For years, scientists thought they knew when H. sapiens became the only kind of human species in existence. The scientists thought that the big change happened about 24,000 years ago, with the extinction of the Neandertals (Homo neanderthalensis).

Recently, however, scientists have found evidence of a previously undiscovered species of humans. The scientists made the find on the island of Flores in Indonesia.

The skull of an adult person who lived long ago on the island of Flores (left) is much smaller than that of a modern human (right).

Peter Brown

The newly discovered species, called Homo floresiensis after the island of its discovery and nicknamed “hobbit” because of its tiny size, lived as recently as 12,000 years ago. Many scientists consider the hobbit to be the most important discovery in anthropology in 50 years.

The finds on Flores indicate that for thousands of years, “we were not alone as a human species,” says Bert Roberts, a senior research fellow at the University of Wollongong in Australia. “Until very recently, there would have been another type of walking, talking, interacting kind of human running around the planet,” he adds. Roberts was a member of the team that discovered H. floresiensis.

Flores, shown here in yellow, is an island that belongs to the country of Indonesia. Other regions of Indonesia are colored green, and other Asian countries are shown in white.

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Finding hobbits

The first signs of the hobbit’s existence emerged in 2001, when a team of Australian and Indonesian researchers started finding small teeth and bones on Flores. The scientists were looking for H. sapiens fossils at the time.

At first, the scientists didn’t suspect anything unusual. They thought that the small fossils belonged to H. sapiens children.

Then, on the last day of the digging season in September 2003, an Indonesian researcher named Thomas Sutikna stumbled across what looked like the top of a skull in the ground. To protect the fossil, he dug out the entire block of sand surrounding it.

“It was only when he started uncovering what was in this block of sand that [the team] realized [he] had [found] a whole new human species,” Roberts says. Skulls often reveal more about a species than other bones can, he adds, and this skull was a clincher. “This really was something completely, remarkably new.”

The tiny skull looked different from any Homo skull ever unearthed. It had a sloping forehead and thick ridges above the eye sockets. It had a receding chin. Its brain—about 23 cubic inches in volume—was just one-fourth as big as a modern human brain.

This photograph of a hobbit skull shows its distinctive sloping forehead and thick eyebrow ridges.

Peter Brown

Further excavations revealed that the creature’s skeleton was different from that of H. sapiens, too. The skull and bones belonged to a woman who was about 30 years old and about 3 feet tall—the size of a typical 4-year-old today. Her feet were flat and broad. And she had long arms, with hands that hung down to her knees.

Those features resembled those of some of our ancient ancestors who lived 2 or 3 million years ago, says Chris Turney, a research fellow at the University of Wollongong who became involved soon after the discovery. So, he expected the new fossils to be that old, too.

Much to everyone’s surprise, Turner’s analysis of the skeleton showed that the bones were just 18,000 years old. The hobbit was a completely new species of human. What’s more scientists had never seen anything like it living so recently. It was a huge discovery.

“I was blown away by this,” Turney says. “I just walked around with a great big grin all day.”

The great debate

The scientists announced their find in 2004. Some anthropologists, like Turner, were amazed by the news. But critics quickly disputed the findings. They claimed that the new skeleton was not a new species. It was simply a member of our own species suffering from a disease called microcephaly. Among other symptoms and deformities, people with microcephaly have smaller than average heads and bodies.

The debate gained steam. Meanwhile, further digging in the island’s limestone caves turned up bones from eight other hobbitlike people with similar bone structures. Analyses revealed that these individuals lived between 95,000 and 12,000 years ago, strengthening the case that the scientists had indeed discovered a new species. As Roberts says, it would be very unusual that an entire population would have microcephaly over that many years.

Most scientists do now believe that H. floresiensis was indeed a separate species from H. sapiens, Roberts says. “I’d say 99.5 percent [of scientists] are in our favor,” he claims.

But not everyone is convinced. Discoveries such as these shake up long-held theories about evolution. The discovery of H. floresiensis, for example, challenges the view of some experts that H. sapiens originated in Africa and then replaced all existing human species as it spread around the world. It suggests instead that H. floresiensis and H. sapiens actually shared the globe for tens of thousands of years.

Getting to the bones of the matter

Because of arguments between researchers, further excavations, which could answer the many remaining questions about the hobbits, stopped in 2004. But now, the anthropologists are ready to pick up their shovels again. This June and July, digging on Flores will resume.

The researchers hope to find more skeletons with features similar to those of H. floresiensis, as well as samples of DNA, which should “settle the dispute once and for all,” Roberts says. More fossils would also give more details about the lives of the hobbits.

Evidence to date suggests that the hobbits were clever, despite their small brains, Roberts says. Explorations of the sites where the bones were found shows that the hobbits used specialized stone tools. They hunted komodo dragons and pygmy elephants. They could make fires. And they found a way to travel to Flores, probably from the mainland of Asia, on their own.

Despite the enthusiasm of Roberts and many others, scientists still cannot prove that H. sapiens and H. floresiensis lived on Flores at the same time. Only more digging, and additional studies of the bones, will resolve this question.

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Word Find: Hobbits

As it turns out, the choices you make now can make a big difference in how you feel later in life. I recently learned this lesson the hard way.

It started with an injury: a cracked shinbone caused by too much running on hard pavement. My doctor suggested a bone scan, which showed that my bones are weaker than average. I don’t have osteoporosis, a disease that causes older people to shrink in height and break bones easily. But I’m close.

Example of a human bone.

