Beaver Knocks Down Tree, Thousands Lose Power

A beaver in Maine's northern Aroostook County was doing what beavers do on Monday night — and chewed down a tree to help build its dam.

The problem is the tree happened to fall on a power transmission line and soon nearly 3,000 residents were out of power, according to a spokesman for the power company, Emera Maine.

"(The downed tree) is in a very remote, wooded area which has been challenging to reach, but workers will remain working to restore power by mid-morning," Bob Potts, spokesperson for Emera, told the Bangor Daily News.

Beavers are known for their impressive construction skills — building dams on rivers and streams, and building their homes in the resulting pond. They use their powerful front teeth to cut down trees for their construction projects.

While beavers tend to enhance their surrounding habitats, making them swampy havens for other wildlife, occasionally their work clashes with human-made systems. The rodents have been known to block irrigation, cause flooding on roads and fields — and knock down power lines.

As often-cited W.T. Cox wrote in a 1940 article in American Forest, "Beavers do not belong in thickly-settled communities, since their flooding operations may become troublesome...In the wild forest country, they do little harm and an immense amount of good."

From Discovery News

Homeopathic Products Under FDA Scrutiny

The Food and Drug Administration is re-examining its position on whether it should regulate homeopathic products, which are often sold alongside (and may be confused with) proven medications with active ingredients in pharmacies across the country.

In 1988 the FDA decided not to require that homeopathic remedies go through the same drug-approval process as standard medicines. Hearings began Monday in Washington and should the FDA decide that homeopathic products fall under its purview, manufacturers would need to prove that their products are safe and effective.

Homeopathy has been extensively studied, and researchers have concluded that it does not work.

In 2010 the British Science and Technology Select Committee conducted an examination of whether homeopathy has any medical or scientific validity; its report concluded that “there is no evidence that homeopathy works beyond the placebo effect (where a patient gets better because of their belief in the treatment).”

Australia’s National Health and Medical Research Council also investigated the effectiveness of homeopathy in a report released last month. It, too, reached the same damning conclusion: “there are no health conditions for which there is reliable evidence that homeopathy is effective.”

According to an article in the “Washington Post” while homeopathy advocates defend their practice, some welcome the proposed FDA oversight. “Ronald Whitmont, a homeopathic doctor in New York and president of the American Institute of Homeopathy, said his organization supports the FDA’s actions to crack down on poor manufacturing practices. ‘There are always bad apples in the manufacturing world, and they need to be policed just like in any other industry,’ he said. ‘We are behind the FDA. Their concern is our concern.’”

Whitmont added that he hoped that the FDA would not end up questioning the legitimacy of homeopathy’s practices or principles. One homeopathic practitioner even claimed in 2012 that homeopathic products could be used to somehow treat and prevent domestic violence.

Earlier this month the Canadian government took similar steps toward regulating homeopathy in the province of Ontario. A new law, the Ontario Homeopathy Act, provides a mechanism for homeopaths to self-regulate in a similar manner to doctors and nurses. Critics of the law, however, expressed concern that the effect would be to legitimize “the health-care equivalent of dowsing rods.”

Among those who testified in favor of the FDA revising its position was Michael De Dora, Director of Public Policy for the Center for Inquiry, a non-profit educational organization dedicated to evidence-based public policy. “I think the FDA is finally revisiting the issue of regulating homeopathy because of several troubling and prominent cases related to homeopathy,” De Dora told Discovery News. “In 2010, there was a situation in which homeopathic products for teething children containing too much belladonna put several kids in the hospital.

More recently, homeopaths have been claiming to own cures for everything from asthma to more pressing public health issues, such as Ebola which has prompted to FDA to write letters and issue consumer warnings.

Still, perhaps the greatest harm caused by homeopathy is not necessarily caused by the products themselves—which, when properly prepared, rarely contain anything other than water and inactive ingredients such as sugars and binding agents—but by the fact that people often rely on homeopathic products to the exclusion of proven scientific remedies.”

