Are birds using quantum entanglement to navigate?
Sounds wild, but it may well be so.
- Birds' navigation using Earth's very faint magnetic fields suggests an incredible level of sensitivity.
- There's reason to think that sensitivity may be based on quantum entanglement in cryptochrome in their eyes.
- Identifying the role of quantum physics in biology could lead, well, who knows where?
Okay, this is far from confirmed, but it's pretty radical, and exciting. It's a possible and plausible answer to a question that's puzzled biologists ever since the manner in which birds navigate became apparent. The question is: How can birds possibly be able to perceive and follow something as faint as the Earth's magnetic field? The possible answer? It may be that they perceive it through the interaction of entangled quantum particles in their eyes.
Behind this hypothesis is years of confirming and seeking to explain birds' phenomenal sensitivity to Earth's magnetic field. The most plausible explanation for it has to do with the effect of the magnetic field on entangled molecules of a chemical in birds' eyes, Cry4, or cryptochrome. Other animals, and plants, share the chemical, though it's believed that birds have developed their own variant. Quantum entanglement, Einstein's "spooky action at a distance," is a topic that comes up often at Big Think because it's a theoretical vehicle upon which some of the strangest and most interesting new ideas ride. Here's what we mean:
- The bizarre and wonderful world of quantum theory—and how understanding it has ultimately changed our lives
- Why a 'genius' scientist thinks our consciousness originates at the quantum level
- The universe may be conscious, say prominent scientists
And now this.
When a photon, a light particle, hits a cryptochrome molecule in a bird's eye, it knocks loose an electron that may then become associated with a second molecule. The two molecules then both have an odd number of electrons, and they become a radical pair. Since the oddness of both of these radicals was created simultaneously by that loosened electron, the spins of one electron in each molecule of cryptochrome become locked together in relation to each other and the radical pair becomes entangled.
This entangled state is extremely fragile, and temporary, so it won't survive beyond just 100 microseconds (1/10,000th of a second). But during that brief interim, the radical pair will be in either one of two states. The suspicion is that the Earth's magnetic field affects the amount of time the molecules spend in either state, and changes to the duration of these states somehow tells the bird where he or she is. The exact means by which the bird perceives them is unknown, though it's been suggested that it may have to do with one or both states causing the presence of absence of some as-yet-unidentifed chemical.
Why this isn’t just craziness
Supercomputer model of Earth's magnetic field.
This might not seem to make sense because magnetic fields are so weak, but it's real. How weak? "The energy of interaction of a molecule with a ≈50-μT magnetic field is >6 orders of magnitude smaller than the average thermal energy kBT, which in turn is 10–100 times smaller than the strength of a chemical bond," according to a 2009 study, Chemical magnetoreception in birds: The radical pair mechanism. However, "It has been known since the 1970s that certain chemical reactions do in fact respond to applied magnetic fields." (Our emphasis.) The study also notes that radicals always seem to be involved.
The radical pair theory is really the best explanation for birds' navigation systems we have, since experiments attempting to detect effects of magnetic fields directly on biological processes — bypassing chemistry — have come up empty-handed.
The study proposes that perhaps photons are throwing electrons far enough from their normal thermal equilibrium that they remain entangled long enough to respond to the subtle cues coming from the planet's magnetic field. Quantum entangled particles created by scientists last for mere nanoseconds. One such scientist, Erik Gauger, tells Nova, "It seems nature has found a way to make these quantum states live much longer than we'd expect, and much longer than we can do in the lab. No one thought that was possible."
Proof of birds' sensitivity
Map of Earth's magnetic field, 1895.
A number of experiments to confirm what's going on are cited in the paper, some of which the authors find more convincing than others. However, the most compelling evidence of birds' amazing sensitivity comes from experiments with caged European robins, whose navigation abilities were easily disrupted. "Linearly polarized radio frequency fields 100 times weaker than the Earth's field (≈500 nT), with frequencies of 7.0 MHz or 1.315 MHz, are sufficient to disrupt the migratory orientation of caged European robins." (Again our emphasis.) Playing with the magnetic field also easily baffled the birds, with researchers finding a "20–30% increase or decrease in the intensity of the ambient magnetic field is sufficient to disorient caged birds."
Clearly, avians possess an almost unbelievably delicate sensing mechanism of some sort. The intersection of quantum mechanics and biology — even human biology — is a fascinating notion. As mentioned above, some wonder if it may also relate to consciousness and other currently bewildering phenomena. If we can come to fully understand the mechanics or chemistry of birds' impressive capabilities, what other mysteries might we be able to unlock?
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Here's the first evidence to challenge the "fastest sperm" narrative.
Experts argue the jaws of an ancient European ape reveal a key human ancestor.
- The jaw bones of an 8-million-year-old ape were discovered at Nikiti, Greece, in the '90s.