For me, the diagnosis was a scary wakeup call. I’m just 27 years old, but already I’m worried about things that normally happen only to women more than twice my age. Will I break my hip if I slip on a patch of ice? Is it safe for me to go skiing, lift heavy boxes, play Ultimate Frisbee?

Perhaps what upsets me most is the realization that I might have avoided all of this if only I had thought ahead earlier in life. Childhood and adolescence are the most important times to build strong bones. For you, there’s still time. Doctors suggest a variety of foods you can eat and exercises you can do as a teenager to build strong bones for life.

Living tissue

Bones are amazing. They’re hard but flexible, and they’re lightweight but tough. Without bones, we’d be just puddles of skin and guts.

An adult person has 206 bones in his or her body. The outer layer of a typical bone is made of a hard material honeycombed with tunnels. This web of hollow pipes allows a bone to be strong and light. It also allows the passage of nutrients and waste. A protein called collagen gives a bone its elasticity. Chemicals known as calcium salts make a bone hard.

But, even though our bones support us, they’re easy to ignore. Unlike a cut or bruise, a weak bone isn’t visible or painful.

Osteoporosis is sometimes called a silent disease. People often don’t realize they have it until it has progressed so far that they break bones while doing ordinary things, such as walking down stairs or lifting heavy objects.

Osteoporosis happens mostly to older people. But I’m not the only woman in her 20s with weak bones. Increasingly, scientists are finding that weak bones are a problem in teenagers and even younger kids. That’s especially troubling because youth is the critical time for bone growth.

If you’ve ever seen a skeleton in a museum, you might think that bones are dead. In fact, bones are living tissue. They reshape and rebuild themselves many times as you grow and age.

Front and back views of a human skeleton. An adult has 206 bones in his or her body.

The cycle of building and breaking down bone changes over a person’s lifetime. Bone-building is fastest during the first 3 years of life and again during adolescence. By the time you’re in your 20s, the tissue in your bones is about as tightly packed as it’s going to get.

Measuring something called bone density tells you how tightly packed the bone tissue is. A high bone density normally shows that you have strong bones.

Once you get to be about 35 years old, bone tissue gets broken down more quickly than it’s replaced. This means that bones tend to lose tissue, and the bone density goes down. That’s when osteoporosis usually becomes a concern. And it’s a bigger risk for women than for men.

Food concerns

Getting the right kind of bone-building nutrition and exercise as a teenager is like putting money in the bank. Your bones can stay strong as you get older.

Unfortunately, many teenagers don’t think about their bones when they order lunch or decide what to do with their free time. They’d rather snack on chips or slurp soda than think about vitamins.

And parents don’t always set the best example. “I was standing by the elevator at Children’s Hospital,” says Susan Coupey, an adolescent medical specialist at Children’s Hospital at Montefiore in Bronx, New York. “There was a 2-year-old child being fed soda by his parents.”

Unlike milk or fortified juice, a soft drink doesn’t provide calcium for helping to build strong bones.

Junk food has few nutrients. It also fills you up, so you don’t eat enough of the good stuff. That’s one reason why many adults want schools to get rid of soda machines.

Doctors urge kids to get plenty of calcium, the mineral that makes bones strong. Calcium is also essential for keeping nerves, blood, and muscles healthy. When you don’t take in enough calcium, your body takes calcium out of your bones, which weakens your bones even more.

Although calcium is abundant in milk, yogurt, cheese, fortified juices, soy milk, and some nuts and vegetables, few people get enough of it. The Institute of Medicine recommends that kids between the ages of 9 and 18 get 1,300 milligrams of calcium every day. That’s roughly the amount of calcium in a quart of milk.

Yet fewer than 10 percent of girls and 25 percent of boys get that much, according to the National Osteoporosis Foundation. “The average calcium intake of adolescent girls in the United States is somewhere around 900 milligrams,” Coupey says. “Many take in just 600 to 700 milligrams.”

Paying attention

Now that I’ve started paying attention, I realize that getting enough calcium takes some effort. Getting 1,300 milligrams of calcium is equivalent to drinking about four glasses of milk, eating 10 cups of cooked broccoli, or having two glasses of milk, a cup of yogurt, and a glass of orange juice—every day!

And that’s not all you need. To absorb the calcium you eat, you have to take in a variety of other vitamins and minerals, including lots of vitamin D.

In the summertime, you get vitamin D from sunlight on your skin. Where I live in Minnesota, though, it’s too dark and cold much of the year to spend a great deal of time outside. To get the recommended 400 to 800 international units of vitamin D recommended for people my age, I drink 2 cups of fortified milk every day, and I take a vitamin supplement. The American Academy of Pediatrics now recommends that teenagers take a daily multivitamin that has 200 international units of vitamin D.

Getting enough exercise is also crucial. “There have been some really excellent studies showing the effectiveness of weight-bearing exercise and strengthening exercises on bone density,” Coupey says.

Any exercise at all is better than sitting in front of the TV. Walking and lifting weights, in particular, are great for building muscles that support and strengthen bone. Playing soccer, tennis, or basketball are also good options.

A recent study found that elementary school girls who did jumping exercises for 10 to 12 minutes, three times a week, built 5 percent more bone mass than did girls who didn’t do the exercises. That’s enough bone mass to buy women some extra bone strength later in life, said the scientists from the University of British Columbia who did the study.

Even if you’re glued to the TV set, why not do some jumping jacks during the commercials? Have a glass of milk or fortified juice and some almonds instead of a can of soda and chips.

The changes are small, but the payoff could be big. You might even be amazed at how good it feels to take care of your bones. Support them, and they will support you for many years to come.

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