrix, which ends at the lunula, or the crescent shape at the bottom of your nail that usually has a whitish tinge. Once the cells reach the edge of the lunula, they lose their nuclei and harden into the protein keratin, which you might know as a fingernail.

The nail bed, which is located right under the visible fingernail, also contributes cells that give the nail more thickness and strength. And another hidden part of the nail, called the dorsal roof, which is located behind your cuticle, provides the cells that give your nails a lustrous shine. [The 7 Biggest Mysteries of the Human Body]

3. How long can they get?

If Chillal's record-breaking feat is any indication, nails can grow to be pretty long. The longest of Chillal's nails is his thumbnail, which measures 6.5 feet (2 m) long and ends in a tightly wound coil.

Of course, most people tend to keep their nails shorter than Chillal's, and even those who strive for length might find that their nails grow more slowly than those of others. Even all the fingernails on one hand don't grow at the same rate. You can see evidence of this by looking at the variation in Chillal's nail length. This variation has also been demonstrated in studies conducted by the late Dr. William Bean, an internist and medical historian who carefully studied the growth of the nails on his left hand for 35 years. His research was published in a series of papers, the latest of which appeared in 1980 in the journal JAMA Internal Medicine.

Bean found that his middle finger's nail was the fastest growing, while the nails on his thumb and little finger were the slowest to grow. The rate of growth for each nail was so consistent that, rather than measuring the growth of all his nails, the doctor eventually just measured his thumbnail growth and used that to calculate the rate of growth of every other finger.

And as Bean aged, he found that his nails grew more slowly. When he started the study, at age 32, his left thumbnail grew about 0.005 inches (0.123 millimeters) a day. By the time he was 67, the same nail grew just 0.0037 inches (0.095 mm) a day.