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Can 'human' become a genus due to space colonization?

Can 'human' become a genus due to space colonization?


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I have read that during the Second World War, some mosquitoes got trapped in the London underground railway system. The mosquitoes never got out and eventually they became a new species by themselves.

I had a similar thought. In the next few centuries, if humans could, in theory, colonize other planets like Mars, Proxima Centauri and beyond, then the environments there are not the same as Earth. So, in the long term, humans who would be born and who would grow up on Mars, for example may become more and more suited to Martian conditions than Earths.

Now, when early humans explored and ventured into new geographical areas, they did change characteristics, but we are still one species Sapiens. But living extraterrestrial, is a whole new thing. The gravity alters, the entire atmospheric composition does. So that is going to have some significant changes on humans.

So, my question is: is it possible that in millions or even billions of years, if humans expand to space, there may arise separate species of humans? And would this new emergence of human species actually result in humans moving one step up the taxonomical ladder: becoming a genus?

EDIT: To avoid confusion and create speculations at the answers, I should specify that I am talking about a very particular case: if Sapiens are living in different planets, then is there a chance that Sapiens will become a new genus, and that Homo can be taken one step higher in the taxonomical order? There would still be Sapiens on Earth, but considering the environmental changes that could happen here too, humans then can be drastically different from humans now. So the question is: can 'Sapiens' become a genus?

Thanks to @tyersome and @jamesqf for pointing this out.


The concept you are referring to is speciation and it has been well studied in a wide variety of different natural organisms. I suppose here we are talking about the biological species concept.

The overall answer is yes it is possible, but critically depends on a few different factors. The reality of speciation in the wild is very complex, but these are some things to consider:

Genetic isolation

If two groups, such as your Martian colony and humans on earth isolate from one another, then for speciation to occur, there needs to be a significant level of genetic differentiation between them. This means substantial differences in the kinds of genetic variants found at positions along the genome.

Genetic differences are eroded by post-isolation gene flow - in your example, that might mean a spaceship flying back to Earth with Martian colonists, who then have offspring with people on Earth.

Although there is plenty of evidence that speciation with gene flow can occur, the general rule of thumb is that increased gene flow means a longer divergence time is required to fully speciate.

In nature, this is often caused by some kind of geographic barrier to gene flow, such as mountains or rivers forming, but it can also be caused by morphological differences, such as variation in sexual appendages. Of course, in our example, this barrier to gene-flow would be the large and difficult to traverse distance between the Earth and Mars.

Divergence time

You alluded to some kind of separation time, and you are right to be talking on the scale of millions of years. Speciation can occur extremely quickly; in Lake Tanganyika cichlids, it has occurred probably within the last 15,000 years. Humans have created whole new species of crops, such as maize, within the past 10,000 years. There is even evidence of some fish speciating in 3000 generations.

However speciation is often a much longer process. For example humans and chimps were thought to speciate in 4.5 millions years.

Of course, there is an interaction with several other factors. All other things being equal, less post-isolation gene flows results in a shorter time to speciation and vice versa. Stronger selective pressure between the different environments leads to a more rapid accumulation of genetic differences.

As Konrad Rudolph correctly points out, divergence time is strongly related to generation time, with all other things being equal, a shorter generation time, results in faster speciation.

Selection pressures & differing environments

I think the last main factor governing speciation is how different the Martian colonists environment was from that on Earth.

Different environments can lead to natural selection occurring in opposing directions in the two populations, leading to ecological speciation. Speciation can proceed without differing environments, where neutral drift in allele frequencies can eventually cause speciation, but this will be a long process.

Speciation will occur much more rapidly if there is a start difference in environment and selection pressures between the two groups.

So in conclusion, given enough time, genetic isolation and differential selection pressures (or some combination of the above), it is plausible that a new species of human could form. However, given the time-scales required, it seems a bit unlikely to me.

EDIT

I think it is worth pointing out what @Jaquez said in the comments. If current terrestrial humans split from an extraterrestrial source to form another species, it would be named as another species within the Homo, such as Homo extraterrestrialis, for example. The addition of a new species does not move the group Homo up to become an e.g. Tribe or Family.


I do not believe it will happen. There are multiple roadblocks:

First, speciation time is measured in generations, not years. The human generation time is long, the 3000 generations mentioned in another answer for a fish translates to nearly 100,000 years. Are human populations not going to interbreed over a time span that long?

Second, the speed of speciation is a function of the evolutionary pressure. We radically alter our environment and change the whole driving force--genes which make one more or less able to survive the rigors of the environment have almost no effect anymore. To the extent that human evolution will occur it will be mostly towards things that favor reproductive success--things which attract mates, a desire for children, contraceptive unreliability. These things aren't going to be substantially different on Mars than on Earth.

Finally, we are already to the point that we can make designer babies to some degree, although we can't yet do it with the sort of reliability needed to ethically do it on humans. I find it inconceivable that we can remain a technological species (as would be required to have a population on Mars) without reaching the point that we can freely rewrite the genetic code at least during reproduction. If there is a speciation event it will come from the lab, not evolution. It's possible that some day there will be a modification developed that is a substantial upgrade but which is not compatible with existing humans--those with the modification can only breed with others that have it.


As others have noted, the key concept is speciation. Imagine some H. sapiens living on Mars. How are they going to breathe? Presumably we have a nuclear reactor generating power, which in turn is used to make oxygen. What is it breaks down? Those who can tolerate low oxygen levels might do better. Here on Earth we invest a lot of energy in building bones and things to resist gravity. On Mars there may be less need to do this, and more need to be efficient with oxygen and tolerate higher levels of CO2. So some mutations that would be sub-optimal on Earth might be beneficial to the colonists. Couple this with isolation, as others have mentioned, and the two populations may drift apart, leading to the eventual emergence of H martiansis (or whatever.).


Colonization

Abstract

Colonization is the arrival of individuals to areas of suitable habitat that are currently uninhabited. Populations are established by the successful colonizers that survive and reproduce. Colonization is a spatial process central to several fundamental concepts in ecology, including species coexistence, disturbance and recovery, succession, metapopulations, biodiversity, invasive species, and speciation. We consider the influence of colonization on each of these processes around the central theme of colonization–extinction balance. At the smallest scale, individual recruitment (colonization) and mortality (extinction) determine the density and persistence of a population. At a slightly larger scale, small disturbances of a competitive dominant can open space allowing good colonizers to coexist with dominant competitors via competition–colonization tradeoff. Large disturbances may result in a landscape with communities in different successional stages and, therefore, higher regional biodiversity. On continental scales, colonization–extinction balance sheds light on patterns of biodiversity through ‘island biogeography theory’. We consider the influence of colonization on disease dynamics, range expansion, and spatial spread, with particular emphasis on anthropogenic effects that enhance colonization rates. Over a longer timescale, colonization of new niche space may lead to niche expansion or speciation.


The Future of Space Colonization – Terraforming or Space Habitats?

The idea of terraforming Mars – aka “Earth’s Twin” – is a fascinating idea. Between melting the polar ice caps, slowly creating an atmosphere, and then engineering the environment to have foliage, rivers, and standing bodies of water, there’s enough there to inspire just about anyone! But just how long would such an endeavor take, what would it cost us, and is it really an effective use of our time and energy?

Such were the questions dealt with by two papers presented at NASA’s “Planetary Science Vision 2050 Workshop” last week (Mon. Feb. 27th – Wed. Mar. 1st). The first, titled “The Terraforming Timeline“, presents an abstract plan for turning the Red Planet into something green and habitable. The second, titled “Mars Terraforming – the Wrong Way“, rejects the idea of terraforming altogether and presents an alternative.

