Skeptics have often wondered why UFOs, if truly alien, would visit Earth so frequently. However, two Harvard scientists propose that these beings might have been here all along.

“While this notion may sound unlikely on first hearing, many observers are persuaded that it is at least conceivable,” the team wrote in their study, pointing out that vast areas of our planet remain largely unexplored and uncharted.

The study represents a collaboration among scientists ensuring that all viable theories about the UFO mystery are considered, particularly amid recent government efforts for declassification.

There are many theories as to why UFOs have gone on a rebranding tour recently. One of the reasons is that UFOs have been a catch-all term for all types of unidentifiable objects, and not all of them fly. USOs (unidentified submerged objects) have become a part of a larger conversation in the world of UFOs.

The study suggests that ancient, highly advanced human civilizations may still be lingering in our modern world, observing us. The second theory suggests that an intelligent species evolved independently of humans in the distant past, possibly from “intelligent dinosaurs,” and is now hiding from us.

Another explanation put forward by controversial Harvard astrophysicist Avi Loeb suggests that ancient civilizations have lived on “planets like Mars or Earth” but were unaware of each other because they lived billions of years apart.

One such area is the “Alaskan Triangle,” a remote, sparsely populated zone between Anchorage, Juneau, and Utqiagvik, which the authors describe as a “hotspot” for UAP sightings and other anomalies.

The Alaska Triangle, while less famous than the Bermuda Triangle, has a mysterious past that started with the disappearance of a small, private craft carrying US House Majority Leader Hale Boggs.

While many suggest that searching for someone in a state less occupied than Maine and twice as large as Texas might be related to the disappearances, others suggest that abducting the other 16,000 missing people.

The researchers also reference intriguing archeological finds suggesting ancient civilizations that could predate known advanced species and might still exist in hiding.

Yonaguni Jima isn’t the only site that many believe aliens had their hands in building. Despite the impressive relics of bygone eras that defy the technological capabilities of their time because of their size and complexity, people assume someone else had to have help.

The conversation has also mentioned Stonehenge as a product of ancient alien activities. The huge circle of stones, which can weigh up to 50 tons, is a Neolithic monument that has been a huge mystery in human history.

Underground regions with the potential to support life also remain unexplored.

They speculate that another hominid species, or even a branch of Homo sapiens, could have adapted to live hundreds of miles below the surface, though they would likely look quite different from us.

The researchers also consider deep underwater ocean trenches and the far side of the moon as potential locations for long-term bases, possibly built by an ancient advanced terrestrial race or extraterrestrial co-inhabitants.

In 1976, NASA’s Viking 1 orbiter took a photograph of shadows on the surface of Mars creating the illusion of a human face. The Cydonia region has sparked speculation about extraterrestrial intelligence on the planet.

“Of course,” the researchers caution, “the limits of our knowledge provide no particular argument for the CTH (cryptoterrestrial hypothesis).”

Dr. Michael Masters, a co-author and professor of biological anthropology at Montana Technological University, previously suggested that beings piloting UFOs might be “extratempestrials” or time travelers.

But not all inhabitable regions on Earth are believed to be the home of these “cryptoterrestrials.” Habitable regions underground could also be home to these species in hiding, as they offer the right conditions to support life.

He argued that the “grey” aliens often described in UFO abduction stories resemble what future humans might evolve to look like in a highly advanced society.

Brendan Case, the associate director for research at Harvard’s Institute for Quantitative Social Science, joined them in advocating for scientific exploration of the cryptoterrestrial UFO hypothesis.

The 33-page NASA documents, detailing information on a recent study of UFOs by an independent team, stated that new scientific techniques, including advanced satellites, could shift perceptions of unidentified flying objects.

A recent study from the Pentagon also examined reported sightings of UFOs over the last century but found no evidence of aliens or extraterrestrial intelligence in these “crash sites.”

While officials say that there is “no evidence” that the US government has encountered alien life, a report submitted to Congress earlier this year states that most UFO sightings are ordinary objects from Earth.