Climate Change Is Making Nearly All Sea Turtles Born on These Beaches Female


Climate change can wipe out a species's food source and destroy its habitat, but rising temperatures are having a more surprising effect on green sea turtles that's no less devastating. According to a report in Current Biology [PDF], up to 99.8 percent of the green sea turtles born on certain beaches in Australia are female, a direct result of the area's warmer-than-average temps.

A turtle's sex is determined by its environment. As The Washington Post reports, a clutch of eggs that incubates in sand that's roughly 85°F will produce about 50 percent females and 50 percent males. A few degrees cooler and the batch skews male; a bit hotter and it's majority female.

This evolutionary mechanism tends to balance itself out, but on beaches in northeast Australia, it's being hijacked by climate change. In order to gauge the size of the impact, researchers with the National Oceanic and Atmospheric Administration sampled the nesting beaches along the coast of Australia adjacent to the Great Barrier Reef, the part that has seen the most dramatic temperature rises and coral bleaching. What they found on the warmer northern beaches was the worst-case scenario: 99.1 percent of juveniles, 99.8 percent of subadults, and 86.8 percent of the overall population was female. Data taken from the southern beaches are only slightly less alarming: Turtles hatched in the relatively cooler sands there were still 65 to 69 percent female. According to the study's authors, "the complete feminization of this population is possible in the near future." That would affect the species' future population growth.

Green sea turtles aren't the only species vulnerable to huge sex shifts by way of climate change. Many other reptiles also rely on temperature-dependent sex determination to keep populations balanced. But above-average temperatures can do more harm beyond messing with sex development: It can also kill embryos before they have the chance to hatch. The authors emphasize that figuring out how to regulate sand temperatures at key rookeries will be essential moving forward. If not, the species could face "a population collapse—or even extinction."

What Pop Culture Gets Wrong About Dissociative Identity Disorder

From the characters in Fight Club to Dr. Jekyll and Mr. Hyde, popular culture is filled with "split" personalities. These dramatic figures might be entertaining, but they're rarely (if ever) scientifically accurate, SciShow Psych's Hank Green explains in the channel's latest video. Most representations contribute to a collective misunderstanding of dissociative identity disorder, or DID, which was once known as multiple personality disorder.

Experts often disagree about DID's diagnostic criteria, what causes it, and in some cases, whether it exists at all. Many, however, agree that people with DID don't have multiple figures living inside their heads, all clamoring to take over their body at a moment's notice. Those with DID do have fragmented personalities, which can cause lapses of memory, psychological distress, and impaired daily function, among other side effects.

Learn more about DID (and what the media gets wrong about mental illness) by watching the video below.

Scientists Reveal Long-Hidden Text in Alexander Hamilton Letter

Age, deterioration, and water damage are just a few of the reasons historians can be short on information that was once readily available on paper. Sometimes, it’s simply a case of missing pages. Other times, researchers can see “lost” text right under their noses.

One example: a letter written by Alexander Hamilton to his future wife, Elizabeth Schuyler, on September 6, 1780. On the surface, it looked very much like a rant about a Revolutionary War skirmish in Camden, South Carolina. But Hamilton scholars were excited by the 14 lines of writing in the first paragraph that had been crossed out. If they could be read, they might reveal some new dimension to one of the better-known Founding Fathers.

Using the practice of multispectral imaging—sometimes called hyperspectral imaging—conservationists at the Library of Congress were recently able to shine a new light on what someone had attempted to scrub out. In multispectral imaging, different wavelengths of light are “bounced” off the paper to reveal (or hide) different ink pigments. By examining a document through these different wavelengths, investigators can tune in to faded or obscured handwriting and make it visible to the naked eye.

A hyperspectral image of Alexander Hamilton's handwriting
Hyperspectral imaging of Hamilton's handwriting, from being obscured (top) to isolated and revealed (bottom).
Library of Congress

The text revealed a more emotional and romantic side to Hamilton, who had used the lines to woo Elizabeth. Technicians uncovered most of what he had written, with words in brackets still obscured and inferred:

Do you know my sensations when I see the
sweet characters from your hand? Yes you do,
by comparing [them] with your [own]
for my Betsey [loves] me and is [acquainted]
with all the joys of fondness. [Would] you
[exchange] them my dear for any other worthy
blessings? Is there any thing you would put
in competition[,] with one glowing [kiss] of
[unreadable], anticipate the delights we [unreadable]
in the unrestrained intercourses of wedded love,
and bet your heart joins mine in [fervent]
[wishes] to heaven that [all obstacles] and [interruptions]
May [be] speedily [removed].

Hamilton and Elizabeth Schuyler married on December 14, 1780. So why did Hamilton try and hide such romantic words during or after their courtship? He probably didn’t. Historians believe that his son, John Church Hamilton, crossed them out before publishing the letter as a part of a book of his father’s correspondence. He may have considered the passage a little too sexy for mass consumption.

[h/t Library of Congress]


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