The former paper was produced by Aaron Berliner from the University of California, Berkeley, and Chris McKay from the Space Sciences Division at NASA Ames Research Center. In their paper, the two researchers present a timeline for the terraforming of Mars that includes a Warming Phase and an Oxygenation Phase, as well as all the necessary steps that would precede and follow.

Artist’s impression of the terraforming of Mars, from its current state to a livable world. Credit: Daein Ballard

As they state in their paper’s Introduction:

“Terraforming Mars can be divided into two phases. The first phase is warming the planet from the present average surface temperature of -60° C to a value close to Earth’s average temperature to +15° C, and recreating a thick CO² atmosphere. This warming phase is relatively easy and quick, and could take

100 years. The second phase is producing levels of O² in the atmosphere that would allow humans and other large mammals to breath normally. This oxygenation phase is relatively difficult and would take 100,000 years or more, unless one postulates a technological breakthrough.”

Before these can begin, Berliner and McKay acknowledge that certain “pre-terraforming” steps need to be taken. These include investigating Mars’ environment to determine the levels of water on the surface, the level of carbon dioxide in the atmosphere and in ice form in the polar regions, and the amount of nitrates in Martian soil. As they explain, all of these are key to the practicality of making a biosphere on Mars.

So far, the available evidence points towards all three elements existing in abundance on Mars. While most of Mars water is currently in the form of ice in the polar regions and polar caps, there is enough there to support a water cycle – complete with clouds, rain, rivers and lakes. Meanwhile, some estimates claim that there is enough CO² in ice form in the polar regions to create an atmosphere equal to the sea level pressure on Earth.

Nitrogen is also a fundamental requirement for life and necessary constituent of a breathable atmosphere, and recent data by the Curiosity Rover indicate that nitrates account for

0.03% by mass of the soil on Mars, which is encouraging for terraforming. On top of that, scientists will need to tackle certain ethical questions related to how terraforming could impact Mars.

Artist’s concept of a possible Mars terraforming plant. Credit: National Geographic Channel

For instance, if there is currently any life on Mars (or life that could be revived), this would present an undeniable ethical dilemma for human colonists – especially if this life is related to life on Earth. As they explain:

“If Martian life is related to Earth life – possibly due to meteorite exchange – then the situation is familiar, and issues of what other types of Earth life to introduce and when must be addressed. However, if Martian life in unrelated to Earth life and clearly represents a second genesis of life, then significant technical and ethical issues are raised.”

To break Phase One – “The Warming Phase” – down succinctly, the authors address an issue familiar to us today. Essentially, we are altering our own climate here on Earth by introducing CO² and “super greenhouse gases” to the atmosphere, which is increasing Earth’s average temperature at a rate of many degrees centigrade per century. And whereas this has been unintentional on Earth, on Mars it could be re-purposed to deliberately warm the environment.

“The timescale for warming Mars after a focused effort of super greenhouse gas production is short, only 100 years or so,” they claim. “If all the solar incident on Mars were to be captured with 100% efficiency, then Mars would warm to Earth-like temperatures in about 10 years. However, the efficiency of the greenhouse effect is plausibly about 10%, thus the time it would take to warm Mars would be

Mars’ south polar ice cap, as seen in April of 2000 by the Mars Odyssey mission. Credit: NASA/JPL/MSSS

Once this thick atmosphere has been created, the next step involves converting it into something breathable for humans – where O² levels would be the equivalent of about 13% of sea level air pressure here on Earth and CO² levels would be less than 1%. This phase, known as the “Oxygenation Phase”, would take considerably longer. Once again, they turn towards a terrestrial example to show how such a process could work.

Here on Earth, they claim, the high levels of oxygen gas (O²) and low levels of CO² are due to photosynthesis. These reactions rely on the sun’s energy to convert water and carbon dioxide into biomass – which is represented by the equation H²O + CO² = CH²O + O². As they illustrate, this process would take between 100,000 and 170,000 years:

“If all the sunlight incident on Mars was harnessed with 100% efficiency to perform this chemical transformation it would take only 17 years to produce high levels of O². However, the likely efficiency of any process that can transform H²O and CO² into biomass and O² is much less than 100%. The only example we have of a process that can globally alter the CO² and O² of an entire plant is global biology. On Earth the efficiency of the global biosphere in using sunlight to produced biomass and O2 is 0.01%. Thus the timescale for producing an O² rich atmosphere on Mars is 10,000 x 17 years, or

However, they make allowances for synthetic biology and other biotechnologies, which they claim could increase the efficiency and reduce the timescale to a solid 100,000 years. In addition, if human beings could utilize natural photosynthesis (which has a comparatively high efficiency of 5%) over the entire planet – i.e. planting foliage all over Mars – then the timescale could be reduced to even a few centuries.

Finally, they outline the steps that need to be taken to get the ball rolling. These steps include adapting current and future robotic missions to assess Martian resources, mathematical and computer models that could examine the processes involved, an initiative to create synthetic organisms for Mars, a means to test terraforming techniques in a limited environment, and a planetary agreement that would establish restrictions and protections.

Quoting Kim Stanley Robinson, author of the Red Mars Trilogy, (the seminal work of science fiction about terraforming Mars) they issue a call to action. Addressing how long the process of terraforming Mars will take, they assert that we “might as well start now”.

To this, Valeriy Yakovlev – an astrophysicist and hydrogeologist from Laboratory of Water Quality in Kharkov, Ukraine – offers a dissenting view. In his paper, “Mars Terraforming – the Wrong Way“, he makes the case for the creation of space biospheres in Low Earth Orbit that would rely on artificial gravity (like an O’Neill Cylinder) to allow humans to grow accustomed to life in space.

Looking to one of the biggest challenges of space colonization, Yakovlev points to how life on bodies like the Moon or Mars could be dangerous for human settlers. In addition to being vulnerable to solar and cosmic radiation, colonists would have to deal with substantially lower gravity. In the case of the Moon, this would be roughly 0.165 times that which humans experience here on Earth (aka. 1 g), whereas on Mars it would be roughly 0.376 times.

Interior view of an O’Neill Cylinder. There are alternating strips of livable surface and “windows” to let light in. Credit: Rick Guidice/NASA Ames Research Center

The long-term effects of this are not known, but it is clear it would include muscle degeneration and bone loss. Looking farther, it is entirely unclear what the effects would be for those children who were born in either environment. Addressing the ways in which these could be mitigated (which include medicine and centrifuges), Yakovlev points out how they would most likely be ineffective:

“The hope for the medicine development will not cancel the physical degradation of the muscles, bones and the whole organism. The rehabilitation in centrifuges is less expedient solution compared with the ship-biosphere where it is possible to provide a substantially constant imitation of the normal gravity and the protection complex from any harmful influences of the space environment. If the path of space exploration is to create a colony on Mars and furthermore the subsequent attempts to terraform the planet, it will lead to the unjustified loss of time and money and increase the known risks of human civilization.”

In addition, he points to the challenges of creating the ideal environment for individuals living in space. Beyond simply creating better vehicles and developing the means to procure the necessary resources, there is also the need to create the ideal space environment for families. Essentially, this requires the development of housing that is optimal in terms of size, stability, and comfort.

In light of this, Yakolev presents what he considers to be the most likely prospects for humanity’s exit to space between now and 2030. This will include the creation of the first space biospheres with artificial gravity, which will lead to key developments in terms of materials technology, life support-systems, and the robotic systems and infrastructure needed to install and service habitats in Low Earth Orbit (LEO).

Artist’s depiction of a pair of O’Neill cylinders. Credit: Rick Guidice/NASA Ames Research Center

These habitats could be serviced thanks to the creation of robotic spacecraft that could harvest resources from nearby bodies – such as the Moon and Near-Earth Objects (NEOs). This concept would not only remove the need for planetary protections – i.e. worries about contaminating Mars’ biosphere (assuming the presence of bacterial life), it would also allow human beings to become accustomed to space more gradually.

