evolution - Is there theory that connects longevity, time-scale of environmental disturbance, and adaptation?

Not exactly matching your question, but I think that the idea (from stochastic demography) that life histories should be buffered against environmental variability in influential vital rates (Pfister, 1998, Morris & Doak, 2004) can be related to this issue, even if it is mainly (originally) dealing with stationary environmental fluctuations.

In general, fluctuations in vital rates cause the stochastic population growth rate to decrease. This can be described by Tuljapurkar's approximation (Tuljapurkar, 1982):

$$log \lambda_s = log \lambda_d - \frac {1}{2\lambda_d^2} \sum_{i,j} V(a_{ij})S^2_{ij}-\phi$$

where $\lambda_s$ is the stochastic growth rate, $\lambda_d$ is the deterministic growth rate based on average conditions, $V(a_{ij})$ is variance in vital rates (here matrix entires) and $S^2_{ij}$ is sensitivity in vital rates. $\phi$ represents covariances between rates, which can be important, but can sometimes be ignored for simplicity. This equation shows that the effect of variability in vital rates on stochastic growth rate (which can be interpreted as a measure of fitness) is a product of sensitivity to change and the amount of variability.

Because of the negative consequences on stochastic population growth, selection is expected to minimize variance in population growth rate. Pfister (1998) predicted (based on an evolutionary argument and the equation above) that a species should have smaller temporal variances in the life history traits it is most sensitive to. Therefore, across species, there should be a negative correlation between the sensitivity and the temporal variance of vital rates. This also means that the evolution of life histories and the tolerance of species to variability in environmental conditions are shaped by their life-history patterns.

A consequence of this is that in a long-lived species (as an example), you should find larger variabilty in juvenile survival than in adult survival, since population growth rate is more sensitive to variability in the latter. The lower variability in adult survival can then be seen as an expression of "hardiness" to variability in environmental conditions, and this theory can therefore be used to understand likely evolutionary trajectories of different species, also under a climate change scenario. The ways to minimize the negative effects of variability in population growth in this theory is to either be hardy in important traits (change in environmental conditions doesn't translate much into variability in vital rate) or to decrease the sensitivity in vital rates that vary a lot (which amounts to modifying the life-history pattern of the species). Your question mainly deals with longevity, and this is influenced by both maturation age and adult survival. Therefore, this theory can be useful to think about which species should develop a "hardy" strategy.

However, this answer completely ignores tipping-points in environmental tolerances, nonlinear responses and the genetic variation that selection can act on.

Related articles you might want to check out are Van de Pool et al (2010), Morris et al. (2008) and Doak et al 2005.

neuroscience - Do people with colorblindness have less cones or no cones of a certain type?

This is a complicated case, as it can have multiple causes.
The genes which are coding for the long (L, yellow) and medium (M, green) wavelength photopigments are located head-to-tail on the X chromosome. This is the reason why this colors are affected much more and especially in men (which only have one copy of this chromosome).

What seems to happen mostly is that the photopigment of one type of cone cells (and their neuronal connectivity) is missing, while the density of the cone cells is still the same. This means that the cells are they, but are not functioning. See these publications (when you have problems getting the articles, let me know in the comments, I can help):

What can additionally happen in some cases is that these cones have a different pigment than they should have. See the third paper above for details.

botany - What's the name of the fibrous strands that hold the seeds in a pumpkin?

If you cut open a pumpkin, the seeds are suspended inside the pumpkin by some fibrous, slimey strands. You can see them in the middle of this sliced-open pumpkin:

I'm writing a post for the Cooking.SE blog, and am trying to find out the proper botanical term. Someone suggested that might be called the endocarp, but I want to make sure and also see if there is a more specific term.

Edit

In "Morpho-Physiological Aspects of Productivity and Quality in Squash and Pumpkins (Cucurbita spp.)" §C.1, I see this:

In the central portion of the fruit, a mass of tough fibers, together with vascular strands connected to the seeds, comprise the placental tissue. The endocarp is made up of small, thin-walled cells that form a membranous tissue that adheres to seed, becoming a transparent skin on dried seeds. (emphasis added)

Am I reading correctly that the name for this part of the pumpkin is "placental tissue", and that the endocarp is just a thin layer on the seeds themselves?

human biology - How does the brain's energy consumption depend on mental activity?

