Evolution

Isthmus of Panama Younger than We Thought

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Split by the Isthmus of Panama: Species of butterfly fish, sand dollar and cone snail that today live on the Pacific and Caribbean coasts of Central America are very closely related. Genetic sequencing shows that only 4 to 3 million years ago, each pair was a single species, demonstrating that marine connections between the oceans must have existed until that time. (Image by Coppard et al., via The Smithsonian)

It’s probably not something you’ve given much thought to, unless perhaps you’ve visited Central America in the past and experienced first-hand the incredible biodiversity displayed in such a small area. Part of the reason why this little strip of land has so many different species of animals and plants is that it connects two very large continents that used to be separate, but it also has given birth to new aquatic species via evolution, as you can see from the image above. Previous thought on the topic had been that the Isthmus of Panama rose from the ocean roughly between 23 and 15 million years ago, but a very large and very interdisciplinary team of researchers – mostly with some link to the Smithsonian Institution, which has its Tropical Research Institute in Panama City – have reaffirmed that the enormously important geological change occurred around 3 million years ago.

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Most Orangutans are Left-handed

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Image © playbuzz.com

It may seem like a strange title, but this post, which partly continues our celebration of orangutans (see how you can help the endangered species by avoiding palm oil), comes from this week’s Science Friday segment on whether other animals display a preference for left or right in their daily lives, the way humans do. A couple of our contributors here are lefties, making up a small percentage of the total, while 66% of orangutans are left-handed! Nicole Wetsman writes:

The human tendency to be right-handed is obvious—especially if you’re a lefty, and have to deal with right-handed desks and scissors, not to mention spiral notebooks.

But humans aren’t the only members of the animal kingdom that show handedness, or the preference for one hand over the other. Other primates exhibit right-handed or left-handed proclivities, as do animals that don’t technically have hands. For instance, research has shown that some mice are righties while others are southpaws, and that some tree frogs preferentially jump away from predators in one direction over another.

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All About Horns

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A dik-dik, a type of dwarf antelope with tiny horns. All photos by National Geographic

Horns are a curious biological development that come in all shapes and sizes and serve different purposes. There are plenty of white-tailed deer around the Gallon Jug Estate, some of which are young bucks with anywhere from one- to five-point antlers, and last night two guests actually watched a pair of these males butting heads within Chan Chich Lodge. An article by National Geographic enlightens us to the horny way of life:

Horns evolved independently in many animals to meet similar needs—first as weapons, and then as defenses against rivals, says Don Moore, director of the Oregon Zoo in Portland.

Horns likely initially inflicted body blows, but became larger and more elaborate as they absorbed blows to the head. This strategy led some animals, like pronghorns, to essentially wrestle (watch a video), whereas others, like sheep, ram their opponents.

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The Big Headed Ant

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Source sciencenews.org

Whether it be inside or outside of our homes, ants are everywhere on land. The Pheidole drogon and Pheidole viserion worker ants, found in the rainforests of Papua New Guinea, are ones that have spines protruding from their thoraxes, an intimidating sight for anyone or anything trying to tangle with them. However, researchers suggest that the thorny-looking spine might instead be a muscular support for the ant’s over-sized head, which is used to crush seeds. Continue reading →

Lights in the Dark

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Galiteuthis. Credit: MBARI

In the past three days, two of the blogs we visit have shared a total of three posts concerning animals that live in the deep sea, where light is scarce. Ed Yong has written for NatGeo’s blog about a “squid that has glowing eyeshadow that acts as an invisibility cloak,” as well as the genetic branches and diversity of species exhibiting bioluminescence; Matt Miller wrote for The Nature Conservancy’s blog about a new book by photographer Danté Fenolio called Life in the Dark: Illuminating Biodiversity in the Shadowy Haunts of Planet Earth. Below, a quick excerpt from each, starting with the squid:

The oceans of the world are home to animals that render themselves invisible with glowing eyeshadow.

They’re called glass squid and, as their name suggests, they are largely transparent. They’d be impossible to see in the darkness of the open ocean were it not for their eyes—the only obviously opaque parts of their bodies.

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A Moth’s Dark Side Evolution

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A mutation giving rise to the black form of peppered moths has been discovered and is estimated to have occurred around 1820. Photo by Ilik Saccheri

The story of moth populations turning from light grey to sooty black in England during the Industrial Revolution is a popular schoolbook lesson of evolution, but an explanation for the genes responsible for the change had not been clear until now. Ed Yong reports for Nat Geo’s Phenomena blog:

In the early 19th century, coal-fired power stations belched a miasma of soot over the English countryside, blackening trees between London and Manchester. The pollution was bad news for the peppered moth. This insect, whose pale speckled body blended perfectly against the barks of normal trees, suddenly became conspicuous—a white beacon against blackened bark, and an easy target for birds.

As the decades ticked by, black peppered moths started appearing. These mutants belonged to the same species, but they had traded in their typical colours for a dark look that once again concealed their bodies against the trees. By the end of the century, almost all the moths in Manchester were black.

