Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/">NASA Earth Observatory</a> features the island of Hainan, China’s southernmost province, in the South China Sea.



According to NASA, the photograph focuses on the landscape around Gangmen Harbor and captures many typical characteristics of Hainan: forested mountain terrain juxtaposed with dense populations.&nbsp;



With tropical beaches along its shoreline, the island spans approximately 1,300 square miles. Floating fishing villages can be found in the shallow waters of the inner bays.



China is a leading country when it comes to wild catch, and also produces about 60 percent of the world’s farmed fish such as carp and tilapia. Aquaculture sites are often paired with fishing ports for sufficient transport.



The photograph was captured by an astronaut onboard the International Space Station (ISS),&nbsp;



Image Credit: NASA Earth Observatory



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

The island of Hainan in the South China Sea

Today's Image of the Day from NASA Earth Observatory features the island of Hainan, China’s southernmost province, in the South China Sea. According to NASA, the photograph focuses on the landscape around Gangmen Harbor and captures many typical characteristics of Hainan: forested mountain terrain juxtaposed with dense populations.&nbsp; With tropical beaches along its shoreline, the island spans approximately 1,300 square miles. Floating fishing villages can be found in the shallow waters of the inner bays. China is a leading country when it comes...

Because David was frightened of the bear's erratic behavior, he humanely put down the creature. He brought the bear, who still mystified him, to a local government officer who was just as puzzled. Photo Credit: brytta / Getty Images

Erratic Behavior

Because David was frightened of the bear's erratic behavior, he...

This animal is a cross between a domestic cow and a yak. They originated in Mongolia and Tibet. They tend to be stronger and larger than cows and yaks, and they also produce larger quantities of milk and meat. Photo Credit: Petr Meissner / Flickr

This animal is a cross between a domestic cow and...

This equestrian beauty is what you get when you mix a zebra and a horse. They were first bred in the nineteenth century by Charles Darwin, but nowadays, they're extremely rare because they're either sterile or infertile. Photo Credit: Wiki Commons

Zorse

This equestrian beauty is what you get when you mix...

Anyone who's seen the film Napoleon Dynamite knows this was Napoleon's favorite animal, but it's also one of the world's most popular hybrids, too. A male lion and female tiger make up this unique beauty. Photo Credit: Maxitup16 / Wiki Commons

Liger

Anyone who's seen the film Napoleon Dynamite knows this was Napoleon's favorite...

This unique breed of cat is often compared to dogs in terms of its loyalty and intelligence, and they can even be trained like dogs as well. The breed mainly exists in the wild, and it's a mix of a domestic house cat and African wild cat. Photo Credit: Michele Keeler / Instagram

Savannah Cat

This unique breed of cat is often compared to dogs...

If you mix together a male camel and female llama, you have yourself a cama. They basically look like smaller, fluffier camels. Scientists artificially reproduced them to create an animal that generated a larger amount of wool than a llama. Photo Credit: Maher Attar / Contributor / Getty Images

Cama

If you mix together a male camel and female llama,...

The gorgeous and almost majestic coat on this animal is the result of a lioness mating with a male leopard. The very first leopon was produced in India in 1910, and by 2018, there were only 100 of them in the world. Photo Credit: TRJN / Wiki Commons

Leopon

The gorgeous and almost majestic coat on this animal is...

These mixtures of male horses and female donkeys are slightly smaller than horses, and they have thicker fur coats. They also cannot reproduce on their own, making them very difficult to obtain. Photo Credit: Wikimedia

Hinny

These mixtures of male horses and female donkeys are slightly...

You can probably guess what two animals make up this species! They were first bred together for people who wanted to own exotic-looking animals. Because they're genetic mixtures of both dogs and wolves, it's difficult to predict physical and behavioral characteristics. Photo Credit: In Search of Britain / YouTube

Wolfdog

You can probably guess what two animals make up this...

Although chimpanzees (Pan troglodytes) are most commonly associated with forested habitats in Africa, there are several countries in both West and East Africa where chimpanzee populations inhabit savannas. This implies that the <a href="https://www.earth.com/news/illegal-cannabis-farms-infringe-on-crucial-animal-habitats/">habitats</a> are more open, with higher temperatures and lower annual rainfall, which has required different adaptive strategies from the chimpanzees living there. 