As Yakovlev told Universe Today via email, the advantages to space habitats can be broken down into four points:

𔄙. This is a universal way of mastering the infinite spaces of the Cosmos, both in the Solar System and outside it. We do not need surfaces for installing houses, but resources that robots will deliver from planets and satellites. 2. The possibility of creating a habitat as close as possible to the earth’s cradle allows one to escape from the inevitable physical degradation under a different gravity. It is easier to create a protective magnetic field.

𔄛. The transfer between worlds and sources of resources will not be a dangerous expedition, but a normal life. Is it good for sailors without their families? 4. The probability of death or degradation of mankind as a result of the global catastrophe is significantly reduced, as the colonization of the planets includes reconnaissance, delivery of goods, shuttle transport of people – and this is much longer than the construction of the biosphere in the Moon’s orbit. Dr. Stephen William Hawking is right, a person does not have much time.”

And with space habitats in place, some very crucial research could begin, including medical and biologic research which would involve the first children born in space. It would also facilitate the development of reliable space shuttles and resource extraction technologies, which will come in handy for the settlement of other bodies – like the Moon, Mars, and even exoplanets.

Ultimately, Yakolev thinks that space biospheres could also be accomplished within a reasonable timeframe – i.e. between 2030 and 2050 – which is simply not possible with terraforming. Citing the growing presence and power of the commercial space sector, Yakolev also believed a lot of the infrastructure that is necessary is already in place (or under development).

“After we overcome the inertia of thinking +20 years, the experimental biosphere (like the settlement in Antarctica with watches), in 50 years the first generation of children born in the Cosmos will grow and the Earth will decrease, because it will enter the legends as a whole… As a result, terraforming will be canceled. And the subsequent conference will open the way for real exploration of the Cosmos. I’m proud to be on the same planet as Elon Reeve Musk. His missiles will be useful to lift designs for the first biosphere from the lunar factories. This is a close and direct way to conquer the Cosmos.”

With NASA scientists and entrepreneurs like Elon Musk and Bas Landorp looking to colonize Mars in the near future, and other commercial aerospace companies developing LEO, the size and shape of humanity’s future in space is difficult to predict. Perhaps we will jointly decide on a path that takes us to the Moon, Mars, and beyond. Perhaps we will see our best efforts directed into near-Earth space.

Or perhaps we will see ourselves going off in multiple directions at once. Whereas some groups will advocate creating space habitats in LEO (and later, elsewhere in the Solar System) that rely on artificial gravity and robotic spaceships mining asteroids for materials, others will focus on establishing outposts on planetary bodies, with the goal of turning them into “new Earths”.

Between them, we can expect that humans will begin developing a degree of “space expertise” in this century, which will certainly come in handy when we start pushing the boundaries of exploration and colonization even further!


Evidence of Late Pleistocene human colonization of isolated islands beyond Wallace's Line

A new article published in Nature Communications applies stable isotope analysis to a collection of fossil human teeth from the islands of Timor and Alor in Wallacea to study the ecological adaptations of the earliest members of our species to reach this isolated part of the world. Because the Wallacean islands are considered extreme, resource poor settings, archaeologists believed that early seafaring populations would have moved rapidly through this region without establishing permanent communities. Nevertheless, this has so far been difficult to test.

This study, led by scientists from the Department of Archaeology, Max Planck Institute for the Science of Human History (MPI SHH), alongside colleagues from the Australian National University and Universitas Gadjah Mada, used an isotopic methodology that reveals the resources consumed by humans during the period of tooth formation. They demonstrate that the earliest human fossil so far found in the region, dating to around 42,000-39,000 years ago, relied upon coastal resources. Yet, from 20,000 years ago, humans show an increasing reliance on tropical forest environments, away from the island coasts. The results support the idea that one distinguishing characteristic of Homo sapiens is high ecological flexibility, especially when compared to other hominins known from the same region.

Pleistocene hominin adaptations in Southeast Asia

Over the last two decades, archaeological evidence from deserts, high-altitude settings, tropical rainforests, and maritime habitats seem to increasingly suggest that Late Pleistocene humans rapidly adapted to a number of extreme environments. By contrast, our closest hominin relatives, such as Homo erectus and Neanderthals, apparently used various mixtures of forests and grasslands, albeit from as far apart as the Levant, Siberia, and Java. However, this apparent distinction needs testing, especially as finds of another closely related hominin, the Denisovans, have been found on the high-altitude Tibetan Plateau.

As one of the corresponding authors on the new paper, Sue O'Connor of Australian National University says, "The islands beyond Wallace's Line are ideal places to test the adaptive differences between our species and other hominins. These islands were never connected to mainland Southeast Asia during the Pleistocene, and would have ensured that hominins had to make water crossings to reach it." Tropical forest settings like those in Wallacea are often considered barriers to human expansion and are a far cry from the sweeping 'savannahs' with an abundance of medium to large mammals that hominins are believed to have relied on.

Fossils and stone tools show that hominins made it to Wallacean islands at least one million years ago, including the famous 'Hobbit,' or Homo floresiensis, on the island of Flores. When our own species arrived 45,000 years ago (or perhaps earlier), it is thought to have quickly developed the specialized use of marine habitats, as evidenced by one of the world's earliest fish hooks found in the region. Nevertheless, as co-author Ceri Shipton puts it "the extent of this maritime adaptation has remained hotly debated and difficult to test using snapshots based on, often poorly preserved, animal remains."

Stable isotope analysis and Late Pleistocene humans

This new paper uses stable carbon isotopes measured from fossil human teeth to directly reconstruct the long-term diets of past populations. Although this method has been used to study the diets and environments of African hominins for nearly half a century, it has thus far been scarcely applied to the earliest members of our own species expanding within and beyond Africa. Using the principle 'you are what you eat,' researchers analyzed powdered hominin tooth enamel from 26 individuals dated between 42,000 and 1,000 years ago to explore the types of resources they consumed during tooth formation.

The new paper shows that the earliest human fossil available from the region, excavated from the site of Asitau Kuru on Timor, was indeed reliant on maritime resources, suggesting a well-tuned adaptation to the colonization of coastal areas. "This fits with our existing models of rapid human movement through Wallacea on the way to Australia," says co-author Shimona Kealy of the Australian National University.

From around 20,000 years ago, however, human diets seem to have switched inland, towards the supposedly impoverished resources of the island forests. Although some individuals maintained the use of coastal habitats, the majority seemingly began to adapt to the populations of small mammals and tropical forest plants in the region. As co-author Mahirta at Universitas Gadjah Mada puts it, "Coastal resources such as shellfish and reef fish are easy to exploit and available year-round, however growing populations likely forced early island occupants to look inland to other resources."

A species defined by flexibility

This study provides the first direct insights into the adaptations of our own species as it settled in a series of challenging island environments in Wallacea. "Early human populations here, and elsewhere, could not only successfully use the enormous variety of often-extreme Pleistocene environments," suggests Patrick Roberts, lead author of the study and Group Leader at MPI SHH, "they could also specialize in them over substantial periods of time. As a result, even if some local populations did fail, the species as a whole would go on to become tremendously prolific."

As dense tropical rainforests replaced mixed grass and woodlands, other hominins in Southeast Asia went extinct. Ecological flexibility, supported by unique technologies and the capacity for social relationships and symbolism, seem to have carried Homo sapiens through the climactic fluctuations of the Late Pleistocene, however. The authors concede that more work is needed to conclusively test the ecological distinction between hominin species. The discovery of Denisovan populations in the tropical environments of Asia or application of this isotopic approach to other hominins in the tropics could yet show Homo sapiens to be less exceptional. Nonetheless, for the time being it seems that it was our species that could best adapt to the variety of environments across the face of the planet, leaving it, by the end of the Pleistocene, the last hominin standing.