Following his testimony De Dora said he was “encouraged by the critical questions the FDA panel posed. The FDA would have never held this hearing if they didn’t have some inclination to regulate homeopathy.

Read more at Discovery News

Were Neanderthals Doomed by Lack of Fire Mastery?

Neanderthals may have died off because they failed to harness the power of fire to the extent their human cousins did, a new data analysis suggests.

Using fire for cooking would have allowed these other groups of ancient human relatives to get more calories from the same amount of food, thereby edging out the Neanderthal population. Over time, the anatomically modern human population would have risen, while the Neanderthal population plummeted toward extinction, according to the model.

"Fire use would have provided a significant advantage for the human population and may indeed have been an important factor in the overall collapse or absorption of the Neanderthal population," said Anna Goldfield, a doctoral candidate in archaeology at Boston University, who presented the findings here on Thursday (April 16) at the 80th Annual Meeting of the Society for American Archaeology.

Mysterious disappearance

One of the enduring mysteries of human history is why the Neanderthals went extinct in most of Europe around 40,000 years ago. Neanderthals had been living on the continent for hundreds of thousands of years when the first modern humans showed up about 45,000 years ago, Goldfield said. Then, in a relatively short span of time, the Neanderthals vanished.

"The arrival of humans had something to do with the extinction of Neanderthals," Goldfield told Live Science.

But the exact cause has been a matter of hot debate. Some have postulated that Neanderthals found it increasingly difficult to access resources they needed given their small group sizes and relatively local trading networks. Other scientists have even proposed that humans cannibalized their Neanderthal rivals.

"The issue of Neanderthal extinction is very complex, and very little is agreed upon," Goldfield said.

Goldfield and her colleague Ross Booton, a mathematical biologist at the University of Sheffield in the United Kingdom, wondered whether fire use had something to do with the demise, they said.

One big difference between the Neanderthals and humans may have been modern humans' mastery of fire. Not only can it provide warmth, but fire also enables people to cook their food. This can kill bacteria, making food safer, and denature proteins, meaning the body can harness more calories from the same amount of food. In addition, Neanderthals may have required more calories to survive in the first place because they had higher average body mass. Thus, modern humans' lower food needs could have given them a decisive edge in the cold, nutritionally sparse environment of Western Europe at the time, Goldfield said.

While some fossil sites suggest Neanderthals used fire, they may not have used it often or consistently. For instance, Neanderthals occupied two sites in southwest France — Roc de Marsal, and Pech de l'Aze IV — for tens of thousands of years. The sites contain tens of thousands of stone tools and animal bones, but almost no evidence of fire making, said Dennis Sandgathe, an archaeologist at Simon Fraser University who has excavated the sites.

"The Neanderthals are somehow just getting by without fire," Sandgathe told Live Science.

Competing resources

To understand the effects of fire use on Neanderthals, the researchers used mathematical models. The simulations helped estimate how the populations of anatomically modern humans and Neanderthals changed when humans were using fire more frequently than Neanderthals, or when both groups used fire about equally. The researchers also looked at the population of reindeer, which both groups ate, under those scenarios.

The numbers showed that the more that modern humans used fire relative to their Neanderthal cousins, the more likely the human population was to increase slightly. That, in turn, would have reduced the number of reindeer available for the Neanderthals to eat. Over time, the human population would have simply outcompeted the Neanderthals for resources, leading to this population's eventual demise.

Read more at Discovery News

Venus and Moon to Snuggle Up as Dazzling Duo Tonight

This evening will be another one of those special occasions when the two brightest objects in the night sky — the moon and a Venus — will get together and, weather permitting, will attract a lot of attention, even to those who normally do not spend much time in gazing up at the sky.

If your local weather is clear tonight (April 21), you're in for a celestial treat. Turn to face west about 45 minutes after sunset, during mid-twilight, and you should see a beautiful crescent moon and floating well off to its right is the dazzling evening star: the planet Venus.

