Panspermia, the theory that cellular life came from a different planet

Before discovering cells, life was believed to emerge suddenly from inorganic matter

Popularized by Aristotle in the 4th century BCE, spontaneous generation was used to explain phenomena like mice appearing in seemingly sealed grain storage. The invention of the compound microscope in the late 16th century led to the identification of cells as the basic unit of life, but it was not until 1855 that their origin from preexisting cells was established.

Mold growth in space raises the hypothesis of life being brought to Earth

Panspermia suggests that life could be carried throughout the cosmos by asteroids, comets, and other objects, but it requires organisms that can withstand the extreme cold of space travel, stellar radiation, lack of water, and intense heat of planetary impacts. The discovery of mold on the International Space Station and experiments showing it can withstand radiation in outer space-like conditions increase the plausibility of the hypothesis.

Abiogenesis explains how Earth's natural processes could have formed organic matter

The theory details how chemical interactions in hydrothermal vents and shallow ponds billions of years ago could have created lipids, proteins, and RNA. As these interactions involve water, life is thought to have started in oceans.

Spontaneous metabolism may give clues to origins of life

Read this article to learn more about the discovery that suggests that metabolism could have begun spontaneously on our planet—and why it means that scientists may need to rethink how we define life’s origins. A team of researchers at the...

The key ingredients to life on Earth—and elsewhere

Life can only arise in incredibly specific conditions, an abundance of certain substances like water and phosphorus, lots of time, and the right proximity to a heat-and-light-providing star. These two experts on evolution of life say above all, life requires luck. Here's a list of eight ingredients to life.

Astrobiology is the study of life's origins and the search for life beyond Earth

The field incorporates observational missions to find and classify exoplanets—planets orbiting stars besides the sun—the probing of Earth's most extreme environments to learn what conditions allow life to exist, and theoretical and lab work to identify and analyze potential biochemical signatures.

Lining up every microbe on Earth would stretch to about 105,000 light-years

There are about 10²⁷ such organisms on the planet, many of which are adapted to produce energy through uncommon reactions in unconventional environments, such as within rocks or near volcanoes on the ocean floor. Studies of these organisms have reframed astrobiologists' search for life beyond Earth by broadening the parameters under which life can exist.

Learn how chloroplasts—the photosynthesis factories—may have once been independent cells

Possessing DNA of their own that differs from that of their host cell and surrounded by cellular membranes like those observed in bacteria, chloroplasts are believed to have evolved from a cyanobacterial cell. The endosymbiotic theory explains that these organelles were absorbed into larger cells, leading to the photosynthetic cells seen today.

Where do genes come from?

There are many more genes on Earth today than when microbial life first spawned on the planet about four billion years ago. Many of these newer genes grew from genetic mutations, misprints that slowly drift from the original blueprint via cellular division. If these mutations drift far enough, they can establish a new family of genes, though this process can take well over a million years.

How humans evolved from single-cell organisms

Humans have had a long history. 3.8 billion years in the making, to be precise. From the primordial puddle to the modern day, here's how humans have evolved from the first life.

Depending on environment, aliens' bodies would have wide-ranging possibilities

Humans tend to imagine aliens as humanlike, but that's probably unlikely. From small space spiders to metallic carnivores, life on other planets—and how we could interact with it—is difficult to imagine.

Scientists used to speculate about life on the moon

In the 17th century, Galileo's observations suggested the moon could be inhabited, leading to fictional speculations about lunar life. In the 19th century, stories were published claiming the discovery of various creatures, including human bats. The Apollo missions in the 20th century explored the possibility of life there, but further exploration showed this idea to be less likely than before.

One researcher posed a theory that aliens played a significant role in human evolution

Researcher Zecharia Sitchin proposed that Sumerian cuneiform tablets revealed that Sumerian gods were aliens who landed on Earth in Mesopotamia and influenced the creation of modern humans. While his ideas gained cultural interest, they are widely rejected by mainstream scholars.

