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Why do we age is a classical question in Evolutionary Biology. There are several things to consider when we think of how genes that cause disease, aging, and death to evolve. One explanation for the evolution of aging is the mutation accumulation (MA) hypothesis. This hypothesis by P. Medawar states that mutations causing late life deleterious (damaging) ...


42

It sounds like you are talking about aeroplankton, a general term for a wide range of tiny life-forms borne on the wind. While some of these are essentially passive while airborne (e.g., pollen, spores), others like arthropods and microbes are quite capable of being active in the air as well. In essence, anything that can be easily swept up by the wind can ...


39

71% of the earth's surface is taken up by water. Not surprisingly therefore, the seas are an important source of oxygen. National Geographic claims that photosynthesis by phytoplankton (mostly single-celled phototrophs, such as cyanobacteria, green algae and diatoms) account for half of the earth's oxygen production. The other half, they claim, is produced ...


25

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 ...


22

This is a very good question. There is a big ongoing field of research called "evolution of aging/senescence" that tackles this question. I won't give you a complete overview of the different hypothesis the could explain why we age but here is a fundamental concept that is to know. We'll assume that there is some extrinsic mortality, mortality against ...


21

Because "any" Coronavirus is so dangerous, much research have been done on viruses with similar properties. They are called "surrogates". Because nCoV is new, we don't have any studies, so we need to estimate it's behavior from previously studied similar viruses. Here: RH = Relative Humidity. Tr = Room Temperature TGEV = Transmissible Gastroenteritis (...


19

Short answer Between 62,000 and 63,500 feet (18,900 and 19,350 meters) blood begins to boil at body temperature. This altitude, referred to as the Armstrong limit, is generally considered to be the absolute limit compatible with life. At this point, humans cannot survive without pressurization measures. Background Atmospheric pressure drops at higher ...


17

The quick answer is: Yes, it can cause harm. Think about it...The septic system (both the tank and your "drain field") rely on bacteria, and antibacterial soap is not designed to kill only specific species of bacteria. In other words, antibacterial soap can kill a whole range of bacteria, and that certainly includes the bacteria needed in your ...


14

Because evolution isn't about individuals: it's about species. What matters to natural selection isn't how long you live, but how many grandchildren you have. A long lifespan can be an evolutionary advantage, but like any trait, it's only an advantage to the extent that allows you to reproduce more. It would seem that a longer lifespan would be advantageous ...


13

Actually, genetically, there is no reason for animals to continue to exist after they have procreated. If you look at salmon, they die immediately after procreating, which is probably the most efficient way to carry the best genes to the next generation. In the case of mammals, they need to teach their offspring where to find food, where to find water and ...


12

According to a number of citations listed on Kenyon College's MicrobeWiki, rain can contain microorganisms via a process called "bioprecipitation." Essentially, microorganisms, dust and other small particles get swept up into the atmosphere, and cold temperatures cause atmospheric water vapor to freeze around the organism/particle. Once the ice-covered ...


10

Photosynthesis. early photosynthesizers, which would have been adapted for a reducing atmosphere, drove themselves extinct as they dumped oxygen into the atmosphere as a waste product. They were incredibly successful because they could live off of little more than the three of the most common materials on the planet. Eventually the oxygen built up to the ...


9

I am not sure which class of organisms have the highest contribution in oxygen production but diatoms do have a significant contribution. The introduction in this paper says that diatoms account for 40% of marine photosynthesis which according to this site is "1/4 of the oxygen we breathe."


9

Polar bears (Ursus maritimus) have white fur all year long. There are probably several other examples. @L.Diago gave sheep as example. There are also all white troglodyte species.


8

There were some experiments done in microgravity in longer space shuttle missions. The reports show that the fungi develop relatively normal but grow in random orientations instead of orientating upwards. See this images: The upper image shows fungi grown on earth which are subjected to normal gravity. The lower image shows fungi (actually only the fruiting ...


8

Following from MarchHo's comment, I have not been able to find class-specific (in the formal sense) estimates, but if you meant 'class' in an informal sense, the following may be useful. A nice infographic covering the relative biomass of all land mammals is here, and a full table for species groups (at the level of domesticated vertebrates, invertebrates, ...


7

Trees are definitely not the only source of oxygen. First, all green plants do photosynthesis, not only trees. Moreover, about half of all photosynthesis on earth is done by microorganisms in the oceans known as phytoplankton.


7

If you take the line of "The Selfish Gene - Richard Dawkins". Evolution doesn't care about individuals, it cares about genes. So as long as the genes are passed along reliably into the future, evolution may do it with 4 generations per 100 years or 100 generations per 100 years.


6

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 ...


5

There is no selection mechanism that would favor high age. By the time it's apparent whether or not an individual can reach a high age healthily, they'll have ceased all reproductive activity. Conversely, people who get cancer at 45 will have likely reproduced already.


5

To an extent it does; in that we live longer than our mouse-like ancestors. So the question becomes: why not keep extending it to immortality. The key thing is that evolution cares only about the survival of your genes; so if you live for 1000 years or if 10 generations of your family have 1 individual's worth of your genes in each generation (each living ...


5

The cost would increase; either because pollination services are not provided and the supply is decreased; or because the cost to producers goes up as they must pay for artificial pollination. See the extremely detailed analysis in Winfree et al. edit I imagine what you're actually asking for is a $ figure "per apple". This depends on the location, crop, ...


5

Hyperparasitism is one possible term. According to the linked article it is commonplace in certain types of insects, but also in fungi. Apparently the cases of at least three levels are known: a fungus on a fungus on a fungus on a tree.


4

Ignoring for the moment the question of politics, let's consider the various definitions of the term "invasive species" that are in use. Colautti and MacIsaac write in their discussion of invasive species terminology (1): The greatest confusion [among the discussed ecological terms] surrounds the common term ‘invasive’ and its various derivatives (...


4

The problem is not really that we don't understand some stuff (lthough this is certainly true) but that an ecosystem, or the biosphere is a highly complex network of interactions. This network is continuously displaying some chaotic (determinist but not foreseeable) behavior. In such a system it becomes very hard or practically impossible to predict what the ...


4

There can be perhaps 10 trillion rodents and bats on the planet, so the humans and livestock probably are small compared to a rainforest rodents and bats. The biggest bat colony is 40 million, they decline without unmanaged forests, can reach 4-10 bats per hectare, and the world population might normally be in 10s of billions, save for the use of pesticides ...


4

Here’s how it works. Every morning when the sun breaks over the horizon — no matter what time of year it is — a clock starts ticking inside the trees. After a specific number of hours, the plants’ cells start producing high levels of a molecule known as the FT protein. This protein is responsible for initiating processes that help the plant grow. But the FT ...


4

The classical division of humans and animals has always been self-centered and artificial. Humans are animals, competing with other organisms under exactly the same rules. Evolution involves trade-offs, strategies, and adaptation. Humans have been set on a path to use their brains to compete, rather than claws. But the concepts are the same. It happens that ...


4

This is better suited for the Chemistry site, but there are two reasons. 1) The gas allows visible light to pass, but blocks infrared. (Which has to do with the nature of the bonds between atoms &c.) 2) It exists in the atmosphere in sufficient quantity to have an effect, which ammonia doesn't: https://www.livescience.com/57305-ammonia-detected-in-...


3

If I understand your question correctly, I've seen this idea in many papers, sometimes stated clearly and sometimes in more implicit terms. After a quick look I found a paper which should be relevant as a starting point for you: Mayor et al. 2007. Spectrum of selection: new approaches to detecting the scale-dependent response to habitat. Ecology 88(7). In ...


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