The future of space colonization – terraforming or space habitats?

Artist's concept of a terraformed Mars (left) and an O'Neill Cylinder. Credit: Ittiz/Wikimedia Commons (left)/Rick Guidice/NASA Ames Research Center (right)

The idea of terraforming Mars – aka "Earth's Twin" – is a fascinating idea. Between melting the polar ice caps, slowly creating an atmosphere, and then engineering the environment to have foliage, rivers, and standing bodies of water, there's enough there to inspire just about anyone! But just how long would such an endeavor take, what would it cost us, and is it really an effective use of our time and energy?

Such were the questions dealt with by two papers presented at NASA's "Planetary Science Vision 2050 Workshop" last week (Mon. Feb. 27th – Wed. Mar. 1st). The first, titled "The Terraforming Timeline", presents an abstract plan for turning the Red Planet into something green and habitable. The second, titled "Mars Terraforming – the Wrong Way", rejects the idea of terraforming altogether and presents an alternative.

The former paper was produced by Aaron Berliner from the University of California, Berkeley, and Chris McKay from the Space Sciences Division at NASA Ames Research Center. In their paper, the two researchers present a timeline for the terraforming of Mars that includes a Warming Phase and an Oxygenation Phase, as well as all the necessary steps that would precede and follow.

As they state in their paper's Introduction:

"Terraforming Mars can be divided into two phases. The first phase is warming the planet from the present average surface temperature of -60° C to a value close to Earth's average temperature to +15° C, and recreating a thick CO² atmosphere. This warming phase is relatively easy and quick, and could take

100 years. The second phase is producing levels of O² in the atmosphere that would allow humans and other large mammals to breath normally. This oxygenation phase is relatively difficult and would take 100,000 years or more, unless one postulates a technological breakthrough."

Before these can begin, Berliner and McKay acknowledge that certain "pre-terraforming" steps need to be taken. These include investigating Mars' environment to determine the levels of water on the surface, the level of carbon dioxide in the atmosphere and in ice form in the polar regions, and the amount of nitrates in Martian soil. As they explain, all of these are key to the practicality of making a biosphere on Mars.

So far, the available evidence points towards all three elements existing in abundance on Mars. While most of Mars water is currently in the form of ice in the polar regions and polar caps, there is enough there to support a water cycle – complete with clouds, rain, rivers and lakes. Meanwhile, some estimates claim that there is enough CO² in ice form in the polar regions to create an atmosphere equal to the sea level pressure on Earth.

Nitrogen is a also fundamental requirement for life and necessary constituent of a breathable atmosphere, and recent data by the Curiosity Rover indicate that nitrates account for

0.03% by mass of the soil on Mars, which is encouraging for terraforming. On top of that, scientists will need to tackle certain ethical questions related to how terraforming could impact Mars.

For instance, if there is currently any life on Mars (or life that could be revived), this would present an undeniable ethical dilemma for human colonists – especially if this life is related to life on Earth. As they explain:

Artist’s impression of the terraforming of Mars, from its current state to a livable world. Credit: Daein Ballard

"If Martian life is related to Earth life – possibly due to meteorite exchange – then the situation is familiar, and issues of what other types of Earth life to introduce and when must be addressed. However, if Martian life in unrelated to Earth life and clearly represents a second genesis of life, then significant technical and ethical issues are raised."

To break Phase One – "The Warming Phase" – down succinctly, the authors address an issue familiar to us today. Essentially, we are altering our own climate here on Earth by introducing CO² and "super greenhouse gases" to the atmosphere, which is increasing Earth's average temperature at a rate of many degrees centigrade per century. And whereas this has been unintentional on Earth, on Mars it could be re-purposed to deliberately warm the environment.

"The timescale for warming Mars after a focused effort of super greenhouse gas production is short, only 100 years or so," they claim. "If all the solar incident on Mars were to be captured with 100% efficiency, then Mars would warm to Earth-like temperatures in about 10 years. However, the efficiency of the greenhouse effect is plausibly about 10%, thus the time it would take to warm Mars would be

Once this thick atmosphere has been created, the next step involves converting it into something breathable for humans – where O² levels would be the equivalent of about 13% of sea level air pressure here on Earth and CO² levels would be less than 1%. This phase, known as the "Oxygenation Phase", would take considerably longer. Once again, they turn towards a terrestrial example to show how such a process could work.

Here on Earth, they claim, the high levels of oxygen gas (O²) and low levels of CO² are due to photosynthesis. These reactions rely on the sun's energy to convert water and carbon dioxide into biomass – which is represented by the equation H²O + CO² = CH²O + O². As they illustrate, this process would take between 100,000 and 170,000 years:

"If all the sunlight incident on Mars was harnessed with 100% efficiency to perform this chemical transformation it would take only 17 years to produce high levels of O². However, the likely efficiency of any process that can transform H²O and CO² into biomass and O² is much less than 100%. The only example we have of a process that can globally alter the CO² and O² of an entire plant is global biology. On Earth the efficiency of the global biosphere in using sunlight to produced biomass and O2 is 0.01%. Thus the timescale for producing an O² rich atmosphere on Mars is 10,000 x 17 years, or

However, they make allowances for synthetic biology and other biotechnologies, which they claim could increase the efficiency and reduce the timescale to a solid 100,000 years. In addition, if human beings could utilize natural photosynthesis (which has a comparatively high efficiency of 5%) over the entire planet – i.e. planting foliage all over Mars – then the timescale could be reduced to even a few centuries.

Finally, they outline the steps that need to be taken to get the ball rolling. These steps include adapting current and future robotic missions to assess Martian resources, mathematical and computer models that could examine the processes involved, an initiative to create synthetic organisms for Mars, a means to test terraforming techniques in a limited environment, and a planetary agreement that would establish restrictions and protections.

Quoting Kim Stanley Robinson, author of the Red Mars Trilogy, (the seminal work of science fiction about terraforming Mars) they issue a call to action. Addressing how long the process of terraforming Mars will take, they assert that we "might as well start now".

Artist’s concept of a possible Mars terraforming plant. Credit: National Geographic Channel

To this, Valeriy Yakovlev – an astrophysicist and hydrogeologist from Laboratory of Water Quality in Kharkov, Ukraine – offers a dissenting view. In his paper, "Mars Terraforming – the Wrong Way", he makes the case for the creation of space biospheres in Low Earth Orbit that would rely on artificial gravity (like an O'Neill Cylinder) to allow humans to grow accustomed to life in space.

Looking to one of the biggest challenges of space colonization, Yakovlev points to how life on bodies like the Moon or Mars could be dangerous for human settlers. In addition to being vulnerable to solar and cosmic radiation, colonists would have to deal with substantially lower gravity. In the case of the Moon, this would be roughly 0.165 times that which humans experience here on Earth (aka. 1 g), whereas on Mars it would be roughly 0.376 times.

The long-term effects of this are not known, but it is clear it would include muscle degeneration and bone loss. Looking farther, it is entirely unclear what the effects would be for those children who were born in either environment. Addressing the ways in which these could be mitigated (which include medicine and centrifuges), Yakovlev points out how they would most likely be ineffective:

"The hope for the medicine development will not cancel the physical degradation of the muscles, bones and the whole organism. The rehabilitation in centrifuges is less expedient solution compared with the ship-biosphere where it is possible to provide a substantially constant imitation of the normal gravity and the protection complex from any harmful influences of the space environment. If the path of space exploration is to create a colony on Mars and furthermore the subsequent attempts to terraform the planet, it will lead to the unjustified loss of time and money and increase the known risks of human civilization."