And as the night gets darker, you might take note of another object, much dimmer than Venus, located to the lower right of the moon at roughly half the distance separating the moon and Venus. Shining with a distinct orange color, it's the 1st-magnitude star Aldebaran in the constellation of Taurus, the Bull.

Venus is the one object has been calling attention to itself as soon as the sun has slipped below the horizon. It currently dazzles in the western sky, about one-third of the way up from the horizon to the overhead point. Predictably, I've gotten quite a few inquiries about it in recent days. Typically they've gone something like this:

"I was out walking last week and was sure I saw a U.F.O.  Was there anything unusual going on in the sky last week?  Is there anything that could explain this 'sighting'?"

Venus is Staying Up Late

Some folks are rather surprised when I tell them that Venus has been an evening object since mid-December. In at least two instances, I've had conversations with people who staunchly claimed that "Venus wasn't there just a week ago!" and that this is the first time that they've caught sight of it.

Of course, earlier in the year, Venus was considerably lower in the west-southwest sky, and setting much earlier in the evening (before 7 p.m. your local time). But now that we are more than a month into spring, with many states (save for Arizona and Hawaii) observing Daylight Saving Time, the viewing circumstances for Venus have changed for the better. Venus is now setting at around 11:15 p.m. local time for most observers.

But the best is yet to come!

On May 10, Venus will attain its highest declination: 26 degrees north of the celestial equator. Less than a month later, on June 6, it reaches its greatest eastern elongation (greatest angular distance east) of the sun of 45 degrees.

Roughly midway between these two extremes, for about two weeks beginning on May 17, Venus will be at the pinnacle of its current evening apparition. It will then be setting more than three and a half hours after local sunset. For New York City, for example, that corresponds to 11:44 p.m. EDT.

Read more at Discovery News

Sex at Nearly 10,000 Feet Below Ocean's Surface

Sex at close to 10,000 feet below the ocean’s surface happens slowly but frequently for at least some denizens of the deep.

Since these creatures — vampire squid — mate at a different pace than other squid and their related species do, a new study reveals how unique reproductive strategies can be at tremendous ocean depths.

The new study is published in the latest issue of the journal Current Biology.

“We know very little about deep-sea organisms and their life-cycle patterns, in particular in the water column of the deep sea,” lead author Henk-Jan Hoving of the GEOMAR Helmholtz Center for Ocean Research Kiel said in a press release. “The patterns we know from coastal and shallow-water organisms may not apply to deep-sea species.”

Vampire squid got their name, not because they feast on blood, but because of their big red eyes and darkly colored cloak-like webbing.

Hoving and his team were going through the vampire squid collections from the 60s and 70s at the Santa Barbara Museum of Natural History, when they noticed something unexpected.

Many of the female vampire squid had spawned, but they had no ripe or developing eggs and were in a reproductive resting phase. This is unheard of for other squid, which reproduce all at once late in their lives and that’s it.

Here is video showing how another squid species, Pholidoteuthis adami from the Gulf of Mexico, mates:

The researchers also investigated female vampire squid. One had released at least 3,800 eggs, yet still retained 6,500 viable oocytes (immature reproductive cells) for future spawning. Assuming an average batch size of 100 eggs, the researchers suggest that this one female had already spawned about 38 times, with eggs in reserve for another 65 or so spawning episodes.

That means vampire squid could have about 100 times more sex than other squid do!

Life at incredible ocean depths goes at a slow pace, however. Vampire squid don’t swim so much as float. They also must survive with very little oxygen, and their diet is a very low calorie one, since they mostly eat zooplankton and organic debris.

Read more at Discovery News

Evidence of Pre-Columbus Trade Found in Alaska

Bronze artifacts discovered in a 1,000-year-old house in Alaska suggest trade was occurring between East Asia and the New World centuries before the voyages of Columbus.

