Life Did Not Originate on Earth? 2 Billion-Year-Old Asteroid With 'Human DNA' Goes Viral

Did humans not originate from Earth? That is a question which has always puzzled scientists. Now, a social media claim has gone viral as it states that a 2 billion-year-old asteroid contains human DNA components and that life on Earth may have indeed come from space. Firstly, the asteroid being talked about is not just two, but actually 4.5 billion years old.

This very contentious idea, which is linked to the theory of panspermia, has always intrigued a lot of people around the world. The excitement in this case is based on results from NASA's OSIRIS-REx mission to the near Earth asteroid Bennu, which returned rock and dust samples in 2023. Shockingly, analysis of these samples has revealed some organic chemistry that existed before life arose on our planet.

However, the interpretation or rather implication, that this makes up human DNA or direct evidence that life originated off Earth could be an overreach to what the science actually shows.

Did Humans Not Originate on Earth?

The viral theory here posits that Bennu, which is a carbon rich asteroid formed over 4.5 billion years ago, contains chemical precursors to DNA and RNA and that these were preserved much before life began on Earth. Also, scientific analysis of Bennu's samples has indeed detected a shocking suite of organic molecules. Among these are 14 of the 20 amino acids used by organisms on Earth to build proteins, and the five nucleobases that form the core components of DNA and RNA molecules on our planet.

Moreover, some of these findings were actually reported by NASA and its collaborators in peer-reviewed studies published in Nature and Nature Astronomy. The detection of these molecules in such pristine extraterrestrial material does support the idea that the basic chemical ingredients for life were present in the early solar system and may have been delivered to Earth by space rock.

Furthermore, beyond amino acids and nucleobases, more discoveries in Bennu's samples include bio essential sugars such as ribose and glucose. Ribose, for context here, plays a main role in the backbone of RNA, and its detection in Bennu's material for the first time in an extraterrestrial sample does, in a way, back up scenarios in which key biochemical components might form naturally in space. Also, these sugars complemented earlier findings of phosphates and other organic compounds, implying that conditions for complex chemical processes were more abundant in the early solar system than previously thought.

Now, in science, such discoveries increase interest in how life's building blocks might form and spread. The theory of panspermia does not claim that fully formed life travelled here from the stars like an ET-like Hollywood scenario, but instead that organic compounds necessary for life could have been delivered to the young Earth by comets, asteroids or even interplanetary dust.

So, if this is correct, it may mean that the raw materials for life are common throughout the cosmos and that life's emergence elsewhere might be more plausible than once thought. But, this is where we hit the caution button because the distinction between delivering organic precursors and delivering living organisms is very important. Current evidence does not support the latter.

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Fact Check and What Science Actually Says

Let us now get to what has actually been proven, because despite the viral theories, there is currently no evidence that Bennu contains human DNA or that life itself originated on the asteroid. What scientists have found are chemical components that on Earth are associated with life's chemistry, but they are not evidence of life. The nucleobases detected in Bennu samples are the same molecules that on Earth serve as the building blocks for DNA and RNA, but they were formed through natural chemical processes unrelated to living organisms as per sources. Similarly, amino acids, the molecules that form proteins, can arise in non-biological contexts as a result of simple chemistry under the right conditions.

Importantly, here, the samples returned from Bennu show equal proportions of left and right handed versions of these molecules. On Earth, biological systems almost always use left handed amino acids, and this 'handedness' or chirality is a basic of life as we know it. The racemic mixture found in Bennu indicates that the asteroid's organic molecules were formed in space without influence from terrestrial biology and that the homochirality essential to life on Earth must have emerged later through processes not yet fully understood.

Scientists are also careful to emphasise that while Bennu's materials are ancient, the samples do not show any evidence of having undergone biological processes. Whether these materials directly contributed to the origin of life here on Earth is still an open question and an active area of research. So, no, life did not arrive here from some alien star or planet, but whether some building blocks of it did, could still be debated.