In addition, he points to the challenges of creating the ideal environment for individuals living in space. Beyond simply creating better vehicles and developing the means to procure the necessary resources, there is also the need to create the ideal space environment for families. Essentially, this requires the development of housing that is optimal in terms of size, stability, and comfort.

In light of this, Yakolev presents what he considers to be the most likely prospects for humanity's exit to space between now and 2030. This will include the creation of the first space biospheres with artificial gravity, which will lead to key developments in terms of materials technology, life support-systems, and the robotic systems and infrastructure needed to install and service habitats in Low Earth Orbit (LEO).

These habitats could be serviced thanks to the creation of robotic spacecraft that could harvest resources from nearby bodies – such as the Moon and Near-Earth Objects (NEOs). This concept would not only remove the need for planetary protections – i.e. worries about contaminating Mars' biosphere (assuming the presence of bacterial life), it would also allow human beings to become accustomed to space more gradually.

As Yakovlev told Universe Today via email, the advantages to space habitats can be broken down into four points:

"1. This is a universal way of mastering the infinite spaces of the Cosmos, both in the Solar System and outside it. We do not need surfaces for installing houses, but resources that robots will deliver from planets and satellites. 2. The possibility of creating a habitat as close as possible to the earth's cradle allows one to escape from the inevitable physical degradation under a different gravity. It is easier to create a protective magnetic field.

Mars’ south polar ice cap, as seen in April of 2000 by the Mars Odyssey mission. Credit: NASA/JPL/MSSS

"3. The transfer between worlds and sources of resources will not be a dangerous expedition, but a normal life. Is it good for sailors without their families? 4. The probability of death or degradation of mankind as a result of the global catastrophe is significantly reduced, as the colonization of the planets includes reconnaissance, delivery of goods, shuttle transport of people – and this is much longer than the construction of the biosphere in the Moon's orbit. Dr. Stephen William Hawking is right, a person does not have much time."

And with space habitats in place, some very crucial research could begin, including medical and biologic research which would involve the first children born in space. It would also facilitate the development of reliable space shuttles and resource extraction technologies, which will come in handy for the settlement of other bodies – like the Moon, Mars, and even exoplanets.

Ultimately, Yakolev thinks that space biospheres could also be accomplished within a reasonable timeframe – i.e. between 2030 and 2050 – which is simply not possible with terraforming. Citing the growing presence and power of the commercial space sector, Yakolev also believed a lot of the infrastructure that is necessary is already in place (or under development).

"After we overcome the inertia of thinking +20 years, the experimental biosphere (like the settlement in Antarctica with watches), in 50 years the first generation of children born in the Cosmos will grow and the Earth will decrease, because it will enter the legends as a whole… As a result, terraforming will be canceled. And the subsequent conference will open the way for real exploration of the Cosmos. I'm proud to be on the same planet as Elon Reeve Musk. His missiles will be useful to lift designs for the first biosphere from the lunar factories. This is a close and direct way to conquer the Cosmos."

With NASA scientists and entrepreneurs like Elon Musk and Bas Landorp looking to colonize Mars in the near future, and other commercial aerospace companies developing LEO, the size and shape of humanity's future in space is difficult to predict. Perhaps we will jointly decide on a path that takes us to the Moon, Mars, and beyond. Perhaps we will see our best efforts directed into near-Earth space.

Or perhaps we will see ourselves going off in multiple directions at once. Whereas some groups will advocate creating space habitats in LEO (and later, elsewhere in the Solar System) that rely on artificial gravity and robotic spaceships mining asteroids for materials, others will focus on establishing outposts on planetary bodies, with the goal of turning them into "new Earths".

Between them, we can expect that humans will begin developing a degree of "space expertise" in this century, which will certainly come in handy when we start pushing the boundaries of exploration and colonization even further.


From World-Changing Ideas

It seems plenty of people want to abandon the Earth. Interest in leaving the home world for a new start on Mars has never been greater and was one of the hot topics at the recent BBC Future World-Changing Ideas Summit in New York.

There is even evidence to suggest it may one day happen. Nasa is tooling-up for production of its new heavy launch vehicle, the Space Launch System (SLS), capable of conveying humans beyond Earth orbit Mars One has recruited hundreds of volunteers for its reality-TV-funded one-way-trip to the Red Planet and the Mars Society is stepping-up its studies into what it takes to be a Martian.

It is easy to imagine that human civilisation on Mars is inevitable. However, before you put all your worldly possessions on eBay and sign-up for a new start in Gale Crater, it is worth considering the obstacles that have to be overcome to build a sustainable extraterrestrial colony. It is not going to be easy.

Here are our five steps to building a new life on Mars:

1. Getting there

Within the next decade Nasa will finally have a spacecraft capable of making the journey to Mars. The massive new 2500 tonne SLS, combined with the Orion capsule, will enable astronauts to explore beyond the safety of low Earth orbit for the first time since the end of the Apollo Moon programme in 1972.

Although any long duration mission is also likely to employ a habitation module, giving the crew a bit more room to move around in, the nine month trip to Mars is going to be uncomfortable and boring. It could also be extremely dangerous.

If humankind is to reach Mars, we will need rockets more powerful than anything built before (Nasa)

Quite apart from the risks of launch (the recent Antares rocket explosion proves we should never take this for granted), during the transit to Mars the crew will be exposed to damaging levels of radiation that will significantly increase their risks of developing cancer. For anyone looking to have healthy Martian children (see below), cosmic radiation could also harm sperm and eggs.

Landing safely on Mars is also a challenge. Nasa used an innovative skycrane to lower its one-tonne Curiosity rover onto the surface in 2012. The Orion capsule weighs almost 10 tonnes and that is before you factor in any service module or landing rockets. The agency is currently developing giant inflatable heatshields designed to slow spacecraft as they approach Mars, making landing larger craft feasible.

The good news is that getting to Mars in one piece is essentially an engineering challenge but, speaking at the BBC Future World-Changing Ideas Summit, former Nasa astronaut Jeff Hoffman put his finger on a far bigger issue.

Astronauts on the International Space Station (ISS) create water supplies from their own urine (Nasa/Getty Images)

“It is going to be expensive,” he admitted. “What it will take to finance the human exploration of Mars is hard to say.”

The final figure is likely to be tens of billions of dollars, but Hoffman suggests that the new generation of entrepreneur billionaires who are “space nuts” might be part of a public-private solution. “[Paypal cofounder] Elon Musk says he wants to go to Mars and I hope he’s successful,” said Hoffman.

2. Become self-sufficient

Having successfully landed on Mars you need air, water, food and power to survive. In the short term you could rely on supplies brought from Earth or sent on supply missions but eventually you are going to have to produce your own.

Nasa’s 2020 rover – essentially an upgrade of Curiosity – will carry an electrolysis experiment to extract oxygen from carbon dioxide in the Martian atmosphere.

The Biosphere 2 project is an attempt to simulate Mars-like conditions on Earth (Science Photo Library)

“For the very first time we’ll produce oxygen on the surface of Mars,” said Hoffman, who’s working on the instrument. “It’s a hundredth of the scale we’ll need for a human expedition, but it’s a start.”

Evidence suggests that Mars was once awash with water – with lakes, rivers and oceans. Today, it is highly likely there is still water at the ice caps and possibly under the surface. Extracting water from urine and sweat through an efficient recycling system – pioneered on the International Space Station (ISS) – will certainly help, but will not be enough to sustain a community, so tapping into a local water source will be essential.