Archaeologists found the artifacts at the “Rising Whale” site at Cape Espenberg.

“When you’re looking at the site from a little ways away, it looks like a bowhead coming to the surface,” said Owen Mason, a research associate at the University of Colorado, who is part of a team excavating the site.

The new discoveries, combined with other finds made over the past 100 years, suggest trade items and ideas were reaching Alaska from East Asian civilizations well before Christopher Columbus arrived in the Caribbean Sea in 1492 archaeologists said.

“We’re seeing the interactions, indirect as they are, with these so-called ‘high civilizations’ of China, Korea or Yakutia,” a region in Russia, Mason said.

Bronze and obsidian

The Rising Whale discoveries include two bronze artifacts, one of which may have originally been used as a buckle or fastener. It has a piece of leather on it thatradiocarbondates to around A.D. 600 (more tests will take place in the future). The other bronze artifact may have been used as a whistle.

Bronze-working had not been developed at this time in Alaska, so archaeologists think the artifacts would have been manufactured in China, Korea or Yakutia, and made their way to Alaska through trade routes.

Also inside that house, researchers found the remains of obsidian artifacts, which have a chemical signature that indicates the obsidian is from the Anadyr River valley in Russia.

Trade routes

The recent discoveries at the Rising Whale site add to over a century of research that indicates trade routes connected the Bering Strait (including the Alaskan side) with the civilizations that flourished in East Asia before Columbus’ time.

In 1913, anthropologist Berthold Laufer published an analysis of texts and artifacts in the journal T’oung Pao in which he found that the Chinese had a great interest in obtaining ivory from narwhals and walruses, acquiring it from people who lived to the northeast of China. Some of the walrus ivory may have come from the Bering Strait, where the animals are found in abundance.

Additionally, a number of researchers have noted similarities in design between the plate armor worn by people in Alaska and that worn in China, Korea, Japan and eastern Mongolia.

For instance, in the 1930s, Smithsonian Institution archaeologist Henry Collins undertook excavations at St. Lawrence Island, off the west coast of Alaska. In his book “The Archaeology of St. Lawrence Island” (Smithsonian, 1937), he wrote that plate armor started appearing on the island around 1,000 years ago. It consisted of overlapping plates made of ivory, bones and sometimes iron.

Plate armor similar to this was developed in several areas of East Asia, including Manchuria (in China), eastern Mongolia and Japan, Collins wrote. The use of plate armor, he said, spread north from these areas, and was eventually introduced to Alaska from across the Bering Strait.

Genetic evidence

Recent genetic research also sheds light on interactions between people from East Asia and the New World.

Many scientists say that humans first arrived in the New World around 15,000 years ago by crossing a land bridge that had formed across the Bering Strait. This land bridge was flooded about 10,000 years ago.

However, a recent genetic study suggests there were also movements of people from East Asia to the New World at a later date. Those who lived at the Rising Whale site may be part of what scientists refer to as the “Birnirk” culture, a group of people who lived on both sides of the Bering Strait and used sophisticated skin boats and harpoons to hunt whales.

The genetic study indicates that people from the Birnirk culture are the ancestors of a people called the “Thule,” who spread out across the North American arctic as far as Greenland. The Thule, in turn, are ancestors of the modern-day Inuit.

Long before Columbus

The Bering Strait wasn’t the only area where interactions between people from the Old World and New World occurred before Columbus’ arrival. By 1,000 years ago, the Vikings had explored parts of Canada and had even established a short-lived settlement at L’Anse aux Meadows in Newfoundland.

Research also indicates that, around this time, the Polynesians had reached South America, bringing sweet potatoes back to Polynesia and possibly bringing chickens to South America.

Read more at Discovery News

Coast Guard Aircraft Spots 100-Year-Old Shipwrecks

A helicopter from the U.S. Coast Guard’s Traverse City, Mich. station was on a routine patrol mission over northern Lake Michigan Friday, when crew members noticed a chilling sight.

