It's advantageous to be able to identify less fit mates, but it's advantageous to look like a fit mate whether you are or not. It's difficult to have honest signals which aren't difficult to fake; you can't stot unless you're fit, you can't make an alarm call only when there are predators around unless you can detect the predator. If grey hair is energetically no more or less favourable than coloured hair then it would be difficult for it to spread as an honest signal of unfitness because it could just as easily be faked.

It seems more likely that grey hair is a signal for something else - age and hence some kind of experience/authority, or a side-effect of something else. Testosterone has a lot of effects, it probably has some that weren't specifically selected for.

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They have different amount of chromosomes? But they seem to be such closely related animals.

Are there other closely related animals that have different number of chromosomes? Like between duck and geese or tiger and lynx, for example?

Does this thing also happened with plants and fungi?

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The evolution of language trumped all other adaptations. Houses and clothing and controlled fire followed soon thereafter. From then on, human evolution cannot be understood without considering culture.

Alpha male?

If you are lying in wait where you know an animal is being driven, why would you decide to chase it to exhaustion in a days-long relay race around its herd, when you could jump out and kill it? So instead of one person wasting days running after a deer, it's...a dozen people wasting days running after one deer?

A days long, pointless, relay race in a big circle around its herd??

And what, the herd does nothing but sit around, and the animal never gets back to them the whole time?

Alpha male???

There isn't really a significance. There are 20 "ancestral" amino-acids, while the genetic code uses triplets from 4 distinct nucleo-bases (ACGT) which yields 64 codons. Redundancy is unavoidable.

Now, why did the genetic code evolve based on triplets... that's kind of a million dollar question

However, there are significant or interesting properties and consequences of redundancy. Maybe this was the question you had in mind?

The X-15 and SpaceShipOne reached space, if we count them then the answer is (pretty trivially) yes.

For non-rocket flight we are looking at the 25-40 km region. In principle the sound waves still have a non-zero amplitude at 100 km, increasing the chance to go above for some molecules beyond briefly, but that's a mathematical result without practical relevance.

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Yes, but it's usually done with a moving average.

So if you have the pixel values 1,3,2,4,3,1,5,2 you could always average in groups of three

1,3,2 => 2
3,2,4 => 3
2,4,3 => 3
4,3,1 => 2.66
3,1,5 => 3
1,5,2 => 2.66

so the blurred image is

2,3,3,2.66,3,2.66

An actual blur filter is usually a bit more complex, a gaussian blur for example weights the original pixels in different amounts (according to a gaussian curve). So instead of just taking the average of 1,3,2 you'd calculate

0.25 * 1 + 0.5 * 3 + 0.25 * 2 = 2.25

And you can choose how broad you want to make the window of values that you consider in the operation etc.

Crucially, if we write the simple blurring operation from the top as a set of equations with the original pixel values unknown and named as x_i:

(x_1 + x_2 + x_3) / 3 = 2
(x_2 + x_3 + x_4) / 3 = 3
(x_3 + x_4 + x_5) / 3 = 3
(x_4 + x_5 + x_6) / 3 = 2.66
(x_5 + x_6 + x_7) / 3 = 3
(x_6 + x_7 + x_8) / 3 = 2.66

you can see that we have 8 unknown values but only 6 equations. If you remember the maths of systems of equations from school we need 8 equations to fully determine 8 unknowns. So this problem is under-determined even in a case of such a simple blurring operation where we know exactly which kind of operation was done to the original image. In a more realistic scenario, where we don't know the exact type of blurring operation done to an image, it gets even less feasible to reverse the operation without somehow using prior knowledge of how unblurred content usually looks like (which is what neural networks are doing when they are used to scale up and unblur small images).

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Yes if you think about it communal bats living in a cave are like humans living crammed in a city, the absolute worst case scenario for disease transmission in a population. Maybe even worse because they don’t have houses they retreat to and are constantly exposed to everyone crawling around.

Aye, might not be a wheel, exactly, but there's at least one insect with interlocking gears in their legs that help them jump. a planthopper! https://www.livescience.com/39577-insects-with-leg-gears-discovered.html

Well, at least on the microscopic scale rotating joints are a thing, some bacteria and archaea have rotating flagella. See https://en.wikipedia.org/wiki/Flagellum

There are some traits that have no impact on survival or reproduction, but are expressed because the genes for that trait are found very close to the genes for another trait that does impact survival or reproduction. This can result in the first trait being passed to the next generation along with the second trait.

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Something not mentioned yet -

Bats have a larger variation in body temperature (10 c to 40 c) and so pathogens which evolve to survive in bats are able to cope better with the much smaller temperature variations in humans. If you have a fever of 39c that's not going to bother a pathogen that's at home in a 40c bat.

https://royalsocietypublishing.org/doi/10.1098/rsif.2021.0211

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Right? I never had to write up any of my female employees for filling their sinuses with grease on a $5 bet, or trying to pin casters to coworkers in order to engage in bizarre "tech races" in which they intended to sit on the be-castered coworker and steer them via a length of nasty rope from the pit in the fashion of an equestrian bit.

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