Producing food on Mars could be much more difficult. The non-profit Mars Society has been experimenting with growing food in its isolated desert research station in Utah. “There was some interesting biology we were generating but not appetising biology,” says software engineer and Mars enthusiast Digby Tarvin of his last stint working at the base 10 years ago.

One of the big challenges will be growing food away from Earth (Getty Images)

Tarvin is about to return to the Utah research station to take command and says a lot of progress has been made since then. “People have grown some edible greens but it’s not at the stage we can live on what we produce,” he says. “One of the research projects we’ll be undertaking is to use the local rock as a growing medium by adding sufficient minerals and additives.” The idea is that, ultimately, colonists could grow crops in Martian soil.

As for power, that should be relatively straightforward, with fuel cells and nuclear batteries augmented by solar arrays. Nevertheless, all these resources will need to be carefully managed, which is why the next step is so essential:

3. Form a government

I have written before of the challenges of governing an extraterrestrial colony. The early missions – particularly those involving space agencies – will almost certainly be run with a hierarchical command system. The past 50 years of human spaceflight have taught us that, in the extreme environment of space, this is the safest way. However, there is a fine line between a Star Trek-type command structure and a brutal military dictatorship, and as the settlement matures, some sort of democracy is going to be favoured.

“A space colony is a tyranny-prone environment,” says Charles Cockell, an astrobiologist from the University of Edinburgh who is also leading research on developing a constitution for space habitats. “If somebody gets control of oxygen, they could very well have control over the whole population and threaten dire consequences in return for extraordinary levels of power.”

As a commander of a space colony on Earth, Tarvin is one of the few people to have any experience of overseeing a Mars base. “It’s certainly not a Star Trek-style military environment,” he says. “It’s a small group of highly motivated people and it really doesn’t take much effort to manage them.”

A government also needs all the structures that go with it. Any new society needs an economy as well as systems to maintain the habitat, provide employment, health, childcare, social care and education. In short: Mars needs bureaucrats.

The first Mars settlers will be living in the capsules they arrive in, perhaps augmented by a few extra capsules sent ahead and maybe some inflatable domes. But just as settlers will be utilising local resources for water, food and energy, they will also hope to use local materials to build a larger colony or even spin-off colonies.

At the very least, it would make sense to use Martian rock to bury the habitats to help shield occupants from radiation. Later, the surface could be drilled to form caves or rock could be excavated for building materials – just as we build houses from stone on Earth. It might also be possible to extract useful minerals for metals or glass.

Robert Zubin, the president of the Mars Society, is one of the leading exponents of terraforming Mars – transforming the planet from an airless, barren world to an oxygen-rich green and pleasant realm with a fully functioning ecosystem.

Colonists could use the rocks from the Red Planet's surface to help build shelters (Nasa)

There is, however, a fundamental problem with trying to imbue Mars with a breathable atmosphere. The Earth’s atmosphere is contained within a magnetic bubble, known as the magnetosphere, generated by our magnetic field. Mars has no such field and any atmosphere it once had is likely to have been torn away by the stream of charged particles, or solar wind, blasted out from the Sun.

The past history of the Martian atmosphere is currently being investigated by the Maven mission but, over the decades, any terraformed atmosphere is likely to suffer the same fate.

5. Have children and establish a culture

Assuming their sperm or eggs have not been zapped by cosmic radiation on the way to Mars (something space agencies are already giving serious thought to), then sooner or later a certain percentage of settlers are going to want to have kids. It is, after all, the only way of perpetuating the colony over generations. For it to be successful, the population needs to be large enough to avoid in-breeding over subsequent generations.

Those colonists that settle on Mars are unlikely to ever set foot on Earth again (Science Photo Library)

Cameron Smith, an anthropologist at Portland State University in Oregon, has suggested that a population of 2,000 would be sufficient to ensure long-term survival. “If we’re going to have a long-term future in space, it won’t be done by a handful of astronauts, it’ll be whole communities,” he told BBC Future earlier this year.

Smith reckons that over generations a new culture would emerge, as humans become Martians rather than migrants. It’s a view shared by Zubrin. “At some point the Mars base breaks out of becoming a base and becomes an actual village,” he says. “A real society with real people living real lives, with children in schools and community orchestras.”

A child born under the red sky of Mars will have a very different outlook to one born on Earth and may never return to the home world – just as many descendants of European settlers in the US do not have passports.

Every step to establishing human civilisation on Mars is perfectly possible. With a focused effort it is very much doable. One question then remains: do you really want to go? I mean really? Mars is a bleak, cold, airless, rust-stained world. Simply staying alive will be a daily challenge.

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This deep-sea brittle star survived 180 million years of evolution

These distant cousins of starfish live on sea floors around the globe.

Let me introduce you to Ophiojura, a bizarre deep-sea animal found in 2011 by scientists from the French Natural History Museum, while trawling the summit of a secluded seamount called Banc Durand, 500 metres below the waves and 200 kilometres east of New Caledonia in the southwest Pacific Ocean.

Ophiojura is a type of brittle star, which are distant cousins of starfish, with snake-like arms radiating from their bodies, that live on sea floors around the globe.

Being an expert in deep-sea animals, I knew at a glance that this one was special when I first saw it in 2015. The eight arms, each 10 centimetres long and armed with rows of hooks and spines. And the teeth! A microscopic scan revealed bristling rows of sharp teeth lining every jaw, which I reckon are used to snare and shred its prey.

(J. Black/University of Melbourne, Author provided)

Bristling teeth poke out from all eight jaws, ready to pierce and shred prey. The colour in this micro-CT scan reflects the density of the skeleton.

As my colleagues and I now report in Proceedings of the Royal Society B, Ophiojura does indeed represent a totally unique and previously undescribed type of animal. It is one of a kind — the last known species of an ancient lineage, like the coelacanth or the tuatara.

We compared DNA from a range of different marine species, and concluded that Ophiojura is separated from its nearest living brittle star relatives by about 180 million years of evolution. This means their most recent common ancestor lived during the Triassic or early Jurassic period, when dinosaurs were just getting going.

Since then, Ophiojura's ancestors continued to evolve, leading ultimately to the situation today, in which it is the only known survivor from an evolutionary lineage stretching back 180 million years.

Amazingly, we have found small fossil bones that look similar to our new species in Jurassic (180 million-year-old) rocks from northern France, which is further evidence of their ancient origin.

Scientists used to call animals like Ophiojura “living fossils", but this isn't quite right. Living organisms don't stay frozen in time for millions of years without changing at all. The ancestors of Ophiojura would have continued evolving, in admittedly very subtle ways, over the past 180 million years.

Perhaps a more accurate way to describe these evolutionary loners is with the term “paleo-endemics" — representatives of a formerly widespread branch of life that is now restricted to just a few small areas and maybe just a single solitary species.

For seafloor life, the centre of palaeo-endemism is on continental margins and seamounts in tropical waters between 200 metres and 1,000 metres deep. This is where we find the “relicts" of ancient marine life — species that have persisted in a relatively primitive form for millions of years.

Seamounts, like the one on which Ophiojura was found, are usually submerged volcanoes that were born millions of years ago. Lava oozes or belches from vents in the seafloor, continually adding layers of basalt rock to the volcano's summit like layers of icing on a cake. The volcano can eventually rise above the sea surface, forming an island volcano such as those in Hawaii, sometimes with coral reefs circling its shoreline.

But eventually the volcano dies, the rock chills, and the heavy basalt causes the seamount to sink into the relatively soft oceanic crust. Given enough time, the seamount will subside hundreds or even thousands of metres below sea level and gradually become covered again in deep-sea fauna. Its sunlit past is remembered in rock as a layer of fossilised reef animals around the summit.