Beneath the crystal clear waters of the lake — now free of ice, but still just above freezing — they could see the wreckage of numerous lost ships on the lake bottom. They took a series of photos and posted them to the station’s Facebook page, and invited local historical buffs to help them identify the wrecks.

One of the wrecks turned out to be a century and a half old. The James McBride, a 121-foot brig  was launched on April Fools Day 1848. On Oct. 19, 1857, the ship was transporting a cargo of wood from the Manitou Islands to Chicago, when she encountered a gale and was driven aground, and then abandoned as a total loss.

Another of the wrecks was the Rising Sun, a 133-foot-long wooden steamer that met its demise on Oct. 29, 1917. The ship broke up, and the remains now sit in 6 to 12 feet of water.

According to an article by local historian George Weeks, the Rising Sun was headed to High Island to get a load of potatoes, rutabagas and lumber, when it was caught in a winter storm. The crew attempted to reach the shore, but one of the ship’s anchors failed to hold and then became caught in a place where each wave that crashed into the ship slammed it into the lake bottom. The captain and four of the ship’s six sailors were swept away to their deaths. The two survivors managed to hang on and survive though the night.

The next morning, a man named Charles Rosman — son of a Great Lakes ship captain –was taking a walk along the beach when he saw the Rising Sun’s broken decks, which were covered with ice, and heard the cries of the surviving sailors. He quickly roused a half-dozen other local men, who used a horse-drawn sleigh to haul a small fishing boat to the beach, and then braved the rough, ice-cold waters to reach the disintegrating vessel and rescue the two sailors. The U.S. government later awarded them a medal for their efforts.

Read more at Discovery News

Mysterious 'Cold Spot': Fingerprint of Largest Structure in the Universe?

At the furthest-most reaches of the observable universe lies one of the most enigmatic mysteries of modern cosmology: the cosmic microwave background (CMB) Cold Spot.

Discovered in 2004, this strange feature etched into the primordial echo of the Big Bang has been the focus of many hypotheses — could it be the presence of another universe? Or is it just instrumental error? Now, astronomers may have acquired strong evidence as to the Cold Spot’s origin and, perhaps unsurprisingly, no multiverse hypothesis is required. But it’s not instrumental error either.

When the Cold Spot was first revealed by NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), astronomers quickly realized that the feature, if real, would be the largest structure ever seen in the cosmos. But with just one space telescope providing the measurements, there was always the concern that something mundane — like instrumental error — could be to blame.

Then the European Planck telescope, that was also launched to measure slight temperature variations in the CMB (known as anisotropies), also saw the Cold Spot. Despite some theories that the feature may actually be an error caused by our statistical analysis methods, it was generally thought that the Cold Spot was real.

One of the most extreme (and, frankly, exciting) hypotheses possibly explaining the Cold Spot focused around the multiverse. Stemming from superstring theory, the multiverse posits that our universe is just one of many universes in a bubbly soup of universes (universi?). And that Cold Spot? Well, it could be one of those neighboring universes nuzzling up against our own.

As I outlined in a recent DNews video, the multiverse hypothesis is certainly one of the more extreme cosmological ideas out there and other explanations for the Cold Spot exist. And one idea that now appears to have gained some meat is that of the existence of a “supervoid” in the universe between us and the Cold Spot imprint in the CMB.

Through the combination of observational data from Hawaii’s Pan-STARRS1 (PS1) telescope located on Haleakala, Maui, and NASA’s Wide Field Survey Explorer (WISE) satellite, István Szapudi of the Institute for Astronomy at the University of Hawaii at Manoa and his collaborators may have found “the largest individual structure ever identified by humanity” and this structure may be creating the anomalous Cold Spot.

