Most plants have mycorrhizae as well as bacteria. The whole area around the roots including the roots is the rhizosphere. There is ectomycorhiza and endomycorhiza. It changes depending on species and abiotic and biotic conditions.

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Given the propensity of people to stay near where they were born and also the propensity of people to marry within social circles, the "expectation" of the number of generations back for every ancestor being unique is probably quite small.

2**15 = 32,768, 15*20 years/generation = 300 years. So 300 years ago, if your community of eligible ancestors was 32,768 or more, each one could be unique. I guess that's not unreasonable depending where they lived, but it doesn't seem likely.

2**20 = 1,048,576, 20*20 years/generation = 400 years. It seems unlikely to me that your community of eligible ancestors 400 years ago would be over 1 million.

Anyway, that's my uneducated guess.

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Have you encountered folks researching vegan regenerative agriculture? I know of people who are able to farm without using animals, but I've never heard of it in drylands. To be honest, I don't know where animal inputs are used in deserts in the first place, since I expect that grazing would increase desertification.

When growing plants in the desert for agricultural purposes, it seems the water you would need to grow them well would be a major concern. Are these plants being bioengineered to require less water, primarily? What about the nutrition the plant needs? How are those needs being addressed and what challenges are particular to the desert environment vs. an environment with loamy soil?

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Would you say research positions like yours are commonly accessible for PhD graduates of plant sciences and other similar biology related degrees or would you consider yourself rather lucky to have gotten the spot? I‘m also studying for a B.Sc. in Biology however I‘m a bit unsure about the job opportunities afterwards.

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I am assuming you mean for an individual not for humanity as a whole.

That's actually a really tough question and is going to be different for each person depending on their ancestry and how often they moved and/or married (Being polite) people from vastly different populations.
based on migration patterns and this I would say you are probably looking at an increase, statistically, every time there was a big colonization push and/or a new travel method became popular enough jack and Jill Average could use it to go somewhere and live for a while.

So based on this I would say 17th Century going forward with a hard stop in 1914.

A recent simulation suggests one possible way is that the impact debris initially coalesced into two bodies. One of those did indeed fall back into Earth, but the other one, due to momentum exchange with the first one, got enough momentum to get a stable orbit. And from there, tidal interactions slowly transferred momentum from the Earth's rotation to the Moon's orbit, widening its orbit and slowing down the rotation.

There's too many variables to answer universally. It would vary wildly depending on the individual you started with.

Edit: See /u/Tidorith's comment below, the rest of what I'm saying here isn't necessarily relevant.

For what it's worth, the point where unique ancestors would outnumber the population is precisely 30 generations. Whereas if we limited it to just the UK, it would be a number in the low twenties. So the possible variance here isn't dozens of generations, but more like fives.

So probably around 15-20 generations back? But again, it's impossible to give a universal answer.

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Do desert plants have the ability to use stored carbon when prolonged drought conditions prevent them from photosynthesizing? And if so, do desert areas change from being sinks of CO2 into being sources of CO2?

I think the problem lies with your model/question. You’re taking it for granted that the math is 2^n , because that works for a couple generations at a time that a human can hold in their brain at once. I think that’s leading you astray. The concept of “generations” is also tenuous and mostly only works for a limited number of generations of specific individual ancestors of one specific single organism you’re looking at. As boomer/millennial discourse has proven, generations are not actually, like, a thing, they’re just these constructs we use to explain things. What makes sense to describe a 30yr period in your own life as you relate to your parents and children does not work very well for describing a 300yr period where the timing of births is all over the place.

When you compare two separate peoples’ family trees, they don’t align neatly, you just get a forest. It’s not like the human population just iterates forwards as a group every so many ticks like in Conway’s Game of Life.

You can perform this simple check on your model: If the population has grown, that means at any instant, the “moment of birth rate”, if you will, will on average be positive. There are more babies being born than people dying. How then can the number get larger as you go back? There were always fewer people each year back. We know that because there are always more people each year forward.

Right, so you can have the same individual appearing in multiple generations, not just different parts of a single generation.

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Explain The Tree of Ténéré to me.

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Are there any known attempts to genetically engineer plants or fungi to grow in deserts to help reverse desertification?