- Researchers speculate it could be a previously unknown species and one of humanity's earliest evolutionary ancestors.
- These fossils may change how we view the evolution of our species.
Homo sapiens have been on earth for 200,000 years — give or take a few ten-thousand-year stretches. Much of that time is shrouded in the fog of prehistory. What we do know has been pieced together by deciphering the fossil record through the principles of evolutionary theory. Yet new discoveries contain the potential to refashion that knowledge and lead scientists to new, previously unconsidered conclusions.
A set of 8-million-year-old teeth may have done just that. Researchers recently inspected the upper and lower jaw of an ancient European ape. Their conclusions suggest that humanity's forebearers may have arisen in Europe before migrating to Africa, potentially upending a scientific consensus that has stood since Darwin's day.
Rethinking humanity's origin story
The frontispiece of Thomas Huxley's Evidence as to Man's Place in Nature (1863) sketched by natural history artist Benjamin Waterhouse Hawkins. (Photo: Wikimedia Commons)
As reported in New Scientist, the 8- to 9-million-year-old hominin jaw bones were found at Nikiti, northern Greece, in the '90s. Scientists originally pegged the chompers as belonging to a member of Ouranopithecus, an genus of extinct Eurasian ape.
David Begun, an anthropologist at the University of Toronto, and his team recently reexamined the jaw bones. They argue that the original identification was incorrect. Based on the fossil's hominin-like canines and premolar roots, they identify that the ape belongs to a previously unknown proto-hominin.
The researchers hypothesize that these proto-hominins were the evolutionary ancestors of another European great ape Graecopithecus, which the same team tentatively identified as an early hominin in 2017. Graecopithecus lived in south-east Europe 7.2 million years ago. If the premise is correct, these hominins would have migrated to Africa 7 million years ago, after undergoing much of their evolutionary development in Europe.
Begun points out that south-east Europe was once occupied by the ancestors of animals like the giraffe and rhino, too. "It's widely agreed that this was the found fauna of most of what we see in Africa today," he told New Scientists. "If the antelopes and giraffes could get into Africa 7 million years ago, why not the apes?"
He recently outlined this idea at a conference of the American Association of Physical Anthropologists.
It's worth noting that Begun has made similar hypotheses before. Writing for the Journal of Human Evolution in 2002, Begun and Elmar Heizmann of the Natural history Museum of Stuttgart discussed a great ape fossil found in Germany that they argued could be the ancestor (broadly speaking) of all living great apes and humans.
"Found in Germany 20 years ago, this specimen is about 16.5 million years old, some 1.5 million years older than similar species from East Africa," Begun said in a statement then. "It suggests that the great ape and human lineage first appeared in Eurasia and not Africa."
Migrating out of Africa
In the Descent of Man, Charles Darwin proposed that hominins descended out of Africa. Considering the relatively few fossils available at the time, it is a testament to Darwin's astuteness that his hypothesis remains the leading theory.
Since Darwin's time, we have unearthed many more fossils and discovered new evidence in genetics. As such, our African-origin story has undergone many updates and revisions since 1871. Today, it has splintered into two theories: the "out of Africa" theory and the "multi-regional" theory.
The out of Africa theory suggests that the cradle of all humanity was Africa. Homo sapiens evolved exclusively and recently on that continent. At some point in prehistory, our ancestors migrated from Africa to Eurasia and replaced other subspecies of the genus Homo, such as Neanderthals. This is the dominant theory among scientists, and current evidence seems to support it best — though, say that in some circles and be prepared for a late-night debate that goes well past last call.
The multi-regional theory suggests that humans evolved in parallel across various regions. According to this model, the hominins Homo erectus left Africa to settle across Eurasia and (maybe) Australia. These disparate populations eventually evolved into modern humans thanks to a helping dollop of gene flow.
Of course, there are the broad strokes of very nuanced models, and we're leaving a lot of discussion out. There is, for example, a debate as to whether African Homo erectus fossils should be considered alongside Asian ones or should be labeled as a different subspecies, Homo ergaster.
Proponents of the out-of-Africa model aren't sure whether non-African humans descended from a single migration out of Africa or at least two major waves of migration followed by a lot of interbreeding.
Did we head east or south of Eden?
Not all anthropologists agree with Begun and his team's conclusions. As noted by New Scientist, it is possible that the Nikiti ape is not related to hominins at all. It may have evolved similar features independently, developing teeth to eat similar foods or chew in a similar manner as early hominins.
Ultimately, Nikiti ape alone doesn't offer enough evidence to upend the out of Africa model, which is supported by a more robust fossil record and DNA evidence. But additional evidence may be uncovered to lend further credence to Begun's hypothesis or lead us to yet unconsidered ideas about humanity's evolution.
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