Biology

Anatomy and physiology

Humans are mammals, and are closely related to other large apes on the planet Earth. Like all placental mammals, they are warm-blooded and give birth to live offspring, and nourish their offspring with milk. They have five fingers, one being an opposable thumb. This hand structure aided them in making tools early in their history.

Unlike Sangheili, their circulatory system is closed and consists of one heart and a network of blood vessels. They have red blood due to their iron-based hemoglobin, as well as two lungs which breathe mainly a nitrogen-oxygen based atmosphere. Externally they have more hair than most Covenant species, but not nearly as much as Jiralhanae. They have an average sense of sight, but compared to Covenant species a poor sense of hearing and smell. They are omnivorous, meaning that they will eat both meats and plants, as well as consume high calcium foods, such as the milk of other animals.

Their bone structure is calcium-based and is designed to withstand moderate stresses, but is generally weaker than the skeletons of Jiralhanae and Sangheili. Their muscular system is, on average, also weaker than most large Covenant species. If in extreme distress, humans can tap into hidden reserves of energy, known as an adrenaline rush, thus giving them drastically increased strength. This response is known as the "Fight or Flight" reflex.

In theory at least, physical conditioning can still negate the disadvantages of human physiology somewhat, and with the right enhancements and equipment, humans can overcome their physical disadvantages to an even further extent as demonstrated by the Spartans. Biological augmentation is not restricted to the Spartans humans have routinely used bioengineering technologies for centuries, first to adapt to different conditions encountered in space and on other worlds, as well as a certain degree of enhancement given to military personnel. ⏊] However, such enhancements do not provide as immediately conspicuous increase in physical prowess as those of the Spartans.

Forerunner connections

Although the human and Forerunner genera exhibit a number of anatomical and physical similarities, they evolved independently on different worlds and are not genetically related. However, the Forerunners themselves were intrigued by the similarities between their own race and humanity. Because of their similarities, some Forerunner scholars theorized that humans were a kindred species, created by the Precursors in their own image, just as the Forerunners believed themselves to be. Β]

The Forerunners chose humans to become the inheritors of their technology along with Forerunners' sacred Mantle, which they formerly believed to have inherited from the Precursors. The Forerunners re-encoded certain aspects of their technology (e.g. the activation index) to only respond to human DNA to stop their advanced technology getting into the hands of other races. In a mixture of guilt and hope, they passed the torch to humanity, in hope that in the future they would defeat the Flood again, which with some help, John-117 did. The Librarian imprinted the human race with a geas, a pattern of information hidden deep in the genetic code and passed on throughout generations. Β] According to the Librarian, this imprint triggered the development of many technologies which proved critical to the survival of humanity after their contact with the Covenant, as well as containing several latent abilities. ⏋] This may also explain the "natural" understanding of Forerunner interfaces some humans have demonstrated despite having no prior contact with Forerunner technology. ⏌] Latent human memories and patterns extracted during the Conservation Measure were also implanted into the genetic code of future human generations. ⏍] ⏎]

Despite this, many Forerunner AI constructs seem to regard humans as Forerunner (although some fail to do so). ⏏] This confusion was also the root of the Covenant's campaign to exterminate humanity. In 2525, a Covenant missionary ship traveled the edge of Covenant-controlled space and discovered a planet that was covered with Forerunner "Reclamation" glyphs, who were actually the humans. Later, a report of the planet's glyphs was sent to the Vice Minister of Tranquility. He took the information to the Minister of Fortitude and he went to see the Oracle (the Forerunner AI, Mendicant Bias, in the Forerunner Dreadnought). Upon activation of the "Oracle", the AI proclaimed, "FOR EONS I HAVE WATCHED. LISTENED TO YOU MISINTERPRET. THIS IS NOT RECLAMATION. THIS IS RECLAIMER. AND THOSE IT REPRESENTS ARE MY MAKERS. I WILL REJECT MY BIAS AND WILL MAKE AMENDS. MY MAKERS ARE MY MASTERS. I WILL BRING THEM SAFELY TO THE ARK." Truth, believing that the humans were actually Forerunners (rather than their inheritors), became panicked and realized that this information could destroy the foundation of the Covenant and, with it, his power. Utilizing his power as High Prophet, Truth proceeded to launch a massive religious crusade against humanity, the Human-Covenant War. At the end of the war, when Truth was preparing to force Sergeant Major Avery Johnson to activate the Halo Array, he still believed humans to be the Forerunners' literal descendants, saying "Your forefathers wisely set aside their compassion. Steeled themselves for what needed to be done. I see now why they left you behind. You were weak. And gods must be strong." ⏐]


Space travel may affect commensal bacteria

Bacterial genes and proteins are expressed differently during space travel and on the ground. For example, several genes (of known and unknown functions) and various types of proteins in Salmonella Typhimurium were differentially regulated/expressed during spaceflight as compared to the ground cultures of the same bacteria (Wilson et al. 2007 ). Microarray pattern revealed the widespread alterations of gene expression distributed globally throughout the chromosome (Wilson et al. 2007 ). Studies have shown that spaceflight promotes the growth of micro-organisms compared to ground controls (Nickerson et al. 2004 ). For example, E. coli exhibited higher growth during flight where the lag phase was shortened followed by the extended log phase, as a result the microbial cell density increased by 88% compared to ground controls (Nickerson et al. 2004 ).

Omics technological advances have allowed the scientific community to carry out genome-wide studies to understand the effects of space travel on microbes. These studies revealed that microgravity altered several microbial characteristics, that is, alter their gene expression, virulence and behaviour. For example, microgravity resulted in the formation of biofilms by opportunistic S. aureus which in turn reduces the growth rate and degree of virulence of these bacteria (Castro et al. 2011 ). Similarly, P. aeruginosa PAO1, drastically altered the expression of certain gene as well as proteins in modelled microgravity, but changes in their virulence is obscure (Crabbé et al. 2011 ). The pathogenic fungus, Candida albicans when grown in space environments changes its budding configuration, cell aggregation and gene expression with no improvement of virulence (Crabbé et al. 2013 ). Furthermore, when Salmonella enterica serovar Typhimurium was grown under virtual microgravity, significant increase in cell number in infected mice, its virulence, and its endurance within a macrophage were observed (Nickerson et al. 2000 Voorhies and Lorenzi 2016 ).

Gut microbiota and diseases

Alterations in the gut microbiota are well known to cause several human diseases, including ASD (Mayer et al. 2014 ). Since the gut microbiota contributes in human metabolism, maintenance of immune system, it may also control the activities of the central nervous system through, endocrine, neural and immune pathways (Sampson and Mazmanian 2015 ), it is assumed that the gut microbiota play a key role in ASD pathophysiology. It is believed that the gut microbiota and the CNS have an indirect link known as “microbiome-gut-brain axis” (Strati et al. 2017 ).

Exposure to space atmosphere induces changes in lipids and glucose metabolism that further causes bone loss, cardiovascular disorders and muscular atrophy in astronaut. The gut microbiota also alters in rodents and humans during pre and post spaceflight for short- and long-term duration (Wang et al. 2019 ). Due to the presence of abundant number of microbes, human has been called a “supra-organism” while the GI flora has been considered as the virtual organ of the body (Saei and Barzegari 2012 ). Also, gut microbiota regulating the mucosal barrier integrity, host metabolism and the maturation of individual’s immune system (Sittipo et al. 2018 ). Fluctuations in gut flora is closely related with several metabolic syndromes such as dyslipidaemia, insulin resistance, obesity, glucose intolerance, and accumulation of fat in the liver (Wang et al. 2019 ).