Savanna chimpanzees are taxonomically identical to forest-dwelling chimpanzees, and thus comparisons of the behavior, morphology and ecology of the two groups help researchers to understand how early humans may have adapted, millions of years ago, when African forests began to recede and be replaced by open savannas.&nbsp;



Certain behaviors and physiological responses in savanna chimpanzees, such as resting in caves or digging to access water, are considered specific adaptations to life in savanna habitats and are not observed in their forest-dwelling counterparts.&nbsp;



Adriana Hernández, Serra Hunter professor at the Faculty of Psychology of the University of Barcelona, co-led a recent study conducted by an international team of primatologists that reviewed the existing research on the behavior and ecology of savanna chimpanzees to understand how these apes adapt to extreme conditions.



“The study on savanna chimpanzees and what we call the&nbsp;landscape savanna effect&nbsp;have important implications for reconstructing the behavior of the first hominins who lived in similar habitats and therefore, it helps us to better understand our own evolution,” said Professor Hernández, who co-led the study with Stacy Lindshield from the University of Purdue.



"We know that early hominins adapted to savanna environments similar to those occupied by chimpanzees today, and researchers think that savanna conditions caused adaptations in our ancestors, such as brain expansion or tolerance to high temperatures."



“Therefore, understanding how our genetically closest living relatives adapt to a dry, hot, seasonal and open environment, very similar to those where early hominins lived, helps us to model how our ancestors might have adapted and how the features that define us as humans might have emerged.”



Chimpanzees share 98.7 percent of their DNA with humans and have a common ancestor that lived between 4.5 and 6 million years ago. This makes them the closest living relatives of modern humans. However, they lack some of the physiological and cultural traits that help humans adapt to extreme heat, such as numerous sweat glands, relative lack of hair and the ability to fashion water containers in which to carry or store water.&nbsp;



The researchers found that savanna chimpanzees have developed specific strategies to help them cope with high temperatures.&nbsp;



“Understanding how they deal with heat can help us better understand what strategies human ancestors may have used to cope with high temperatures. Some strategies are probably the same for chimpanzees and hominins, such as the use of caves or going into water pools to cool down,” noted Professor Hernández. They also try to hydrate themselves during the advanced dry season by digging for water in certain places. “Early hominins also had to deal with low water availability during part of the year."



The study also found that chimpanzee social groups in the savanna have unusually large home ranges of around 100 km², whereas chimpanzees living in more forested areas have ranges between 3 and 30 km². "However, although group sizes are similar in different habitats, chimpanzees in the savanna have a much lower population density, which could be explained by the low availability of food in this habitat."



It is thought that there are fewer chimpanzees living in savanna habitats than in forests, although the exact numbers are not known. In general, knowledge about savanna chimpanzees is incomplete and much more research is needed.&nbsp;



"It should be noted that there are far fewer sites where savanna chimpanzees have been studied, as there are only two study sites where savanna chimpanzees are habituated to humans and their behavior can be observed directly. In contrast, there are many study sites where chimpanzees are fully habituated to researchers in the forest, a habitat where these primates have been studied for decades," explained Professor Hernández.



This study also makes a contribution to understanding the potential effects of climate change on forest chimpanzees, in particular. "The adaptation of savanna chimpanzees to extreme climates can help us model how chimpanzees that currently inhabit forests might adapt to changes that climate studies project will make their environments drier and warmer," said the researchers.



"This is important, since the species is categorized as Endangered and the West African subspecies (Pan troglodytes verus) is Critically Endangered."



The study is published in the journal&nbsp;<a href="https://onlinelibrary.wiley.com/journal/15206505">Evolutionary Anthropology</a>.



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Chimpanzees give us clues about early human evolution

Although chimpanzees (Pan troglodytes) are most commonly associated with forested...

In evolution, it’s usually thought that organisms avoid competition through resource partitioning, which allows a greater diversity of organisms than otherwise possible. For instance, if two birds live in the same <a href="https://www.earth.com/news/old-oak-trees-ramp-up-photosynthesis-in-response-to-rising-co2/">tree</a> and eat the same types of insects, one bird may specialize in the top of the tree while the other specializes in the bottom of the tree. This works with plants as well as animals and other organisms.&nbsp;



In a new report from <a href="http://www.okayama-u.ac.jp/index_e.html">Okayama University</a>,&nbsp; researchers suggest that resource partitioning is not always necessary for plants to coexist. A theory called the “pre-emptive selfing hypothesis” proposes that if plants can evolve self pollination, they may be able to coexist without resource partitioning. To validate their theory, the Japanese scientists used mathematical modeling and computer simulations.&nbsp;



The model simulated individual-based scenarios to look at the conditions where evolution favored selfing, or self pollination, in the face of competition with other plants.&nbsp;



"In a previous study, we found that two species of Asian dayflower, Commelina communis and C. communis f. ciliata, have flowers that look similar, share the same pollinators, and compete through pollinator-mediated reproductive interference. However, this observation had no explanation in the existing theory," said lead researcher Dr. Koki R. Katsuhara.



