The most alien-looking place on Earth

George Wynn Brereton Huntingford was a British anthropologist, linguist, and historian, who traveled widely and was famed for his perceptive observations of societies and cultures.  And if you had to guess which of the many places he traveled during his 77 year life he labeled "the most alien-looking place on Earth," what would you come up with?

His vote was for the island of Socotra, a 132-by-42 kilometer island which lies at at the mouth of the Gulf of Aden.  To the north is the Arabian Sea; to the southwest, the Guardafui Channel separates it from the Horn of Africa.  It's nearer to Africa than to the Arabian Peninsula (232 versus 380 kilometers), but is controlled by the government of Yemen, as much as Yemen's political disaster is currently controlling anything.

Most of Socotra is desert to semi-desert:

[Image licensed under the Creative Commons Rod Waddington from Kergunyah, Australia, Socotra Island (11007223546), CC BY-SA 2.0]

Although it does get more rainfall than either Yemen and Oman (to the north) or Somalia (to the east), so it has a great deal more vegetation than its neighbors:

[Image licensed under the Creative Commons Rod Waddington from Kergunyah, Australia, Wadi, Socotra Island (14495206039), CC BY-SA 2.0]

The main reason for Socotra's uniqueness -- and why evolutionary biologist Lisa Banfield called it "the Galapagos of the Indian Ocean" -- isn't the climate; it's the fact that geologically, it's part of Africa.  During the Miocene Period, about twenty million years ago, Africa and the Arabian Peninsula were joined, but a rift formed that split the two, opening up the Gulf of Aden.  Socotra is a chunk of the Somali Plate that was torn loose and got separated from the rest of the land mass that now forms the easternmost part of Africa.  (Interestingly, the rifting has continued, joining up with a fault system that runs up north through the Red Sea and south into the East African Rift Zone, which one day will tear away a much huger chunk of Africa -- all the way down to Mozambique.)

The issue is that since Socotra's separation from Africa around twenty million years ago, it's been largely isolated, so evolution has veered the community off into its own direction..  This has led to a high degree of endemism -- the fraction of species found nowhere else on Earth.  11% of its bird species, 37% of its plants, 90% of its reptiles, and 95% of its mollusk species are endemic.  One of the most iconic plants is the "dragon's blood tree" (Dracaena cinnabari), which looks like it was invented by Dr. Seuss:

[Image licensed under the Creative Commons Alex38, Dragonblood tree in Socotra 2, CC BY 4.0]

Then, there's the cucumber tree (Dendrosicyos socotranus), which -- as the name would suggest -- is the only species in the cucumber family (Cucurbitaceae) that grows into a tree.  As far as I've heard, though, the fruit isn't edible, which is a good thing, because it'd be a hell of a climb to harvest one for your dinner salad:

[Image licensed under the Creative Commons Gerry & Bonni, Cucumber tree (6407165121), CC BY 2.0]

Like many places with unique and isolated ecosystems, Socotra's oddball assemblage of biota are endangered, from introduced species like cats and rats, from land use by the island's sixty-thousand-odd inhabitants, and from climate change.  The ongoing Yemeni civil war isn't helping, either; the government's priority is certainly not protecting peculiar-looking trees, and the ecotourists whose revenue might help the situation are mostly staying away for their own safety.

In any case, that's one anthropologist's vote for "the most alien-looking place on Earth" -- an island that's geologically African, politically and culturally Arabian, and biologically like nowhere else.  It's a place I'd love to visit one day if the situation calms down.  Adding some bird species to my life list that are found only on one speck of land in the Arabian Sea would be amazing.

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An alpine gem in China

In order to produce new species -- so goes the evolutionary model -- you need two things: isolation (splitting off the population that will eventually become the new species from the parent population) and selection (environmental conditions that favor different traits in the splinter population than the ones favoring the parent population).  Given those two, and sufficient time, sooner or later you'll have two (or more) separate species.

The classic example of this, of course, is the group of birds called "Darwin's finches," that evolved from a parent population of tanagers from mainland South America (their closest relative is the Dull-colored Grassquit of Colombia, Ecuador, and Peru) something on the order of two million years ago.  Once arrived in the islands, they thereafter fragmented to fill the available niches in a process that has been nicknamed adaptive radiation.

So split off a population and give it some new conditions to contend with, and you'll end up with new species.  Which is what happened to a whole ecosystem's worth of species thirty million years ago -- leading to one of the most biodiverse spots on Earth.

New research into the genetics of the dozens of unique species in the Hengduan Mountains and Qinghai Plateau of western China has given us a fascinating lens into this process.  In "Ancient Orogenic and Monsoon-Driven Assembly of the World’s Richest Temperate Alpine Flora," by Wen-Na Ding, Robert Spicer, and Yao-Wu Xing of the Chinese Academy of Sciences and Richard Ree of Chicago's Field Museum, we read about a biotic province created by mountain building that not only raised the elevation (and thus lowered the average temperature), but altered wind currents to create monsoons -- and isolated the populations trapped there from their relatives on the other side of the mountain range.

"The theory is, if you increase the ruggedness of a landscape, you're more likely to have populations restricted in their movement because it's harder to cross a deeper valley than a shallow valley," said study co-author Richard Ree, in an interview with Science Daily.  "So any time you start increasing the patchiness and barriers between populations, you expect evolution to accelerate...  The combined effect of mountain-building and monsoons was like pouring jet fuel onto this flame of species origination.  The monsoon wasn't simply giving more water for plants to grow, it had this huge role in creating a more rugged topography.  It caused erosion, resulting in deeper valleys and more incised mountain ranges."

This all started back in the Oligocene Epoch, thirty million years ago, and the area has been pretty well isolated ever since.  The result is plants like the Himalayan lantern (Agapetes lacei):

.... which you wouldn't guess is a relative of rhododendrons and azaleas; the alpine monkshood (Aconitum gymnandrum):

... the gorgeous little Paraquilegia microphyllum:

... and literally hundreds of others, species found there and nowhere else on Earth.

The remoteness and general inaccessibility of the area has limited the human impact (fortunately), but scientists are rightly concerned with the effects that climate change will have on these subalpine valleys and plateaus.  Even if we're not directly damaging the ecosystem, our actions elsewhere imperil it, just as our out-of-control fossil fuel use has led to the thawing of the Arctic and the threat of ice sheet collapse in Antarctica -- the latter of which recent research has suggested could add three meters to the average sea level over a very short period, with catastrophic consequences.

But for now, let's just focus on this pristine gem of an ecosystem, and marvel at the processes that created it.  Once again, we see the truth of Darwin's words, with which he ended The Origin of Species: "There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved."

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This week's Skeptophilia book recommendation is a fun and amusing discussion of a very ominous topic; how the universe will end.

In The End of Everything (Astrophysically Speaking) astrophysicist Katie Mack takes us through all the known possibilities -- a "Big Crunch" (the Big Bang in reverse), the cheerfully-named "Heat Death" (the material of the universe spread out at uniform density and a uniform temperature of only a few degrees above absolute zero), the terrifying -- but fortunately extremely unlikely -- Vacuum Decay (where the universe tears itself apart from the inside out), and others even wilder.

The cool thing is that all of it is scientifically sound.  Mack is a brilliant theoretical astrophysicist, and her explanations take cutting-edge research and bring it to a level a layperson can understand.  And along the way, her humor shines through, bringing a touch of lightness and upbeat positivity to a subject that will take the reader to the edges of the known universe and the end of time.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]