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Have Biocompass, Will Travel

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A huge variety of animals seem capable of reading Earth’s geomagnetic field. The question is how they do it. ILLUSTRATION BY NATALIE ANDREWSON

From the New Yorker website, the beginning of an answer to a question we ponder every so often:

HOW DO ANIMALS KEEP FROM GETTING LOST?

By M. R. O’Connor

Every three years, the Royal Institute of Navigation organizes a conference focussed solely on animals. This April, the event was held southwest of London, at Royal Holloway College, whose ornate Victorian-era campus has appeared in “Downton Abbey.” For several days, the world’s foremost animal-navigation researchers presented their data and findings in a small amphitheatre. Most of the talks dealt with magnetoreception—the ability to sense Earth’s weak but ever-present magnetic field—in organisms as varied as mice, salmon, pigeons, frogs, and cockroaches. This marked a change from previous years, Continue reading →

If You Happen To Be In New York

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A horseshoe crab. Brian Harkin for The New York Times

Thanks to a Nature essay in the New York Times, timed to be read over the Memorial Day weekend typically associated with the beginning of summer in the USA, a reminder of one of the joys of the season (at least on the Atlantic coast of the USA) just beginning:

Time for Horseshoe Crabs and the Shorebirds That Love Them

By DAVE TAFT

Humans may be quick to judge, but only one horseshoe crab can ultimately gauge the loveliness of another. When these crabs appear on a beach — suddenly and in large numbers — they can seem fearsome and even malevolent, and that’s before you glimpse beneath their intimidating, pointy-tailed carapace at a mouth set in the center of 12 madly churning legs. Beauty, in this case, is in the compound eyes of the beholder: Horseshoe crabs each have a total of 10 eyes, through which they obviously find one another appealing. These trilobite relatives have been attracting mates successfully for well over 400 million years. Continue reading →

Not A Cute Cat Video

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It is science, folks. Thanks to BBC Earth, here we ask for a minute and a half of your time in the interest of understanding exactly how cats do what they do. As we see it, this may translate into your future action in the interest of conservation of their natural habitat (the wild cats, of course, not the backyard bird-eating domestic variety):

How do cats always land on their feet?

This cat not only defies gravity but lands again safely and it all happens in less than a second

Caracals are expert bird hunters, capable of catching them in mid-flight with incredible leaps. Continue reading →

Hello Again, Robert Krulwich

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Artist’s reconstruction of a forest during the Carboniferous period. From ‘Science for All’ by Robert Brown (London, c1880). Illustration by World History Archive, Alamy

National Geographic‘s website has enlisted one of our favorite science communicators for its Phenomena section, and we are suddenly aware of how long it has been since we featured one of his ponderings (and excellent illustrations):

… whose trees “would appear fantastic to us in their strangeness,” write Peter Ward and Joseph Kirschvink in their book A New History of Life.

Some of them were giants: 160 feet tall, with delicate fernlike leaves that sat on top of pencil-thin trunks. This was the age when plants were evolving, climbing higher and higher, using cellulose and a tough fiber called lignin to stay upright. Had you been there, you would have felt mouse-sized.

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Thanks To Humboldt

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In the “oops, forgot to post on this” category, we recommend you start with the introductory video above, then continue on to the author’s website:

55054_us_humboldt_cov“The Invention of Nature” reveals the extraordinary life of the visionary German naturalist Alexander von Humboldt (1769-1859) and how he created the way we understand nature today. Though almost forgotten today, his name lingers everywhere from the Humboldt Current to the Humboldt penguin. Humboldt was an intrepid explorer and the most famous scientist of his age. His restless life was packed with adventure and discovery, whether climbing the highest volcanoes in the world, paddling down the Orinoco or racing through anthrax–infested Siberia. Perceiving nature as an interconnected global force, Humboldt discovered similarities between climate zones across the world and predicted

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What Is This Bird Saying?

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Thanks to the Science section of the New York Times for this recent “how” series, which you can see past examples of once this video stops playing (including how a boa constrictor “feeds,”)  but especially for this video explaining one of our favorite birds. The related article The Hummingbird’s Tongue: How it Works is worth an additional few minutes:

Hummingbirds are great subjects for evolutionary biologists because they are so extreme. They live at a fast pace, wings a blur, tongue darting in and out of flowers at a frenetic pace, often 15 or 20 times a second. Continue reading →

Notes from a Natural History Museum

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Harvard Natural History Museum

I recently had the chance to visit the Harvard Natural History Museum. Despite having lived in Cambridge for nearly a year, and having often thought about visiting the museum when I passed by going to and from my apartment, I had not stopped in until now. What a treat! The collections are full, diverse, and well curated. On this occasion, I spent most of my time in the animal wing, but I plan to return soon to take in the flora and minerals, and spend much more time in choice display rooms (e.g. the absolutely gorgeous Mammals/Birds of the World permanent exhibit: see below for pictures).

A ground sloth skeleton. It is hard to get an idea of the size of this creature from this photo, but it probably weighed several tons while alive!

