Have aliens been here?
Scientists are highly skeptical, but such “cosmic wanderlust" isn't a bad thing.
This is one issue that gets people fired up on both sides of the aisle.
Most scientists would agree that there is no compelling evidence to support any kind of visitation from extraterrestrial interstellar travelers on planet Earth, past or present. Believers, on the other hand, are adamant. There are two main areas of potential “alien activity" on Earth: ancient large-scale engineering projects and, more recently, abductions.
Today, I'd like to focus on aliens as technology consultants to our ancestors. I've written about abductions elsewhere (with a clever title, no less!). They're a hot topic for sensational TV programming, and even Saturday Night Live even got in on the act with this funny routine.
But what about alien engineers? Could they have visited us before?
Growing up, I remember the 1968 explosive bestseller by Erich von Däniken, Chariots of the Gods? Unsolved Mysteries of the Past. Using cave paintings, tribal engravings, and dubious archeological evidence, Däniken suggests that the technologies of the past—think Egyptian and Mayan pyramids, Stonehenge, and the Nazca Lines in Peru (shown above), for example—were built under the guidance of our friends from outer space.
My father was a big fan and had a well-thumbed copy by his bedside table. The book remains in print, and had a fancy 50th-anniversary edition last year. Despite overwhelming criticism and accusations of fraud, Däniken, now 83, remains adamant that his thesis holds. (See the Afterword of the 50th-anniversary edition on the link above.)
The premise is fascinating. Could there be intelligent life elsewhere in the galaxy, advanced enough to build interstellar traveling machines? The honest answer from a rigorous scientific standpoint is disappointing: We don't know. There could indeed be technological civilizations in outer space. My colleague at 13.8, Adam Frank, has argued convincingly for high odds in his book Light of the Stars: Alien Worlds and the Fate of the Earth. If so, it is conceivable that they would have spotted Earth and decided to take a trip or more down here.
Lots of questions
For the sake of argument, let's imagine that they did come here a few thousand years ago to help our ancestors on their worshipping monuments. A few questions immediately come up. Why do the pyramids and Stonehenge and Nazca Lines show no trace of a truly remarkably advanced technology, one inherited from beings able to cross interstellar distances? Why aren't there any remains of such alien technologies or visits? What was the purpose of such strange interference with their human hosts? Why did they leave and decide not to come back? Why aren't there other samples of such advanced technologies, for example, ancient dams or power stations? Why didn't they teach their human hosts some more advanced science and mathematics, the use of electricity and nuclear energy, for example?
Däniken's arguments are circumstantial and very human-centric. The interpretation of engravings and ancient maps—with human-like creatures with what appear to be globes on their heads (as depicted on the cover of an early edition of Chariots)—does not lead to convincing scientific proof that the models were real aliens.
Complex engineering monuments from thousands of years back do inspire awe. But it is easy to demonstrate that vast amounts of animal and human power, ropes, and a lot of time and resilience can do the job—as shown in this short documentary from Naked Science. And another one, about the building itself in more detail.
Let's consider interstellar travel for a moment. The nearest star system to us are the three stars in the Alpha Centauri system, some 4.3 light-years away. They are the focus of Cixin Liu's amazing best-selling novel The Three-Body Problem, where he speculates about aliens there (the "Trisolarians") and their (evil) plans toward us. If those aliens built a spaceship that could travel at the speed of light, it would only take them 4.3 years to reach Earth. But it would take our current fastest spaceship about 100,000 years to reach Alpha Centauri—not a feasible prospect for us. So unless these aliens had developed significantly more sophisticated forms of space travel, there's reason to be highly skeptical.
Clearly, efficient interstellar travel requires some undreamt technology. Even at the speed of light, taking a nine-year round trip to visit our nearest neighbors seems unpractical. More realistically, at about one-tenth of light's speed (potentially possible, using solar sails and lasers), it would be 90 years. And that's the next-door neighbor. The Milky Way galaxy spans some 100,000 light-years in diameter. Exploring such vast distances requires magical technology (at least to us), huge amounts of time, and, very importantly, the will to do so—a kind of cosmic wanderlust.
If aliens do have cosmic wanderlust, why aren't they visiting more often? Why have they forsaken us?
No extraordinary evidence
J. William Schopf, a paleontologist at the University of California, once said that extraordinary claims demand extraordinary evidence, a phrase Carl Sagan used often with respect to alien visitations. This sort of cold scientific logic frustrates those who say “I Want to Believe," to quote the famous poster hanging on the wall of FBI agent Fox Mulder of television's X-Files series.
It's important to note that scientists are skeptics not because they're stubborn, nasty, insensitive, or blind; we would love to have evidence of extraterrestrial life, especially intelligent life! Some of us have dedicated decades of research to the question of life in other worlds. (I recommend this video by Jill Tarter, a pioneer in the search for extraterrestrial intelligence and a model of scientific integrity.
The discovery of intelligent alien life—or, for that matter, any kind of alien life—would be a true game-changer for humankind, forcing a deep revision of our worldview. There would be so much to learn.