"Then I hit upon the pre-emptive selfing hypothesis that offered a plausible explanation for their existence and figured that this idea might apply to plant species other than Commelina."



The study shows that the evolutionary mechanism of coexistence between similar species of flowering plants is more complex than previously understood. It also shows that coexistence of two plants even within the same ecological niche is possible.&nbsp;



"This work will lead to an improved understanding of plant species coexistence, which, in turn, could help us manage plant diversity in a sustainable way, as well as rescue native species threatened by an invasive alien species," said Dr. Katsuhara.



The study is published in the <a href="https://www.britishecologicalsociety.org/publications/journals/journal-of-ecology/">Journal of Ecology</a>.



---By <a href="mailto:zachfitzner@yahoo.com">Zach Fitzner</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

When faced with competition, some plants learn to self-pollinate

In evolution, it’s usually thought that organisms avoid competition through...

There has been much debate and hypothesizing about the origins of <a href="https://www.earth.com/news/domestication-shrunk-rabbits-brains/">domestication</a> in horses (Equus caballus). Where were they first domesticated, and by whom? How did they spread around the globe and what were their ancestors like? Many previous studies have attempted to answer these questions but no final resolution has been forthcoming, and the early domestication of the horse has remained exceedingly difficult to trace in the archeological record.&nbsp;



In a new study led by Professor Ludovic Orlando of <a href="https://www.cnrs.fr/">CNRS</a>, a team of 162 international scientists has had a breakthrough. The experts, who specialize in archeology, paleogenetics and linguistics used the modern technologies of genetic analysis.&nbsp;



In recent years, a scientific consensus had emerged linking the Botai culture of northern Kazakhstan with the first domestication of horses, based on the presence of 5,500-year-old skeletal remains with damage to the dentition that is commonly linked to the use of bridle mouthpieces. However, when Ludovic Orlando's team looked at the DNA from the archeological remains, they found that the animals were Przewalsky’s horses (Equus przewalski), a totally different species from modern domesticated horses.&nbsp;



In all other locations hypothesized to be potential foci for domestication, for example Anatolia, Siberia and the Iberian Peninsula, the evidence turned out to be false. “We knew that the time period between 4,000 to 6,000 years ago was critical but no smoking guns could ever be found,” said Professor Orlando.&nbsp;



The scientific team thus decided to extend their study and analyze the genomes of 273 horses that lived between 50,000 and 200 years BC, at sites throughout Eurasia. This information was sequenced at the Centre for Anthropobiology and Genomics of Toulouse (CNRS/Université Toulouse III – Paul Sabatier) and Genoscope&nbsp;(CNRS/CEA/Université d’Évry) before being compared with the genomes of modern domestic horses.



The results indicated that, although Eurasia was once populated by genetically distinct horse populations, a dramatic change occurred between 2000 and 2200 BC. “That was a chance: the horses living in Anatolia, Europe, Central Asia and Siberia used to be genetically quite distinct,” explained study first author Dr. Pablo Librado. 



Then, a single genetic profile, previously found only on the Pontic steppes (North Caucasus), began to spread beyond its native region, replacing all the wild horse populations from the Atlantic to Mongolia. From this the authors conclude that horses were first domesticated in the Pontic-Caspian steppes,&nbsp;northern Caucasus, before spreading out through the rest of Eurasia within a few centuries.&nbsp;



“The genetic data also point to an explosive demography at the time, with no equivalent in the last 100,000 years,” said Professor Orlando. “This is when we took control over the reproduction of the animal and produced them in astronomic numbers.”



Two striking differences were found in the genome of this horse that spread so rapidly throughout Eurasia: the new horses had more docile behavior and stronger backbones than the breeds they replaced. The researchers suggest that these characteristics ensured the animals’ success at a time when horse travel was becoming more commonplace and widespread.



Indeed, the research also showed that the genetically different horse spread throughout Asia at the same time as spoke-wheeled chariots and Indo-Iranian languages. However, the migrations of Indo-European populations, from the steppes to Europe during the third millennium BC&nbsp;could not have been based on the horse, as its domestication and diffusion came later. This demonstrates the importance of incorporating the history of animals when studying human migrations and encounters between cultures, state the authors.



