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30

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) ...


12

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 ...


10

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 ...


9

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 ...


7

Months to years - although the actual duration in a specific environment depends on the nature of that environment and is tied to oxygen level. Higher oxygen, faster degradation. Less oxygen, the estrogen molecules interconvert among various closely related molecules which hampers both their detection and their degradation. For more info, please see: ...


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, ...


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

The roots do actually continue to hold soil without being alie. The stabilizing properties are structural in nature. You begin to lose those though as the roots decompose, and the important roots against erosion, millions of fine root hairs, will go first. But leaving the roots in on a dead tree will help for a bit, but isn't a long term solution.


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 ...


3

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 ...


3

Most animals are not well adapted to deal with avalanches. For example, more mountain goats are killed by rock slides than by predators. http://www.nationalgeographic.com/lewisandclark/record_species_150_11_2.html Meanwhile, a mountain at risk of snow avalanche must be deep in snow, right? At that point, there is very little food to be found; it's all ...


3

Many organisms including plants, bacteria, insects, fishes and even mammals have been GMed. Most of them have experimental purposes, but GM crops have been released for commercial purposes. Maybe the most amazing between them is triticale, which is a hybrid of wheat (Triticum) and rye (Secale). Triticale, BT Potato, BT Tomato, BT Maize (I am not sure), BT ...


3

Remi.b's answer is spot on - predicting the effects of losing a given species is nigh on impossible. However, I do think that there are some general trends that can give us some intuition, and make the campaign to protect certain species more than just an ethical issue. Biodiversity (i.e. having a wide range of different organisms (and genetically diverse ...


2

Calories and dollars are the most obvious and straightforward, but including additional variables complicates the accounting. . A great paper that used energy has been updated in a more recent publication. Emergy is an interesting alternative. Current work includes the Natural Captial project that "aims to integrate the values of nature into all major ...


2

From some of the MSDS (1, 2) I come across, a major component of thermal grease is aluminum oxide. Risk Management for Hazardous Chemicals by Jeffrey Wayne Vincoli states in page 101 that aluminum oxide has both acute and chronic toxic effects to aquatic life; it also states that aluminum oxide has a half-life longer than 200 days in water; finally, it ...


2

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 ...


2

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.


2

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.


1

If I understand you 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 my mind, ...


1

I've usually observed wild Indian Bees (Apis cerana) orient their hives in an East-West direction. The entrances are usually oriented towards the Sun. This is purely from my own observation (in South India) and not from any research.



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