Previous studies have shown that there is little evidence for a very distant structure in the direction of the Cold Spot. But, paridoxically, it is harder to identify large structures that are closer to us than further away. By constructing a 3-D map of galaxies, the researchers discovered a vast region, only 3 billion light-years away (that’s close in the grand cosmological scheme of things), that has a lower density of galaxies than the rest of the known universe. This supervoid is huge, measuring about 1.8 billion light-years wide. This vast supervoid could therefore be the largest structure ever identified by humanity.

So Szapudi’s team may have identified a vast supervoid in space, what’s that got to do with the CMB Cold Spot?

The radiation from the CMB is the most ancient form of radiation known in the universe. Created just after the Big Bang nearly 14 billion years ago, this weak glow has to travel from the most distant edge of our observable universe to be detected by our instrumentation. The medium that this radiation travels through is therefore very important.

As the CMB radiation encountered the supervoid, a region of space with a density much lower than the rest of the universe, the Integrated Sachs-Wolfe (ISW) effect may have altered the characteristics of any radiation traveling through it. As the universe is expanding, the radiation traveling through the supervoid will lose more energy than radiation traveling though ‘normal’ space, creating an anomalously cool imprint in the WMAP and Plank anisotrophy maps. This imprint would manifest itself as a huge Cold Spot.

Read more at Discovery News

Dating the moon-forming impact event with meteorites

Through a combination of data analysis and numerical modeling work, researchers have found a record of the ancient Moon-forming giant impact observable in stony meteorites. Their work will appear in the April 2015 issue of the Journal Science. The work was done by NASA Solar System Exploration Research Virtual Institute (SSERVI) researchers led by Principal Investigator Bill Bottke of the Institute for the Science of Exploration Targets (ISET) team at the Southwest Research Institute and included Tim Swindle, director of the University of Arizona's Lunar and Planetary Laboratory.

The inner Solar System's biggest known collision was the Moon-forming giant impact between a large protoplanet and the proto-Earth. The timing of this giant impact, however, is uncertain, with the ages of the most ancient lunar samples returned by the Apollo astronauts still being debated. Numerical simulations of the giant impact indicate this event not only created a disk of debris near Earth that formed the Moon, but it also ejected huge amounts of debris completely out of the Earth-Moon system. The fate of this material, comprising as much as several percent of an Earth mass, has not been closely examined until recently. However, it is likely some of it blasted main belt asteroids, with a record plausibly left behind in their near-surface rocks. Collisions on these asteroids in more recent times delivered these shocked remnants to Earth, which scientists have now used to date the age of the Moon.

The research indicates numerous kilometer-sized fragments from the giant impact struck main belt asteroids at much higher velocities than typical main belt collisions, heating the surface and leaving behind a permanent record of the impact event. Evidence that the giant impact produced a large number of kilometer-sized fragments can be inferred from laboratory and numerical impact experiments, the ancient lunar impact record itself, and the numbers and sizes of fragments produced by major main belt asteroid collisions.

Once the team concluded that pieces of the Moon-forming impact hit main belt asteroids and left a record of shock heating events in some meteorites, they set out to deduce both the timing and the relative magnitude of the bombardment. By modeling the evolution of giant impact debris over time and fitting the results to ancient impact heat signatures in stony meteorites, the team was able to infer the Moon formed about 4.47 billion years ago, in agreement with many previous estimates. The most ancient Solar System materials found in meteorites are about one hundred million years older than this age.

Insights into the last stages of planet formation in the inner solar system can be gleaned from these impact signatures. For example, the team is exploring how they can be used to place new constraints on how many asteroid-like bodies still existed in the inner Solar System in the aftermath of planet formation. They can also help researchers deduce the earliest bombardment history of ancient bodies like Vesta, one of the targets of NASA's Dawn mission and a main belt asteroid whose fragments were delivered to Earth in the form of meteorites. It is even possible that tiny remnants of the Moon-forming impactor or proto-Earth might still be found within meteorites that show signs of shock heating by giant impact debris. This would allow scientists to explore for the first time the unknown primordial nature of our homeworld.