The study is published in the journal <a href="https://www.nature.com/">Nature</a>.



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

The origin of horse domestication has finally been revealed

There has been much debate and hypothesizing about the origins...

Until recently, it was thought that Christopher Columbus was the first European to reach the Americas in 1492. However, a new study led by the <a href="https://www.rug.nl/?lang=en">University of Groningen</a> has found that the <a href="https://www.earth.com/news/the-vikings-had-the-worlds-deadliest-virus-1400-years-ago/">Vikings</a> got there centuries beforehand, and were already active in Newfoundland, Canada, in 1021 AD.&nbsp;



The Vikings sailed great distances in their longships, and established settlements in Iceland, Greenland, and L’Anse aux Meadows in Newfoundland, Canada. Yet, the precise number of Viking expeditions to the Americas, and the duration of their stays over the Atlantic remain unknown.&nbsp;



Previous dates for the Viking presence in the Americas have relied heavily on the Icelandic Sagas that began as oral histories and were written down centuries after the events they describe. Although these Sagas often describe both violent and amiable encounters between the Vikings and indigenous American populations, little archaeological evidence has been uncovered to support such exchanges.



In this new study, published in the journal <a href="https://dx.doi.org/10.1038/s41586-021-03972-8">Nature</a>, the chopping of wood by Vikings at L'Anse aux Meadows was dated to the year 1021 AD. The scientists studied three pieces of wood from three different trees that displayed clear evidence of cutting and slicing by metal blades coming from contexts attributable to the Vikings. The precise dating of these operations was possible because a massive solar storm occurred in 992 AD which produced a distinct radiocarbon signal in tree rings from the following year.



"The distinct uplift in radiocarbon production that occurred between 992 and 993 AD has been detected in tree-ring archives from all over the world" explained study senior author Michael Dee, an associate professor in the <a href="https://www.rug.nl/research/esrig/?lang=en">Energy and Sustainability Research Institute</a> at the University of Groningen. "Finding the signal from the solar storm 29 growth rings in from the bark allowed us to conclude that the cutting activity took place in the year 1021 AD," added&nbsp;study lead author&nbsp;Margot Kuitems, a postdoctoral researcher in the same institute.



This date also marks the earliest known time at which the Atlantic had been crossed, and human migration had finally encircled the entire planet.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

The Vikings reached America long before Columbus

Until recently, it was thought that Christopher Columbus was the...

According to a new study led by the <a href="https://medicine.wustl.edu/">Washington University School of Medicine</a> in St. Louis, like many other things in life, <a href="https://www.earth.com/news/poor-sleep-quality-is-associated-with-mental-illness/">sleep</a> is best in moderation. Through a longitudinal study of older adults, scientists have discovered that both short and long sleepers experience greater cognitive decline than people who sleep moderately.



Both poor sleep and Alzheimer’s disease are associated with cognitive decline. Thus, separating the effects of each has proven challenging. By tracking the cognitive functioning of a group of 100 older adults over 4.5 years and analyzing it against levels of proteins related to Alzheimer’s disease and measures of brain activity during sleep, the scientists have shed new light on the complex relationship among sleep, Alzheimer’s disease, and cognitive functioning.



“It’s been challenging to determine how sleep and different stages of Alzheimer’s disease are related, but that’s what you need to know to start designing interventions,” said study lead author&nbsp;Brendan Lucey, an associate professor of Neurology and director of the Washington University&nbsp;<a href="https://u7061146.ct.sendgrid.net/ls/click?upn=4tNED-2FM8iDZJQyQ53jATUUOrhW-2FAaQ3u4vk6vdUg1mvTrnTAtBrEOmwAeYJBqRi6y3qh_qUUMznMkXGT9vocK663RhihR1E3P7Zhw8trthuwelyTfR-2BnsLMSwOQIMF0GjbacMCc3OzgSGJNEF-2B2N6cD3eKEvG2HlsfjpnB1jpUBbe5O9IlB7tEy56cOGuT7q19fXHNsbMCsrKAnW7J6nRb05tLvZC1X2ytS4TQ3xmyJue3XmP0s4HzBllG-2FqaWXesoRM6RrO1MD3zQxgVImnnArPYAwIzZvy9uY2ikay6upHyAtl5B7R-2F7RPsI6xaZ4oIovH3NO5pgoKIeQYgduhqHTfI-2FecROPms0BXQs-2BQZm7mxUsE2p3cp2UYbmouhwpeG-2FRONxuQMbWrfWGStUkrHtzXj4ULF1cgUR52VM9Fcl-2BOBagQ-3D">Sleep Medicine Center</a>.&nbsp;



The researchers found that cognitive scores declined for the persons who slept either less than 4.5 hours or more than 6.5 hours per night, while scores remained stable for those in the middle of the range. While previous studies argued that short amounts of sleep lead to mental health issues, these new findings show that too much sleep can also be harmful. This suggests that sleep quality could be more important than quantity. Moreover, sleep problems appears to accelerate the brain damage caused by Alzheimer’s.