I answered on the facts of this question already on skeptics.SE, here and here. You should read both papers very carefully, I highlighted the most important facts but this is a very tricky question, esp. when it comes to defining what mental activitiy is. The papers also give an explanation of how fMRI signal is linked to NEURONAL activity, as far as I remember there is no strong direct link.

You assume in your question that a mathematician solving a differential equation needs higher mental activity than a child reading a book. Is this legitimate? It seems intuitive but also very subjective. In the paper they mention that for the highest and lowest energy consumption we lose consciousness. I will not draw conclusions from this. However, you are talking about conscious mental activities so this may answer your question. To me it means more that the understanding of the human brain in neurobiololgy is on the level of the Rutherford Atomic Model in Physics at the beginning of the 20th century. We have not really got a clue how information is processed and how it's constrained by physical laws and principles of entropy and energy. By reading the 2 papers it looks more like the human brain is not raising energy consumption as a computer would (the computer analogy pretty much fails when compared to the human brain). Most of the energy is used for unconscious processes in "standby mode".

As in physics, extreme cases such as savants and the mentally disabled are probably the best starting point to exclude possible models of human brain and physical boundary conditions as we cannot approach the questions of human brain in a reductionistic way. How can savants like Kim Peek process such huge amounts of information AND save it. He is able to scan books pages just once and know them by heart thereafter. His brain does not, however, consume more energy than an average human brain. So mental activity is probably not a very good term, quantity, or even really suited to be scientifically used. Does neuronal activity mean mental activity (in the sense of your definition?) Reading the papers, the problem is the separation of mental and neuronal activities. At first you have to know what are the basic brain functions and processes that are consuming most of the energy. However the brain is not built in modular way like a computer (most energy is used here for constantly refreshing RAM). So there is not really a objective way to analyse and separate this modular energy consumption, if it even is modular.

In my opinion, most models about information processing in human brain are intuitive guessing (again Rutherford). We need much more detailed experiments and data (Blue Brain Project). fMRi is like analysing a atom with a magnifying glass. Also, the more prosperous approach from a biophysical perspective is probably not the level of "mental activity" but the hard-based amount of information processed by human brains and linked energy consumption (Kim Peek). But therefore we need a model of how this information is saved in human brain. Do normal humans save the same information as Kim Peek scanning a page or are we just unable to recall it consciouscly? When solving a differential equation, how much energy do you consume when recalling facts and is that experience not similar to reading a book? How much is mental logical tasks and is there really a difference at all?

I will stop here, hope you gained some insight that the question is of course important but too early to be definitively answered. I think we will learn a lot more from projects like Blue Brain as we have from fMRI experiments.

biochemistry - Which hydroxyl from either the phosphate or the glycerol is taken during synthesis of a phospholipid head?

My recollection is that the formation of a phospholipid normally involves acylation of glycerol 3-phosphate. Glycerol 3-phosphate is a glycolytic intermediate, and so there is no actual phosphorylation of a glycerol; the phosphate on the glycerol will have come from the phosphorylation of glucose or of fructose 6-phosphate.

In a kinase reaction the oxygen of the -OH in the acceptor acts as a nucleophile at the P of the phosphate, so in terms of your question the O atom comes from the acceptor, not the donor. Presumably if there was a glycerol kinase (I expect there is) it would have the same mechanism so the O would come from the glycerol.

human biology - Does difference in expected life duration between men and women have biological nature?

It is known that men in most countries live less than women. I wonder whether it is due to different life conditions or because male and female organisms differ?

For example, I heard that testosterone may cause cardiovascular deceases. Is it true? Are there other biological mechanisms that can shorten men's lifespan?

biochemistry - Why can't the brain and red blood cells use fuels other than glucose?

The question is rather straight forward: I have always been curious as to why, but cannot find an explanation online.

I can imagine that the mechanism is different for each, but why does brain tissue and red blood cells use specifically and only glucose for energy metabolism?