Co-author Swindle, who specializes in finding the times when meteorites or lunar samples were involved in large collisions, said: "Bill Bottke had the idea of looking at the asteroid belt to see what effect a Moon-forming giant impact would have, and realized that you would expect a lot of collisions in the period shortly after that.

"Here at LPL, we had been determining ages of impact events that affected meteorites, and when we got together, we found that our data matched his predictions," he added. "It's a great example of taking advantage of groups that work in two different specialties -- orbital dynamics and chronology -- and combining their expertise."

Intriguingly, some debris may have also returned to hit the Earth and Moon after remaining in solar orbit over timescales ranging from tens of thousands of years to 400 million years.

Read more at Science Daily

Repeated marine predator evolution tracks changes in ancient and Anthropocene oceans

For more than 250 million years, four-limbed land animals known as tetrapods have repeatedly conquered the Earth's oceans. These creatures--such as plesiosaurs, penguins and sea turtles--descended from separate groups of terrestrial vertebrates that convergently evolved to thrive in aquatic environments.

In a new scientific review, a team of Smithsonian scientists synthesized decades of scientific discoveries to illuminate the common and unique patterns driving the extraordinary transitions that whales, dolphins, seals and other species underwent as they moved from land to sea. Drawing on recent breakthroughs in diverse fields such as paleontology, molecular biology and conservation ecology, their findings offer a comprehensive look at how life in the ocean has responded to environmental change over time. The paper also highlights how evolutionary history informs an understanding of the impact of human activities on marine species today. More information is available in the April 17 issue of Science.

Marine tetrapods represent a diverse group of living and extinct species of mammals, reptiles, amphibians and birds that all play--or played--a critical role as large ocean predators in marine ecosystems. The repeated transitions between land and sea have driven innovation, convergence and diversification against a backdrop of changing marine ecosystems and mass extinctions dating back to the Triassic period. In this way, they provide ideal models for testing hypotheses about the evolution of species over long periods of time. Modern species of marine tetrapods now face a suite of human-driven impacts to their environment, including climate change, habitat degradation, ship collisions and underwater noise.

"We know from the fossil record that previous times of profound change in the oceans were important turning points in the evolutionary history of marine species," said Neil Kelley, a Peter Buck post-doctoral researcher in the National Museum of Natural History's department of paleobiology and lead author in the study. "Today's oceans continue to change, largely from human activities. This paper provides the evolutionary context for understanding how living species of marine predators will evolve and adapt to life in the Anthropocene."

Recent investigations in the fossil record have provided new insight into the evolution of traits that allowed marine tetrapods to thrive in the sea. In some cases, similar anatomy evolved among lineages that adapted to marine lifestyles. For example, modern dolphins and extinct marine reptiles called ichthyosaurs descended from distinct terrestrial species, but independently converged on an extremely similar fish-like body plan although they were separated in time by more than 50 million years. The repeated transformation of legs adapted for walking on land into fins is another classic example of convergent evolution. Species ranging from seals to mosasaurs independently developed streamlined forelimbs as they transitioned from living on land to the ocean, allowing them to move quickly and efficiently in the water. This transformation may have been achieved by parallel changes at the genome level.

"Land to sea transitions have happened dozens of times among reptiles, mammals and birds, across major mass extinctions," said Nicholas Pyenson, the museum's curator of fossil marine mammals. "You often get similar looking results but convergence is more than skin deep. It can be seen on a broad range of scales, from molecules to food webs, over hundreds of millions of years."

In the case of deep divers such as beaked whales and seals, these species have independently evolved to have positively charged oxygen-binding proteins called myoglobin in their muscles, allowing them to survive underwater for long periods of time. Scientists also have found identical genetic sequences in different marine species, such as whales, seals and sea cows. Whether these invisible molecular similarities account for larger-scale visible patterns of convergent evolution, or whether convergent anatomy follows different genetic pathways in different groups, remains an important open question to be tackled as genomic sequences become available for more species.

Read more at Science Daily