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Coral Manipulation

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Coral garden in Indonesia. Credit: Global Environment Facility via Flickr (Creative Commons License)

Coral garden in Indonesia. Credit: Global Environment Facility via Flickr (Creative Commons License)

We’re keeping an eye on the health of coral reefs in the Caribbean with the help of RAXA contributor Phil Karp, who has been writing specifically about the impact of invasive lionfish on the marine ecosystem.  In this piece for Conservation Magazine, Sarah DeWeerdt discusses the option of taking a more active role in improving the health of corals through acclimatization:

The past several decades have been tough on the world’s coral reefs. Warming waters, ocean acidification, invasive predators, and toxic runoff have hammered these iconic hotspots of underwater biodiversity.

In response, conservationists have developed coral ‘gardens’ where young corals are reared to help rebuild damaged reefs. But some scientists worry that existing restoration strategies won’t match the pace and magnitude of the threats these animals face.

In a paper published February 2 in the Proceedings of the National Academy of Sciences, biologists from the Australian Institute of Marine Science and the Hawaii Institute of Marine biology propose a more radical approach, which they call assisted evolution.

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Predatory Selection

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© BBC

Writing for the BBC Earth section, Colin Barras explores “how the ‘art of killing’ changed the world.” Did multicellular organisms arise because single-celled ones were too easily attacked? Did skeletons evolve primarily as protection against predators? And, maybe the hardest question to answer with certainty: did animals move from water to land because it would be easier to avoid getting eaten? Read the excerpted introduction below and follow the link to learn about these theories and others from Barras.

If you’ve ever seen a lion or a polar bear on the hunt, you know how powerful predators can be. Life may well have been troubled by these killer species since its very beginning, over 3.5 billion years ago, and they have wrought untold death and destruction. As a result they get a bad press: even the word “predator” stems from the Latin term to rob or plunder. Small wonder that, when people imagine paradise, it normally doesn’t have any predators in it.

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Geckos, A 10th Latitude Lovely

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Geckos are in most of our favorite places–Kerala, Costa Rica, Ghana–which share some 10th Latitude commonalities in different continents.  They are one tiny example of the commonalities, but one that most of us love, for reasons we cannot begin to explain. So for us this story is a welcome puzzle solver for mysteries we did not know needed explaining, yet enjoy the answers:

SCIENCETAKE

Climbing a Glass Building? Try a Gecko’s Sticky Pads

By JAMES GORMAN

The lizard and, well, Spider-Man, have ideal tools for scaling slippery surfaces. Engineers have copied the gecko’s clingy foot pads.

Past, Present & Future Food

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Top row: escargots, sardines, and fava beans (Crete); naan in salty yak-milk tea (Afghanistan); fried geranium leaves (Crete); boiled crab (Malaysia); raw beetroot and oranges (Crete); chapati, yak butter, and rock salt (Pakistan). Middle row: dried-apricot soup (Pakistan); boiled plantains (Bolivia); fried coral reef fish (Malaysia); bulgur, boiled eggs, and parsley (Tajikistan); stewed-seaweed salad (Malaysia); boiled ptarmigan (Greenland). Bottom row: grilled tuna (Malaysia); cooked potatoes, tomatoes, and fava beans in olive oil (Crete); rice with melted yak butter (Afghanistan); fried fish with tamarind (Malaysia); dried apricots (Pakistan); grilled impala (Tanzania; photographer’s utensils shown).

Thanks to National Geographic for this article:

The Evolution of Diet

BY ANN GIBBONS

PHOTOGRAPHS BY MATTHIEU PALEY

Some experts say modern humans should eat from a Stone Age menu. What’s on it may surprise you.

It’s suppertime in the Amazon of lowland Bolivia, and Ana Cuata Maito is stirring a porridge of plantains and sweet manioc over a fire smoldering on the dirt floor of her thatched hut, listening for the voice of her husband as he returns from the forest with his scrawny hunting dog. Continue reading →

Nature Has The Long View

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When you love what you do, the hope is that you will do it indefinitely. E.O. Wilson shows little sign of slowing down any time soon, and his new book is the best evidence to date. Not exactly light weekend reading, nor summer beach fare, but from the sound of this review, worth the effort:

LOOKING FOR ETERNITY? LOOK TO NATURE

May 2, 2014

A Review of “A Window on Eternity” by E.O. Wilson

By Bill Chameides

To say that E.O. Wilson, arguably the greatest living biologist, is prolific is a bit of an understatement. At 84, Wilson continues to churn out books at a rate of one to two each year. Yesterday, Earth Day 2014, marks the release of his latest book, A Window on Eternity: A Biologist’s Walk Through Gorongosa National Park  (Simon and Schuster), and a DVD companion titled “The Guide.” Continue reading →

Professors, aka Heroes, Who Teach What Others Might Shun

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Thanks to the New York Times for the weekly Tuesday Science section:

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What Fish Teach Us About Us

Interview by CLAUDIA DREIFUS

Neil H. Shubin, the paleontologist who helped discover a fossil hailed as a missing link between sea and land animals, talks about his television series, “Your Inner Fish,” and why he teaches anatomy classes.