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  • Prolonged space travel takes a severe toll on the human body.

  • Microgravity impairs muscle and bone growth,

  • and high doses of radiation cause irreversible mutations.

  • As we seriously consider the human species becoming space-faring,

  • a big question stands.

  • Even if we break free from Earth's orbit

  • and embark on long-duration journeys among the stars,

  • can we adapt to the extreme environments of space?

  • This won't be the first time that humans have adapted to harsh environments

  • and evolved superhuman capabilities.

  • Not fantastical powers like laser vision or invisibility,

  • but physiological adaptations for survival in tough conditions.

  • For example, on the Himalayan mountains

  • where the highest elevation is nine kilometers above sea level,

  • an unacclimated lowland human will experience symptoms of hypoxia,

  • commonly known as mountain sickness.

  • At these altitudes, the body usually produces extra red blood cells,

  • thickening the blood and impeding its flow.

  • But Himalayans who have lived on these mountains for thousands of years

  • permanently evolved mechanisms to circumvent this process

  • and maintain normal blood flow.

  • Cases like that prove that humans can develop permanent lifesaving traits.

  • But natural adaptation for entire human populations

  • could take tens of thousands of years.

  • Recent scientific advances may help us accelerate human adaptation

  • to single generations.

  • To thrive as a species during space travel,

  • we could potentially develop methods

  • to quickly program protective abilities into ourselves.

  • A beta version of these methods is gene therapy,

  • which we can currently use to correct genetic diseases.

  • Gene editing technology, which is improving rapidly,

  • allows scientists to directly change the human genome

  • to stop undesirable processes or make helpful substances.

  • An example of an unwanted process

  • is what happens when our bodies are exposed to ionizing radiation.

  • Without an atmospheric barrier and a magnetic field like Earth's,

  • most planets and moons are bombarded with these dangerous subatomic particles.

  • They can pass through nearly anything

  • and would cause potentially cancerous DNA damage to space explorers.

  • But what if we could turn the tables on radiation?

  • Human skin produces a pigment called melanin

  • that protects us from the filtered radiation on Earth.

  • Melanin exists in many forms across species,

  • and some melanin-expressing fungi

  • use the pigment to convert radiation into chemical energy.

  • Instead of trying to shield the human body,

  • or rapidly repair damage,

  • we could potentially engineer humans

  • to adopt and express these fungal, melanin-based energy- systems.

  • They'd then convert radiation into useful energy while protecting our DNA.

  • This sounds pretty sci-fi,

  • but may actually be achievable with current technology.

  • But technology isn't the only obstacle.

  • There are ongoing debates on the consequences

  • and ethics of such radical alterations to our genetic fabric.

  • Besides radiation,

  • variation in gravitational strength is another challenge for space travelers.

  • Until we develop artificial gravity in a space ship or on another planet,

  • we should assume that astronauts will spend time living in microgravity.

  • On Earth, human bone and muscle custodial cells

  • respond to the stress of gravity's incessant tugging

  • by renewing old cells in processes known as remodeling and regeneration.

  • But in a microgravity environment like Mars,

  • human bone and muscle cells won't get these cues,

  • resulting in osteoporosis and muscle atrophy.

  • So, how could we provide an artificial signal for cells

  • to counteract bone and muscle loss?

  • Again, this is speculative,

  • but biochemically engineered microbes inside our bodies

  • could churn out bone and muscle remodeling signaling factors.

  • Or humans could be genetically engineered

  • to produce more of these signals in the absence of gravity.

  • Radiation exposure and microgravity are only two of the many challenges

  • we will encounter in the hostile conditions of space.

  • But if we're ethically prepared to use them,

  • gene editing and microbial engineering are two flexible tools

  • that could be adapted to many scenarios.

  • In the near future, we may decide to further develop

  • and tune these genetic tools for the harsh realities of space living.

Prolonged space travel takes a severe toll on the human body.

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TED-ED】長期の宇宙旅行を生き残れるか?- リサ・ニップ (【TED-Ed】Could we survive prolonged space travel? - Lisa Nip)

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    VoiceTube に公開 2021 年 01 月 14 日
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