Earth used to be purple, new NASA study shows
NASA research finds a new direction in searching for signs of life in the Universe.
- NASA-funded research says retinal, not chlorophyll, gave the early Earth its color
- The two pigments co-evolved but retinal came first
- We should be looking for retinal-based life throughout the Universe
Earth used to be a color the late musician Prince would approve of - a shade of purple. Such is the intriguing possibility raised by new NASA-supported research which says a purple-tinged molecule called "retinal" likely gave the early Earth a distinct look. The idea also gives us a potential new direction in the search for planets similar to ours.
If you walk outside, chances are, you'll see a lot of green - sorry, desert-dwelling readers. This green found in nature is the result of photosynthesis - the process by which plants convert energy coming from the sun into useful chemical energy they need to live while producing oxygen for the rest of us. A key part of this process is the pigment chlorophyll which gives plants their green color. It absorbs energy from sunlight and uses it to convert carbon dioxide and water into sugars.
Now a new study argues that retinal likely preceded chlorophyll as the dominant sunlight-absorbing molecule. The scientists focused their attention on retinal-containing proteins, especially ones like bacteriorhodopsin that absorb sunlight in the range inaccessible to chlorophyll. The biologists propose that retinal and chlorophyll co-evolved together, but that retinal likely came first because it's simpler molecule.
Since retinal pigments absorb green and yellow light while transmitting red and blue, life that's based on retinal would look purple. Hence, it's possible that there was a stage of our planet's history that the researchers dubbed "Purple Earth". That time would date somewhere between 2.4 to 3.5 billion years ago, prior to the Great Oxygenation Event, which was likely due to the rise chlorophyll-based photosynthesis.
The study comes from Shiladitya DasSarma, Professor of molecular biology at the University of Maryland, and Dr. Edward Schwieterman, an astrobiologist at the University of California, Riverside.
"Retinal-based phototrophic metabolisms are still prevalent throughout the world, especially in the oceans, and represent one of the most important bioenergetic processes on Earth," said DasSarma to Astrobiology Magazine.
Purple microorganisms and purple membrane. (a) Australian salt pond with a bloom of purple microorganisms (Courtesy Cheetham Salt Co.). (b) Sucrose gradient separating Halobacterium sp. cell lysate, including both red (upper) and purple (lower) pigments (Credit: Victoria Laye and Priya DasSarma).
Another interesting aspect of the paper is that if Earth had a retinal stage and since retinal is a simpler molecule than chlorophyll, then it stands to reason that we should take this into account when looking for new inhabitable (or already inhabited) planets. In fact, it's entirely possible that retinal-based life could be more widespread throughout the Universe.
From the counter-intuitive standpoint of color wavelengths viewed through a spectroscope, we should be looking for a "green edge" in a planet's spectrum to spot retinal biosignatures, say the researchers.
Check out the new paper "Early evolution of purple retinal pigments on Earth and implications for exoplanet biosignatures" in the International Journal of Astrobiology. It was supported by NASA Astrobiology.
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A new study shows that some men's reaction to sex is not what you'd expect, resulting in a condition previously observed in women.
Is this proof of a dramatic shift?
- Map details dramatic shift from CNN to Fox News over 10-year period
- Does it show the triumph of "fake news" — or, rather, its defeat?
- A closer look at the map's legend allows for more complex analyses
Dramatic and misleading
Image: Reddit / SICResearch
The situation today: CNN pushed back to the edges of the country.
Over the course of no more than a decade, America has radically switched favorites when it comes to cable news networks. As this sequence of maps showing TMAs (Television Market Areas) suggests, CNN is out, Fox News is in.
The maps are certainly dramatic, but also a bit misleading. They nevertheless provide some insight into the state of journalism and the public's attitudes toward the press in the US.
Let's zoom in:
- It's 2008, on the eve of the Obama Era. CNN (blue) dominates the cable news landscape across America. Fox News (red) is an upstart (°1996) with a few regional bastions in the South.
- By 2010, Fox News has broken out of its southern heartland, colonizing markets in the Midwest and the Northwest — and even northern Maine and southern Alaska.
