Sunlight may save kids' sight

Exposure to sunlight may boost kids' dopamine levels, which reduces their chances of myopia, scientists say




Exposure to sunlight could be a critical factor in stopping children from becoming short-sighted, Australian researchers have found.

The findings, presented to the Australasian Ophthalmic and Visual Sciences Meeting in Canberra this week, appear to overturn the long-held view that education and close work are the key drivers of myopia.

Instead they suggest the ability to develop myopia is strongly influenced by environmental factors.

They will also be a boon to public health officials in the region as myopia is reaching epidemic proportions across urban Asia.

Dr Ian Morgan, of the Australian Research Council Centre of Excellence in Vision Science, says there has been a dramatic escalation in myopia rates in East Asia during the past 30 years.

Morgan says 90% of conscription-aged males in Singapore are now myopic.

This compares with figures from the 1960s to the 70s when only 20-30% of 17-year-old males had myopia.

During the same period, rates of myopia in Australia have increased from about 15% to 20-25%.

Morgan says it has been suggested there may be an East Asian genetic susceptibility to environmental risk factors associated with intensive education and urbanisation.

But he says this can be discounted because those of South Asian, or Indian, ethnicity growing up in Singapore are as myopic as the Chinese and Malay populations.

"This phenomenon cannot plausibly be explained in terms of changes in gene pools," the Australian National University researcher says.

"A gene pool doesn't change that fast."


Playing outside
Instead Morgan and colleague Dr Kathy Rose, of the Faculty of Health Sciences at the University of Sydney, have found the time children spend outdoors is the critical factor.

A comparison of children of Chinese origin living in Singapore and Sydney, which matched the subjects for age and parental myopia, shows the rate of myopia in Singaporean children is 10 times higher.

But Morgan says the Sydney-based children spend significantly more time in near-work activity, reading twice as many books per week.

The key difference in their weekly activities was in time spent outdoors with Sydney-based children outside almost four times longer than their Singapore counterparts.

"What children are doing in Australia at the moment seems to be right," he says.


Dopamine
Morgan believes the exposure to sunlight cuts myopia rates by encouraging the release of dopamine.

Dopamine is known to inhibit eye growth and myopia is a condition caused by excessive eye growth.

Morgan says while they will begin experiments to assess this theory, the findings are concrete enough to inform public health policy.

"The findings provide a means of prevention and are enough to start authorities thinking about time outdoors as a public health strategy."

Morgan says a prevention strategy is needed because severe myopia increases the risk of retinal detachment, which can lead to blindness.

He says Singapore faces the serious public health threat of having as much as 10% of its population developing a serious retinal problem later in life.


Benefits of Sunlight
However surprising it may be, some doctors are now describing sunlight as beneficial rather than a cancer risk to be avoided at all costs. Though the dangers of sun exposure–like skin cancer and blindness–should still be taken into consideration, sunlight is still a part of a healthy lifestyle.

Sunlight can reduce the effects of SAD, or seasonal affective disorder—more commonly known as seasonal depression. Doctors have suggested taking walks daily for people who suffer from this disorder, even when the sky is overcast. This has shown to help improve seasonal depression even more than the use of sunlamps.



It appears, through years’ long studies of people who live in sunnier climates and people who are exposed to sunlight through their work situations, that sunlight can actually decrease risk of colon and breast cancer.

In another study, patients who were put in hospital rooms that were sunny requested less pain medication than patients in windowless rooms. Whether the pain is lessened by the sunlight or the patients’ awareness of their pain levels decreased during the study is unclear.

People who are suffering from jet lag can use the sunlight in the area of their destination to reset their internal clock. Exposure to daylight can hasten the body’s ability to get on a sleep schedule that matches the time zone they are in.

Sunlight provides the body with the means to produce Vitamin D. Vitamin D helps the body in various biological functions: It promotes calcium absorption, which in turn deters bone loss; it may help maintain a healthy immune system; it could possibly be a part of the process of cell differentiation.

Of course, it is always smart to practice moderation in everything. However, the connection between good health and sunlight can not be ignored.