The fundamental precept of science is that solid, verifiable data must back claims, be they simple or remarkable. Otherwise, why give science any credibility? Planes fly, cars run, power stations work for a reason: because science works.
It's really too bad that we can't (yet) fly to the stars. But given the explosive growth in space exploration and the privatization of the space race, that day may come.
And when it does, odds are that we're the ones who'll be the visiting aliens.
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Evolution doesn't clean up after itself very well.
- An evolutionary biologist got people swapping ideas about our lingering vestigia.
- Basically, this is the stuff that served some evolutionary purpose at some point, but now is kind of, well, extra.
- Here are the six traits that inaugurated the fun.
The plica semilunaris<img class="rm-lazyloadable-image rm-shortcode" type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTA5NjgwMS9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTY3NDg5NTg1NX0.kdBYMvaEzvCiJjcLEPgnjII_KVtT9RMEwJFuXB68D8Q/img.png?width=980" id="59914" width="429" height="350" data-rm-shortcode-id="b11e4be64c5e1f58bf4417d8548bedc7" data-rm-shortcode-name="rebelmouse-image" />
The human eye in alarming detail. Image source: Henry Gray / Wikimedia commons<p>At the inner corner of our eyes, closest to the nasal ridge, is that little pink thing, which is probably what most of us call it, called the caruncula. Next to it is the plica semilunairs, and it's what's left of a third eyelid that used to — ready for this? — blink horizontally. It's supposed to have offered protection for our eyes, and some birds, reptiles, and fish have such a thing.</p>
Palmaris longus<img class="rm-lazyloadable-image rm-shortcode" type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTA5NjgwNy9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzMzQ1NjUwMn0.dVor41tO_NeLkGY9Tx46SwqhSVaA8HZQmQAp532xLxA/img.jpg?width=980" id="879be" width="1920" height="2560" data-rm-shortcode-id="4089a32ea9fbb1a0281db14332583ccd" data-rm-shortcode-name="rebelmouse-image" />
Palmaris longus muscle. Image source: Wikimedia commons<p> We don't have much need these days, at least most of us, to navigate from tree branch to tree branch. Still, about 86 percent of us still have the wrist muscle that used to help us do it. To see if you have it, place the back of you hand on a flat surface and touch your thumb to your pinkie. If you have a muscle that becomes visible in your wrist, that's the palmaris longus. If you don't, consider yourself more evolved (just joking).</p>
Darwin's tubercle<img class="rm-lazyloadable-image rm-shortcode" type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTA5NjgxMi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0ODUyNjA1MX0.8RuU-OSRf92wQpaPPJtvFreOVvicEwn39_jnbegiUOk/img.jpg?width=980" id="687a0" width="819" height="1072" data-rm-shortcode-id="ff5edf0a698e0681d11efde1d7872958" data-rm-shortcode-name="rebelmouse-image" />
Darwin's tubercle. Image source: Wikimedia commons<p> Yes, maybe the shell of you ear does feel like a dried apricot. Maybe not. But there's a ridge in that swirly structure that's a muscle which allowed us, at one point, to move our ears in the direction of interesting sounds. These days, we just turn our heads, but there it is.</p>
Goosebumps<img class="rm-lazyloadable-image rm-shortcode" type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTA5NzMxNC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyNzEyNTc2Nn0.aVMa5fsKgiabW5vkr7BOvm2pmNKbLJF_50bwvd4aRo4/img.jpg?width=980" id="d8420" width="1440" height="960" data-rm-shortcode-id="8827e55511c8c3aed8c36d21b6541dbd" data-rm-shortcode-name="rebelmouse-image" />
Goosebumps. Photo credit: Tyler Olson via Shutterstock<p>It's not entirely clear what purpose made goosebumps worth retaining evolutionarily, but there are two circumstances in which they appear: fear and cold. For fear, they may have been a way of making body hair stand up so we'd appear larger to predators, much the way a cat's tail puffs up — numerous creatures exaggerate their size when threatened. In the cold, they may have trapped additional heat for warmth.</p>
Tailbone<img class="rm-lazyloadable-image rm-shortcode" type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTA5NzMxNi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY3MzQwMjc3N30.nBGAfc_O9sgyK_lOUo_MHzP1vK-9kJpohLlj9ax1P8s/img.jpg?width=980" id="9a2f6" width="1440" height="1440" data-rm-shortcode-id="4fe28368d2ed6a91a4c928d4254cc02a" data-rm-shortcode-name="rebelmouse-image" />
Image source: Decade3d-anatomy online via Shutterstock<p>Way back, we had tails that probably helped us balance upright, and was useful moving through trees. We still have the stump of one when we're embryos, from 4–6 weeks, and then the body mostly dissolves it during Weeks 6–8. What's left is the coccyx.</p>