Microbial imbalance has also been observed during spaceflight. During space flight, beneficial bacteria, that is, Lactobacillus and Bifidobacterium species reduces in astronauts’ body and in contrast, the pathogenic/opportunistic microbes (Clostridium, E. coli, Fusobacterium nucleatum and P. aeruginosa) accumulate and increases their population (Smirnov and Lizko 1987 Ritchie et al. 2015 Garrett-Bakelman et al. 2019 ). This shows that space conditions, that is, diet, microgravity, stress and radiation (Mardanov et al. 2013 ), may change the structure as well as composition of gut microbiota. Mice and rats on space flight have shown higher level of liver gluconeogenesis and liver glycogen content (Wang et al. 2019 ).


Culture drives human evolution more than genetics

In a new study, University of Maine researchers found that culture helps humans adapt to their environment and overcome challenges better and faster than genetics.

After conducting an extensive review of the literature and evidence of long-term human evolution, scientists Tim Waring and Zach Wood concluded that humans are experiencing a "special evolutionary transition" in which the importance of culture, such as learned knowledge, practices and skills, is surpassing the value of genes as the primary driver of human evolution.

Culture is an under-appreciated factor in human evolution, Waring says. Like genes, culture helps people adjust to their environment and meet the challenges of survival and reproduction. Culture, however, does so more effectively than genes because the transfer of knowledge is faster and more flexible than the inheritance of genes, according to Waring and Wood.

Culture is a stronger mechanism of adaptation for a couple of reasons, Waring says. It's faster: gene transfer occurs only once a generation, while cultural practices can be rapidly learned and frequently updated. Culture is also more flexible than genes: gene transfer is rigid and limited to the genetic information of two parents, while cultural transmission is based on flexible human learning and effectively unlimited with the ability to make use of information from peers and experts far beyond parents. As a result, cultural evolution is a stronger type of adaptation than old genetics.

Waring, an associate professor of social-ecological systems modeling, and Wood, a postdoctoral research associate with the School of Biology and Ecology, have just published their findings in a literature review in the Proceedings of the Royal Society B, the flagship biological research journal of The Royal Society in London.

"This research explains why humans are such a unique species. We evolve both genetically and culturally over time, but we are slowly becoming ever more cultural and ever less genetic," Waring says.

Culture has influenced how humans survive and evolve for millenia. According to Waring and Wood, the combination of both culture and genes has fueled several key adaptations in humans such as reduced aggression, cooperative inclinations, collaborative abilities and the capacity for social learning. Increasingly, the researchers suggest, human adaptations are steered by culture, and require genes to accommodate.

Waring and Wood say culture is also special in one important way: it is strongly group-oriented. Factors like conformity, social identity and shared norms and institutions -- factors that have no genetic equivalent -- make cultural evolution very group-oriented, according to researchers. Therefore, competition between culturally organized groups propels adaptations such as new cooperative norms and social systems that help groups survive better together.

According to researchers, "culturally organized groups appear to solve adaptive problems more readily than individuals, through the compounding value of social learning and cultural transmission in groups." Cultural adaptations may also occur faster in larger groups than in small ones.

With groups primarily driving culture and culture now fueling human evolution more than genetics, Waring and Wood found that evolution itself has become more group-oriented.

"In the very long term, we suggest that humans are evolving from individual genetic organisms to cultural groups which function as superorganisms, similar to ant colonies and beehives," Waring says. "The 'society as organism' metaphor is not so metaphorical after all. This insight can help society better understand how individuals can fit into a well-organized and mutually beneficial system. Take the coronavirus pandemic, for example. An effective national epidemic response program is truly a national immune system, and we can therefore learn directly from how immune systems work to improve our COVID response."


A single gene mutation may have helped humans become optimal long-distance runners

Credit: CC0 Public Domain

Two to three million years ago, the functional loss of a single gene triggered a series of significant changes in what would eventually become the modern human species, altering everything from fertility rates to increasing cancer risk from eating red meat.

In a new paper, published in the September 12 issue of the Proceedings of the Royal Society B, researchers at University of California San Diego School of Medicine report on studies of mice engineered to lack the same gene, called CMAH, and resulting data that suggest the lost gene may also have contributed to humanity's well-documented claim to be among the best long-distance runners in the animal kingdom.

At roughly the same time as the CMAH mutation took hold, human ancestors were transitioning from forest dwellers to life primarily upon the arid savannahs of Africa. While they were already walking upright, the bodies and abilities of these early hominids were evolving dramatically, in particular major changes in skeletal biomechanics and physiology that resulted in long, springy legs, big feet, powerful gluteal muscles and an expansive system of sweat glands able to dissipate heat much more effectively than other larger mammals.

Such changes, say scientists, helped fuel the emergence of the human ability to run long distances relatively tirelessly, allowing ancestors to hunt in the heat of the day when other carnivores were resting and to pursue prey to their point of exhaustion, a technique called persistence hunting.

"We discovered this first clear genetic difference between humans and our closest living evolutionary relatives, the chimpanzees, more than 20 years ago," said senior author Ajit Varki, MD, Distinguished Professor of Medicine and Cellular and Molecular Medicine at UC San Diego School of Medicine and co-director of the UC San Diego/Salk Center for Academic Research and Training in Anthropogeny.

Given the approximate timing of the mutation and its documented impact on fertility in a mouse model with the same mutation, Varki and Pascal Gagneux, Ph.D., professor of anthropology and pathology, began investigating how the genetic difference might have contributed to the origin of Homo, the genus that includes modern Homo sapiens and extinct species like Homo habilis and Homo erectus.

"Since the mice were also more prone to muscle dystrophy, I had a hunch that there was a connection to the increased long distance running and endurance of Homo," said Varki, "but I had no expertise on the issue and could not convince anyone in my lab to organize this long-shot experiment."

Ultimately, a graduate student named Jon Okerblom took up the task, building mouse running wheels and borrowing a mouse treadmill. "We evaluated the exercise capacity (of mice lacking the CMAH gene), and noted an increased performance during treadmill testing and after 15 days of voluntary wheel running," said Okerblom, the study's first author. The researchers then consulted Ellen Breen, Ph.D., a research scientist in the division of physiology, part of the Department of Medicine in the UC San Diego School of Medicine, who added observations that the mice displayed greater resistance to fatigue, increased mitochondrial respiration and hind-limb muscle, with more capillaries to increase blood and oxygen supply.

Taken together, Varki said the data suggest CMAH loss contributed to improved skeletal muscle capacity for oxygen utilization. "And if the findings translate to humans, they may have provided early hominids with a selective advantage in their move from trees to becoming permanent hunter-gatherers on the open range."

When the CMAH gene mutated in the genus Homo two to three million years ago, perhaps in response to evolutionary pressures caused by an ancient pathogen, it altered how subsequent hominids and modern humans used sialic acids—a family of sugar molecules that coat the surfaces of all animal cells, where they serve as vital contact points for interaction with other cells and with the surrounding environment.

The human mutation causes loss of a sialic acid called N-glycolylneuraminic acid (Neu5Gc), and accumulation of its precursor, called N-acetylneuraminic acid or Neu5Ac, which differs by only a single oxygen atom.

This seemingly minor difference affects almost every cell type in the human body—and has proved to be a mixed blessing. Varki and others have linked the loss of the CMAH gene and sialic acids to not just improved long-distance running ability, but also enhanced innate immunity in early hominids. Sialic acids may also be a biomarker for cancer risk.

Conversely, they have also reported that certain sialic acids are associated with increased risk of type 2 diabetes may contribute to elevated cancer risk associated with red meat consumption and trigger inflammation.

"They are a double-edged sword," said Varki. "The consequence of a single lost gene and a small molecular change that appears to have profoundly altered human biology and abilities going back to our origins."


Watch the video: Die Reise der Menschheit 13 . Ganze Folge Terra X (May 2022).


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