Quantum mechanics-based technology may explain the Fermi paradox

It describes the discrepancy between the high likelihood of life beyond Earth given the vastness of the universe and the lack of evidence for such life, since extraterrestrial civilizations have not communicated with us. However, quantum communication—a more information-dense and effective method than classical means—requires massive receivers and very narrow signals, which would easily miss Earth, making a lack of signals expected.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

David Attenborough discusses creationism and his position as an agnostic

Attenborough argues that accounts of humanity's origins from different cultures cannot all be correct because they often differ, whereas geological records are consistent worldwide, meaning science provides the best understanding of the natural world. However, he acknowledges that, just as insects lack awareness of human goings-on, humans may be unaware of the existence of a deity.

The formation and breakup of Pangaea altered Earth’s geology and biodiversity

Coming from the Greek words for “all” (pan) and “Earth” (gaia), the supercontinent existed from about 320 million to 195 million years ago. The tectonic activity that split Pangaea into today’s continents may one day bring the continents back together, forming Pangaea Proxima.

Panpsychism suggests that all matter possesses consciousness

The theory describes consciousness as a fundamental, ubiquitous property, rather than separate or emerging from matter. Cosmopsychism posits that the universe is conscious, while some critics argue that consciousness itself may be an illusion.

How do planets form? An interview with a planetary scientist

Dr Farzana Meru, assistant professor and planetary scientist, shares how planets come to be in this interview. Protoplanetary discs are swirling, dusty, and gaseous formations that form and revolve around stars. Some 4,000 extra-solar planets have already been discovered, and through these protoplanetary discs more are on the way.

The universe may have been reborn from a state of emptiness

Some physicists propose the universe might be the latest in an eternal cycle of universes, each emerging from the empty remains of the one before. This model is inspired partly by Norse and Egyptian myth, suggesting the universe is a cosmic ouroboros—a self-consuming serpent representing an eternal return.

How humans are engineering the planet

One fact about our time is becoming increasingly well-known. No matter how far you travel, no matter in which direction you point, there is nowhere on Earth that remains free from the traces of human activity.

Up to 8% of the human genome consists of ancient viral DNA

Human endogenous retroviruses are remnants of infections that affected human primate ancestors millions of years ago and were passed on by infiltrating sperm and egg cells. Studies have shown that this DNA may play a role in immune responses and in placental formation.

The inner life of a cell

White blood cells are responsible for protecting the human body from infection. This video uses biophysical data from Harvard researchers to accurately demonstrate what goes on inside one white blood cell as it works within the immune system.

The quest to find natural ways to extend lifespan

Tales of searching for the Fountain of Youth persist. Our modern-day version is marked by promises of pharmaceutical miracles and a proliferation of viral "biohacking" routines. One doctor’s quest to unlock the keys to longevity stimulated much of this renewed fervor, though his ideas are often taken out of context.

The science of symmetry | The Royal Society

Nature is full of symmetries, from spiral galaxies to florets of broccoli. So why do complex creatures break the pattern?This short video discusses why symmetry came to dominate life on Earth, and how many complex life forms, such as humans, transitioned from radial to lateral symmetry.

Computational and biological systems share fundamental principles, like randomness

Proposed by Alan Turing and John von Neumann, the concept originates from how DNA and computers run by executing encoded instructions in parallel. The advent of AI and the temperature parameter has seen neural networks mimic the randomness of protein encoding.

After NASA's Voyager 1 captured Earth as a single pixel as it left the solar system in 1990, astronomer Carl Sagan used the image to reflect on humanity's fragility and the responsibility to protect 'the only world we've ever known.'

Apeirophobia is an overwhelming fear of living forever, perhaps stemming from the brain's inability to conceptualize an infinite life.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

Watch how viruses like Ebola can spill over from animals to humans—and vice-versa.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

Massive blooms of microscopic plankton called dinoflagellates produce the neon blue light seen in glowing tides.

Salvador Dalí believed he was his own dead brother, who had died nine months before he was born

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

In 2018, 26-year-old missionary John Allen Chau was killed by tribesmen after attempting to reach and evangelize on India's isolated North Sentinel Island

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

Explore fun facts from the USPS, including unique post office buildings, a stamp that traveled past Pluto, and more.

Learn more about the history of fireworks, which dates back to an accidental invention during an alchemist's quest for information about immortality.

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

This site reaches millions of visitors who are tired of AI chatbots and seeking human connection. Pretend to be an AI chatbot and ask questions, provide answers, and draw for people in real time.