New fossil haul could offer clues to when humans first set foot on Cyprus

Scientists study extinct dwarf hippo graveyard


An abattoir used by early Cypriots, a cemetery where animals went to die, or simple a shelter that ultimately proved a death trap?

Cypriot and Greek scientists are trying to unravel the riddle of a collapsed cave brimming with the fossilized remains of extinct dwarf hippopotamuses that were descendants of a group believed to have migrated here as far back as a quarter million years ago.

Paleontologists have unearthed an estimated 80 dwarf hippopotamuses in recent digs at the site located just outside the resort of Ayia Napa on the island's southeastern coast.

But possibly hundreds more may be lying beneath an exposed layer of jumbled fossils embedded in the crevices of an ancient coral reef formation that now overlooks the coastline.

Scientists hope the new fossil haul dated to 9,000-11,500 B.C. could offer vital clues to solving the long-standing quandary over when humans first set foot on this east Mediterranean island.

"It's about our origins," said Ioannis Panayides, the Cyprus Geological Survey Department official in charge of excavations carried out in conjunction with the University of Athens. "Knowledge of our geological history makes us more knowledgeable about ourselves."

Until the Ayia Napa discovery, the earliest trace of humans on the island dated back to 8,000 B.C. But signs of human activity like stone tools and the remains of fires at the cave could turn back the clock on the first Cypriots by as much as 2,500 years.

"That's very significant, but we can't be certain yet. The task of examining is laborious and time consuming," said University of Athens Professor George Theodorou tasked with examining some 1.5 tons of fossils.

The dwarf hippopotamuses were herbivores just like their modern-day cousins but only a fraction of their size, measuring roughly 0.70 meters (2.3 feet) tall and 1.2 meters (3.9 feet) long.

Their physical traits also differed. Unlike modern hippos whose upturned nostrils that sit high up on the snout are appropriate for swimming, Cypriot hippos had lower-slung nostrils better suited to foraging on land.

According to Panayides, the fossils show the Cypriot hippos had legs and feet adapted to land rather than water, enabling them to stand on their hind legs to reach low-lying tree branches.

Panayides explained that was the result of a "remarkably swift" evolutionary adaptation to their new environment — a characteristic shared by dwarf hippos unearthed in other Mediterranean, islands including Sicily and Crete.

Hippos arrived in Cyprus in more familiar dimensions between 100,000 to 250,000 ago, but they likely shrank to adapt to a more hilly island landscape. A reliance on footpower to secure their next meal prompted the massive girth reduction.

Scientists are also perplexed as to just how hippos arrived on an island that has never been physically linked to another land mass.

Panayides said paleontologists theorize the hippos may have either swum or floated here from what is now Turkey to the north and Syria to the east during a Pleistocene ice age. They may have clung onto tree trunks and other debris during the crossing.

Lower sea levels at the time mean the island was much larger than its present-day 9,250 square kilometers (about 3570 square miles), so it was significantly closer to neighboring land masses. By some estimates, what is now Syria was a mere 30 kilometers (18 miles) away — less than a third of its present-day distance.

Digs over the last century uncovered dwarf hippo fossils — and in much lesser quantities the fossilized remains of dwarf elephants — at 40 separate locations across the island.

One such cave discovered in Akrotiri west of the southern coastal resort of Limassol some 20 years ago produced evidence of fire, stone tools and scorched bones indicating the dwarf hippos were hunted by what are believed to be the earliest humans to inhabit the island.

Carbon dating on hippo fossils found there showed the site dates back to 8,000 B.C. Evidence of human activity at Ayia Napa means the island may have been settled by sea-faring humans as much as 2,500 years before the current scientific consensus.

human footprint at the Ayia Napa site could bolster the theory that the island's earliest inhabitants could have driven the dwarf hippos to extinction through hunting, said Panayides.

Panayides said indications that hippo bones at the Ayia Napa cave had been crushed as if trampled on by other hippos compounds the mystery as to why successive generations kept coming back to the cave.

Shelter is the most likely explanation, but Panayides didn't rule out the possibility the hippos returned to an ancient burial ground to die.

Panayides said it is hoped that DNA could be extracted to determine the hippos' exact origins.