The palmar grasp reflex<img class="rm-lazyloadable-image rm-shortcode" type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTA5NzMyMC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzNjY0MDY5NX0.OSwReKLmNZkbAS12-AvRaxgCM7zyukjQUaG4vmhxTtM/img.jpg?width=980" id="8804c" width="1440" height="960" data-rm-shortcode-id="67542ee1c5a85807b0a7e63399e44575" data-rm-shortcode-name="rebelmouse-image" />
Palmar reflex activated! Photo credit: Raul Luna on Flickr<p> You've probably seen how non-human primate babies grab onto their parents' hands to be carried around. We used to do this, too. So still, if you touch your finger to a baby's palm, or if you touch the sole of their foot, the palmar grasp reflex will cause the hand or foot to try and close around your finger.</p>
Other people's suggestions<p>Amir's followers dove right in, offering both cool and questionable additions to her list. </p>
Fangs?<blockquote class="twitter-tweet" data-conversation="none" data-lang="en"><p lang="en" dir="ltr">Lower mouth plate behind your teeth. Some have protruding bone under the skin which is a throw back to large fangs. Almost like an upsidedown Sabre Tooth.</p>— neil crud (@neilcrud66) <a href="https://twitter.com/neilcrud66/status/1085606005000601600?ref_src=twsrc%5Etfw">January 16, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
Hiccups<blockquote class="twitter-tweet" data-conversation="none" data-lang="en"><p lang="en" dir="ltr">Sure: <a href="https://t.co/DjMZB1XidG">https://t.co/DjMZB1XidG</a></p>— Stephen Roughley (@SteBobRoughley) <a href="https://twitter.com/SteBobRoughley/status/1085529239556968448?ref_src=twsrc%5Etfw">January 16, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
Hypnic jerk as you fall asleep<blockquote class="twitter-tweet" data-conversation="none" data-lang="en"><p lang="en" dir="ltr">What about when you “jump” just as you’re drifting off to sleep, I heard that was a reflex to prevent falling from heights.</p>— Bann face (@thebanns) <a href="https://twitter.com/thebanns/status/1085554171879788545?ref_src=twsrc%5Etfw">January 16, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script> <p> This thing, often called the "alpha jerk" as you drop into alpha sleep, is properly called the hypnic jerk,. It may actually be a carryover from our arboreal days. The <a href="https://www.livescience.com/39225-why-people-twitch-falling-asleep.html" target="_blank" data-vivaldi-spatnav-clickable="1">hypothesis</a> is that you suddenly jerk awake to avoid falling out of your tree.</p>
Nails screeching on a blackboard response?<blockquote class="twitter-tweet" data-conversation="none" data-lang="en"><p lang="en" dir="ltr">Everyone hate the sound of fingernails on a blackboard. It's _speculated_ that this is a vestigial wiring in our head, because the sound is similar to the shrill warning call of a chimp. <a href="https://t.co/ReyZBy6XNN">https://t.co/ReyZBy6XNN</a></p>— Pet Rock (@eclogiter) <a href="https://twitter.com/eclogiter/status/1085587006258888706?ref_src=twsrc%5Etfw">January 16, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
Ear hair<blockquote class="twitter-tweet" data-conversation="none" data-lang="en"><p lang="en" dir="ltr">Ok what is Hair in the ears for? I think cuz as we get older it filters out the BS.</p>— Sarah21 (@mimix3) <a href="https://twitter.com/mimix3/status/1085684393593561088?ref_src=twsrc%5Etfw">January 16, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
Nervous laughter<blockquote class="twitter-tweet" data-lang="en"><p lang="en" dir="ltr">You may be onto something. Tooth-bearing with the jaw clenched is generally recognized as a signal of submission or non-threatening in primates. Involuntary smiling or laughing in tense situations might have signaled that you weren’t a threat.</p>— Jager Tusk (@JagerTusk) <a href="https://twitter.com/JagerTusk/status/1085316201104912384?ref_src=twsrc%5Etfw">January 15, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
Um, yipes.<blockquote class="twitter-tweet" data-conversation="none" data-lang="en"><p lang="en" dir="ltr">Sometimes it feels like my big toe should be on the side of my foot, was that ever a thing?</p>— B033? K@($ (@whimbrel17) <a href="https://twitter.com/whimbrel17/status/1085559016011563009?ref_src=twsrc%5Etfw">January 16, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
Research has shown how important empathy is to relationships, but there are limits to its power.
- Empathy is a useful tool that allows humans (and other species) to connect and form mutually beneficial bonds, but knowing how and when to be empathic is just as important as having empathy.
- Filmmaker Danfung Dennis, Bill Nye, and actor Alan Alda discuss the science of empathy and the ways that the ability can be cultivated and practiced to affect meaningful change, both on a personal and community level.
- But empathy is not a cure all. Paul Bloom explains the psychological differences between empathy and compassion, and how the former can "get in the way" of some of life's crucial relationships.
Ultimately, this is a fight between a giant reptile and a giant primate.
The 2021 film “Godzilla vs. Kong" pits the two most iconic movie monsters of all time against each other. And fans are now picking sides.