“Our study suggests that there is a middle range, or ‘sweet spot,’ for total sleep time where cognitive performance was stable over time. Short and long sleep times were associated with worse cognitive performance, perhaps due to insufficient sleep or poor sleep quality,” explained Professor Lucey.



“An unanswered question is if we can intervene to improve sleep, such as increasing sleep time for short sleepers by an hour or so, would that have a positive effect on their cognitive performance so they no longer decline? We need more longitudinal data to answer this question.”



However, according to Lucey, each person’s sleep needs are unique and people who wake up rested on either short or long sleeping schedules should not feel compelled to change their habits.



The study is published in the journal <a href="https://academic.oup.com/brain">Brain</a>.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Moderate sleep reduces the risk of cognitive decline

According to a new study led by the Washington University...

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Today's Video of the Day from the <a href="https://www.esa.int/">European Space Agency</a> features the North Frisian Islands, also known as the Wadden Islands, located just off the coast of northern Europe.



The Frisian Islands stretch from the northwest of the Netherlands through Germany to the west of Denmark. The archipelago is divided into three regions - the East, West, and North Frisian Islands.



The low-lying islands form a unique zone between the mainland and the North Sea known as the Wadden Sea that is the largest unbroken system of intertidal sand and mud flats in the world.



The Wadden Sea is a UNESCO world heritage site, and is considered one of the most important areas for migratory birds in the world. The biodiverse region is also home to thousands of other plant and animal species.&nbsp;



The North Frisian Islands include Sylt, Föhr, Amrum, and Pellworm. The largest of the islands is Sylt in Northern Germany, which is well known for the distinctive shape of its shoreline. The island extends more than 35 kilometers in length - yet in some places, is only one kilometer wide.&nbsp;



The image was captured on June 1, 2020 by the Copernicus Sentinel-2 mission.



Video Credit: ESA&nbsp;



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

The North Frisian Islands

[sendtonews key="tKnkYx7vrT-1569028-12187" type="single"] Today's Video of the Day from the...

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A quadrillion tons of diamonds are beneath Earth's surface Today's Video of the Day from the <a href="https://www.acs.org/">American Chemical Society</a> describes how seismic waves were used to locate trillions of tons of diamonds deep below Earth's surface.



Scientists at MIT estimate that a quadrillion tons of diamonds are located about 100 miles deep in the Earth. This figure, which is one thousand times more than one trillion, is mind boggling.



Seismic waves move through various materials at different speeds, depending on how rigid the material is.&nbsp;



Using sound waves to make measurements, the MIT team discovered that seismic waves were moving much faster at about 90 to 150 miles below the Earth's surface.



The experts matched the speed of the sound waves to the density of diamonds. Compared to other rocks, sound travels through diamonds twice as fast. Scientists discover tons of diamond' beneath Earth's surface By analysing seismic activity - the way that sound waves travel through the planet - scientists may have found the mother lode. 



Video Credit: ACS&nbsp;



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

A quadrillion tons of diamonds are beneath Earth's surface

[sendtonews key="LEzIWXppFc-1567614-12187" type="single"] A quadrillion tons of diamonds are beneath...

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Maharloo Lake in southwest Iran Today's Video of the Day from the <a href="https://www.esa.int/">European Space Agency</a> features a satellite view of Maharloo Lake, a seasonal salt lake in southwest Iran.



According to ESA, yearly evaporation in this desert region southeast of Shiraz is much greater than the yearly rainfall, meaning that Maharloo Lake is often very dry.



Such a high evaporation rate has gradually left the lake bed covered by salt. The increased salinity promotes a variety of organisms that display colors ranging from pink to orange to red, with the strength of the color differing in various periods of the year, explains ESA.



The image was captured by the Copernicus Sentinel-2 mission.



Video Credit: ESA&nbsp;



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Maharloo Lake in southwest Iran

[sendtonews key="MCH0PpygXb-1565707-12187" type="single"] Maharloo Lake in southwest Iran Today's Video...