Let us cross back 5 million years ago when human ancestors had just bid farewell to chimpanzees. Somewhere in Africa. One day, the wind raised the dust from the ground to the sky and then blow it to the South Pole. These dusts are loaded with thousands of microbes from Africa. When the Antarctic snowfall, the dust falls back to the ground with the snow and is permanently frozen in the ice, and the microbes are also sealed up by the “time capsule.”
Until the arrival of humans who are keen to explore, they will see the sky again. Humans extract an ice core, melt it, and culture it in the laboratory. A few months later, amazing things happened: ancient microbes began to grow.
This is not the first ancient creature to be resurrected. In 2000, scientists even revived a microbe that was 250 million years ago. These lives, which were once between life and death, provide a unique opportunity for us to explore the nature of life.
Life is endless, repairs are non-stop
Life can still be resurrected after millions of years of freezing. At first glance, this seems to violate scientific common sense. Take the case of the resurrected Sarado bacterium 2.5 million years ago. In harsh environments, the bacteria grow into hard shells and become dormant spores. Metabolism slows down to the point of death—meaning that their repair of DNA damage has ceased, and these damages are caused by radioactive radiation in the surrounding environment.
This poses a fundamental problem: under ideal conditions of preservation, DNA that cannot be repaired has a half-life of about 160,000 years (ie half of the DNA is degraded during that time). According to this calculation, the biological resources of 2.5 million before, the DNA is only one third of the present! With this DNA alone, you can resurrect your life and make fun of it? Therefore, some people suspect that the so-called resurrected bacteria are nothing but modern bacteria that contaminate the sample.
But biologists who are doing resurrection feats don’t think so. They say that cells can repair their DNA damage as long as they don’t really die, even if the repair work is slow.
This view is supported by a study. The scientists placed a 20,000-year-old bacterium that was extracted and revived from Siberian frozen soil at a freezing temperature of -15 ° C, and then irradiated with ultraviolet rays that could destroy DNA. Within a few hundred days, the DNA in the bacteria is constantly damaged and it seems that there are no signs of repair. But then, some bacteria began to slowly re-bond their DNA fragments together.
Lack of food, own magic
What is interesting about the lives of these “souls and souls” is that they can live for so long by what they eat? Change to us, even if you bring a food cabinet, for a few years, the shelves may have been empty.
But bringing a “food cabinet” can really increase the probability of survival. In 2009, a research team reported that they revived microbes from 30,000 years of salt crystals. The key point is that individuals who have successfully resurrected are frozen with algae cells without exception. They live by eating glycerin that overflows from dead algae cells. It is estimated that glycerol provided by only one algae cell can maintain a microbial organism for 12 million years of survival.
In addition, one thing helps them to survive. When water forms ice, any impurities (including nutrients) are squeezed out of the ice crystals into liquid vesicles with very high salinity. This blisters can remain liquid at -15 °C. Most of the revived microorganisms live in these blisters. Concentrated nutrients allow them to survive on the edge of hunger for a long time.
However, then again, even if food is scarce, they have a coup. Scientists have discovered that after a few months of starving the revived microbes, their rod-shaped bodies mechanically split into small spheres. This may be their survival strategy. Because smaller body types require less energy, and after splitting, the total volume does not change, but the total surface area in contact with the outside world is greatly increased. This means they are more likely to absorb the surrounding nutrients.
Of course, there are things that can be saved, such as reproduction, and microbes are known for their amazing rate of reproduction. Usually, a bacterium will breed for ten generations before it dies. However, in the “time capsule” of microorganisms, breeding activities seem to stop, otherwise limited resources will soon be exhausted.
Evolution has also stagnated
One thing that people are interested in is that evolution is generally inevitable for all life: through generations of reproduction, the body accumulates tiny mutations that drive evolution. But if it can’t breed, will it still evolve?
A research team analyzed bacterial DNA collected from under the seabed, some of which have been buried for more than 5,000 years. They found that although these bacteria did not multiply, their DNA was almost identical to the DNA of bacteria that normally multiply on the seabed. In other words, there is no evidence that bacteria have accumulated mutations in order to adapt to underground life. This is surprising because these biomes have undergone thousands of years of environmental change, from the seabed to the deep underground, and they have not evolved adaptively. This seems to violate the biological rules we usually understand.
This gives biologists an unusual opportunity to study evolution itself. For example, there is a miniature crustacean living in a freshwater lake called otter. Their eggs are attached to the lake bed. Any eggs that are not hatched in time will be gradually buried in the mud at the bottom of the lake. The scientists collected the eggs from the sediment and allowed them to hatch in the laboratory. Thus, an ancient otter was born. Some eggs are six or seven hundred years old. To date, mink is the oldest animal to be resurrected.
Subsequently, scientists will sip otters and modern otters that have been hatched from ancient eggs, or in waters with less nutrients to simulate the ancient environment; or in waters with more nutrients to mimic the modern environment. Then observe their survival competition. Unexpectedly, modern otters always win in both ancient and modern environments. Is modern otter more adapted to the ancient environment than its ancestors? For example, is it easier for modern people to adapt to the ancient environment of no water, no electricity, no nets than the ancients of six or seven hundred years ago? This confusing mystery remains unresolved.
Resurrection creatures everywhere
The presence of resurrection microbes may be more prevalent than we might think. Imagine that the frequent geological activities on the surface of the Earth often bring some microorganisms buried in the ground back to the surface. If they are still alive, they can even hybridize with modern microorganisms. This “crossing” type of mating may be widespread in the wild. Some researchers believe that the evolution of microbes accelerated after the glacial period, partly because of this.
As the global warming warms, the resurrection of ancient creatures is increasingly closely related to human life. For example, in 2016, the embers in Siberia broke out, causing at least one death. The pathogen responsible for this accident is allegedly from the remains of reindeer that died of anthrax 70 years ago. For decades, the body has been preserved in permafrost, but a heat wave thawed it, and the deadly anthrax was resurrected and released.