- Two years later, Fox News has lost those two outliers, but has filled up in the middle: it now boasts two large, contiguous blocks in the southeast and northwest, almost touching.
- In 2014, Fox News seems past its prime. The northwestern block has shrunk, the southeastern one has fragmented.
- Energised by Trump's 2016 presidential campaign, Fox News is back with a vengeance. Not only have Maine and Alaska gone from entirely blue to entirely red, so has most of the rest of the U.S. Fox News has plugged the Nebraska Gap: it's no longer possible to walk from coast to coast across CNN territory.
- By 2018, the fortunes from a decade earlier have almost reversed. Fox News rules the roost. CNN clings on to the Pacific Coast, New Mexico, Minnesota and parts of the Northeast — plus a smattering of metropolitan areas in the South and Midwest.
Image source: Reddit / SICResearch
This sequence of maps, showing America turning from blue to red, elicited strong reactions on the Reddit forum where it was published last week. For some, the takeover by Fox News illustrates the demise of all that's good and fair about news journalism. Among the comments?
- "The end is near."
- "The idiocracy grows."
- "(It's) like a spreading disease."
- "One of the more frightening maps I've seen."
- "LOL that's what happens when you're fake news!"
- "CNN went down the toilet on quality."
- "A Minecraft YouTuber could beat CNN's numbers."
- "CNN has become more like a high-school production of a news show."
Not a few find fault with both channels, even if not always to the same degree:
- "That anybody considers either of those networks good news sources is troubling."
- "Both leave you understanding less rather than more."
- "This is what happens when you spout bullsh-- for two years straight. People find an alternative — even if it's just different bullsh--."
- "CNN is sh-- but it's nowhere close to the outright bullsh-- and baseless propaganda Fox News spews."
"Old people learning to Google"
Image: Google Trends
CNN vs. Fox News search terms (200!-2018)
But what do the maps actually show? Created by SICResearch, they do show a huge evolution, but not of both cable news networks' audience size (i.e. Nielsen ratings). The dramatic shift is one in Google search trends. In other words, it shows how often people type in "CNN" or "Fox News" when surfing the web. And that does not necessarily reflect the relative popularity of both networks. As some commenters suggest:
- "I can't remember the last time that I've searched for a news channel on Google. Is it really that difficult for people to type 'cnn.com'?"
- "More than anything else, these maps show smart phone proliferation (among older people) more than anything else."
- "This is a map of how old people and rural areas have learned to use Google in the last decade."
- "This is basically a map of people who don't understand how the internet works, and it's no surprise that it leans conservative."
A visual image as strong as this map sequence looks designed to elicit a vehement response — and its lack of context offers viewers little new information to challenge their preconceptions. Like the news itself, cartography pretends to be objective, but always has an agenda of its own, even if just by the selection of its topics.
The trick is not to despair of maps (or news) but to get a good sense of the parameters that are in play. And, as is often the case (with both maps and news), what's left out is at least as significant as what's actually shown.
One important point: while Fox News is the sole major purveyor of news and opinion with a conservative/right-wing slant, CNN has more competition in the center/left part of the spectrum, notably from MSNBC.
Another: the average age of cable news viewers — whether they watch CNN or Fox News — is in the mid-60s. As a result of a shift in generational habits, TV viewing is down across the board. Younger people are more comfortable with a "cafeteria" approach to their news menu, selecting alternative and online sources for their information.
It should also be noted, however, that Fox News, according to Harvard's Nieman Lab, dominates Facebook when it comes to engagement among news outlets.
CNN, Fox and MSNBC
Image: Google Trends
CNN vs. Fox (without the 'News'; may include searches for actual foxes). See MSNBC (in yellow) for comparison
For the record, here are the Nielsen ratings for average daily viewer total for the three main cable news networks, for 2018 (compared to 2017):
- Fox News: 1,425,000 (-5%)
- MSNBC: 994,000 (+12%)
- CNN: 706,000 (-9%)
And according to this recent overview, the top 50 of the most popular websites in the U.S. includes cnn.com in 28th place, and foxnews.com in... 27th place.The top 5, in descending order, consists of google.com, youtube.com, facebook.com, amazon.com and yahoo.com — the latter being the highest-placed website in the News and Media category.
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